samd51: add support for async SPI using DMA

rp2040: add SPI DMA support
machine: add dummy async SPI methods
2026-07-27 23:28:42 +00:00 · 2023-11-05 19:35:00 +01:00 · 2023-11-04 16:18:45 +01:00 · 2023-11-04 16:14:47 +01:00
199 changed files with 4320 additions and 5903 deletions
@@ -10,12 +10,12 @@ commands:
    steps:
      - restore_cache:
          keys:
-            - llvm-source-17-v1
+            - llvm-source-16-v3
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-17-v1
+          key: llvm-source-16-v3
          paths:
            - llvm-project/clang/lib/Headers
            - llvm-project/clang/include
@@ -75,10 +75,10 @@ commands:
      - run: go install -tags=llvm<<parameters.llvm>> .
      - restore_cache:
          keys:
-            - wasi-libc-sysroot-systemclang-v7
+            - wasi-libc-sysroot-systemclang-v6
      - run: make wasi-libc
      - save_cache:
-          key: wasi-libc-sysroot-systemclang-v7
+          key: wasi-libc-sysroot-systemclang-v6
          paths:
            - lib/wasi-libc/sysroot
      - when:
@@ -105,9 +105,9 @@ jobs:
      - test-linux:
          llvm: "15"
    resource_class: large
-  test-llvm17-go122:
+  test-llvm17-go121:
    docker:
-      - image: golang:1.22-bullseye
+      - image: golang:1.21-bullseye
    steps:
      - test-linux:
          llvm: "17"
@@ -119,5 +119,5 @@ workflows:
      # This tests our lowest supported versions of Go and LLVM, to make sure at
      # least the smoke tests still pass.
      - test-llvm15-go118
-      # This tests LLVM 17 support when linking against system libraries.
-      - test-llvm17-go122
+      # This tests the upcoming LLVM 17 support.
+      - test-llvm17-go121
@@ -14,36 +14,26 @@ concurrency:
 jobs:
  build-macos:
    name: build-macos
-    strategy:
-      matrix:
-        # macos-12: amd64 (oldest supported version as of 05-02-2024)
-        # macos-14: arm64 (oldest arm64 version)
-        os: [macos-12, macos-14]
-        include:
-          - os: macos-12
-            goarch: amd64
-          - os: macos-14
-            goarch: arm64
-    runs-on: ${{ matrix.os }}
+    runs-on: macos-11
    steps:
      - name: Install Dependencies
        shell: bash
        run: |
          HOMEBREW_NO_AUTO_UPDATE=1 brew install qemu binaryen
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: true
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Restore LLVM source cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-${{ matrix.os }}-v1
+          key: llvm-source-16-macos-v1
          path: |
            llvm-project/clang/lib/Headers
            llvm-project/clang/include
@@ -54,7 +44,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save LLVM source cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -65,10 +55,10 @@ jobs:
            llvm-project/lld/include
            llvm-project/llvm/include
      - name: Restore LLVM build cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-build
        with:
-          key: llvm-build-17-${{ matrix.os }}-v1
+          key: llvm-build-16-macos-v1
          path: llvm-build
      - name: Build LLVM
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -83,16 +73,16 @@ jobs:
          make llvm-build
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Save LLVM build cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-build.outputs.cache-primary-key }}
          path: llvm-build
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
-          key: wasi-libc-sysroot-${{ matrix.os }}-v1
+          key: wasi-libc-sysroot-v4
          path: lib/wasi-libc/sysroot
      - name: Build wasi-libc
        if: steps.cache-wasi-libc.outputs.cache-hit != 'true'
@@ -108,7 +98,7 @@ jobs:
        run: make tinygo-test
      - name: Make release artifact
        shell: bash
-        run: cp -p build/release.tar.gz build/tinygo.darwin-${{ matrix.goarch }}.tar.gz
+        run: cp -p build/release.tar.gz build/tinygo.darwin-amd64.tar.gz 
      - name: Publish release artifact
        # Note: this release artifact is double-zipped, see:
        # https://github.com/actions/upload-artifact/issues/39
@@ -116,10 +106,10 @@ jobs:
        # - have a double-zipped artifact when downloaded from the UI
        # - have a very slow artifact upload
        # We're doing the former here, to keep artifact uploads fast.
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v2
        with:
-          name: darwin-${{ matrix.goarch }}-double-zipped
-          path: build/tinygo.darwin-${{ matrix.goarch }}.tar.gz
+          name: darwin-amd64-double-zipped
+          path: build/tinygo.darwin-amd64.tar.gz
      - name: Smoke tests
        shell: bash
        run: make smoketest TINYGO=$(PWD)/build/tinygo
@@ -130,30 +120,31 @@ jobs:
      matrix:
        version: [16, 17]
    steps:
-      - name: Set up Homebrew
-        uses: Homebrew/actions/setup-homebrew@master
+      - name: Update Homebrew
+        run: brew update
      - name: Fix Python symlinks
        run: |
          # Github runners have broken symlinks, so relink
          # see: https://github.com/actions/setup-python/issues/577
-          brew list -1 | grep python | while read formula; do brew unlink $formula; brew link --overwrite $formula; done
+          brew unlink python
+          brew link --overwrite python
      - name: Install LLVM
        run: |
-          brew install llvm@${{ matrix.version }}
+          HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@${{ matrix.version }}
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Build TinyGo (LLVM ${{ matrix.version }})
        run: go install -tags=llvm${{ matrix.version }}
      - name: Check binary
        run: tinygo version
      - name: Build TinyGo (default LLVM)
-        if: matrix.version == 17
+        if: matrix.version == 16
        run: go install
      - name: Check binary
-        if: matrix.version == 17
+        if: matrix.version == 16
        run: tinygo version
@@ -19,26 +19,15 @@ jobs:
      packages: write
      contents: read
    steps:
-      - name: Free Disk space
-        shell: bash
-        run: |
-          df -h
-          sudo rm -rf /opt/hostedtoolcache
-          sudo rm -rf /usr/local/lib/android
-          sudo rm -rf /usr/share/dotnet
-          sudo rm -rf /opt/ghc
-          sudo rm -rf /usr/local/graalvm
-          sudo rm -rf /usr/local/share/boost
-          df -h
      - name: Check out the repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: recursive
      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v2
      - name: Docker meta
        id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v4
        with:
          images: |
            tinygo/tinygo-dev
@@ -47,24 +36,24 @@ jobs:
            type=sha,format=long
            type=raw,value=latest
      - name: Log in to Docker Hub
-        uses: docker/login-action@v3
+        uses: docker/login-action@v2
        with:
          username: ${{ secrets.DOCKER_HUB_USERNAME }}
          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
      - name: Log in to Github Container Registry
-        uses: docker/login-action@v3
+        uses: docker/login-action@v2
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v3
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
-          build-contexts: tinygo-llvm-build=docker-image://tinygo/llvm-17
+          build-contexts: tinygo-llvm-build=docker-image://tinygo/llvm-16
          cache-from: type=gha
          cache-to: type=gha,mode=max
      - name: Trigger Drivers repo build on Github Actions
@@ -18,10 +18,10 @@ jobs:
    # statically linked binary.
    runs-on: ubuntu-latest
    container:
-      image: golang:1.22-alpine
+      image: golang:1.21-alpine
    steps:
      - name: Install apk dependencies
-        # tar: needed for actions/cache@v4
+        # tar: needed for actions/cache@v3
        # git+openssh: needed for checkout (I think?)
        # ruby: needed to install fpm
        run: apk add tar git openssh make g++ ruby
@@ -29,21 +29,21 @@ jobs:
        # We're not on a multi-user machine, so this is safe.
        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: true
      - name: Cache Go
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        with:
          key: go-cache-linux-alpine-v1-${{ hashFiles('go.mod') }}
          path: |
            ~/.cache/go-build
            ~/go/pkg/mod
      - name: Restore LLVM source cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-linux-alpine-v1
+          key: llvm-source-16-linux-alpine-v1
          path: |
            llvm-project/clang/lib/Headers
            llvm-project/clang/include
@@ -54,7 +54,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save LLVM source cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -65,10 +65,10 @@ jobs:
            llvm-project/lld/include
            llvm-project/llvm/include
      - name: Restore LLVM build cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-build
        with:
-          key: llvm-build-17-linux-alpine-v1
+          key: llvm-build-16-linux-alpine-v1
          path: llvm-build
      - name: Build LLVM
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -83,13 +83,13 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Save LLVM build cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-build.outputs.cache-primary-key }}
          path: llvm-build
      - name: Cache Binaryen
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-alpine-v1
@@ -100,10 +100,10 @@ jobs:
          apk add cmake samurai python3
          make binaryen STATIC=1
      - name: Cache wasi-libc
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
-          key: wasi-libc-sysroot-linux-alpine-v2
+          key: wasi-libc-sysroot-linux-alpine-v1
          path: lib/wasi-libc/sysroot
      - name: Build wasi-libc
        if: steps.cache-wasi-libc.outputs.cache-hit != 'true'
@@ -119,7 +119,7 @@ jobs:
          cp -p build/release.tar.gz /tmp/tinygo.linux-amd64.tar.gz
          cp -p build/release.deb    /tmp/tinygo_amd64.deb
      - name: Publish release artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v3
        with:
          name: linux-amd64-double-zipped
          path: |
@@ -131,11 +131,11 @@ jobs:
    needs: build-linux
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Install wasmtime
        run: |
@@ -144,7 +144,7 @@ jobs:
          tar -C $HOME/.wasmtime/bin --wildcards -xf wasmtime-v14.0.4-x86_64-linux.tar.xz --strip-components=1 wasmtime-v14.0.4-x86_64-linux/*
          echo "$HOME/.wasmtime/bin" >> $GITHUB_PATH
      - name: Download release artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v3
        with:
          name: linux-amd64-double-zipped
      - name: Extract release tarball
@@ -161,7 +161,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: true
      - name: Install apt dependencies
@@ -176,14 +176,14 @@ jobs:
              simavr \
              ninja-build
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v3
        with:
-          node-version: '18'
+          node-version: '16'
      - name: Install wasmtime
        run: |
          mkdir -p $HOME/.wasmtime $HOME/.wasmtime/bin
@@ -191,10 +191,10 @@ jobs:
          tar -C $HOME/.wasmtime/bin --wildcards -xf wasmtime-v14.0.4-x86_64-linux.tar.xz --strip-components=1 wasmtime-v14.0.4-x86_64-linux/*
          echo "$HOME/.wasmtime/bin" >> $GITHUB_PATH
      - name: Restore LLVM source cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-linux-asserts-v1
+          key: llvm-source-16-linux-asserts-v1
          path: |
            llvm-project/clang/lib/Headers
            llvm-project/clang/include
@@ -205,7 +205,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save LLVM source cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -216,10 +216,10 @@ jobs:
            llvm-project/lld/include
            llvm-project/llvm/include
      - name: Restore LLVM build cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-build
        with:
-          key: llvm-build-17-linux-asserts-v1
+          key: llvm-build-16-linux-asserts-v1
          path: llvm-build
      - name: Build LLVM
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -232,13 +232,13 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Save LLVM build cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-build.outputs.cache-primary-key }}
          path: llvm-build
      - name: Cache Binaryen
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-asserts-v1
@@ -247,10 +247,10 @@ jobs:
        if: steps.cache-binaryen.outputs.cache-hit != 'true'
        run: make binaryen
      - name: Cache wasi-libc
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
-          key: wasi-libc-sysroot-linux-asserts-v6
+          key: wasi-libc-sysroot-linux-asserts-v5
          path: lib/wasi-libc/sysroot
      - name: Build wasi-libc
        if: steps.cache-wasi-libc.outputs.cache-hit != 'true'
@@ -290,7 +290,7 @@ jobs:
    needs: build-linux
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install apt dependencies
        run: |
          sudo apt-get update
@@ -299,15 +299,15 @@ jobs:
              g++-${{ matrix.toolchain }} \
              libc6-dev-${{ matrix.libc }}-cross
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Restore LLVM source cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-linux-v1
+          key: llvm-source-16-linux-v1
          path: |
            llvm-project/clang/lib/Headers
            llvm-project/clang/include
@@ -318,7 +318,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save LLVM source cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -329,10 +329,10 @@ jobs:
            llvm-project/lld/include
            llvm-project/llvm/include
      - name: Restore LLVM build cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-build
        with:
-          key: llvm-build-17-linux-${{ matrix.goarch }}-v1
+          key: llvm-build-16-linux-${{ matrix.goarch }}-v1
          path: llvm-build
      - name: Build LLVM
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -347,13 +347,13 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Save LLVM build cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-build.outputs.cache-primary-key }}
          path: llvm-build
      - name: Cache Binaryen
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-${{ matrix.goarch }}-v3
@@ -373,7 +373,7 @@ jobs:
        run: |
          make CROSS=${{ matrix.toolchain }}
      - name: Download amd64 release
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v3
        with:
          name: linux-amd64-double-zipped
      - name: Extract amd64 release
@@ -390,7 +390,7 @@ jobs:
          cp -p build/release.tar.gz /tmp/tinygo.linux-${{ matrix.goarch }}.tar.gz
          cp -p build/release.deb    /tmp/tinygo_${{ matrix.libc }}.deb
      - name: Publish release artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v3
        with:
          name: linux-${{ matrix.goarch }}-double-zipped
          path: |
@@ -25,18 +25,18 @@ jobs:
      contents: read
    steps:
      - name: Check out the repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: recursive
      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v2
      - name: Docker meta
        id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v4
        with:
          images: |
-            tinygo/llvm-17
-            ghcr.io/${{ github.repository_owner }}/llvm-17
+            tinygo/llvm-16
+            ghcr.io/${{ github.repository_owner }}/llvm-16
          tags: |
            type=sha,format=long
            type=raw,value=latest
@@ -46,13 +46,13 @@ jobs:
          username: ${{ secrets.DOCKER_HUB_USERNAME }}
          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
      - name: Log in to Github Container Registry
-        uses: docker/login-action@v3
+        uses: docker/login-action@v2
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v4
        with:
          target: tinygo-llvm-build
          context: .
@@ -16,22 +16,22 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Pull musl
        run: |
            git submodule update --init lib/musl
      - name: Restore LLVM source cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-linux-nix-v1
+          key: llvm-source-16-linux-nix-v1
          path: |
            llvm-project/compiler-rt
      - name: Download LLVM source
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save LLVM source cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -1,12 +0,0 @@
-# Command that's part of sizediff.yml. This is put in a separate file so that it
-# still works after checking out the dev branch (that is, when going from LLVM
-# 16 to LLVM 17 for example, both Clang 16 and Clang 17 are installed).
-
-echo 'deb https://apt.llvm.org/jammy/ llvm-toolchain-jammy-17 main' | sudo tee /etc/apt/sources.list.d/llvm.list
-wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-sudo apt-get update
-sudo apt-get install --no-install-recommends -y \
-    llvm-17-dev \
-    clang-17 \
-    libclang-17-dev \
-    lld-17
@@ -18,24 +18,32 @@ jobs:
        run: |
          echo "$HOME/go/bin" >> $GITHUB_PATH
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          fetch-depth: 0 # fetch all history (no sparse checkout)
          submodules: true
      - name: Install apt dependencies
-        run: ./.github/workflows/sizediff-install-pkgs.sh
+        run: |
+          echo 'deb https://apt.llvm.org/jammy/ llvm-toolchain-jammy-16 main' | sudo tee /etc/apt/sources.list.d/llvm.list
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+          sudo apt-get update
+          sudo apt-get install --no-install-recommends -y \
+              llvm-16-dev \
+              clang-16 \
+              libclang-16-dev \
+              lld-16
      - name: Restore LLVM source cache
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-sizediff-v1
+          key: llvm-source-16-sizediff-v1
          path: |
            llvm-project/compiler-rt
      - name: Download LLVM source
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache Go
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        with:
          key: go-cache-linux-sizediff-v1-${{ hashFiles('go.mod') }}
          path: |
@@ -47,25 +55,22 @@ jobs:
      - name: Save HEAD
        run: git branch github-actions-saved-HEAD HEAD

-      # Compute sizes for the PR branch
-      - name: Build tinygo binary for the PR branch
-        run: go install
-      - name: Determine binary sizes on the PR branch
-        run: (cd drivers; make smoke-test XTENSA=0 | tee sizes-pr.txt)
-
      # Compute sizes for the dev branch
      - name: Checkout dev branch
-        run: |
-          git reset --hard origin/dev
-          git checkout --no-recurse-submodules `git merge-base HEAD origin/dev`
-      - name: Install apt dependencies on the dev branch
-        # this is only needed on a PR that changes the LLVM version
-        run: ./.github/workflows/sizediff-install-pkgs.sh
+        run: git checkout --no-recurse-submodules `git merge-base HEAD origin/dev`
      - name: Build tinygo binary for the dev branch
        run: go install
      - name: Determine binary sizes on the dev branch
        run: (cd drivers; make smoke-test XTENSA=0 | tee sizes-dev.txt)

+      # Compute sizes for the PR branch
+      - name: Checkout PR branch
+        run: git checkout --no-recurse-submodules github-actions-saved-HEAD
+      - name: Build tinygo binary for the PR branch
+        run: go install
+      - name: Determine binary sizes on the PR branch
+        run: (cd drivers; make smoke-test XTENSA=0 | tee sizes-pr.txt)
+
      # Create comment
      # TODO: add a summary, something like:
      #  - overall size difference (percent)
@@ -16,7 +16,7 @@ jobs:
    runs-on: windows-2022
    steps:
      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
+        uses: al-cheb/configure-pagefile-action@v1.3
        with:
          minimum-size: 8GB
          maximum-size: 24GB
@@ -29,19 +29,19 @@ jobs:
        run: |
          scoop install ninja binaryen
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
        with:
          submodules: true
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Restore cached LLVM source
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-source
        with:
-          key: llvm-source-17-windows-v1
+          key: llvm-source-16-windows-v1
          path: |
            llvm-project/clang/lib/Headers
            llvm-project/clang/include
@@ -52,7 +52,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Save cached LLVM source
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
@@ -63,10 +63,10 @@ jobs:
            llvm-project/lld/include
            llvm-project/llvm/include
      - name: Restore cached LLVM build
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v3
        id: cache-llvm-build
        with:
-          key: llvm-build-17-windows-v1
+          key: llvm-build-16-windows-v2
          path: llvm-build
      - name: Build LLVM
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -80,16 +80,16 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Save cached LLVM build
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v3
        if: steps.cache-llvm-build.outputs.cache-hit != 'true'
        with:
          key: ${{ steps.cache-llvm-build.outputs.cache-primary-key }}
          path: llvm-build
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v4
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
-          key: wasi-libc-sysroot-v5
+          key: wasi-libc-sysroot-v4
          path: lib/wasi-libc/sysroot
      - name: Build wasi-libc
        if: steps.cache-wasi-libc.outputs.cache-hit != 'true'
@@ -116,7 +116,7 @@ jobs:
        # - have a dobule-zipped artifact when downloaded from the UI
        # - have a very slow artifact upload
        # We're doing the former here, to keep artifact uploads fast.
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v3
        with:
          name: windows-amd64-double-zipped
          path: build/release/release.zip
@@ -126,7 +126,7 @@ jobs:
    needs: build-windows
    steps:
      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
+        uses: al-cheb/configure-pagefile-action@v1.3
        with:
          minimum-size: 8GB
          maximum-size: 24GB
@@ -139,14 +139,14 @@ jobs:
        run: |
          scoop install binaryen
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Download TinyGo build
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v2
        with:
          name: windows-amd64-double-zipped
          path: build/
@@ -163,20 +163,20 @@ jobs:
    needs: build-windows
    steps:
      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
+        uses: al-cheb/configure-pagefile-action@v1.3
        with:
          minimum-size: 8GB
          maximum-size: 24GB
          disk-root: "C:"
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Download TinyGo build
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v2
        with:
          name: windows-amd64-double-zipped
          path: build/
@@ -192,7 +192,7 @@ jobs:
    needs: build-windows
    steps:
      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
+        uses: al-cheb/configure-pagefile-action@v1.3
        with:
          minimum-size: 8GB
          maximum-size: 24GB
@@ -205,14 +205,14 @@ jobs:
        run: |
          scoop install binaryen && scoop install wasmtime@14.0.4
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v3
      - name: Install Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.22'
+          go-version: '1.21'
          cache: true
      - name: Download TinyGo build
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v2
        with:
          name: windows-amd64-double-zipped
          path: build/
@@ -9,11 +9,10 @@
 	url = https://github.com/avr-rust/avr-mcu.git
 [submodule "lib/cmsis-svd"]
 	path = lib/cmsis-svd
-	url = https://github.com/cmsis-svd/cmsis-svd-data.git
-	branch = main
+	url = https://github.com/tinygo-org/cmsis-svd
 [submodule "lib/wasi-libc"]
 	path = lib/wasi-libc
-	url = https://github.com/WebAssembly/wasi-libc
+	url = https://github.com/CraneStation/wasi-libc
 [submodule "lib/picolibc"]
 	path = lib/picolibc
 	url = https://github.com/keith-packard/picolibc.git
@@ -35,7 +34,3 @@
 [submodule "lib/renesas-svd"]
 	path = lib/renesas-svd
 	url = https://github.com/tinygo-org/renesas-svd.git
-[submodule "src/net"]
-	path = src/net
-	url = https://github.com/tinygo-org/net.git
-	branch = dev
@@ -1,15 +1,10 @@
 # tinygo-llvm stage obtains the llvm source for TinyGo
-FROM golang:1.22 AS tinygo-llvm
+FROM golang:1.21 AS tinygo-llvm

 RUN apt-get update && \
-    apt-get install -y apt-utils make cmake clang-15 ninja-build && \
-    rm -rf \
-        /var/lib/apt/lists/* \
-        /var/log/* \
-        /var/tmp/* \
-        /tmp/*
+    apt-get install -y apt-utils make cmake clang-15 ninja-build

-COPY ./GNUmakefile /tinygo/GNUmakefile
+COPY ./Makefile /tinygo/Makefile

 RUN cd /tinygo/ && \
    make llvm-source
@@ -20,24 +15,26 @@ FROM tinygo-llvm AS tinygo-llvm-build
 RUN cd /tinygo/ && \
    make llvm-build

-# tinygo-compiler-build stage builds the compiler itself
-FROM tinygo-llvm-build AS tinygo-compiler-build
+# tinygo-compiler stage builds the compiler itself
+FROM tinygo-llvm-build AS tinygo-compiler

 COPY . /tinygo

-# build the compiler and tools
+# update submodules
 RUN cd /tinygo/ && \
-    git submodule update --init --recursive && \
+    rm -rf ./lib/*/ && \
+    git submodule sync && \
+    git submodule update --init --recursive --force
+
+RUN cd /tinygo/ && \
+    make
+
+# tinygo-tools stage installs the needed dependencies to compile TinyGo programs for all platforms.
+FROM tinygo-compiler AS tinygo-tools
+
+RUN cd /tinygo/ && \
+    make wasi-libc binaryen && \
    make gen-device -j4 && \
-    make build/release
+    cp build/* $GOPATH/bin/

-# tinygo-compiler copies the compiler build over to a base Go container (without
-# all the build tools etc).
-FROM golang:1.21 AS tinygo-compiler
-
-# Copy tinygo build.
-COPY --from=tinygo-compiler-build /tinygo/build/release/tinygo /tinygo
-
-# Configure the container.
-ENV PATH="${PATH}:/tinygo/bin"
 CMD ["tinygo"]
@@ -238,7 +238,7 @@ gen-device-renesas: build/gen-device-svd

 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/llvm:
-	git clone -b xtensa_release_17.0.1 --depth=1 https://github.com/espressif/llvm-project $(LLVM_PROJECTDIR)
+	git clone -b xtensa_release_16.x --depth=1 https://github.com/espressif/llvm-project $(LLVM_PROJECTDIR)
 llvm-source: $(LLVM_PROJECTDIR)/llvm

 # Configure LLVM.
@@ -269,14 +269,14 @@ lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a:

 # Check for Node.js used during WASM tests.
 NODEJS_VERSION := $(word 1,$(subst ., ,$(shell node -v | cut -c 2-)))
-MIN_NODEJS_VERSION=18
+MIN_NODEJS_VERSION=16

 .PHONY: check-nodejs-version
 check-nodejs-version:
 ifeq (, $(shell which node))
-	@echo "Install NodeJS version 18+ to run tests."; exit 1;
+	@echo "Install NodeJS version 16+ to run tests."; exit 1;
 endif
-	@if [ $(NODEJS_VERSION) -lt $(MIN_NODEJS_VERSION) ]; then echo "Install NodeJS version 18+ to run tests."; exit 1; fi
+	@if [ $(NODEJS_VERSION) -lt $(MIN_NODEJS_VERSION) ]; then echo "Install NodeJS version 16+ to run tests."; exit 1; fi

 # Build the Go compiler.
 tinygo:
@@ -684,8 +684,6 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-nrf52840    examples/usb-midi
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=nrf52840-s140v6-uf2-generic	examples/serial
-	@$(MD5SUM) test.hex
 ifneq ($(STM32), 0)
 	$(TINYGO) build -size short -o test.hex -target=bluepill            examples/blinky1
 	@$(MD5SUM) test.hex
@@ -719,11 +717,7 @@ ifneq ($(STM32), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=swan                examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=mksnanov3           examples/blinky1
-	@$(MD5SUM) test.hex
 endif
-	$(TINYGO) build -size short -o test.hex -target=atmega328pb         examples/blinkm
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=atmega1284p         examples/serial
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino             examples/blinky1
@@ -760,7 +754,9 @@ ifneq ($(XTENSA), 0)
 	$(TINYGO) build -size short -o test.bin -target mch2022             examples/serial
 	@$(MD5SUM) test.bin
 endif
-	$(TINYGO) build -size short -o test.bin -target=qtpy-esp32c3        examples/serial
+	$(TINYGO) build -size short -o test.bin -target=esp32c3             examples/serial
+	@$(MD5SUM) test.bin
+	$(TINYGO) build -size short -o test.bin -target=esp32c3-12f         examples/serial
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.bin -target=m5stamp-c3          examples/serial
 	@$(MD5SUM) test.bin
@@ -773,7 +769,6 @@ endif
 ifneq ($(WASM), 0)
 	$(TINYGO) build -size short -o wasm.wasm -target=wasm               examples/wasm/export
 	$(TINYGO) build -size short -o wasm.wasm -target=wasm               examples/wasm/main
-	$(TINYGO) build -size short -o wasm.wasm -target=wasm-unknown       examples/hello-wasm-unknown
 endif
 	# test various compiler flags
 	$(TINYGO) build -size short -o test.hex -target=pca10040 -gc=none -scheduler=none examples/blinky1
@@ -782,8 +777,6 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040 -serial=none examples/echo
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040 -serial=rtt examples/echo
-	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o test.nro -target=nintendoswitch      examples/serial
 	@$(MD5SUM) test.nro
 	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=0     ./testdata/stdlib.go
@@ -843,7 +836,6 @@ endif
 	@cp -rp lib/musl/src/include         build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/internal        build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/legacy          build/release/tinygo/lib/musl/src
-	@cp -rp lib/musl/src/linux           build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/malloc          build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/mman            build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/math            build/release/tinygo/lib/musl/src
@@ -197,7 +197,6 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 		Scheduler:          config.Scheduler(),
 		AutomaticStackSize: config.AutomaticStackSize(),
 		DefaultStackSize:   config.StackSize(),
-		MaxStackAlloc:      config.MaxStackAlloc(),
 		NeedsStackObjects:  config.NeedsStackObjects(),
 		Debug:              !config.Options.SkipDWARF, // emit DWARF except when -internal-nodwarf is passed
 	}
@@ -808,8 +807,21 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe

 			// Run wasm-opt for wasm binaries
 			if arch := strings.Split(config.Triple(), "-")[0]; arch == "wasm32" {
-				optLevel, _, _ := config.OptLevel()
-				opt := "-" + optLevel
+				var opt string
+				switch config.Options.Opt {
+				case "none", "0":
+					opt = "-O0"
+				case "1":
+					opt = "-O1"
+				case "2":
+					opt = "-O2"
+				case "s":
+					opt = "-Os"
+				case "z":
+					opt = "-Oz"
+				default:
+					return fmt.Errorf("unknown opt level: %q", config.Options.Opt)
+				}

 				var args []string

@@ -35,7 +35,6 @@ func TestClangAttributes(t *testing.T) {
 		"riscv-qemu",
 		"wasi",
 		"wasm",
-		"wasm-unknown",
 	}
 	if hasBuiltinTools {
 		// hasBuiltinTools is set when TinyGo is statically linked with LLVM,
@@ -1,12 +1,5 @@
 //go:build byollvm

-// Source: https://github.com/llvm/llvm-project/blob/main/clang/tools/driver/cc1as_main.cpp
-// This file needs to be updated each LLVM release.
-// There are a few small modifications to make, like:
-//   * ExecuteAssembler is made non-static.
-//   * The struct AssemblerImplementation is moved to cc1as.h so it can be
-//     included elsewhere.
-
 //===-- cc1as.cpp - Clang Assembler  --------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
@@ -28,8 +21,8 @@
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Frontend/Utils.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCAsmInfo.h"
@@ -53,6 +46,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
@@ -61,8 +55,6 @@
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/TargetParser/Host.h"
-#include "llvm/TargetParser/Triple.h"
 #include <memory>
 #include <optional>
 #include <system_error>
@@ -159,7 +151,8 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,

  for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ)) {
    auto Split = StringRef(Arg).split('=');
-    Opts.DebugPrefixMap.emplace_back(Split.first, Split.second);
+    Opts.DebugPrefixMap.insert(
+        {std::string(Split.first), std::string(Split.second)});
  }

  // Frontend Options
@@ -232,9 +225,6 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
            .Case("default", EmitDwarfUnwindType::Default);
  }

-  Opts.EmitCompactUnwindNonCanonical =
-      Args.hasArg(OPT_femit_compact_unwind_non_canonical);
-
  Opts.AsSecureLogFile = Args.getLastArgValue(OPT_as_secure_log_file);

  return Success;
@@ -270,8 +260,8 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
      MemoryBuffer::getFileOrSTDIN(Opts.InputFile, /*IsText=*/true);

  if (std::error_code EC = Buffer.getError()) {
-    return Diags.Report(diag::err_fe_error_reading)
-           << Opts.InputFile << EC.message();
+    Error = EC.message();
+    return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
  }

  SourceMgr SrcMgr;
@@ -288,7 +278,6 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,

  MCTargetOptions MCOptions;
  MCOptions.EmitDwarfUnwind = Opts.EmitDwarfUnwind;
-  MCOptions.EmitCompactUnwindNonCanonical = Opts.EmitCompactUnwindNonCanonical;
  MCOptions.AsSecureLogFile = Opts.AsSecureLogFile;

  std::unique_ptr<MCAsmInfo> MAI(
@@ -1,6 +1,3 @@
-// Source: https://github.com/llvm/llvm-project/blob/main/clang/tools/driver/cc1as_main.cpp
-// See cc1as.cpp for details.
-
 //===-- cc1as.h - Clang Assembler  ----------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
@@ -47,7 +44,7 @@ struct AssemblerInvocation {
  std::string DwarfDebugFlags;
  std::string DwarfDebugProducer;
  std::string DebugCompilationDir;
-  llvm::SmallVector<std::pair<std::string, std::string>, 0> DebugPrefixMap;
+  std::map<const std::string, const std::string> DebugPrefixMap;
  llvm::DebugCompressionType CompressDebugSections =
      llvm::DebugCompressionType::None;
  std::string MainFileName;
@@ -92,10 +89,6 @@ struct AssemblerInvocation {
  /// Whether to emit DWARF unwind info.
  EmitDwarfUnwindType EmitDwarfUnwind;

-  // Whether to emit compact-unwind for non-canonical entries.
-  // Note: maybe overriden by other constraints.
-  unsigned EmitCompactUnwindNonCanonical : 1;
-
  /// The name of the relocation model to use.
  std::string RelocationModel;

@@ -135,7 +128,6 @@ public:
    DwarfVersion = 0;
    EmbedBitcode = 0;
    EmitDwarfUnwind = EmitDwarfUnwindType::Default;
-    EmitCompactUnwindNonCanonical = false;
  }

  static bool CreateFromArgs(AssemblerInvocation &Res,
@@ -11,7 +11,7 @@
 #include <clang/FrontendTool/Utils.h>
 #include <llvm/ADT/IntrusiveRefCntPtr.h>
 #include <llvm/Option/Option.h>
-#include <llvm/TargetParser/Host.h>
+#include <llvm/Support/Host.h>

 using namespace llvm;
 using namespace clang;
@@ -27,10 +27,10 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 	if err != nil {
 		return nil, err
 	}
-	if major != 1 || minor < 18 || minor > 22 {
+	if major != 1 || minor < 18 || minor > 21 {
 		// Note: when this gets updated, also update the Go compatibility matrix:
 		// https://github.com/tinygo-org/tinygo-site/blob/dev/content/docs/reference/go-compat-matrix.md
-		return nil, fmt.Errorf("requires go version 1.18 through 1.22, got go%d.%d", major, minor)
+		return nil, fmt.Errorf("requires go version 1.18 through 1.21, got go%d.%d", major, minor)
 	}

 	return &compileopts.Config{
@@ -5,11 +5,7 @@
 #include <lld/Common/Driver.h>
 #include <llvm/Support/Parallel.h>

-LLD_HAS_DRIVER(coff)
-LLD_HAS_DRIVER(elf)
-LLD_HAS_DRIVER(mingw)
-LLD_HAS_DRIVER(macho)
-LLD_HAS_DRIVER(wasm)
+extern "C" {

 static void configure() {
 #if _WIN64
@@ -20,13 +16,28 @@ static void configure() {
 #endif
 }

-extern "C" {
-
-bool tinygo_link(int argc, char **argv) {
+bool tinygo_link_elf(int argc, char **argv) {
 	configure();
 	std::vector<const char*> args(argv, argv + argc);
-	lld::Result r = lld::lldMain(args, llvm::outs(), llvm::errs(), LLD_ALL_DRIVERS);
-	return !r.retCode;
+	return lld::elf::link(args, llvm::outs(), llvm::errs(), false, false);
+}
+
+bool tinygo_link_macho(int argc, char **argv) {
+	configure();
+	std::vector<const char*> args(argv, argv + argc);
+	return lld::macho::link(args, llvm::outs(), llvm::errs(), false, false);
+}
+
+bool tinygo_link_mingw(int argc, char **argv) {
+	configure();
+	std::vector<const char*> args(argv, argv + argc);
+	return lld::mingw::link(args, llvm::outs(), llvm::errs(), false, false);
+}
+
+bool tinygo_link_wasm(int argc, char **argv) {
+	configure();
+	std::vector<const char*> args(argv, argv + argc);
+	return lld::wasm::link(args, llvm::outs(), llvm::errs(), false, false);
 }

 } // external "C"
@@ -119,7 +119,6 @@ var Musl = Library{
 			"internal/syscall_ret.c",
 			"internal/vdso.c",
 			"legacy/*.c",
-			"linux/*.c",
 			"malloc/*.c",
 			"malloc/mallocng/*.c",
 			"mman/*.c",
@@ -337,12 +337,6 @@ var picolibcSourcesLarge = []string{
 	"libm/common/math_err_may_uflow.c",
 	"libm/common/math_err_check_uflow.c",
 	"libm/common/math_err_check_oflow.c",
-	"libm/common/math_errf_divzerof.c",
-	"libm/common/math_errf_invalidf.c",
-	"libm/common/math_errf_may_uflowf.c",
-	"libm/common/math_errf_oflowf.c",
-	"libm/common/math_errf_uflowf.c",
-	"libm/common/math_errf_with_errnof.c",
 	"libm/common/math_inexact.c",
 	"libm/common/math_inexactf.c",
 	"libm/common/log.c",
@@ -41,9 +41,9 @@ func TestBinarySize(t *testing.T) {
 	// This is a small number of very diverse targets that we want to test.
 	tests := []sizeTest{
 		// microcontrollers
-		{"hifive1b", "examples/echo", 4476, 280, 0, 2252},
+		{"hifive1b", "examples/echo", 4484, 280, 0, 2252},
 		{"microbit", "examples/serial", 2724, 388, 8, 2256},
-		{"wioterminal", "examples/pininterrupt", 5996, 1484, 116, 6816},
+		{"wioterminal", "examples/pininterrupt", 6000, 1484, 116, 6816},

 		// TODO: also check wasm. Right now this is difficult, because
 		// wasm binaries are run through wasm-opt and therefore the
@@ -12,7 +12,10 @@ import (
 #include <stdbool.h>
 #include <stdlib.h>
 bool tinygo_clang_driver(int argc, char **argv);
-bool tinygo_link(int argc, char **argv);
+bool tinygo_link_elf(int argc, char **argv);
+bool tinygo_link_macho(int argc, char **argv);
+bool tinygo_link_mingw(int argc, char **argv);
+bool tinygo_link_wasm(int argc, char **argv);
 */
 import "C"

@@ -23,7 +26,16 @@ const hasBuiltinTools = true
 // This version actually runs the tools because TinyGo was compiled while
 // linking statically with LLVM (with the byollvm build tag).
 func RunTool(tool string, args ...string) error {
-	args = append([]string{tool}, args...)
+	linker := "elf"
+	if tool == "ld.lld" && len(args) >= 2 {
+		if args[0] == "-m" && (args[1] == "i386pep" || args[1] == "arm64pe") {
+			linker = "mingw"
+		} else if args[0] == "-flavor" {
+			linker = args[1]
+			args = args[2:]
+		}
+	}
+	args = append([]string{"tinygo:" + tool}, args...)

 	var cflag *C.char
 	buf := C.calloc(C.size_t(len(args)), C.size_t(unsafe.Sizeof(cflag)))
@@ -39,8 +51,19 @@ func RunTool(tool string, args ...string) error {
 	switch tool {
 	case "clang":
 		ok = C.tinygo_clang_driver(C.int(len(args)), (**C.char)(buf))
-	case "ld.lld", "wasm-ld":
-		ok = C.tinygo_link(C.int(len(args)), (**C.char)(buf))
+	case "ld.lld":
+		switch linker {
+		case "darwin":
+			ok = C.tinygo_link_macho(C.int(len(args)), (**C.char)(buf))
+		case "elf":
+			ok = C.tinygo_link_elf(C.int(len(args)), (**C.char)(buf))
+		case "mingw":
+			ok = C.tinygo_link_mingw(C.int(len(args)), (**C.char)(buf))
+		default:
+			return errors.New("unknown linker: " + linker)
+		}
+	case "wasm-ld":
+		ok = C.tinygo_link_wasm(C.int(len(args)), (**C.char)(buf))
 	default:
 		return errors.New("unknown tool: " + tool)
 	}
@@ -25,15 +25,9 @@ import (
 	"golang.org/x/tools/go/ast/astutil"
 )

-// Function that's only defined in Go 1.22.
-var setASTFileFields = func(f *ast.File, start, end token.Pos) {
-}
-
 // cgoPackage holds all CGo-related information of a package.
 type cgoPackage struct {
 	generated       *ast.File
-	packageName     string
-	cgoFiles        []*ast.File
 	generatedPos    token.Pos
 	errors          []error
 	currentDir      string // current working directory
@@ -171,9 +165,8 @@ func GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 // functions), the CFLAGS and LDFLAGS found in #cgo lines, and a map of file
 // hashes of the accessed C header files. If there is one or more error, it
 // returns these in the []error slice but still modifies the AST.
-func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cflags []string) ([]*ast.File, []string, []string, []string, map[string][]byte, []error) {
+func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cflags []string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
 	p := &cgoPackage{
-		packageName:     files[0].Name.Name,
 		currentDir:      dir,
 		importPath:      importPath,
 		fset:            fset,
@@ -209,7 +202,6 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 		// This is always a bug in the cgo package.
 		panic("unexpected error: " + err.Error())
 	}
-	p.cgoFiles = append(p.cgoFiles, p.generated)
 	// If the Comments field is not set to nil, the go/format package will get
 	// confused about where comments should go.
 	p.generated.Comments = nil
@@ -340,7 +332,7 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 	// Print the newly generated in-memory AST, for debugging.
 	//ast.Print(fset, p.generated)

-	return p.cgoFiles, p.cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
+	return p.generated, p.cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
 }

 func (p *cgoPackage) newCGoFile(file *ast.File, index int) *cgoFile {
@@ -1,17 +0,0 @@
-//go:build go1.22
-
-package cgo
-
-// Code specifically for Go 1.22.
-
-import (
-	"go/ast"
-	"go/token"
-)
-
-func init() {
-	setASTFileFields = func(f *ast.File, start, end token.Pos) {
-		f.FileStart = start
-		f.FileEnd = end
-	}
-}
@@ -55,7 +55,7 @@ func TestCGo(t *testing.T) {
 			}

 			// Process the AST with CGo.
-			cgoFiles, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", "main", fset, cflags)
+			cgoAST, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", "main", fset, cflags)

 			// Check the AST for type errors.
 			var typecheckErrors []error
@@ -66,7 +66,7 @@ func TestCGo(t *testing.T) {
 				Importer: simpleImporter{},
 				Sizes:    types.SizesFor("gccgo", "arm"),
 			}
-			_, err = config.Check("", fset, append([]*ast.File{f}, cgoFiles...), nil)
+			_, err = config.Check("", fset, []*ast.File{f, cgoAST}, nil)
 			if err != nil && len(typecheckErrors) == 0 {
 				// Only report errors when no type errors are found (an
 				// unexpected condition).
@@ -91,7 +91,7 @@ func TestCGo(t *testing.T) {
 				}
 				buf.WriteString("\n")
 			}
-			err = format.Node(buf, fset, cgoFiles[0])
+			err = format.Node(buf, fset, cgoAST)
 			if err != nil {
 				t.Errorf("could not write out CGo AST: %v", err)
 			}
@@ -589,13 +589,6 @@ func (p *cgoPackage) getClangLocationPosition(location C.CXSourceLocation, tu C.
 		f := p.fset.AddFile(filename, -1, int(size))
 		f.SetLines(lines)
 		p.tokenFiles[filename] = f
-		// Add dummy file AST, to satisfy the type checker.
-		astFile := &ast.File{
-			Package: f.Pos(0),
-			Name:    ast.NewIdent(p.packageName),
-		}
-		setASTFileFields(astFile, f.Pos(0), f.Pos(int(size)))
-		p.cgoFiles = append(p.cgoFiles, astFile)
 	}
 	positionFile := p.tokenFiles[filename]

@@ -1,4 +1,4 @@
-//go:build !byollvm && llvm16
+//go:build !byollvm && !llvm15 && !llvm17

 package cgo

@@ -1,4 +1,4 @@
-//go:build !byollvm && !llvm15 && !llvm16
+//go:build !byollvm && llvm17

 package cgo

@@ -74,12 +74,7 @@ func (c *Config) GOARM() string {

 // BuildTags returns the complete list of build tags used during this build.
 func (c *Config) BuildTags() []string {
-	tags := append(c.Target.BuildTags, []string{
-		"tinygo",                                     // that's the compiler
-		"purego",                                     // to get various crypto packages to work
-		"math_big_pure_go",                           // to get math/big to work
-		"gc." + c.GC(), "scheduler." + c.Scheduler(), // used inside the runtime package
-		"serial." + c.Serial()}...) // used inside the machine package
+	tags := append(c.Target.BuildTags, []string{"tinygo", "math_big_pure_go", "gc." + c.GC(), "scheduler." + c.Scheduler(), "serial." + c.Serial()}...)
 	for i := 1; i <= c.GoMinorVersion; i++ {
 		tags = append(tags, fmt.Sprintf("go1.%d", i))
 	}
@@ -87,6 +82,12 @@ func (c *Config) BuildTags() []string {
 	return tags
 }

+// CgoEnabled returns true if (and only if) CGo is enabled. It is true by
+// default and false if CGO_ENABLED is set to "0".
+func (c *Config) CgoEnabled() bool {
+	return goenv.Get("CGO_ENABLED") == "1"
+}
+
 // GC returns the garbage collection strategy in use on this platform. Valid
 // values are "none", "leaking", "conservative" and "precise".
 func (c *Config) GC() string {
@@ -188,15 +189,6 @@ func (c *Config) StackSize() uint64 {
 	return c.Target.DefaultStackSize
 }

-// MaxStackAlloc returns the size of the maximum allocation to put on the stack vs heap.
-func (c *Config) MaxStackAlloc() uint64 {
-	if c.StackSize() > 32*1024 {
-		return 1024
-	}
-
-	return 256
-}
-
 // RP2040BootPatch returns whether the RP2040 boot patch should be applied that
 // calculates and patches in the checksum for the 2nd stage bootloader.
 func (c *Config) RP2040BootPatch() bool {
@@ -280,6 +272,10 @@ func (c *Config) CFlags(libclang bool) []string {
 		cflags = append(cflags,
 			"-resource-dir="+resourceDir,
 		)
+		if strings.HasPrefix(c.Triple(), "xtensa") {
+			// workaround needed in LLVM 16, see: https://github.com/espressif/llvm-project/issues/83
+			cflags = append(cflags, "-isystem", filepath.Join(resourceDir, "include"))
+		}
 	}
 	switch c.Target.Libc {
 	case "darwin-libSystem":
@@ -10,7 +10,7 @@ import (
 var (
 	validGCOptions            = []string{"none", "leaking", "conservative", "custom", "precise"}
 	validSchedulerOptions     = []string{"none", "tasks", "asyncify"}
-	validSerialOptions        = []string{"none", "uart", "usb", "rtt"}
+	validSerialOptions        = []string{"none", "uart", "usb"}
 	validPrintSizeOptions     = []string{"none", "short", "full"}
 	validPanicStrategyOptions = []string{"print", "trap"}
 	validOptOptions           = []string{"none", "0", "1", "2", "s", "z"}
@@ -23,7 +23,6 @@ type Options struct {
 	GOOS            string // environment variable
 	GOARCH          string // environment variable
 	GOARM           string // environment variable (only used with GOARCH=arm)
-	Directory       string // working dir, leave it unset to use the current working dir
 	Target          string
 	Opt             string
 	GC              string
@@ -49,6 +48,7 @@ type Options struct {
 	Programmer      string
 	OpenOCDCommands []string
 	LLVMFeatures    string
+	Directory       string
 	PrintJSON       bool
 	Monitor         bool
 	BaudRate        int
@@ -301,10 +301,10 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	switch goarch {
 	case "386":
 		spec.CPU = "pentium4"
-		spec.Features = "+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
+		spec.Features = "+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
 	case "amd64":
 		spec.CPU = "x86-64"
-		spec.Features = "+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
+		spec.Features = "+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
 	case "arm":
 		spec.CPU = "generic"
 		spec.CFlags = append(spec.CFlags, "-fno-unwind-tables", "-fno-asynchronous-unwind-tables")
@@ -320,10 +320,8 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		spec.CPU = "generic"
 		if goos == "darwin" {
 			spec.Features = "+neon"
-		} else if goos == "windows" {
+		} else { // windows, linux
 			spec.Features = "+neon,-fmv"
-		} else { // linux
-			spec.Features = "+neon,-fmv,-outline-atomics"
 		}
 	case "wasm":
 		spec.CPU = "generic"
@@ -351,20 +349,6 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		spec.RTLib = "compiler-rt"
 		spec.Libc = "musl"
 		spec.LDFlags = append(spec.LDFlags, "--gc-sections")
-		if goarch == "arm64" {
-			// Disable outline atomics. For details, see:
-			// https://cpufun.substack.com/p/atomics-in-aarch64
-			// A better way would be to fully support outline atomics, which
-			// makes atomics slightly more efficient on systems with many cores.
-			// But the instructions are only supported on newer aarch64 CPUs, so
-			// this feature is normally put in a system library which does
-			// feature detection for you.
-			// We take the lazy way out and simply disable this feature, instead
-			// of enabling it in compiler-rt (which is a bit more complicated).
-			// We don't really need this feature anyway as we don't even support
-			// proper threading.
-			spec.CFlags = append(spec.CFlags, "-mno-outline-atomics")
-		}
 	} else if goos == "windows" {
 		spec.Linker = "ld.lld"
 		spec.Libc = "mingw-w64"
@@ -53,7 +53,6 @@ type Config struct {
 	Scheduler          string
 	AutomaticStackSize bool
 	DefaultStackSize   uint64
-	MaxStackAlloc      uint64
 	NeedsStackObjects  bool
 	Debug              bool // Whether to emit debug information in the LLVM module.
 }
@@ -1998,8 +1997,8 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) {
 	case *ssa.Alloc:
 		typ := b.getLLVMType(expr.Type().Underlying().(*types.Pointer).Elem())
 		size := b.targetData.TypeAllocSize(typ)
-		// Move all "large" allocations to the heap.
-		if expr.Heap || size > b.MaxStackAlloc {
+		// Move all "large" allocations to the heap.  This value is also transform.maxStackAlloc.
+		if expr.Heap || size > 256 {
 			// Calculate ^uintptr(0)
 			maxSize := llvm.ConstNot(llvm.ConstInt(b.uintptrType, 0, false)).ZExtValue()
 			if size > maxSize {
@@ -3262,11 +3261,7 @@ func (b *builder) createUnOp(unop *ssa.UnOp) (llvm.Value, error) {
 			// Instead of a load from the global, create a bitcast of the
 			// function pointer itself.
 			name := strings.TrimSuffix(unop.X.(*ssa.Global).Name(), "$funcaddr")
-			pkg := b.fn.Pkg
-			if pkg == nil {
-				pkg = b.fn.Origin().Pkg
-			}
-			_, fn := b.getFunction(pkg.Members[name].(*ssa.Function))
+			_, fn := b.getFunction(b.fn.Pkg.Members[name].(*ssa.Function))
 			if fn.IsNil() {
 				return llvm.Value{}, b.makeError(unop.Pos(), "cgo function not found: "+name)
 			}
@@ -684,25 +684,19 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {

 	actualTypeNum := b.CreateExtractValue(itf, 0, "interface.type")
 	commaOk := llvm.Value{}
+	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
+		// Type assert on interface type.
+		// This is a call to an interface type assert function.
+		// The interface lowering pass will define this function by filling it
+		// with a type switch over all concrete types that implement this
+		// interface, and returning whether it's one of the matched types.
+		// This is very different from how interface asserts are implemented in
+		// the main Go compiler, where the runtime checks whether the type
+		// implements each method of the interface. See:
+		// https://research.swtch.com/interfaces
+		fn := b.getInterfaceImplementsFunc(expr.AssertedType)
+		commaOk = b.CreateCall(fn.GlobalValueType(), fn, []llvm.Value{actualTypeNum}, "")

-	if intf, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
-		if intf.Empty() {
-			// intf is the empty interface => no methods
-			// This type assertion always succeeds, so we can just set commaOk to true.
-			commaOk = llvm.ConstInt(b.ctx.Int1Type(), 1, true)
-		} else {
-			// Type assert on interface type with methods.
-			// This is a call to an interface type assert function.
-			// The interface lowering pass will define this function by filling it
-			// with a type switch over all concrete types that implement this
-			// interface, and returning whether it's one of the matched types.
-			// This is very different from how interface asserts are implemented in
-			// the main Go compiler, where the runtime checks whether the type
-			// implements each method of the interface. See:
-			// https://research.swtch.com/interfaces
-			fn := b.getInterfaceImplementsFunc(expr.AssertedType)
-			commaOk = b.CreateCall(fn.GlobalValueType(), fn, []llvm.Value{actualTypeNum}, "")
-		}
 	} else {
 		name, _ := getTypeCodeName(expr.AssertedType)
 		globalName := "reflect/types.typeid:" + name
@@ -20,16 +20,16 @@
    },
    "nixpkgs": {
      "locked": {
-        "lastModified": 1703068421,
-        "narHash": "sha256-WSw5Faqlw75McIflnl5v7qVD/B3S2sLh+968bpOGrWA=",
+        "lastModified": 1696983906,
+        "narHash": "sha256-L7GyeErguS7Pg4h8nK0wGlcUTbfUMDu+HMf1UcyP72k=",
        "owner": "NixOS",
        "repo": "nixpkgs",
-        "rev": "d65bceaee0fb1e64363f7871bc43dc1c6ecad99f",
+        "rev": "bd1cde45c77891214131cbbea5b1203e485a9d51",
        "type": "github"
      },
      "original": {
        "id": "nixpkgs",
-        "ref": "nixos-23.11",
+        "ref": "nixos-23.05",
        "type": "indirect"
      }
    },
@@ -35,7 +35,7 @@
  inputs = {
    # Use a recent stable release, but fix the version to make it reproducible.
    # This version should be updated from time to time.
-    nixpkgs.url = "nixpkgs/nixos-23.11";
+    nixpkgs.url = "nixpkgs/nixos-23.05";
    flake-utils.url = "github:numtide/flake-utils";
  };
  outputs = { self, nixpkgs, flake-utils }:
@@ -49,12 +49,11 @@
          buildInputs = [
            # These dependencies are required for building tinygo (go install).
            go
-            llvmPackages_17.llvm
-            llvmPackages_17.libclang
-            llvmPackages_17.libcxx
+            llvmPackages_16.llvm
+            llvmPackages_16.libclang
            # Additional dependencies needed at runtime, for building and/or
            # flashing.
-            llvmPackages_17.lld
+            llvmPackages_16.lld
            avrdude
            binaryen
            # Additional dependencies needed for on-chip debugging.
@@ -69,7 +68,7 @@
            # Without setting these explicitly, Homebrew versions might be used
            # or the default `ar` and `nm` tools might be used (which don't
            # support wasi).
-            export CLANG="clang-17 -resource-dir ${llvmPackages_17.clang.cc.lib}/lib/clang/17"
+            export CLANG="clang-16 -resource-dir ${llvmPackages_16.clang.cc.lib}/lib/clang/16"
            export LLVM_AR=llvm-ar
            export LLVM_NM=llvm-nm

@@ -78,7 +77,7 @@
            export MD5SUM=md5sum

            # Ugly hack to make the Clang resources directory available.
-            export GOFLAGS="\"-ldflags=-X github.com/tinygo-org/tinygo/goenv.clangResourceDir=${llvmPackages_17.clang.cc.lib}/lib/clang/17"\"
+            export GOFLAGS="\"-ldflags=-X github.com/tinygo-org/tinygo/goenv.clangResourceDir=${llvmPackages_16.clang.cc.lib}/lib/clang/16"\"
          '';
        };
      }
@@ -15,11 +15,10 @@ require (
 	github.com/mattn/go-tty v0.0.4
 	github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3
 	go.bug.st/serial v1.6.0
-	golang.org/x/net v0.20.0
-	golang.org/x/sys v0.16.0
-	golang.org/x/tools v0.17.0
+	golang.org/x/sys v0.11.0
+	golang.org/x/tools v0.12.0
 	gopkg.in/yaml.v2 v2.4.0
-	tinygo.org/x/go-llvm v0.0.0-20240106122909-c2c543540318
+	tinygo.org/x/go-llvm v0.0.0-20231014233752-75a8a9fe6f74
 )

 require (
@@ -31,5 +30,4 @@ require (
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mattn/go-isatty v0.0.12 // indirect
-	golang.org/x/text v0.14.0 // indirect
 )
@@ -48,9 +48,7 @@ github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3/go.mod h1:9/etS5gpQq9
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 go.bug.st/serial v1.6.0 h1:mAbRGN4cKE2J5gMwsMHC2KQisdLRQssO9WSM+rbZJ8A=
 go.bug.st/serial v1.6.0/go.mod h1:UABfsluHAiaNI+La2iESysd9Vetq7VRdpxvjx7CmmOE=
-golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
-golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
-golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=
+golang.org/x/mod v0.12.0 h1:rmsUpXtvNzj340zd98LZ4KntptpfRHwpFOHG188oHXc=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -58,16 +56,14 @@ golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201207223542-d4d67f95c62d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20211124211545-fe61309f8881/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.16.0 h1:xWw16ngr6ZMtmxDyKyIgsE93KNKz5HKmMa3b8ALHidU=
-golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
-golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
-golang.org/x/tools v0.17.0 h1:FvmRgNOcs3kOa+T20R1uhfP9F6HgG2mfxDv1vrx1Htc=
-golang.org/x/tools v0.17.0/go.mod h1:xsh6VxdV005rRVaS6SSAf9oiAqljS7UZUacMZ8Bnsps=
+golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=
+golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/tools v0.12.0 h1:YW6HUoUmYBpwSgyaGaZq1fHjrBjX1rlpZ54T6mu2kss=
+golang.org/x/tools v0.12.0/go.mod h1:Sc0INKfu04TlqNoRA1hgpFZbhYXHPr4V5DzpSBTPqQM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
-tinygo.org/x/go-llvm v0.0.0-20240106122909-c2c543540318 h1:4KjZvPtcN1UwobevcGbdzeinx0L1i8HDdJu84bu7NI8=
-tinygo.org/x/go-llvm v0.0.0-20240106122909-c2c543540318/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
+tinygo.org/x/go-llvm v0.0.0-20231014233752-75a8a9fe6f74 h1:tW8XhLI9gUZLL+2pG0HYb5dc6bpMj1aqtESpizXPnMY=
+tinygo.org/x/go-llvm v0.0.0-20231014233752-75a8a9fe6f74/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
@@ -142,8 +142,11 @@ func Get(name string) string {
 		}
 		return filepath.Join(dir, "tinygo")
 	case "CGO_ENABLED":
-		// Always enable CGo. It is required by a number of targets, including
-		// macOS and the rp2040.
+		val := os.Getenv("CGO_ENABLED")
+		if val == "1" || val == "0" {
+			return val
+		}
+		// Default to enabling CGo.
 		return "1"
 	case "TINYGOROOT":
 		return sourceDir()
@@ -239,8 +239,7 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				// already be emitted in initAll.
 				continue
 			case strings.HasPrefix(callFn.name, "runtime.print") || callFn.name == "runtime._panic" || callFn.name == "runtime.hashmapGet" || callFn.name == "runtime.hashmapInterfaceHash" ||
-				callFn.name == "os.runtime_args" || callFn.name == "internal/task.start" || callFn.name == "internal/task.Current" ||
-				callFn.name == "time.startTimer" || callFn.name == "time.stopTimer" || callFn.name == "time.resetTimer":
+				callFn.name == "os.runtime_args" || callFn.name == "internal/task.start" || callFn.name == "internal/task.Current":
 				// These functions should be run at runtime. Specifically:
 				//   * Print and panic functions are best emitted directly without
 				//     interpreting them, otherwise we get a ton of putchar (etc.)
@@ -253,8 +252,6 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				//     at runtime.
 				//   * internal/task.start, internal/task.Current: start and read shcheduler state,
 				//     which is modified elsewhere.
-				//   * Timer functions access runtime internal state which may
-				//     not be initialized.
 				err := r.runAtRuntime(fn, inst, locals, &mem, indent)
 				if err != nil {
 					return nil, mem, err
@@ -232,7 +232,6 @@ func pathsToOverride(goMinor int, needsSyscallPackage bool) map[string]bool {
 		"":                      true,
 		"crypto/":               true,
 		"crypto/rand/":          false,
-		"crypto/tls/":           false,
 		"device/":               false,
 		"examples/":             false,
 		"internal/":             true,
@@ -242,9 +241,7 @@ func pathsToOverride(goMinor int, needsSyscallPackage bool) map[string]bool {
 		"internal/task/":        false,
 		"machine/":              false,
 		"net/":                  true,
-		"net/http/":             false,
 		"os/":                   true,
-		"os/user/":              false,
 		"reflect/":              false,
 		"runtime/":              false,
 		"sync/":                 true,
@@ -22,8 +22,12 @@ func List(config *compileopts.Config, extraArgs, pkgs []string) (*exec.Cmd, erro
 		args = append(args, "-tags", strings.Join(config.BuildTags(), " "))
 	}
 	args = append(args, pkgs...)
+	cgoEnabled := "0"
+	if config.CgoEnabled() {
+		cgoEnabled = "1"
+	}
 	cmd := exec.Command(filepath.Join(goenv.Get("GOROOT"), "bin", "go"), args...)
-	cmd.Env = append(os.Environ(), "GOROOT="+goroot, "GOOS="+config.GOOS(), "GOARCH="+config.GOARCH(), "CGO_ENABLED=1")
+	cmd.Env = append(os.Environ(), "GOROOT="+goroot, "GOOS="+config.GOOS(), "GOARCH="+config.GOARCH(), "CGO_ENABLED="+cgoEnabled)
 	if config.Options.Directory != "" {
 		cmd.Dir = config.Options.Directory
 	}
@@ -27,8 +27,6 @@ import (
 	"github.com/tinygo-org/tinygo/goenv"
 )

-var initFileVersions = func(info *types.Info) {}
-
 // Program holds all packages and some metadata about the program as a whole.
 type Program struct {
 	config      *compileopts.Config
@@ -380,24 +378,6 @@ func (p *Package) Check() error {
 		typeErrors = append(typeErrors, err)
 	}
 	checker.Importer = p
-	if p.Module.GoVersion != "" {
-		// Setting the Go version for a module makes sure the type checker
-		// errors out on language features not supported in that particular
-		// version.
-		checker.GoVersion = "go" + p.Module.GoVersion
-	} else {
-		// Version is not known, so use the currently installed Go version.
-		// This is needed for `tinygo run` for example.
-		// Normally we'd use goenv.GorootVersionString(), but for compatibility
-		// with Go 1.20 and below we need a version in the form of "go1.12" (no
-		// patch version).
-		major, minor, err := goenv.GetGorootVersion()
-		if err != nil {
-			return err
-		}
-		checker.GoVersion = fmt.Sprintf("go%d.%d", major, minor)
-	}
-	initFileVersions(&p.info)

 	// Do typechecking of the package.
 	packageName := p.ImportPath
@@ -467,7 +447,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		if errs != nil {
 			fileErrs = append(fileErrs, errs...)
 		}
-		files = append(files, generated...)
+		files = append(files, generated)
 		p.program.LDFlags = append(p.program.LDFlags, ldflags...)
 	}

@@ -1,17 +0,0 @@
-//go:build go1.22
-
-// types.Info.FileVersions was added in Go 1.22, so we can only initialize it
-// when built with Go 1.22.
-
-package loader
-
-import (
-	"go/ast"
-	"go/types"
-)
-
-func init() {
-	initFileVersions = func(info *types.Info) {
-		info.FileVersions = make(map[*ast.File]string)
-	}
-}
@@ -532,7 +532,7 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 		return fmt.Errorf("unknown flash method: %s", flashMethod)
 	}
 	if options.Monitor {
-		return Monitor(result.Executable, "", config)
+		return Monitor(result.Executable, "", options)
 	}
 	return nil
 }
@@ -1740,9 +1740,7 @@ func main() {
 				fmt.Printf("%s %4s %4s %s\n", s.Name, s.VID, s.PID, s.Target)
 			}
 		} else {
-			config, err := builder.NewConfig(options)
-			handleCompilerError(err)
-			err = Monitor("", *port, config)
+			err := Monitor("", *port, options)
 			handleCompilerError(err)
 		}
 	case "targets":
@@ -69,7 +69,6 @@ func TestBuild(t *testing.T) {
 		"json.go",
 		"map.go",
 		"math.go",
-		"oldgo/",
 		"print.go",
 		"reflect.go",
 		"slice.go",
@@ -91,9 +90,6 @@ func TestBuild(t *testing.T) {
 	if minor >= 21 {
 		tests = append(tests, "go1.21.go")
 	}
-	if minor >= 22 {
-		tests = append(tests, "go1.22/")
-	}

 	if *testTarget != "" {
 		// This makes it possible to run one specific test (instead of all),
@@ -210,6 +206,10 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 				// limited amount of memory.
 				continue

+			case "gc.go":
+				// Does not pass due to high mark false positive rate.
+				continue
+
 			case "json.go", "stdlib.go", "testing.go":
 				// Too big for AVR. Doesn't fit in flash/RAM.
 				continue
@@ -333,11 +333,8 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	path := TESTDATA + "/" + name
 	// Get the expected output for this test.
 	txtpath := path[:len(path)-3] + ".txt"
-	pkgName := "./" + path
 	if path[len(path)-1] == '/' {
 		txtpath = path + "out.txt"
-		options.Directory = path
-		pkgName = "."
 	}
 	expected, err := os.ReadFile(txtpath)
 	if err != nil {
@@ -351,7 +348,7 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c

 	// Build the test binary.
 	stdout := &bytes.Buffer{}
-	_, err = buildAndRun(pkgName, config, stdout, cmdArgs, environmentVars, time.Minute, func(cmd *exec.Cmd, result builder.BuildResult) error {
+	_, err = buildAndRun("./"+path, config, stdout, cmdArgs, environmentVars, time.Minute, func(cmd *exec.Cmd, result builder.BuildResult) error {
 		return cmd.Run()
 	})
 	if err != nil {
@@ -1,7 +1,6 @@
 package main

 import (
-	"bufio"
 	"debug/dwarf"
 	"debug/elf"
 	"debug/macho"
@@ -10,7 +9,6 @@ import (
 	"fmt"
 	"go/token"
 	"io"
-	"net"
 	"os"
 	"os/signal"
 	"regexp"
@@ -19,6 +17,7 @@ import (
 	"time"

 	"github.com/mattn/go-tty"
+	"github.com/tinygo-org/tinygo/builder"
 	"github.com/tinygo-org/tinygo/compileopts"

 	"go.bug.st/serial"
@@ -26,152 +25,45 @@ import (
 )

 // Monitor connects to the given port and reads/writes the serial port.
-func Monitor(executable, port string, config *compileopts.Config) error {
-	const timeout = time.Second * 3
-	var exit func() // function to be called before exiting
-	var serialConn io.ReadWriter
-
-	if config.Options.Serial == "rtt" {
-		// Use the RTT interface, which is documented (in part) here:
-		// https://wiki.segger.com/RTT
-
-		// Try to find the "machine.rttSerialInstance" symbol, which is the RTT
-		// control block.
-		file, err := elf.Open(executable)
-		if err != nil {
-			return fmt.Errorf("could not open ELF file to determine RTT control block: %w", err)
-		}
-		defer file.Close()
-		symbols, err := file.Symbols()
-		if err != nil {
-			return fmt.Errorf("could not read ELF symbol table to determine RTT control block: %w", err)
-		}
-		var address uint64
-		for _, symbol := range symbols {
-			if symbol.Name == "machine.rttSerialInstance" {
-				address = symbol.Value
-				break
-			}
-		}
-		if address == 0 {
-			return fmt.Errorf("could not find RTT control block in ELF file")
-		}
-
-		// Start an openocd process in the background.
-		args, err := config.OpenOCDConfiguration()
-		if err != nil {
-			return err
-		}
-		args = append(args,
-			"-c", fmt.Sprintf("rtt setup 0x%x 16 \"SEGGER RTT\"", address),
-			"-c", "init",
-			"-c", "rtt server start 0 0")
-		cmd := executeCommand(config.Options, "openocd", args...)
-		stderr, err := cmd.StderrPipe()
-		if err != nil {
-			return err
-		}
-		cmd.Stdout = os.Stdout
-		err = cmd.Start()
-		if err != nil {
-			return err
-		}
-		defer cmd.Process.Kill()
-		exit = func() {
-			// Make sure the openocd process is terminated at exit.
-			// This does not happen through the defer above when exiting through
-			// os.Exit.
-			cmd.Process.Kill()
-		}
-
-		// Read the stderr, which logs various important messages we need.
-		r := bufio.NewReader(stderr)
-		var telnet net.Conn
-		var timeoutAt time.Time
-		for {
-			// Read the next line from the openocd process.
-			lineBytes, err := r.ReadBytes('\n')
-			if err != nil {
-				return err
-			}
-			line := string(lineBytes)
-
-			if line == "Info : rtt: No control block found\n" {
-				// Message that is sent back when OpenOCD can't find the control
-				// block after a 'rtt start' message.
-				if time.Now().After(timeoutAt) {
-					return fmt.Errorf("RTT timeout (could not locate RTT control block at 0x%08x)", address)
-				}
-				time.Sleep(time.Millisecond * 100)
-				telnet.Write([]byte("rtt start\r\n"))
-			} else if strings.HasPrefix(line, "Info : Listening on port") {
-				// We need two different ports for controlling OpenOCD
-				// (typically port 4444) and the RTT channel 0 socket (arbitrary
-				// port).
-				var port int
-				var protocol string
-				fmt.Sscanf(line, "Info : Listening on port %d for %s connections\n", &port, &protocol)
-				if protocol == "telnet" && telnet == nil {
-					// Connect to the "telnet" command line interface.
-					telnet, err = net.Dial("tcp4", fmt.Sprintf("localhost:%d", port))
-					if err != nil {
-						return err
-					}
-					// Tell OpenOCD to start scanning for the RTT control block.
-					telnet.Write([]byte("rtt start\r\n"))
-					// Also make sure we will time out if the control block just
-					// can't be found.
-					timeoutAt = time.Now().Add(timeout)
-				} else if protocol == "rtt" {
-					// Connect to the RTT channel, for both stdin and stdout.
-					conn, err := net.Dial("tcp4", fmt.Sprintf("localhost:%d", port))
-					if err != nil {
-						return err
-					}
-					serialConn = conn
-				}
-			} else if strings.HasPrefix(line, "Info : rtt: Control block found at") {
-				// Connection established!
-				break
-			}
-		}
-	} else { // -serial=uart or -serial=usb
-		var err error
-		wait := 300
-		for i := 0; i <= wait; i++ {
-			port, err = getDefaultPort(port, config.Target.SerialPort)
-			if err != nil {
-				if i < wait {
-					time.Sleep(10 * time.Millisecond)
-					continue
-				}
-				return err
-			}
-			break
-		}
-
-		br := config.Options.BaudRate
-		if br <= 0 {
-			br = 115200
-		}
-
-		wait = 300
-		var p serial.Port
-		for i := 0; i <= wait; i++ {
-			p, err = serial.Open(port, &serial.Mode{BaudRate: br})
-			if err != nil {
-				if i < wait {
-					time.Sleep(10 * time.Millisecond)
-					continue
-				}
-				return err
-			}
-			serialConn = p
-			break
-		}
-		defer p.Close()
+func Monitor(executable, port string, options *compileopts.Options) error {
+	config, err := builder.NewConfig(options)
+	if err != nil {
+		return err
 	}

+	wait := 300
+	for i := 0; i <= wait; i++ {
+		port, err = getDefaultPort(port, config.Target.SerialPort)
+		if err != nil {
+			if i < wait {
+				time.Sleep(10 * time.Millisecond)
+				continue
+			}
+			return err
+		}
+		break
+	}
+
+	br := options.BaudRate
+	if br <= 0 {
+		br = 115200
+	}
+
+	wait = 300
+	var p serial.Port
+	for i := 0; i <= wait; i++ {
+		p, err = serial.Open(port, &serial.Mode{BaudRate: br})
+		if err != nil {
+			if i < wait {
+				time.Sleep(10 * time.Millisecond)
+				continue
+			}
+			return err
+		}
+		break
+	}
+	defer p.Close()
+
 	tty, err := tty.Open()
 	if err != nil {
 		return err
@@ -185,9 +77,6 @@ func Monitor(executable, port string, config *compileopts.Config) error {
 	go func() {
 		<-sig
 		tty.Close()
-		if exit != nil {
-			exit()
-		}
 		os.Exit(0)
 	}()

@@ -199,7 +88,7 @@ func Monitor(executable, port string, config *compileopts.Config) error {
 		buf := make([]byte, 100*1024)
 		var line []byte
 		for {
-			n, err := serialConn.Read(buf)
+			n, err := p.Read(buf)
 			if err != nil {
 				errCh <- fmt.Errorf("read error: %w", err)
 				return
@@ -235,7 +124,7 @@ func Monitor(executable, port string, config *compileopts.Config) error {
 			if r == 0 {
 				continue
 			}
-			serialConn.Write([]byte(string(r)))
+			p.Write([]byte(string(r)))
 		}
 	}()

@@ -1,7 +1,4 @@
-//go:build nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3
-
-// If you update the above build constraint, you'll probably also need to update
-// src/runtime/rand_hwrng.go.
+//go:build nrf || stm32 || (sam && atsamd51) || (sam && atsame5x)

 package rand

@@ -1,447 +0,0 @@
-// TINYGO: The following is copied and modified from Go 1.19.3 official implementation.
-
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tls
-
-import (
-	"context"
-	"crypto"
-	"crypto/x509"
-	"io"
-	"net"
-	"sync"
-	"time"
-)
-
-// CurveID is the type of a TLS identifier for an elliptic curve. See
-// https://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8.
-//
-// In TLS 1.3, this type is called NamedGroup, but at this time this library
-// only supports Elliptic Curve based groups. See RFC 8446, Section 4.2.7.
-type CurveID uint16
-
-// ConnectionState records basic TLS details about the connection.
-type ConnectionState struct {
-	// TINYGO: empty; TLS connection offloaded to device
-}
-
-// ClientAuthType declares the policy the server will follow for
-// TLS Client Authentication.
-type ClientAuthType int
-
-// ClientSessionCache is a cache of ClientSessionState objects that can be used
-// by a client to resume a TLS session with a given server. ClientSessionCache
-// implementations should expect to be called concurrently from different
-// goroutines. Up to TLS 1.2, only ticket-based resumption is supported, not
-// SessionID-based resumption. In TLS 1.3 they were merged into PSK modes, which
-// are supported via this interface.
-type ClientSessionCache interface {
-	// Get searches for a ClientSessionState associated with the given key.
-	// On return, ok is true if one was found.
-	Get(sessionKey string) (session *ClientSessionState, ok bool)
-
-	// Put adds the ClientSessionState to the cache with the given key. It might
-	// get called multiple times in a connection if a TLS 1.3 server provides
-	// more than one session ticket. If called with a nil *ClientSessionState,
-	// it should remove the cache entry.
-	Put(sessionKey string, cs *ClientSessionState)
-}
-
-//go:generate stringer -type=SignatureScheme,CurveID,ClientAuthType -output=common_string.go
-
-// SignatureScheme identifies a signature algorithm supported by TLS. See
-// RFC 8446, Section 4.2.3.
-type SignatureScheme uint16
-
-// ClientHelloInfo contains information from a ClientHello message in order to
-// guide application logic in the GetCertificate and GetConfigForClient callbacks.
-type ClientHelloInfo struct {
-	// CipherSuites lists the CipherSuites supported by the client (e.g.
-	// TLS_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).
-	CipherSuites []uint16
-
-	// ServerName indicates the name of the server requested by the client
-	// in order to support virtual hosting. ServerName is only set if the
-	// client is using SNI (see RFC 4366, Section 3.1).
-	ServerName string
-
-	// SupportedCurves lists the elliptic curves supported by the client.
-	// SupportedCurves is set only if the Supported Elliptic Curves
-	// Extension is being used (see RFC 4492, Section 5.1.1).
-	SupportedCurves []CurveID
-
-	// SupportedPoints lists the point formats supported by the client.
-	// SupportedPoints is set only if the Supported Point Formats Extension
-	// is being used (see RFC 4492, Section 5.1.2).
-	SupportedPoints []uint8
-
-	// SignatureSchemes lists the signature and hash schemes that the client
-	// is willing to verify. SignatureSchemes is set only if the Signature
-	// Algorithms Extension is being used (see RFC 5246, Section 7.4.1.4.1).
-	SignatureSchemes []SignatureScheme
-
-	// SupportedProtos lists the application protocols supported by the client.
-	// SupportedProtos is set only if the Application-Layer Protocol
-	// Negotiation Extension is being used (see RFC 7301, Section 3.1).
-	//
-	// Servers can select a protocol by setting Config.NextProtos in a
-	// GetConfigForClient return value.
-	SupportedProtos []string
-
-	// SupportedVersions lists the TLS versions supported by the client.
-	// For TLS versions less than 1.3, this is extrapolated from the max
-	// version advertised by the client, so values other than the greatest
-	// might be rejected if used.
-	SupportedVersions []uint16
-
-	// Conn is the underlying net.Conn for the connection. Do not read
-	// from, or write to, this connection; that will cause the TLS
-	// connection to fail.
-	Conn net.Conn
-
-	// config is embedded by the GetCertificate or GetConfigForClient caller,
-	// for use with SupportsCertificate.
-	config *Config
-
-	// ctx is the context of the handshake that is in progress.
-	ctx context.Context
-}
-
-// CertificateRequestInfo contains information from a server's
-// CertificateRequest message, which is used to demand a certificate and proof
-// of control from a client.
-type CertificateRequestInfo struct {
-	// AcceptableCAs contains zero or more, DER-encoded, X.501
-	// Distinguished Names. These are the names of root or intermediate CAs
-	// that the server wishes the returned certificate to be signed by. An
-	// empty slice indicates that the server has no preference.
-	AcceptableCAs [][]byte
-
-	// SignatureSchemes lists the signature schemes that the server is
-	// willing to verify.
-	SignatureSchemes []SignatureScheme
-
-	// Version is the TLS version that was negotiated for this connection.
-	Version uint16
-
-	// ctx is the context of the handshake that is in progress.
-	ctx context.Context
-}
-
-// RenegotiationSupport enumerates the different levels of support for TLS
-// renegotiation. TLS renegotiation is the act of performing subsequent
-// handshakes on a connection after the first. This significantly complicates
-// the state machine and has been the source of numerous, subtle security
-// issues. Initiating a renegotiation is not supported, but support for
-// accepting renegotiation requests may be enabled.
-//
-// Even when enabled, the server may not change its identity between handshakes
-// (i.e. the leaf certificate must be the same). Additionally, concurrent
-// handshake and application data flow is not permitted so renegotiation can
-// only be used with protocols that synchronise with the renegotiation, such as
-// HTTPS.
-//
-// Renegotiation is not defined in TLS 1.3.
-type RenegotiationSupport int
-
-// A Config structure is used to configure a TLS client or server.
-// After one has been passed to a TLS function it must not be
-// modified. A Config may be reused; the tls package will also not
-// modify it.
-type Config struct {
-	// Rand provides the source of entropy for nonces and RSA blinding.
-	// If Rand is nil, TLS uses the cryptographic random reader in package
-	// crypto/rand.
-	// The Reader must be safe for use by multiple goroutines.
-	Rand io.Reader
-
-	// Time returns the current time as the number of seconds since the epoch.
-	// If Time is nil, TLS uses time.Now.
-	Time func() time.Time
-
-	// Certificates contains one or more certificate chains to present to the
-	// other side of the connection. The first certificate compatible with the
-	// peer's requirements is selected automatically.
-	//
-	// Server configurations must set one of Certificates, GetCertificate or
-	// GetConfigForClient. Clients doing client-authentication may set either
-	// Certificates or GetClientCertificate.
-	//
-	// Note: if there are multiple Certificates, and they don't have the
-	// optional field Leaf set, certificate selection will incur a significant
-	// per-handshake performance cost.
-	Certificates []Certificate
-
-	// NameToCertificate maps from a certificate name to an element of
-	// Certificates. Note that a certificate name can be of the form
-	// '*.example.com' and so doesn't have to be a domain name as such.
-	//
-	// Deprecated: NameToCertificate only allows associating a single
-	// certificate with a given name. Leave this field nil to let the library
-	// select the first compatible chain from Certificates.
-	NameToCertificate map[string]*Certificate
-
-	// GetCertificate returns a Certificate based on the given
-	// ClientHelloInfo. It will only be called if the client supplies SNI
-	// information or if Certificates is empty.
-	//
-	// If GetCertificate is nil or returns nil, then the certificate is
-	// retrieved from NameToCertificate. If NameToCertificate is nil, the
-	// best element of Certificates will be used.
-	//
-	// Once a Certificate is returned it should not be modified.
-	GetCertificate func(*ClientHelloInfo) (*Certificate, error)
-
-	// GetClientCertificate, if not nil, is called when a server requests a
-	// certificate from a client. If set, the contents of Certificates will
-	// be ignored.
-	//
-	// If GetClientCertificate returns an error, the handshake will be
-	// aborted and that error will be returned. Otherwise
-	// GetClientCertificate must return a non-nil Certificate. If
-	// Certificate.Certificate is empty then no certificate will be sent to
-	// the server. If this is unacceptable to the server then it may abort
-	// the handshake.
-	//
-	// GetClientCertificate may be called multiple times for the same
-	// connection if renegotiation occurs or if TLS 1.3 is in use.
-	//
-	// Once a Certificate is returned it should not be modified.
-	GetClientCertificate func(*CertificateRequestInfo) (*Certificate, error)
-
-	// GetConfigForClient, if not nil, is called after a ClientHello is
-	// received from a client. It may return a non-nil Config in order to
-	// change the Config that will be used to handle this connection. If
-	// the returned Config is nil, the original Config will be used. The
-	// Config returned by this callback may not be subsequently modified.
-	//
-	// If GetConfigForClient is nil, the Config passed to Server() will be
-	// used for all connections.
-	//
-	// If SessionTicketKey was explicitly set on the returned Config, or if
-	// SetSessionTicketKeys was called on the returned Config, those keys will
-	// be used. Otherwise, the original Config keys will be used (and possibly
-	// rotated if they are automatically managed).
-	GetConfigForClient func(*ClientHelloInfo) (*Config, error)
-
-	// VerifyPeerCertificate, if not nil, is called after normal
-	// certificate verification by either a TLS client or server. It
-	// receives the raw ASN.1 certificates provided by the peer and also
-	// any verified chains that normal processing found. If it returns a
-	// non-nil error, the handshake is aborted and that error results.
-	//
-	// If normal verification fails then the handshake will abort before
-	// considering this callback. If normal verification is disabled (on the
-	// client when InsecureSkipVerify is set, or on a server when ClientAuth is
-	// RequestClientCert or RequireAnyClientCert), then this callback will be
-	// considered but the verifiedChains argument will always be nil. When
-	// ClientAuth is NoClientCert, this callback is not called on the server.
-	// rawCerts may be empty on the server if ClientAuth is RequestClientCert or
-	// VerifyClientCertIfGiven.
-	//
-	// This callback is not invoked on resumed connections, as certificates are
-	// not re-verified on resumption.
-	//
-	// verifiedChains and its contents should not be modified.
-	VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error
-
-	// VerifyConnection, if not nil, is called after normal certificate
-	// verification and after VerifyPeerCertificate by either a TLS client
-	// or server. If it returns a non-nil error, the handshake is aborted
-	// and that error results.
-	//
-	// If normal verification fails then the handshake will abort before
-	// considering this callback. This callback will run for all connections,
-	// including resumptions, regardless of InsecureSkipVerify or ClientAuth
-	// settings.
-	VerifyConnection func(ConnectionState) error
-
-	// RootCAs defines the set of root certificate authorities
-	// that clients use when verifying server certificates.
-	// If RootCAs is nil, TLS uses the host's root CA set.
-	RootCAs *x509.CertPool
-
-	// NextProtos is a list of supported application level protocols, in
-	// order of preference. If both peers support ALPN, the selected
-	// protocol will be one from this list, and the connection will fail
-	// if there is no mutually supported protocol. If NextProtos is empty
-	// or the peer doesn't support ALPN, the connection will succeed and
-	// ConnectionState.NegotiatedProtocol will be empty.
-	NextProtos []string
-
-	// ServerName is used to verify the hostname on the returned
-	// certificates unless InsecureSkipVerify is given. It is also included
-	// in the client's handshake to support virtual hosting unless it is
-	// an IP address.
-	ServerName string
-
-	// ClientAuth determines the server's policy for
-	// TLS Client Authentication. The default is NoClientCert.
-	ClientAuth ClientAuthType
-
-	// ClientCAs defines the set of root certificate authorities
-	// that servers use if required to verify a client certificate
-	// by the policy in ClientAuth.
-	ClientCAs *x509.CertPool
-
-	// InsecureSkipVerify controls whether a client verifies the server's
-	// certificate chain and host name. If InsecureSkipVerify is true, crypto/tls
-	// accepts any certificate presented by the server and any host name in that
-	// certificate. In this mode, TLS is susceptible to machine-in-the-middle
-	// attacks unless custom verification is used. This should be used only for
-	// testing or in combination with VerifyConnection or VerifyPeerCertificate.
-	InsecureSkipVerify bool
-
-	// CipherSuites is a list of enabled TLS 1.0–1.2 cipher suites. The order of
-	// the list is ignored. Note that TLS 1.3 ciphersuites are not configurable.
-	//
-	// If CipherSuites is nil, a safe default list is used. The default cipher
-	// suites might change over time.
-	CipherSuites []uint16
-
-	// PreferServerCipherSuites is a legacy field and has no effect.
-	//
-	// It used to control whether the server would follow the client's or the
-	// server's preference. Servers now select the best mutually supported
-	// cipher suite based on logic that takes into account inferred client
-	// hardware, server hardware, and security.
-	//
-	// Deprecated: PreferServerCipherSuites is ignored.
-	PreferServerCipherSuites bool
-
-	// SessionTicketsDisabled may be set to true to disable session ticket and
-	// PSK (resumption) support. Note that on clients, session ticket support is
-	// also disabled if ClientSessionCache is nil.
-	SessionTicketsDisabled bool
-
-	// SessionTicketKey is used by TLS servers to provide session resumption.
-	// See RFC 5077 and the PSK mode of RFC 8446. If zero, it will be filled
-	// with random data before the first server handshake.
-	//
-	// Deprecated: if this field is left at zero, session ticket keys will be
-	// automatically rotated every day and dropped after seven days. For
-	// customizing the rotation schedule or synchronizing servers that are
-	// terminating connections for the same host, use SetSessionTicketKeys.
-	SessionTicketKey [32]byte
-
-	// ClientSessionCache is a cache of ClientSessionState entries for TLS
-	// session resumption. It is only used by clients.
-	ClientSessionCache ClientSessionCache
-
-	// UnwrapSession is called on the server to turn a ticket/identity
-	// previously produced by [WrapSession] into a usable session.
-	//
-	// UnwrapSession will usually either decrypt a session state in the ticket
-	// (for example with [Config.EncryptTicket]), or use the ticket as a handle
-	// to recover a previously stored state. It must use [ParseSessionState] to
-	// deserialize the session state.
-	//
-	// If UnwrapSession returns an error, the connection is terminated. If it
-	// returns (nil, nil), the session is ignored. crypto/tls may still choose
-	// not to resume the returned session.
-	UnwrapSession func(identity []byte, cs ConnectionState) (*SessionState, error)
-
-	// WrapSession is called on the server to produce a session ticket/identity.
-	//
-	// WrapSession must serialize the session state with [SessionState.Bytes].
-	// It may then encrypt the serialized state (for example with
-	// [Config.DecryptTicket]) and use it as the ticket, or store the state and
-	// return a handle for it.
-	//
-	// If WrapSession returns an error, the connection is terminated.
-	//
-	// Warning: the return value will be exposed on the wire and to clients in
-	// plaintext. The application is in charge of encrypting and authenticating
-	// it (and rotating keys) or returning high-entropy identifiers. Failing to
-	// do so correctly can compromise current, previous, and future connections
-	// depending on the protocol version.
-	WrapSession func(ConnectionState, *SessionState) ([]byte, error)
-
-	// MinVersion contains the minimum TLS version that is acceptable.
-	//
-	// By default, TLS 1.2 is currently used as the minimum when acting as a
-	// client, and TLS 1.0 when acting as a server. TLS 1.0 is the minimum
-	// supported by this package, both as a client and as a server.
-	//
-	// The client-side default can temporarily be reverted to TLS 1.0 by
-	// including the value "x509sha1=1" in the GODEBUG environment variable.
-	// Note that this option will be removed in Go 1.19 (but it will still be
-	// possible to set this field to VersionTLS10 explicitly).
-	MinVersion uint16
-
-	// MaxVersion contains the maximum TLS version that is acceptable.
-	//
-	// By default, the maximum version supported by this package is used,
-	// which is currently TLS 1.3.
-	MaxVersion uint16
-
-	// CurvePreferences contains the elliptic curves that will be used in
-	// an ECDHE handshake, in preference order. If empty, the default will
-	// be used. The client will use the first preference as the type for
-	// its key share in TLS 1.3. This may change in the future.
-	CurvePreferences []CurveID
-
-	// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
-	// When true, the largest possible TLS record size is always used. When
-	// false, the size of TLS records may be adjusted in an attempt to
-	// improve latency.
-	DynamicRecordSizingDisabled bool
-
-	// Renegotiation controls what types of renegotiation are supported.
-	// The default, none, is correct for the vast majority of applications.
-	Renegotiation RenegotiationSupport
-
-	// KeyLogWriter optionally specifies a destination for TLS master secrets
-	// in NSS key log format that can be used to allow external programs
-	// such as Wireshark to decrypt TLS connections.
-	// See https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format.
-	// Use of KeyLogWriter compromises security and should only be
-	// used for debugging.
-	KeyLogWriter io.Writer
-
-	// mutex protects sessionTicketKeys and autoSessionTicketKeys.
-	mutex sync.RWMutex
-	// sessionTicketKeys contains zero or more ticket keys. If set, it means
-	// the keys were set with SessionTicketKey or SetSessionTicketKeys. The
-	// first key is used for new tickets and any subsequent keys can be used to
-	// decrypt old tickets. The slice contents are not protected by the mutex
-	// and are immutable.
-	sessionTicketKeys []ticketKey
-	// autoSessionTicketKeys is like sessionTicketKeys but is owned by the
-	// auto-rotation logic. See Config.ticketKeys.
-	autoSessionTicketKeys []ticketKey
-}
-
-// ticketKey is the internal representation of a session ticket key.
-type ticketKey struct {
-	aesKey  [16]byte
-	hmacKey [16]byte
-	// created is the time at which this ticket key was created. See Config.ticketKeys.
-	created time.Time
-}
-
-// A Certificate is a chain of one or more certificates, leaf first.
-type Certificate struct {
-	Certificate [][]byte
-	// PrivateKey contains the private key corresponding to the public key in
-	// Leaf. This must implement crypto.Signer with an RSA, ECDSA or Ed25519 PublicKey.
-	// For a server up to TLS 1.2, it can also implement crypto.Decrypter with
-	// an RSA PublicKey.
-	PrivateKey crypto.PrivateKey
-	// SupportedSignatureAlgorithms is an optional list restricting what
-	// signature algorithms the PrivateKey can be used for.
-	SupportedSignatureAlgorithms []SignatureScheme
-	// OCSPStaple contains an optional OCSP response which will be served
-	// to clients that request it.
-	OCSPStaple []byte
-	// SignedCertificateTimestamps contains an optional list of Signed
-	// Certificate Timestamps which will be served to clients that request it.
-	SignedCertificateTimestamps [][]byte
-	// Leaf is the parsed form of the leaf certificate, which may be initialized
-	// using x509.ParseCertificate to reduce per-handshake processing. If nil,
-	// the leaf certificate will be parsed as needed.
-	Leaf *x509.Certificate
-}
@@ -1,16 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tls
-
-// A SessionState is a resumable session.
-type SessionState struct {
-}
-
-// ClientSessionState contains the state needed by a client to
-// resume a previous TLS session.
-type ClientSessionState struct {
-	ticket  []byte
-	session *SessionState
-}
@@ -1,114 +0,0 @@
-// TINYGO: The following is copied and modified from Go 1.21.4 official implementation.
-
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package tls partially implements TLS 1.2, as specified in RFC 5246,
-// and TLS 1.3, as specified in RFC 8446.
-package tls
-
-// BUG(agl): The crypto/tls package only implements some countermeasures
-// against Lucky13 attacks on CBC-mode encryption, and only on SHA1
-// variants. See http://www.isg.rhul.ac.uk/tls/TLStiming.pdf and
-// https://www.imperialviolet.org/2013/02/04/luckythirteen.html.
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"net"
-)
-
-// Client returns a new TLS client side connection
-// using conn as the underlying transport.
-// The config cannot be nil: users must set either ServerName or
-// InsecureSkipVerify in the config.
-func Client(conn net.Conn, config *Config) *net.TLSConn {
-	panic("tls.Client() not implemented")
-	return nil
-}
-
-// A listener implements a network listener (net.Listener) for TLS connections.
-type listener struct {
-	net.Listener
-	config *Config
-}
-
-// NewListener creates a Listener which accepts connections from an inner
-// Listener and wraps each connection with Server.
-// The configuration config must be non-nil and must include
-// at least one certificate or else set GetCertificate.
-func NewListener(inner net.Listener, config *Config) net.Listener {
-	l := new(listener)
-	l.Listener = inner
-	l.config = config
-	return l
-}
-
-// DialWithDialer connects to the given network address using dialer.Dial and
-// then initiates a TLS handshake, returning the resulting TLS connection. Any
-// timeout or deadline given in the dialer apply to connection and TLS
-// handshake as a whole.
-//
-// DialWithDialer interprets a nil configuration as equivalent to the zero
-// configuration; see the documentation of Config for the defaults.
-//
-// DialWithDialer uses context.Background internally; to specify the context,
-// use Dialer.DialContext with NetDialer set to the desired dialer.
-func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*net.TLSConn, error) {
-	switch network {
-	case "tcp", "tcp4":
-	default:
-		return nil, fmt.Errorf("Network %s not supported", network)
-	}
-
-	return net.DialTLS(addr)
-}
-
-// Dial connects to the given network address using net.Dial
-// and then initiates a TLS handshake, returning the resulting
-// TLS connection.
-// Dial interprets a nil configuration as equivalent to
-// the zero configuration; see the documentation of Config
-// for the defaults.
-func Dial(network, addr string, config *Config) (*net.TLSConn, error) {
-	return DialWithDialer(new(net.Dialer), network, addr, config)
-}
-
-// Dialer dials TLS connections given a configuration and a Dialer for the
-// underlying connection.
-type Dialer struct {
-	// NetDialer is the optional dialer to use for the TLS connections'
-	// underlying TCP connections.
-	// A nil NetDialer is equivalent to the net.Dialer zero value.
-	NetDialer *net.Dialer
-
-	// Config is the TLS configuration to use for new connections.
-	// A nil configuration is equivalent to the zero
-	// configuration; see the documentation of Config for the
-	// defaults.
-	Config *Config
-}
-
-// DialContext connects to the given network address and initiates a TLS
-// handshake, returning the resulting TLS connection.
-//
-// The provided Context must be non-nil. If the context expires before
-// the connection is complete, an error is returned. Once successfully
-// connected, any expiration of the context will not affect the
-// connection.
-//
-// The returned Conn, if any, will always be of type *Conn.
-func (d *Dialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	return nil, errors.New("tls:DialContext not implmented")
-}
-
-// LoadX509KeyPair reads and parses a public/private key pair from a pair
-// of files. The files must contain PEM encoded data. The certificate file
-// may contain intermediate certificates following the leaf certificate to
-// form a certificate chain. On successful return, Certificate.Leaf will
-// be nil because the parsed form of the certificate is not retained.
-func LoadX509KeyPair(certFile, keyFile string) (Certificate, error) {
-	return Certificate{}, errors.New("tls:LoadX509KeyPair not implemented")
-}
@@ -1,18 +0,0 @@
-// this is intended to be used as wasm32-unknown-unknown module.
-// to compile it, run:
-// tinygo build -size short -o hello-unknown.wasm -target wasm-unknown -gc=leaking -no-debug ./src/examples/hello-wasm-unknown/
-package main
-
-var x int32
-
-//go:wasmimport hosted echo_i32
-func echo(x int32)
-
-//go:export update
-func update() {
-	x++
-	echo(x)
-}
-
-func main() {
-}
@@ -1,6 +1,6 @@
 // to override the USB Manufacturer or Product names:
 //
-// tinygo flash -target circuitplay-express -ldflags="-X main.usbManufacturer='TinyGopher Labs' -X main.usbProduct='GopherKeyboard' -X main.usbSerial='XXXXX'" examples/hid-keyboard
+// tinygo flash -target circuitplay-express -ldflags="-X main.usbManufacturer='TinyGopher Labs' -X main.usbProduct='GopherKeyboard'" examples/hid-keyboard
 //
 // you can also override the VID/PID. however, only set this if you know what you are doing,
 // since changing it can make it difficult to reflash some devices.
@@ -15,7 +15,7 @@ import (
 )

 var usbVID, usbPID string
-var usbManufacturer, usbProduct, usbSerial string
+var usbManufacturer, usbProduct string

 func main() {
 	button := machine.BUTTON
@@ -49,8 +49,4 @@ func init() {
 	if usbProduct != "" {
 		usb.Product = usbProduct
 	}
-
-	if usbSerial != "" {
-		usb.Serial = usbSerial
-	}
 }
@@ -1,14 +1,5 @@
 package bytealg

-// Some code in this file has been copied from the Go source code, and has
-// copyright of their original authors:
-//
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-//
-// This is indicated specifically in the file.
-
 const (
 	// Index can search any valid length of string.

@@ -134,6 +125,10 @@ func IndexString(str, sub string) int {
 	return -1
 }

+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 // The following code has been copied from the Go 1.15 release tree.

 // PrimeRK is the prime base used in Rabin-Karp algorithm.
@@ -141,8 +136,6 @@ const PrimeRK = 16777619

 // HashStrBytes returns the hash and the appropriate multiplicative
 // factor for use in Rabin-Karp algorithm.
-//
-// This function was removed in Go 1.22.
 func HashStrBytes(sep []byte) (uint32, uint32) {
 	hash := uint32(0)
 	for i := 0; i < len(sep); i++ {
@@ -160,9 +153,7 @@ func HashStrBytes(sep []byte) (uint32, uint32) {

 // HashStr returns the hash and the appropriate multiplicative
 // factor for use in Rabin-Karp algorithm.
-//
-// This function was removed in Go 1.22.
-func HashStr[T string | []byte](sep T) (uint32, uint32) {
+func HashStr(sep string) (uint32, uint32) {
 	hash := uint32(0)
 	for i := 0; i < len(sep); i++ {
 		hash = hash*PrimeRK + uint32(sep[i])
@@ -179,8 +170,6 @@ func HashStr[T string | []byte](sep T) (uint32, uint32) {

 // HashStrRevBytes returns the hash of the reverse of sep and the
 // appropriate multiplicative factor for use in Rabin-Karp algorithm.
-//
-// This function was removed in Go 1.22.
 func HashStrRevBytes(sep []byte) (uint32, uint32) {
 	hash := uint32(0)
 	for i := len(sep) - 1; i >= 0; i-- {
@@ -198,9 +187,7 @@ func HashStrRevBytes(sep []byte) (uint32, uint32) {

 // HashStrRev returns the hash of the reverse of sep and the
 // appropriate multiplicative factor for use in Rabin-Karp algorithm.
-//
-// Copied from the Go 1.22rc1 source tree.
-func HashStrRev[T string | []byte](sep T) (uint32, uint32) {
+func HashStrRev(sep string) (uint32, uint32) {
 	hash := uint32(0)
 	for i := len(sep) - 1; i >= 0; i-- {
 		hash = hash*PrimeRK + uint32(sep[i])
@@ -217,8 +204,6 @@ func HashStrRev[T string | []byte](sep T) (uint32, uint32) {

 // IndexRabinKarpBytes uses the Rabin-Karp search algorithm to return the index of the
 // first occurence of substr in s, or -1 if not present.
-//
-// This function was removed in Go 1.22.
 func IndexRabinKarpBytes(s, sep []byte) int {
 	// Rabin-Karp search
 	hashsep, pow := HashStrBytes(sep)
@@ -243,18 +228,16 @@ func IndexRabinKarpBytes(s, sep []byte) int {
 }

 // IndexRabinKarp uses the Rabin-Karp search algorithm to return the index of the
-// first occurrence of sep in s, or -1 if not present.
-//
-// Copied from the Go 1.22rc1 source tree.
-func IndexRabinKarp[T string | []byte](s, sep T) int {
+// first occurence of substr in s, or -1 if not present.
+func IndexRabinKarp(s, substr string) int {
 	// Rabin-Karp search
-	hashss, pow := HashStr(sep)
-	n := len(sep)
+	hashss, pow := HashStr(substr)
+	n := len(substr)
 	var h uint32
 	for i := 0; i < n; i++ {
 		h = h*PrimeRK + uint32(s[i])
 	}
-	if h == hashss && string(s[:n]) == string(sep) {
+	if h == hashss && s[:n] == substr {
 		return 0
 	}
 	for i := n; i < len(s); {
@@ -262,7 +245,7 @@ func IndexRabinKarp[T string | []byte](s, sep T) int {
 		h += uint32(s[i])
 		h -= pow * uint32(s[i-n])
 		i++
-		if h == hashss && string(s[i-n:i]) == string(sep) {
+		if h == hashss && s[i-n:i] == substr {
 			return i - n
 		}
 	}
@@ -278,50 +261,3 @@ func MakeNoZero(n int) []byte {
 	// malloc function implemented in the runtime).
 	return make([]byte, n)
 }
-
-// Copied from the Go 1.22rc1 source tree.
-func LastIndexByte(s []byte, c byte) int {
-	for i := len(s) - 1; i >= 0; i-- {
-		if s[i] == c {
-			return i
-		}
-	}
-	return -1
-}
-
-// Copied from the Go 1.22rc1 source tree.
-func LastIndexByteString(s string, c byte) int {
-	for i := len(s) - 1; i >= 0; i-- {
-		if s[i] == c {
-			return i
-		}
-	}
-	return -1
-}
-
-// LastIndexRabinKarp uses the Rabin-Karp search algorithm to return the last index of the
-// occurrence of sep in s, or -1 if not present.
-//
-// Copied from the Go 1.22rc1 source tree.
-func LastIndexRabinKarp[T string | []byte](s, sep T) int {
-	// Rabin-Karp search from the end of the string
-	hashss, pow := HashStrRev(sep)
-	n := len(sep)
-	last := len(s) - n
-	var h uint32
-	for i := len(s) - 1; i >= last; i-- {
-		h = h*PrimeRK + uint32(s[i])
-	}
-	if h == hashss && string(s[last:]) == string(sep) {
-		return last
-	}
-	for i := last - 1; i >= 0; i-- {
-		h *= PrimeRK
-		h += uint32(s[i])
-		h -= pow * uint32(s[i+n])
-		if h == hashss && string(s[i:i+n]) == string(sep) {
-			return i
-		}
-	}
-	return -1
-}
@@ -1,5 +1,3 @@
-//go:build tinygo
-
 // Only generate .debug_frame, don't generate .eh_frame.
 .cfi_sections .debug_frame

@@ -1,5 +1,3 @@
-//go:build tinygo
-
 .section .bss.tinygo_systemStack
 .global tinygo_systemStack
 .type   tinygo_systemStack, %object
@@ -1,5 +1,3 @@
-//go:build tinygo
-
 // Only generate .debug_frame, don't generate .eh_frame.
 .cfi_sections .debug_frame

@@ -52,17 +52,17 @@ func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
 }

 func (s *state) resume() {
-	tinygo_switchToTask(s.sp)
+	switchToTask(s.sp)
 }

 //export tinygo_switchToTask
-func tinygo_switchToTask(uintptr)
+func switchToTask(uintptr)

 //export tinygo_switchToScheduler
-func tinygo_switchToScheduler(*uintptr)
+func switchToScheduler(*uintptr)

 func (s *state) pause() {
-	tinygo_switchToScheduler(&s.sp)
+	switchToScheduler(&s.sp)
 }

 // SystemStack returns the system stack pointer. On Cortex-M, it is always
@@ -1,5 +1,3 @@
-//go:build tinygo
-
 .section .text.tinygo_startTask,"ax",@progbits
 .global  tinygo_startTask
 .type    tinygo_startTask, %function
@@ -1,5 +1,3 @@
-//go:build tinygo
-
 .section .text.tinygo_startTask,"ax",@progbits
 .global  tinygo_startTask
 .type    tinygo_startTask, %function
@@ -1,5 +1,3 @@
-//go:build tinygo
-
 .section .text.tinygo_startTask
 .global  tinygo_startTask
 .type    tinygo_startTask, %function
@@ -2,6 +2,11 @@

 package machine

+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 16000000
+}
+
 // Digital pins, marked as plain numbers on the board.
 const (
 	D0  = PD0 // RX
@@ -2,6 +2,11 @@

 package machine

+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 16000000
+}
+
 // Digital pins.
 const (
 	D0  = PD0 // RX0
@@ -63,9 +63,6 @@ var UART1 = &sercomUSART3
 // UART2 on the Arduino Nano 33 connects to the normal TX/RX pins.
 var UART2 = &sercomUSART5

-// UART_NINA on the Arduino Nano 33 connects to the NINA HCI.
-var UART_NINA = &sercomUSART2
-
 // I2C pins
 const (
 	SDA_PIN Pin = A4 // SDA: SERCOM4/PAD[1]
@@ -102,17 +99,8 @@ const (
 	NINA_GPIO0  Pin = PA27
 	NINA_RESETN Pin = PA08
 	NINA_ACK    Pin = PA28
-	NINA_TX     Pin = PA12
-	NINA_RX     Pin = PA13
-	NINA_RTS    Pin = PA14
-	NINA_CTS    Pin = PA15
-)
-
-// NINA-W102 settings
-const (
-	NINA_BAUDRATE         = 912600
-	NINA_RESET_INVERTED   = true
-	NINA_SOFT_FLOWCONTROL = false
+	NINA_TX     Pin = PA22
+	NINA_RX     Pin = PA23
 )

 // I2S pins
@@ -2,11 +2,6 @@

 package machine

-// Return the current CPU frequency in hertz.
-func CPUFrequency() uint32 {
-	return 16000000
-}
-
 const (
 	// Note: start at port B because there is no port A.
 	portB Pin = iota * 8
@@ -1,51 +0,0 @@
-//go:build avr && atmega328pb
-
-package machine
-
-// Return the current CPU frequency in hertz.
-func CPUFrequency() uint32 {
-	return 16000000
-}
-
-const (
-	// Note: start at port B because there is no port A.
-	portB Pin = iota * 8
-	portC
-	portD
-	portE
-)
-
-const (
-	PB0 = portB + 0
-	PB1 = portB + 1 // peripherals: Timer1 channel A
-	PB2 = portB + 2 // peripherals: Timer1 channel B
-	PB3 = portB + 3 // peripherals: Timer2 channel A
-	PB4 = portB + 4
-	PB5 = portB + 5
-	PB6 = portB + 6
-	PB7 = portB + 7
-	PC0 = portC + 0
-	PC1 = portC + 1
-	PC2 = portC + 2
-	PC3 = portC + 3
-	PC4 = portC + 4
-	PC5 = portC + 5
-	PC6 = portC + 6
-	PC7 = portC + 7
-	PD0 = portD + 0
-	PD1 = portD + 1
-	PD2 = portD + 2
-	PD3 = portD + 3 // peripherals: Timer2 channel B
-	PD4 = portD + 4
-	PD5 = portD + 5 // peripherals: Timer0 channel B
-	PD6 = portD + 6 // peripherals: Timer0 channel A
-	PD7 = portD + 7
-	PE0 = portE + 0
-	PE1 = portE + 1
-	PE2 = portE + 2
-	PE3 = portE + 3
-	PE4 = portE + 4
-	PE5 = portE + 5
-	PE6 = portE + 6
-	PE7 = portE + 7
-)
@@ -73,7 +73,7 @@ const (

 // USB CDC identifiers
 const (
-	usb_STRING_PRODUCT      = "Gopher Badge"
+	usb_STRING_PRODUCT      = "Gopher Badger"
 	usb_STRING_MANUFACTURER = "TinyGo"
 )

@@ -62,15 +62,6 @@ var (
 	UART2 = &sercomUSART0

 	DefaultUART = UART1
-
-	UART_NINA = UART2
-)
-
-// NINA-W102 settings
-const (
-	NINA_BAUDRATE         = 115200
-	NINA_RESET_INVERTED   = true
-	NINA_SOFT_FLOWCONTROL = true
 )

 const (
@@ -79,12 +70,9 @@ const (
 	NINA_GPIO0  = PB01
 	NINA_RESETN = PB05

-	// pins used for the ESP32 connection do not allow hardware
-	// flow control, which is required. have to emulate with software.
 	NINA_TX  = PA04
 	NINA_RX  = PA07
-	NINA_CTS = NINA_ACK
-	NINA_RTS = NINA_GPIO0
+	NINA_RTS = PB23
 )

 // I2C pins
@@ -1,142 +0,0 @@
-//go:build mksnanov3
-
-// The MKS Robin Nano V3.X board.
-// Documented at https://github.com/makerbase-mks/MKS-Robin-Nano-V3.X.
-
-package machine
-
-import (
-	"device/stm32"
-	"runtime/interrupt"
-)
-
-// LED is also wired to the SD card card detect (CD) pin.
-const LED = PD12
-
-// UART pins
-const (
-	UART_TX_PIN = PB10
-	UART_RX_PIN = PB11
-)
-
-// EXP1 and EXP2 expansion ports for connecting
-// the MKS TS35 V2.0 expansion board.
-const (
-	BEEPER = EXP1_1
-
-	// LCD pins.
-	LCD_DC        = EXP1_8
-	LCD_CS        = EXP1_7
-	LCD_RS        = EXP1_4
-	LCD_BACKLIGHT = EXP1_3
-
-	// Touch pins. Note that some pins are shared with the
-	// LCD SPI1 interface.
-	TOUCH_CLK  = EXP2_2
-	TOUCH_CS   = EXP1_5
-	TOUCH_DIN  = EXP2_6
-	TOUCH_DOUT = EXP2_1
-	TOUCH_IRQ  = EXP1_6
-
-	BUTTON         = BUTTON_JOG
-	BUTTON_JOG     = EXP1_2
-	BUTTON_JOG_CCW = EXP2_3
-	BUTTON_JOG_CW  = EXP2_5
-
-	EXP1_1 = PC5
-	EXP1_2 = PE13
-	EXP1_3 = PD13
-	EXP1_4 = PC6
-	EXP1_5 = PE14
-	EXP1_6 = PE15
-	EXP1_7 = PD11
-	EXP1_8 = PD10
-
-	EXP2_1 = PA6
-	EXP2_2 = PA5
-	EXP2_3 = PE8
-	EXP2_4 = PE10
-	EXP2_5 = PE11
-	EXP2_6 = PA7
-	EXP2_7 = PE12
-)
-
-var (
-	UART3  = &_UART3
-	_UART3 = UART{
-		Buffer:            NewRingBuffer(),
-		Bus:               stm32.USART3,
-		TxAltFuncSelector: AF7_USART1_2_3,
-		RxAltFuncSelector: AF7_USART1_2_3,
-	}
-	DefaultUART = UART3
-)
-
-// set up RX IRQ handler. Follow similar pattern for other UARTx instances
-func init() {
-	UART3.Interrupt = interrupt.New(stm32.IRQ_USART3, _UART3.handleInterrupt)
-}
-
-// SPI pins
-const (
-	SPI1_SCK_PIN = EXP2_2
-	SPI1_SDI_PIN = EXP2_1
-	SPI1_SDO_PIN = EXP2_6
-	SPI0_SCK_PIN = SPI1_SCK_PIN
-	SPI0_SDI_PIN = SPI1_SDI_PIN
-	SPI0_SDO_PIN = SPI1_SDO_PIN
-)
-
-// Since the first interface is named SPI1, both SPI0 and SPI1 refer to SPI1.
-var (
-	SPI0 = SPI{
-		Bus:             stm32.SPI1,
-		AltFuncSelector: AF5_SPI1_SPI2,
-	}
-	SPI1 = &SPI0
-)
-
-const (
-	I2C0_SCL_PIN = PB6
-	I2C0_SDA_PIN = PB7
-)
-
-var (
-	I2C0 = &I2C{
-		Bus:             stm32.I2C1,
-		AltFuncSelector: AF4_I2C1_2_3,
-	}
-)
-
-// Motor control pins.
-const (
-	X_ENABLE = PE4
-	X_STEP   = PE3
-	X_DIR    = PE2
-	X_DIAG   = PA15
-	X_UART   = PD5
-
-	Y_ENABLE = PE1
-	Y_STEP   = PE0
-	Y_DIR    = PB9
-	Y_DIAG   = PD2
-	Y_UART   = PD7
-
-	Z_ENABLE = PB8
-	Z_STEP   = PB5
-	Z_DIR    = PB4
-	Z_DIAG   = PC8
-	Z_UART   = PD4
-
-	E0_ENABLE = PB3
-	E0_STEP   = PD6
-	E0_DIR    = PD3
-	E0_DIAG   = PC4
-	E0_UART   = PD9
-
-	E1_ENABLE = PA3
-	E1_STEP   = PD15
-	E1_DIR    = PA1
-	E1_DIAG   = PE7
-	E1_UART   = PD8
-)
@@ -87,17 +87,8 @@ const (
 	NINA_GPIO0  Pin = GPIO2
 	NINA_RESETN Pin = GPIO3

-	NINA_TX  Pin = GPIO8
-	NINA_RX  Pin = GPIO9
-	NINA_CTS Pin = GPIO10
-	NINA_RTS Pin = GPIO11
-)
-
-// NINA-W102 settings
-const (
-	NINA_BAUDRATE         = 115200
-	NINA_RESET_INVERTED   = true
-	NINA_SOFT_FLOWCONTROL = false
+	NINA_TX Pin = GPIO9
+	NINA_RX Pin = GPIO8
 )

 // Onboard crystal oscillator frequency, in MHz.
@@ -132,20 +123,10 @@ var (
 		Buffer: NewRingBuffer(),
 		Bus:    rp.UART0,
 	}
-
-	UART1  = &_UART1
-	_UART1 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    rp.UART1,
-	}
-
-	// UART_NINA on the Arduino Nano RP2040 connects to the NINA HCI.
-	UART_NINA = UART1
 )

 var DefaultUART = UART0

 func init() {
 	UART0.Interrupt = interrupt.New(rp.IRQ_UART0_IRQ, _UART0.handleInterrupt)
-	UART1.Interrupt = interrupt.New(rp.IRQ_UART1_IRQ, _UART1.handleInterrupt)
 }
@@ -1,25 +0,0 @@
-//go:build nrf52840 && nrf52840_generic
-
-package machine
-
-var (
-	LED          = NoPin
-	SDA_PIN      = NoPin
-	SCL_PIN      = NoPin
-	UART_TX_PIN  = NoPin
-	UART_RX_PIN  = NoPin
-	SPI0_SCK_PIN = NoPin
-	SPI0_SDO_PIN = NoPin
-	SPI0_SDI_PIN = NoPin
-
-	// https://pid.codes/org/TinyGo/
-	usb_VID uint16 = 0x1209
-	usb_PID uint16 = 0x9090
-
-	usb_STRING_MANUFACTURER = "TinyGo"
-	usb_STRING_PRODUCT      = "nRF52840 Generic board"
-)
-
-var (
-	DefaultUART = UART0
-)
@@ -130,33 +130,3 @@ var (
 	usb_VID uint16 = 0x239A
 	usb_PID uint16 = 0x8033
 )
-
-// NINA-W102 settings when using AirLift WiFi FeatherWing
-const (
-	NINA_BAUDRATE         = 115200
-	NINA_RESET_INVERTED   = true
-	NINA_SOFT_FLOWCONTROL = true
-)
-
-const (
-	NINA_CS     = D13
-	NINA_ACK    = D11
-	NINA_GPIO0  = D10
-	NINA_RESETN = D12
-
-	// pins used for the ESP32 connection do not allow hardware
-	// flow control, which is required. have to emulate with software.
-	NINA_TX  = UART_TX_PIN
-	NINA_RX  = UART_RX_PIN
-	NINA_CTS = NINA_ACK
-	NINA_RTS = NINA_GPIO0
-
-	NINA_SDO = SPI0_SDO_PIN
-	NINA_SDI = SPI0_SDI_PIN
-	NINA_SCK = SPI0_SCK_PIN
-)
-
-var (
-	NINA_SPI  = SPI0
-	UART_NINA = UART1
-)
@@ -53,12 +53,9 @@ const (
 	NINA_GPIO0  = D6
 	NINA_RESETN = D7

-	// pins used for the ESP32 connection do not allow hardware
-	// flow control, which is required. have to emulate with software.
 	NINA_TX  = D1
 	NINA_RX  = D0
-	NINA_CTS = NINA_ACK
-	NINA_RTS = NINA_GPIO0
+	NINA_RTS = D51

 	LCD_DATA0 = D34

@@ -114,15 +111,6 @@ var (
 	UART1 = &sercomUSART4

 	DefaultUART = UART1
-
-	UART_NINA = UART1
-)
-
-// NINA-W102 settings
-const (
-	NINA_BAUDRATE         = 115200
-	NINA_RESET_INVERTED   = true
-	NINA_SOFT_FLOWCONTROL = true
 )

 // I2C pins
@@ -1,60 +0,0 @@
-//go:build qtpy_esp32c3
-
-// This file contains the pin mappings for the Adafruit QtPy ESP32C3 boards.
-//
-// https://learn.adafruit.com/adafruit-qt-py-esp32-c3-wifi-dev-board/pinouts
-package machine
-
-// Digital Pins
-const (
-	D0 = GPIO4
-	D1 = GPIO3
-	D2 = GPIO1
-	D3 = GPIO0
-)
-
-// Analog pins (ADC1)
-const (
-	A0 = GPIO4
-	A1 = GPIO3
-	A2 = GPIO1
-	A3 = GPIO0
-)
-
-// UART pins
-const (
-	RX_PIN = GPIO20
-	TX_PIN = GPIO21
-
-	UART_RX_PIN = RX_PIN
-	UART_TX_PIN = TX_PIN
-)
-
-// I2C pins
-const (
-	SDA_PIN = GPIO5
-	SCL_PIN = GPIO6
-
-	I2C0_SDA_PIN = SDA_PIN
-	I2C0_SCL_PIN = SCL_PIN
-)
-
-// SPI pins
-const (
-	SCK_PIN = GPIO10
-	MI_PIN  = GPIO8
-	MO_PIN  = GPIO7
-
-	SPI_SCK_PIN = SCK_PIN
-	SPI_SDI_PIN = MI_PIN
-	SPI_SDO_PIN = MO_PIN
-)
-
-const (
-	NEOPIXEL = GPIO2
-	WS2812   = GPIO2
-
-	// also used for boot button.
-	// set it to be an input-with-pullup
-	BUTTON = GPIO9
-)
@@ -353,9 +353,6 @@ var (

 	// RTL8720D (tx: PB24, rx: PC24)
 	UART3 = &sercomUSART0
-
-	// Right-hand grove port (tx: D0, rx: D1)
-	UART4 = &sercomUSART4
 )

 // I2C pins
@@ -4,6 +4,8 @@ import (
 	"runtime/volatile"
 )

+const bufferSize = 128
+
 // RingBuffer is ring buffer implementation inspired by post at
 // https://www.embeddedrelated.com/showthread/comp.arch.embedded/77084-1.php
 type RingBuffer struct {
@@ -1,5 +0,0 @@
-//go:build atmega
-
-package machine
-
-const bufferSize = 32
@@ -1,5 +0,0 @@
-//go:build !atmega
-
-package machine
-
-const bufferSize = 128
@@ -1,4 +1,4 @@
-//go:build atmega || nrf || sam || stm32 || fe310 || k210 || rp2040 || mimxrt1062 || (esp32c3 && !m5stamp_c3)
+//go:build atmega || nrf || sam || stm32 || fe310 || k210 || rp2040 || mimxrt1062

 package machine

@@ -11,20 +11,11 @@ import (

 // I2C on AVR.
 type I2C struct {
-	srReg *volatile.Register8
-	brReg *volatile.Register8
-	crReg *volatile.Register8
-	drReg *volatile.Register8
-
-	srPS0 byte
-	srPS1 byte
-	crEN  byte
-	crINT byte
-	crSTO byte
-	crEA  byte
-	crSTA byte
 }

+// I2C0 is the only I2C interface on most AVRs.
+var I2C0 *I2C = nil
+
 // I2CConfig is used to store config info for I2C.
 type I2CConfig struct {
 	Frequency uint32
@@ -46,16 +37,16 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 // SetBaudRate sets the communication speed for I2C.
 func (i2c *I2C) SetBaudRate(br uint32) error {
 	// Initialize twi prescaler and bit rate.
-	i2c.srReg.SetBits((i2c.srPS0 | i2c.srPS1))
+	avr.TWSR.SetBits((avr.TWSR_TWPS0 | avr.TWSR_TWPS1))

 	// twi bit rate formula from atmega128 manual pg. 204:
 	// SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
 	// NOTE: TWBR should be 10 or higher for controller mode.
 	// It is 72 for a 16mhz board with 100kHz TWI
-	i2c.brReg.Set(uint8(((CPUFrequency() / br) - 16) / 2))
+	avr.TWBR.Set(uint8(((CPUFrequency() / br) - 16) / 2))

 	// Enable twi module.
-	i2c.crReg.Set(i2c.crEN)
+	avr.TWCR.Set(avr.TWCR_TWEN)

 	return nil
 }
@@ -86,10 +77,10 @@ func (i2c *I2C) Tx(addr uint16, w, r []byte) error {
 // start starts an I2C communication session.
 func (i2c *I2C) start(address uint8, write bool) {
 	// Clear TWI interrupt flag, put start condition on SDA, and enable TWI.
-	i2c.crReg.Set((i2c.crINT | i2c.crSTA | i2c.crEN))
+	avr.TWCR.Set((avr.TWCR_TWINT | avr.TWCR_TWSTA | avr.TWCR_TWEN))

 	// Wait till start condition is transmitted.
-	for !i2c.crReg.HasBits(i2c.crINT) {
+	for !avr.TWCR.HasBits(avr.TWCR_TWINT) {
 	}

 	// Write 7-bit shifted peripheral address.
@@ -103,23 +94,23 @@ func (i2c *I2C) start(address uint8, write bool) {
 // stop ends an I2C communication session.
 func (i2c *I2C) stop() {
 	// Send stop condition.
-	i2c.crReg.Set(i2c.crEN | i2c.crINT | i2c.crSTO)
+	avr.TWCR.Set(avr.TWCR_TWEN | avr.TWCR_TWINT | avr.TWCR_TWSTO)

 	// Wait for stop condition to be executed on bus.
-	for !i2c.crReg.HasBits(i2c.crSTO) {
+	for !avr.TWCR.HasBits(avr.TWCR_TWSTO) {
 	}
 }

 // writeByte writes a single byte to the I2C bus.
 func (i2c *I2C) writeByte(data byte) error {
 	// Write data to register.
-	i2c.drReg.Set(data)
+	avr.TWDR.Set(data)

 	// Clear TWI interrupt flag and enable TWI.
-	i2c.crReg.Set(i2c.crEN | i2c.crINT)
+	avr.TWCR.Set(avr.TWCR_TWEN | avr.TWCR_TWINT)

 	// Wait till data is transmitted.
-	for !i2c.crReg.HasBits(i2c.crINT) {
+	for !avr.TWCR.HasBits(avr.TWCR_TWINT) {
 	}
 	return nil
 }
@@ -127,13 +118,13 @@ func (i2c *I2C) writeByte(data byte) error {
 // readByte reads a single byte from the I2C bus.
 func (i2c *I2C) readByte() byte {
 	// Clear TWI interrupt flag and enable TWI.
-	i2c.crReg.Set(i2c.crEN | i2c.crINT | i2c.crEA)
+	avr.TWCR.Set(avr.TWCR_TWEN | avr.TWCR_TWINT | avr.TWCR_TWEA)

 	// Wait till read request is transmitted.
-	for !i2c.crReg.HasBits(i2c.crINT) {
+	for !avr.TWCR.HasBits(avr.TWCR_TWINT) {
 	}

-	return byte(i2c.drReg.Get())
+	return byte(avr.TWDR.Get())
 }

 // Always use UART0 as the serial output.
@@ -179,18 +170,10 @@ func (uart *UART) Configure(config UARTConfig) {
 		config.BaudRate = 9600
 	}

-	// Prescale formula for u2x mode from AVR MiniCore source code.
-	// Same as formula from specification but taking into account rounding error.
-	ps := (CPUFrequency()/4/config.BaudRate - 1) / 2
-	uart.statusRegA.SetBits(avr.UCSR0A_U2X0)
-
-	// Hardcoded exception for 57600 for compatibility with older bootloaders.
-	// Also, prescale cannot be > 4095, so switch back to non-u2x mode if the baud rate is too low.
-	if (CPUFrequency() == 16000000 && config.BaudRate == 57600) || ps > 0xfff {
-		ps = (CPUFrequency()/8/config.BaudRate - 1) / 2
-		uart.statusRegA.ClearBits(avr.UCSR0A_U2X0)
-	}
-
+	// Set baud rate based on prescale formula from
+	// https://www.microchip.com/webdoc/AVRLibcReferenceManual/FAQ_1faq_wrong_baud_rate.html
+	// ((F_CPU + UART_BAUD_RATE * 8L) / (UART_BAUD_RATE * 16L) - 1)
+	ps := ((CPUFrequency()+config.BaudRate*8)/(config.BaudRate*16) - 1)
 	uart.baudRegH.Set(uint8(ps >> 8))
 	uart.baudRegL.Set(uint8(ps & 0xff))

@@ -238,17 +221,6 @@ type SPI struct {
 	spdr *volatile.Register8
 	spsr *volatile.Register8

-	spcrR0   byte
-	spcrR1   byte
-	spcrCPHA byte
-	spcrCPOL byte
-	spcrDORD byte
-	spcrSPE  byte
-	spcrMSTR byte
-
-	spsrI2X  byte
-	spsrSPIF byte
-
 	// The io pins for the SPIx port set by the chip
 	sck Pin
 	sdi Pin
@@ -292,39 +264,39 @@ func (s SPI) Configure(config SPIConfig) error {

 	switch {
 	case frequencyDivider >= 128:
-		s.spcr.SetBits(s.spcrR0 | s.spcrR1)
+		s.spcr.SetBits(avr.SPCR_SPR0 | avr.SPCR_SPR1)
 	case frequencyDivider >= 64:
-		s.spcr.SetBits(s.spcrR1)
+		s.spcr.SetBits(avr.SPCR_SPR1)
 	case frequencyDivider >= 32:
-		s.spcr.SetBits(s.spcrR1)
-		s.spsr.SetBits(s.spsrI2X)
+		s.spcr.SetBits(avr.SPCR_SPR1)
+		s.spsr.SetBits(avr.SPSR_SPI2X)
 	case frequencyDivider >= 16:
-		s.spcr.SetBits(s.spcrR0)
+		s.spcr.SetBits(avr.SPCR_SPR0)
 	case frequencyDivider >= 8:
-		s.spcr.SetBits(s.spcrR0)
-		s.spsr.SetBits(s.spsrI2X)
+		s.spcr.SetBits(avr.SPCR_SPR0)
+		s.spsr.SetBits(avr.SPSR_SPI2X)
 	case frequencyDivider >= 4:
 		// The clock is already set to all 0's.
 	default: // defaults to fastest which is /2
-		s.spsr.SetBits(s.spsrI2X)
+		s.spsr.SetBits(avr.SPSR_SPI2X)
 	}

 	switch config.Mode {
 	case Mode1:
-		s.spcr.SetBits(s.spcrCPHA)
+		s.spcr.SetBits(avr.SPCR_CPHA)
 	case Mode2:
-		s.spcr.SetBits(s.spcrCPHA)
+		s.spcr.SetBits(avr.SPCR_CPOL)
 	case Mode3:
-		s.spcr.SetBits(s.spcrCPHA | s.spcrCPOL)
+		s.spcr.SetBits(avr.SPCR_CPHA | avr.SPCR_CPOL)
 	default: // default is mode 0
 	}

 	if config.LSBFirst {
-		s.spcr.SetBits(s.spcrDORD)
+		s.spcr.SetBits(avr.SPCR_DORD)
 	}

 	// enable SPI, set controller, set clock rate
-	s.spcr.SetBits(s.spcrSPE | s.spcrMSTR)
+	s.spcr.SetBits(avr.SPCR_SPE | avr.SPCR_MSTR)

 	return nil
 }
@@ -333,7 +305,7 @@ func (s SPI) Configure(config SPIConfig) error {
 func (s SPI) Transfer(b byte) (byte, error) {
 	s.spdr.Set(uint8(b))

-	for !s.spsr.HasBits(s.spsrSPIF) {
+	for !s.spsr.HasBits(avr.SPSR_SPIF) {
 	}

 	return byte(s.spdr.Get()), nil
@@ -1,548 +0,0 @@
-//go:build avr && (atmega328p || atmega328pb)
-
-package machine
-
-import (
-	"device/avr"
-	"runtime/interrupt"
-	"runtime/volatile"
-)
-
-// PWM is one PWM peripheral, which consists of a counter and two output
-// channels (that can be connected to two fixed pins). You can set the frequency
-// using SetPeriod, but only for all the channels in this PWM peripheral at
-// once.
-type PWM struct {
-	num uint8
-}
-
-var (
-	Timer0 = PWM{0} // 8 bit timer for PD5 and PD6
-	Timer1 = PWM{1} // 16 bit timer for PB1 and PB2
-	Timer2 = PWM{2} // 8 bit timer for PB3 and PD3
-)
-
-// Configure enables and configures this PWM.
-//
-// For the two 8 bit timers, there is only a limited number of periods
-// available, namely the CPU frequency divided by 256 and again divided by 1, 8,
-// 64, 256, or 1024. For a MCU running at 16MHz, this would be a period of 16µs,
-// 128µs, 1024µs, 4096µs, or 16384µs.
-func (pwm PWM) Configure(config PWMConfig) error {
-	switch pwm.num {
-	case 0, 2: // 8-bit timers (Timer/counter 0 and Timer/counter 2)
-		// Calculate the timer prescaler.
-		// While we could configure a flexible top, that would sacrifice one of
-		// the PWM output compare registers and thus a PWM channel. I've chosen
-		// to instead limit this timer to a fixed number of frequencies.
-		var prescaler uint8
-		switch config.Period {
-		case 0, (uint64(1e9) * 256 * 1) / uint64(CPUFrequency()):
-			prescaler = 1
-		case (uint64(1e9) * 256 * 8) / uint64(CPUFrequency()):
-			prescaler = 2
-		case (uint64(1e9) * 256 * 64) / uint64(CPUFrequency()):
-			prescaler = 3
-		case (uint64(1e9) * 256 * 256) / uint64(CPUFrequency()):
-			prescaler = 4
-		case (uint64(1e9) * 256 * 1024) / uint64(CPUFrequency()):
-			prescaler = 5
-		default:
-			return ErrPWMPeriodTooLong
-		}
-
-		if pwm.num == 0 {
-			avr.TCCR0B.Set(prescaler)
-			// Set the PWM mode to fast PWM (mode = 3).
-			avr.TCCR0A.Set(avr.TCCR0A_WGM00 | avr.TCCR0A_WGM01)
-			// monotonic timer is using the same time as PWM:0
-			// we must adust internal settings of monotonic timer when PWM:0 settings changed
-			adjustMonotonicTimer()
-		} else {
-			avr.TCCR2B.Set(prescaler)
-			// Set the PWM mode to fast PWM (mode = 3).
-			avr.TCCR2A.Set(avr.TCCR2A_WGM20 | avr.TCCR2A_WGM21)
-		}
-	case 1: // Timer/counter 1
-		// The top value is the number of PWM ticks a PWM period takes. It is
-		// initially picked assuming an unlimited counter top and no PWM
-		// prescaler.
-		var top uint64
-		if config.Period == 0 {
-			// Use a top appropriate for LEDs. Picking a relatively low period
-			// here (0xff) for consistency with the other timers.
-			top = 0xff
-		} else {
-			// The formula below calculates the following formula, optimized:
-			//     top = period * (CPUFrequency() / 1e9)
-			// By dividing the CPU frequency first (an operation that is easily
-			// optimized away) the period has less chance of overflowing.
-			top = config.Period * (uint64(CPUFrequency()) / 1000000) / 1000
-		}
-
-		avr.TCCR1A.Set(avr.TCCR1A_WGM11)
-
-		// The ideal PWM period may be larger than would fit in the PWM counter,
-		// which is 16 bits (see maxTop). Therefore, try to make the PWM clock
-		// speed lower with a prescaler to make the top value fit the maximum
-		// top value.
-		const maxTop = 0x10000
-		switch {
-		case top <= maxTop:
-			avr.TCCR1B.Set(3<<3 | 1) // no prescaling
-		case top/8 <= maxTop:
-			avr.TCCR1B.Set(3<<3 | 2) // divide by 8
-			top /= 8
-		case top/64 <= maxTop:
-			avr.TCCR1B.Set(3<<3 | 3) // divide by 64
-			top /= 64
-		case top/256 <= maxTop:
-			avr.TCCR1B.Set(3<<3 | 4) // divide by 256
-			top /= 256
-		case top/1024 <= maxTop:
-			avr.TCCR1B.Set(3<<3 | 5) // divide by 1024
-			top /= 1024
-		default:
-			return ErrPWMPeriodTooLong
-		}
-
-		// A top of 0x10000 is at 100% duty cycle. Subtract one because the
-		// counter counts from 0, not 1 (avoiding an off-by-one).
-		top -= 1
-
-		avr.ICR1H.Set(uint8(top >> 8))
-		avr.ICR1L.Set(uint8(top))
-	}
-	return nil
-}
-
-// SetPeriod updates the period of this PWM peripheral.
-// To set a particular frequency, use the following formula:
-//
-//	period = 1e9 / frequency
-//
-// If you use a period of 0, a period that works well for LEDs will be picked.
-//
-// SetPeriod will not change the prescaler, but also won't change the current
-// value in any of the channels. This means that you may need to update the
-// value for the particular channel.
-//
-// Note that you cannot pick any arbitrary period after the PWM peripheral has
-// been configured. If you want to switch between frequencies, pick the lowest
-// frequency (longest period) once when calling Configure and adjust the
-// frequency here as needed.
-func (pwm PWM) SetPeriod(period uint64) error {
-	if pwm.num != 1 {
-		return ErrPWMPeriodTooLong // TODO better error message
-	}
-
-	// The top value is the number of PWM ticks a PWM period takes. It is
-	// initially picked assuming an unlimited counter top and no PWM
-	// prescaler.
-	var top uint64
-	if period == 0 {
-		// Use a top appropriate for LEDs. Picking a relatively low period
-		// here (0xff) for consistency with the other timers.
-		top = 0xff
-	} else {
-		// The formula below calculates the following formula, optimized:
-		//     top = period * (CPUFrequency() / 1e9)
-		// By dividing the CPU frequency first (an operation that is easily
-		// optimized away) the period has less chance of overflowing.
-		top = period * (uint64(CPUFrequency()) / 1000000) / 1000
-	}
-
-	prescaler := avr.TCCR1B.Get() & 0x7
-	switch prescaler {
-	case 1:
-		top /= 1
-	case 2:
-		top /= 8
-	case 3:
-		top /= 64
-	case 4:
-		top /= 256
-	case 5:
-		top /= 1024
-	}
-
-	// A top of 0x10000 is at 100% duty cycle. Subtract one because the counter
-	// counts from 0, not 1 (avoiding an off-by-one).
-	top -= 1
-
-	if top > 0xffff {
-		return ErrPWMPeriodTooLong
-	}
-
-	// Warning: this change is not atomic!
-	avr.ICR1H.Set(uint8(top >> 8))
-	avr.ICR1L.Set(uint8(top))
-
-	// ... and because of that, set the counter back to zero to avoid most of
-	// the effects of this non-atomicity.
-	avr.TCNT1H.Set(0)
-	avr.TCNT1L.Set(0)
-
-	return nil
-}
-
-// Top returns the current counter top, for use in duty cycle calculation. It
-// will only change with a call to Configure or SetPeriod, otherwise it is
-// constant.
-//
-// The value returned here is hardware dependent. In general, it's best to treat
-// it as an opaque value that can be divided by some number and passed to Set
-// (see Set documentation for more information).
-func (pwm PWM) Top() uint32 {
-	if pwm.num == 1 {
-		// Timer 1 has a configurable top value.
-		low := avr.ICR1L.Get()
-		high := avr.ICR1H.Get()
-		return uint32(high)<<8 | uint32(low) + 1
-	}
-	// Other timers go from 0 to 0xff (0x100 or 256 in total).
-	return 256
-}
-
-// Counter returns the current counter value of the timer in this PWM
-// peripheral. It may be useful for debugging.
-func (pwm PWM) Counter() uint32 {
-	switch pwm.num {
-	case 0:
-		return uint32(avr.TCNT0.Get())
-	case 1:
-		mask := interrupt.Disable()
-		low := avr.TCNT1L.Get()
-		high := avr.TCNT1H.Get()
-		interrupt.Restore(mask)
-		return uint32(high)<<8 | uint32(low)
-	case 2:
-		return uint32(avr.TCNT2.Get())
-	}
-	// Unknown PWM.
-	return 0
-}
-
-// Period returns the used PWM period in nanoseconds. It might deviate slightly
-// from the configured period due to rounding.
-func (pwm PWM) Period() uint64 {
-	var prescaler uint8
-	switch pwm.num {
-	case 0:
-		prescaler = avr.TCCR0B.Get() & 0x7
-	case 1:
-		prescaler = avr.TCCR1B.Get() & 0x7
-	case 2:
-		prescaler = avr.TCCR2B.Get() & 0x7
-	}
-	top := uint64(pwm.Top())
-	switch prescaler {
-	case 1: // prescaler 1
-		return 1 * top * 1000 / uint64(CPUFrequency()/1e6)
-	case 2: // prescaler 8
-		return 8 * top * 1000 / uint64(CPUFrequency()/1e6)
-	case 3: // prescaler 64
-		return 64 * top * 1000 / uint64(CPUFrequency()/1e6)
-	case 4: // prescaler 256
-		return 256 * top * 1000 / uint64(CPUFrequency()/1e6)
-	case 5: // prescaler 1024
-		return 1024 * top * 1000 / uint64(CPUFrequency()/1e6)
-	default: // unknown clock source
-		return 0
-	}
-}
-
-// Channel returns a PWM channel for the given pin.
-func (pwm PWM) Channel(pin Pin) (uint8, error) {
-	pin.Configure(PinConfig{Mode: PinOutput})
-	pin.Low()
-	switch pwm.num {
-	case 0:
-		switch pin {
-		case PD6: // channel A
-			avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
-			return 0, nil
-		case PD5: // channel B
-			avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
-			return 1, nil
-		}
-	case 1:
-		switch pin {
-		case PB1: // channel A
-			avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
-			return 0, nil
-		case PB2: // channel B
-			avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
-			return 1, nil
-		}
-	case 2:
-		switch pin {
-		case PB3: // channel A
-			avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
-			return 0, nil
-		case PD3: // channel B
-			avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
-			return 1, nil
-		}
-	}
-	return 0, ErrInvalidOutputPin
-}
-
-// SetInverting sets whether to invert the output of this channel.
-// Without inverting, a 25% duty cycle would mean the output is high for 25% of
-// the time and low for the rest. Inverting flips the output as if a NOT gate
-// was placed at the output, meaning that the output would be 25% low and 75%
-// high with a duty cycle of 25%.
-//
-// Note: the invert state may not be applied on the AVR until the next call to
-// ch.Set().
-func (pwm PWM) SetInverting(channel uint8, inverting bool) {
-	switch pwm.num {
-	case 0:
-		switch channel {
-		case 0: // channel A
-			if inverting {
-				avr.PORTB.SetBits(1 << 6) // PB6 high
-				avr.TCCR0A.SetBits(avr.TCCR0A_COM0A0)
-			} else {
-				avr.PORTB.ClearBits(1 << 6) // PB6 low
-				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0A0)
-			}
-		case 1: // channel B
-			if inverting {
-				avr.PORTB.SetBits(1 << 5) // PB5 high
-				avr.TCCR0A.SetBits(avr.TCCR0A_COM0B0)
-			} else {
-				avr.PORTB.ClearBits(1 << 5) // PB5 low
-				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0B0)
-			}
-		}
-	case 1:
-		// Note: the COM1A0/COM1B0 bit is not set with the configuration below.
-		// It will be set the following call to Set(), however.
-		switch channel {
-		case 0: // channel A, PB1
-			if inverting {
-				avr.PORTB.SetBits(1 << 1) // PB1 high
-			} else {
-				avr.PORTB.ClearBits(1 << 1) // PB1 low
-			}
-		case 1: // channel B, PB2
-			if inverting {
-				avr.PORTB.SetBits(1 << 2) // PB2 high
-			} else {
-				avr.PORTB.ClearBits(1 << 2) // PB2 low
-			}
-		}
-	case 2:
-		switch channel {
-		case 0: // channel A
-			if inverting {
-				avr.PORTB.SetBits(1 << 3) // PB3 high
-				avr.TCCR2A.SetBits(avr.TCCR2A_COM2A0)
-			} else {
-				avr.PORTB.ClearBits(1 << 3) // PB3 low
-				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2A0)
-			}
-		case 1: // channel B
-			if inverting {
-				avr.PORTD.SetBits(1 << 3) // PD3 high
-				avr.TCCR2A.SetBits(avr.TCCR2A_COM2B0)
-			} else {
-				avr.PORTD.ClearBits(1 << 3) // PD3 low
-				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2B0)
-			}
-		}
-	}
-}
-
-// Set updates the channel value. This is used to control the channel duty
-// cycle, in other words the fraction of time the channel output is high (or low
-// when inverted). For example, to set it to a 25% duty cycle, use:
-//
-//	pwm.Set(channel, pwm.Top() / 4)
-//
-// pwm.Set(channel, 0) will set the output to low and pwm.Set(channel,
-// pwm.Top()) will set the output to high, assuming the output isn't inverted.
-func (pwm PWM) Set(channel uint8, value uint32) {
-	switch pwm.num {
-	case 0:
-		value := uint16(value)
-		switch channel {
-		case 0: // channel A
-			if value == 0 {
-				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0A1)
-			} else {
-				avr.OCR0A.Set(uint8(value - 1))
-				avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
-			}
-		case 1: // channel B
-			if value == 0 {
-				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0B1)
-			} else {
-				avr.OCR0B.Set(uint8(value) - 1)
-				avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
-			}
-		}
-		// monotonic timer is using the same time as PWM:0
-		// we must adust internal settings of monotonic timer when PWM:0 settings changed
-		adjustMonotonicTimer()
-	case 1:
-		mask := interrupt.Disable()
-		switch channel {
-		case 0: // channel A, PB1
-			if value == 0 {
-				avr.TCCR1A.ClearBits(avr.TCCR1A_COM1A1 | avr.TCCR1A_COM1A0)
-			} else {
-				value := uint16(value) - 1 // yes, this is safe (it relies on underflow)
-				avr.OCR1AH.Set(uint8(value >> 8))
-				avr.OCR1AL.Set(uint8(value))
-				if avr.PORTB.HasBits(1 << 1) { // is PB1 high?
-					// Yes, set the inverting bit.
-					avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1 | avr.TCCR1A_COM1A0)
-				} else {
-					// No, output is non-inverting.
-					avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
-				}
-			}
-		case 1: // channel B, PB2
-			if value == 0 {
-				avr.TCCR1A.ClearBits(avr.TCCR1A_COM1B1 | avr.TCCR1A_COM1B0)
-			} else {
-				value := uint16(value) - 1 // yes, this is safe (it relies on underflow)
-				avr.OCR1BH.Set(uint8(value >> 8))
-				avr.OCR1BL.Set(uint8(value))
-				if avr.PORTB.HasBits(1 << 2) { // is PB2 high?
-					// Yes, set the inverting bit.
-					avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1 | avr.TCCR1A_COM1B0)
-				} else {
-					// No, output is non-inverting.
-					avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
-				}
-			}
-		}
-		interrupt.Restore(mask)
-	case 2:
-		value := uint16(value)
-		switch channel {
-		case 0: // channel A
-			if value == 0 {
-				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2A1)
-			} else {
-				avr.OCR2A.Set(uint8(value - 1))
-				avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
-			}
-		case 1: // channel B
-			if value == 0 {
-				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2B1)
-			} else {
-				avr.OCR2B.Set(uint8(value - 1))
-				avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
-			}
-		}
-	}
-}
-
-// Pin Change Interrupts
-type PinChange uint8
-
-const (
-	PinRising PinChange = 1 << iota
-	PinFalling
-	PinToggle = PinRising | PinFalling
-)
-
-func (pin Pin) SetInterrupt(pinChange PinChange, callback func(Pin)) (err error) {
-
-	switch {
-	case pin >= PB0 && pin <= PB7:
-		// PCMSK0 - PCINT0-7
-		pinStates[0] = avr.PINB.Get()
-		pinIndex := pin - PB0
-		if pinChange&PinRising > 0 {
-			pinCallbacks[0][pinIndex][0] = callback
-		}
-		if pinChange&PinFalling > 0 {
-			pinCallbacks[0][pinIndex][1] = callback
-		}
-		if callback != nil {
-			avr.PCMSK0.SetBits(1 << pinIndex)
-		} else {
-			avr.PCMSK0.ClearBits(1 << pinIndex)
-		}
-		avr.PCICR.SetBits(avr.PCICR_PCIE0)
-		interrupt.New(avr.IRQ_PCINT0, handlePCINT0Interrupts)
-	case pin >= PC0 && pin <= PC7:
-		// PCMSK1 - PCINT8-14
-		pinStates[1] = avr.PINC.Get()
-		pinIndex := pin - PC0
-		if pinChange&PinRising > 0 {
-			pinCallbacks[1][pinIndex][0] = callback
-		}
-		if pinChange&PinFalling > 0 {
-			pinCallbacks[1][pinIndex][1] = callback
-		}
-		if callback != nil {
-			avr.PCMSK1.SetBits(1 << pinIndex)
-		} else {
-			avr.PCMSK1.ClearBits(1 << pinIndex)
-		}
-		avr.PCICR.SetBits(avr.PCICR_PCIE1)
-		interrupt.New(avr.IRQ_PCINT1, handlePCINT1Interrupts)
-	case pin >= PD0 && pin <= PD7:
-		// PCMSK2 - PCINT16-23
-		pinStates[2] = avr.PIND.Get()
-		pinIndex := pin - PD0
-		if pinChange&PinRising > 0 {
-			pinCallbacks[2][pinIndex][0] = callback
-		}
-		if pinChange&PinFalling > 0 {
-			pinCallbacks[2][pinIndex][1] = callback
-		}
-		if callback != nil {
-			avr.PCMSK2.SetBits(1 << pinIndex)
-		} else {
-			avr.PCMSK2.ClearBits(1 << pinIndex)
-		}
-		avr.PCICR.SetBits(avr.PCICR_PCIE2)
-		interrupt.New(avr.IRQ_PCINT2, handlePCINT2Interrupts)
-	default:
-		return ErrInvalidInputPin
-	}
-
-	return nil
-}
-
-var pinCallbacks [3][8][2]func(Pin)
-var pinStates [3]uint8
-
-func handlePCINTInterrupts(intr uint8, port *volatile.Register8) {
-	current := port.Get()
-	change := pinStates[intr] ^ current
-	pinStates[intr] = current
-	for i := uint8(0); i < 8; i++ {
-		if (change>>i)&0x01 != 0x01 {
-			continue
-		}
-		pin := Pin(intr*8 + i)
-		value := pin.Get()
-		if value && pinCallbacks[intr][i][0] != nil {
-			pinCallbacks[intr][i][0](pin)
-		}
-		if !value && pinCallbacks[intr][i][1] != nil {
-			pinCallbacks[intr][i][1](pin)
-		}
-	}
-}
-
-func handlePCINT0Interrupts(intr interrupt.Interrupt) {
-	handlePCINTInterrupts(0, avr.PINB)
-}
-
-func handlePCINT1Interrupts(intr interrupt.Interrupt) {
-	handlePCINTInterrupts(1, avr.PINC)
-}
-
-func handlePCINT2Interrupts(intr interrupt.Interrupt) {
-	handlePCINTInterrupts(2, avr.PIND)
-}
@@ -4,49 +4,12 @@ package machine

 import (
 	"device/avr"
+	"runtime/interrupt"
 	"runtime/volatile"
 )

 const irq_USART0_RX = avr.IRQ_USART_RX

-// I2C0 is the only I2C interface on most AVRs.
-var I2C0 = &I2C{
-	srReg: avr.TWSR,
-	brReg: avr.TWBR,
-	crReg: avr.TWCR,
-	drReg: avr.TWDR,
-	srPS0: avr.TWSR_TWPS0,
-	srPS1: avr.TWSR_TWPS1,
-	crEN:  avr.TWCR_TWEN,
-	crINT: avr.TWCR_TWINT,
-	crSTO: avr.TWCR_TWSTO,
-	crEA:  avr.TWCR_TWEA,
-	crSTA: avr.TWCR_TWSTA,
-}
-
-// SPI configuration
-var SPI0 = SPI{
-	spcr: avr.SPCR,
-	spdr: avr.SPDR,
-	spsr: avr.SPSR,
-
-	spcrR0:   avr.SPCR_SPR0,
-	spcrR1:   avr.SPCR_SPR1,
-	spcrCPHA: avr.SPCR_CPHA,
-	spcrCPOL: avr.SPCR_CPOL,
-	spcrDORD: avr.SPCR_DORD,
-	spcrSPE:  avr.SPCR_SPE,
-	spcrMSTR: avr.SPCR_MSTR,
-
-	spsrI2X:  avr.SPSR_SPI2X,
-	spsrSPIF: avr.SPSR_SPIF,
-
-	sck: PB5,
-	sdo: PB3,
-	sdi: PB4,
-	cs:  PB2,
-}
-
 // getPortMask returns the PORTx register and mask for the pin.
 func (p Pin) getPortMask() (*volatile.Register8, uint8) {
 	switch {
@@ -58,3 +21,552 @@ func (p Pin) getPortMask() (*volatile.Register8, uint8) {
 		return avr.PORTD, 1 << uint8(p-portD)
 	}
 }
+
+// PWM is one PWM peripheral, which consists of a counter and two output
+// channels (that can be connected to two fixed pins). You can set the frequency
+// using SetPeriod, but only for all the channels in this PWM peripheral at
+// once.
+type PWM struct {
+	num uint8
+}
+
+var (
+	Timer0 = PWM{0} // 8 bit timer for PD5 and PD6
+	Timer1 = PWM{1} // 16 bit timer for PB1 and PB2
+	Timer2 = PWM{2} // 8 bit timer for PB3 and PD3
+)
+
+// Configure enables and configures this PWM.
+//
+// For the two 8 bit timers, there is only a limited number of periods
+// available, namely the CPU frequency divided by 256 and again divided by 1, 8,
+// 64, 256, or 1024. For a MCU running at 16MHz, this would be a period of 16µs,
+// 128µs, 1024µs, 4096µs, or 16384µs.
+func (pwm PWM) Configure(config PWMConfig) error {
+	switch pwm.num {
+	case 0, 2: // 8-bit timers (Timer/counter 0 and Timer/counter 2)
+		// Calculate the timer prescaler.
+		// While we could configure a flexible top, that would sacrifice one of
+		// the PWM output compare registers and thus a PWM channel. I've chosen
+		// to instead limit this timer to a fixed number of frequencies.
+		var prescaler uint8
+		switch config.Period {
+		case 0, (uint64(1e9) * 256 * 1) / uint64(CPUFrequency()):
+			prescaler = 1
+		case (uint64(1e9) * 256 * 8) / uint64(CPUFrequency()):
+			prescaler = 2
+		case (uint64(1e9) * 256 * 64) / uint64(CPUFrequency()):
+			prescaler = 3
+		case (uint64(1e9) * 256 * 256) / uint64(CPUFrequency()):
+			prescaler = 4
+		case (uint64(1e9) * 256 * 1024) / uint64(CPUFrequency()):
+			prescaler = 5
+		default:
+			return ErrPWMPeriodTooLong
+		}
+
+		if pwm.num == 0 {
+			avr.TCCR0B.Set(prescaler)
+			// Set the PWM mode to fast PWM (mode = 3).
+			avr.TCCR0A.Set(avr.TCCR0A_WGM00 | avr.TCCR0A_WGM01)
+			// monotonic timer is using the same time as PWM:0
+			// we must adust internal settings of monotonic timer when PWM:0 settings changed
+			adjustMonotonicTimer()
+		} else {
+			avr.TCCR2B.Set(prescaler)
+			// Set the PWM mode to fast PWM (mode = 3).
+			avr.TCCR2A.Set(avr.TCCR2A_WGM20 | avr.TCCR2A_WGM21)
+		}
+	case 1: // Timer/counter 1
+		// The top value is the number of PWM ticks a PWM period takes. It is
+		// initially picked assuming an unlimited counter top and no PWM
+		// prescaler.
+		var top uint64
+		if config.Period == 0 {
+			// Use a top appropriate for LEDs. Picking a relatively low period
+			// here (0xff) for consistency with the other timers.
+			top = 0xff
+		} else {
+			// The formula below calculates the following formula, optimized:
+			//     top = period * (CPUFrequency() / 1e9)
+			// By dividing the CPU frequency first (an operation that is easily
+			// optimized away) the period has less chance of overflowing.
+			top = config.Period * (uint64(CPUFrequency()) / 1000000) / 1000
+		}
+
+		avr.TCCR1A.Set(avr.TCCR1A_WGM11)
+
+		// The ideal PWM period may be larger than would fit in the PWM counter,
+		// which is 16 bits (see maxTop). Therefore, try to make the PWM clock
+		// speed lower with a prescaler to make the top value fit the maximum
+		// top value.
+		const maxTop = 0x10000
+		switch {
+		case top <= maxTop:
+			avr.TCCR1B.Set(3<<3 | 1) // no prescaling
+		case top/8 <= maxTop:
+			avr.TCCR1B.Set(3<<3 | 2) // divide by 8
+			top /= 8
+		case top/64 <= maxTop:
+			avr.TCCR1B.Set(3<<3 | 3) // divide by 64
+			top /= 64
+		case top/256 <= maxTop:
+			avr.TCCR1B.Set(3<<3 | 4) // divide by 256
+			top /= 256
+		case top/1024 <= maxTop:
+			avr.TCCR1B.Set(3<<3 | 5) // divide by 1024
+			top /= 1024
+		default:
+			return ErrPWMPeriodTooLong
+		}
+
+		// A top of 0x10000 is at 100% duty cycle. Subtract one because the
+		// counter counts from 0, not 1 (avoiding an off-by-one).
+		top -= 1
+
+		avr.ICR1H.Set(uint8(top >> 8))
+		avr.ICR1L.Set(uint8(top))
+	}
+	return nil
+}
+
+// SetPeriod updates the period of this PWM peripheral.
+// To set a particular frequency, use the following formula:
+//
+//	period = 1e9 / frequency
+//
+// If you use a period of 0, a period that works well for LEDs will be picked.
+//
+// SetPeriod will not change the prescaler, but also won't change the current
+// value in any of the channels. This means that you may need to update the
+// value for the particular channel.
+//
+// Note that you cannot pick any arbitrary period after the PWM peripheral has
+// been configured. If you want to switch between frequencies, pick the lowest
+// frequency (longest period) once when calling Configure and adjust the
+// frequency here as needed.
+func (pwm PWM) SetPeriod(period uint64) error {
+	if pwm.num != 1 {
+		return ErrPWMPeriodTooLong // TODO better error message
+	}
+
+	// The top value is the number of PWM ticks a PWM period takes. It is
+	// initially picked assuming an unlimited counter top and no PWM
+	// prescaler.
+	var top uint64
+	if period == 0 {
+		// Use a top appropriate for LEDs. Picking a relatively low period
+		// here (0xff) for consistency with the other timers.
+		top = 0xff
+	} else {
+		// The formula below calculates the following formula, optimized:
+		//     top = period * (CPUFrequency() / 1e9)
+		// By dividing the CPU frequency first (an operation that is easily
+		// optimized away) the period has less chance of overflowing.
+		top = period * (uint64(CPUFrequency()) / 1000000) / 1000
+	}
+
+	prescaler := avr.TCCR1B.Get() & 0x7
+	switch prescaler {
+	case 1:
+		top /= 1
+	case 2:
+		top /= 8
+	case 3:
+		top /= 64
+	case 4:
+		top /= 256
+	case 5:
+		top /= 1024
+	}
+
+	// A top of 0x10000 is at 100% duty cycle. Subtract one because the counter
+	// counts from 0, not 1 (avoiding an off-by-one).
+	top -= 1
+
+	if top > 0xffff {
+		return ErrPWMPeriodTooLong
+	}
+
+	// Warning: this change is not atomic!
+	avr.ICR1H.Set(uint8(top >> 8))
+	avr.ICR1L.Set(uint8(top))
+
+	// ... and because of that, set the counter back to zero to avoid most of
+	// the effects of this non-atomicity.
+	avr.TCNT1H.Set(0)
+	avr.TCNT1L.Set(0)
+
+	return nil
+}
+
+// Top returns the current counter top, for use in duty cycle calculation. It
+// will only change with a call to Configure or SetPeriod, otherwise it is
+// constant.
+//
+// The value returned here is hardware dependent. In general, it's best to treat
+// it as an opaque value that can be divided by some number and passed to Set
+// (see Set documentation for more information).
+func (pwm PWM) Top() uint32 {
+	if pwm.num == 1 {
+		// Timer 1 has a configurable top value.
+		low := avr.ICR1L.Get()
+		high := avr.ICR1H.Get()
+		return uint32(high)<<8 | uint32(low) + 1
+	}
+	// Other timers go from 0 to 0xff (0x100 or 256 in total).
+	return 256
+}
+
+// Counter returns the current counter value of the timer in this PWM
+// peripheral. It may be useful for debugging.
+func (pwm PWM) Counter() uint32 {
+	switch pwm.num {
+	case 0:
+		return uint32(avr.TCNT0.Get())
+	case 1:
+		mask := interrupt.Disable()
+		low := avr.TCNT1L.Get()
+		high := avr.TCNT1H.Get()
+		interrupt.Restore(mask)
+		return uint32(high)<<8 | uint32(low)
+	case 2:
+		return uint32(avr.TCNT2.Get())
+	}
+	// Unknown PWM.
+	return 0
+}
+
+// Period returns the used PWM period in nanoseconds. It might deviate slightly
+// from the configured period due to rounding.
+func (pwm PWM) Period() uint64 {
+	var prescaler uint8
+	switch pwm.num {
+	case 0:
+		prescaler = avr.TCCR0B.Get() & 0x7
+	case 1:
+		prescaler = avr.TCCR1B.Get() & 0x7
+	case 2:
+		prescaler = avr.TCCR2B.Get() & 0x7
+	}
+	top := uint64(pwm.Top())
+	switch prescaler {
+	case 1: // prescaler 1
+		return 1 * top * 1000 / uint64(CPUFrequency()/1e6)
+	case 2: // prescaler 8
+		return 8 * top * 1000 / uint64(CPUFrequency()/1e6)
+	case 3: // prescaler 64
+		return 64 * top * 1000 / uint64(CPUFrequency()/1e6)
+	case 4: // prescaler 256
+		return 256 * top * 1000 / uint64(CPUFrequency()/1e6)
+	case 5: // prescaler 1024
+		return 1024 * top * 1000 / uint64(CPUFrequency()/1e6)
+	default: // unknown clock source
+		return 0
+	}
+}
+
+// Channel returns a PWM channel for the given pin.
+func (pwm PWM) Channel(pin Pin) (uint8, error) {
+	pin.Configure(PinConfig{Mode: PinOutput})
+	pin.Low()
+	switch pwm.num {
+	case 0:
+		switch pin {
+		case PD6: // channel A
+			avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
+			return 0, nil
+		case PD5: // channel B
+			avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
+			return 1, nil
+		}
+	case 1:
+		switch pin {
+		case PB1: // channel A
+			avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
+			return 0, nil
+		case PB2: // channel B
+			avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
+			return 1, nil
+		}
+	case 2:
+		switch pin {
+		case PB3: // channel A
+			avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
+			return 0, nil
+		case PD3: // channel B
+			avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
+			return 1, nil
+		}
+	}
+	return 0, ErrInvalidOutputPin
+}
+
+// SetInverting sets whether to invert the output of this channel.
+// Without inverting, a 25% duty cycle would mean the output is high for 25% of
+// the time and low for the rest. Inverting flips the output as if a NOT gate
+// was placed at the output, meaning that the output would be 25% low and 75%
+// high with a duty cycle of 25%.
+//
+// Note: the invert state may not be applied on the AVR until the next call to
+// ch.Set().
+func (pwm PWM) SetInverting(channel uint8, inverting bool) {
+	switch pwm.num {
+	case 0:
+		switch channel {
+		case 0: // channel A
+			if inverting {
+				avr.PORTB.SetBits(1 << 6) // PB6 high
+				avr.TCCR0A.SetBits(avr.TCCR0A_COM0A0)
+			} else {
+				avr.PORTB.ClearBits(1 << 6) // PB6 low
+				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0A0)
+			}
+		case 1: // channel B
+			if inverting {
+				avr.PORTB.SetBits(1 << 5) // PB5 high
+				avr.TCCR0A.SetBits(avr.TCCR0A_COM0B0)
+			} else {
+				avr.PORTB.ClearBits(1 << 5) // PB5 low
+				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0B0)
+			}
+		}
+	case 1:
+		// Note: the COM1A0/COM1B0 bit is not set with the configuration below.
+		// It will be set the following call to Set(), however.
+		switch channel {
+		case 0: // channel A, PB1
+			if inverting {
+				avr.PORTB.SetBits(1 << 1) // PB1 high
+			} else {
+				avr.PORTB.ClearBits(1 << 1) // PB1 low
+			}
+		case 1: // channel B, PB2
+			if inverting {
+				avr.PORTB.SetBits(1 << 2) // PB2 high
+			} else {
+				avr.PORTB.ClearBits(1 << 2) // PB2 low
+			}
+		}
+	case 2:
+		switch channel {
+		case 0: // channel A
+			if inverting {
+				avr.PORTB.SetBits(1 << 3) // PB3 high
+				avr.TCCR2A.SetBits(avr.TCCR2A_COM2A0)
+			} else {
+				avr.PORTB.ClearBits(1 << 3) // PB3 low
+				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2A0)
+			}
+		case 1: // channel B
+			if inverting {
+				avr.PORTD.SetBits(1 << 3) // PD3 high
+				avr.TCCR2A.SetBits(avr.TCCR2A_COM2B0)
+			} else {
+				avr.PORTD.ClearBits(1 << 3) // PD3 low
+				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2B0)
+			}
+		}
+	}
+}
+
+// Set updates the channel value. This is used to control the channel duty
+// cycle, in other words the fraction of time the channel output is high (or low
+// when inverted). For example, to set it to a 25% duty cycle, use:
+//
+//	pwm.Set(channel, pwm.Top() / 4)
+//
+// pwm.Set(channel, 0) will set the output to low and pwm.Set(channel,
+// pwm.Top()) will set the output to high, assuming the output isn't inverted.
+func (pwm PWM) Set(channel uint8, value uint32) {
+	switch pwm.num {
+	case 0:
+		value := uint16(value)
+		switch channel {
+		case 0: // channel A
+			if value == 0 {
+				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0A1)
+			} else {
+				avr.OCR0A.Set(uint8(value - 1))
+				avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
+			}
+		case 1: // channel B
+			if value == 0 {
+				avr.TCCR0A.ClearBits(avr.TCCR0A_COM0B1)
+			} else {
+				avr.OCR0B.Set(uint8(value) - 1)
+				avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
+			}
+		}
+		// monotonic timer is using the same time as PWM:0
+		// we must adust internal settings of monotonic timer when PWM:0 settings changed
+		adjustMonotonicTimer()
+	case 1:
+		mask := interrupt.Disable()
+		switch channel {
+		case 0: // channel A, PB1
+			if value == 0 {
+				avr.TCCR1A.ClearBits(avr.TCCR1A_COM1A1 | avr.TCCR1A_COM1A0)
+			} else {
+				value := uint16(value) - 1 // yes, this is safe (it relies on underflow)
+				avr.OCR1AH.Set(uint8(value >> 8))
+				avr.OCR1AL.Set(uint8(value))
+				if avr.PORTB.HasBits(1 << 1) { // is PB1 high?
+					// Yes, set the inverting bit.
+					avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1 | avr.TCCR1A_COM1A0)
+				} else {
+					// No, output is non-inverting.
+					avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
+				}
+			}
+		case 1: // channel B, PB2
+			if value == 0 {
+				avr.TCCR1A.ClearBits(avr.TCCR1A_COM1B1 | avr.TCCR1A_COM1B0)
+			} else {
+				value := uint16(value) - 1 // yes, this is safe (it relies on underflow)
+				avr.OCR1BH.Set(uint8(value >> 8))
+				avr.OCR1BL.Set(uint8(value))
+				if avr.PORTB.HasBits(1 << 2) { // is PB2 high?
+					// Yes, set the inverting bit.
+					avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1 | avr.TCCR1A_COM1B0)
+				} else {
+					// No, output is non-inverting.
+					avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
+				}
+			}
+		}
+		interrupt.Restore(mask)
+	case 2:
+		value := uint16(value)
+		switch channel {
+		case 0: // channel A
+			if value == 0 {
+				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2A1)
+			} else {
+				avr.OCR2A.Set(uint8(value - 1))
+				avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
+			}
+		case 1: // channel B
+			if value == 0 {
+				avr.TCCR2A.ClearBits(avr.TCCR2A_COM2B1)
+			} else {
+				avr.OCR2B.Set(uint8(value - 1))
+				avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
+			}
+		}
+	}
+}
+
+// SPI configuration
+var SPI0 = SPI{
+	spcr: avr.SPCR,
+	spdr: avr.SPDR,
+	spsr: avr.SPSR,
+	sck:  PB5,
+	sdo:  PB3,
+	sdi:  PB4,
+	cs:   PB2}
+
+// Pin Change Interrupts
+type PinChange uint8
+
+const (
+	PinRising PinChange = 1 << iota
+	PinFalling
+	PinToggle = PinRising | PinFalling
+)
+
+func (pin Pin) SetInterrupt(pinChange PinChange, callback func(Pin)) (err error) {
+
+	switch {
+	case pin >= PB0 && pin <= PB7:
+		// PCMSK0 - PCINT0-7
+		pinStates[0] = avr.PINB.Get()
+		pinIndex := pin - PB0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[0][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[0][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK0.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK0.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE0)
+		interrupt.New(avr.IRQ_PCINT0, handlePCINT0Interrupts)
+	case pin >= PC0 && pin <= PC7:
+		// PCMSK1 - PCINT8-14
+		pinStates[1] = avr.PINC.Get()
+		pinIndex := pin - PC0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[1][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[1][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK1.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK1.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE1)
+		interrupt.New(avr.IRQ_PCINT1, handlePCINT1Interrupts)
+	case pin >= PD0 && pin <= PD7:
+		// PCMSK2 - PCINT16-23
+		pinStates[2] = avr.PIND.Get()
+		pinIndex := pin - PD0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[2][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[2][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK2.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK2.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE2)
+		interrupt.New(avr.IRQ_PCINT2, handlePCINT2Interrupts)
+	default:
+		return ErrInvalidInputPin
+	}
+
+	return nil
+}
+
+var pinCallbacks [3][8][2]func(Pin)
+var pinStates [3]uint8
+
+func handlePCINTInterrupts(intr uint8, port *volatile.Register8) {
+	current := port.Get()
+	change := pinStates[intr] ^ current
+	pinStates[intr] = current
+	for i := uint8(0); i < 8; i++ {
+		if (change>>i)&0x01 != 0x01 {
+			continue
+		}
+		pin := Pin(intr*8 + i)
+		value := pin.Get()
+		if value && pinCallbacks[intr][i][0] != nil {
+			pinCallbacks[intr][i][0](pin)
+		}
+		if !value && pinCallbacks[intr][i][1] != nil {
+			pinCallbacks[intr][i][1](pin)
+		}
+	}
+}
+
+func handlePCINT0Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(0, avr.PINB)
+}
+
+func handlePCINT1Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(1, avr.PINC)
+}
+
+func handlePCINT2Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(2, avr.PIND)
+}
@@ -4,105 +4,10 @@ package machine

 import (
 	"device/avr"
-	"runtime/interrupt"
 	"runtime/volatile"
 )

 const irq_USART0_RX = avr.IRQ_USART0_RX
-const irq_USART1_RX = avr.IRQ_USART1_RX
-
-var (
-	UART1  = &_UART1
-	_UART1 = UART{
-		Buffer: NewRingBuffer(),
-
-		dataReg:    avr.UDR1,
-		baudRegH:   avr.UBRR1H,
-		baudRegL:   avr.UBRR1L,
-		statusRegA: avr.UCSR1A,
-		statusRegB: avr.UCSR1B,
-		statusRegC: avr.UCSR1C,
-	}
-)
-
-func init() {
-	// Register the UART interrupt.
-	interrupt.New(irq_USART1_RX, _UART1.handleInterrupt)
-}
-
-// I2C0 is the only I2C interface on most AVRs.
-var I2C0 = &I2C{
-	srReg: avr.TWSR0,
-	brReg: avr.TWBR0,
-	crReg: avr.TWCR0,
-	drReg: avr.TWDR0,
-	srPS0: avr.TWSR0_TWPS0,
-	srPS1: avr.TWSR0_TWPS1,
-	crEN:  avr.TWCR0_TWEN,
-	crINT: avr.TWCR0_TWINT,
-	crSTO: avr.TWCR0_TWSTO,
-	crEA:  avr.TWCR0_TWEA,
-	crSTA: avr.TWCR0_TWSTA,
-}
-
-var I2C1 = &I2C{
-	srReg: avr.TWSR1,
-	brReg: avr.TWBR1,
-	crReg: avr.TWCR1,
-	drReg: avr.TWDR1,
-	srPS0: avr.TWSR1_TWPS10,
-	srPS1: avr.TWSR1_TWPS11,
-	crEN:  avr.TWCR1_TWEN1,
-	crINT: avr.TWCR1_TWINT1,
-	crSTO: avr.TWCR1_TWSTO1,
-	crEA:  avr.TWCR1_TWEA1,
-	crSTA: avr.TWCR1_TWSTA1,
-}
-
-// SPI configuration
-var SPI0 = SPI{
-	spcr: avr.SPCR0,
-	spdr: avr.SPDR0,
-	spsr: avr.SPSR0,
-
-	spcrR0:   avr.SPCR0_SPR0,
-	spcrR1:   avr.SPCR0_SPR1,
-	spcrCPHA: avr.SPCR0_CPHA,
-	spcrCPOL: avr.SPCR0_CPOL,
-	spcrDORD: avr.SPCR0_DORD,
-	spcrSPE:  avr.SPCR0_SPE,
-	spcrMSTR: avr.SPCR0_MSTR,
-
-	spsrI2X:  avr.SPSR0_SPI2X,
-	spsrSPIF: avr.SPSR0_SPIF,
-
-	sck: PB5,
-	sdo: PB3,
-	sdi: PB4,
-	cs:  PB2,
-}
-
-var SPI1 = SPI{
-	spcr: avr.SPCR1,
-	spdr: avr.SPDR1,
-	spsr: avr.SPSR1,
-
-	spcrR0:   avr.SPCR1_SPR10,
-	spcrR1:   avr.SPCR1_SPR11,
-	spcrCPHA: avr.SPCR1_CPHA1,
-	spcrCPOL: avr.SPCR1_CPOL1,
-	spcrDORD: avr.SPCR1_DORD1,
-	spcrSPE:  avr.SPCR1_SPE1,
-	spcrMSTR: avr.SPCR1_MSTR1,
-
-	spsrI2X:  avr.SPSR1_SPI2X1,
-	spsrSPIF: avr.SPSR1_SPIF1,
-
-	sck: PC1,
-	sdo: PE3,
-	sdi: PC0,
-	cs:  PE2,
-}

 // getPortMask returns the PORTx register and mask for the pin.
 func (p Pin) getPortMask() (*volatile.Register8, uint8) {
@@ -111,9 +16,94 @@ func (p Pin) getPortMask() (*volatile.Register8, uint8) {
 		return avr.PORTB, 1 << uint8(p-portB)
 	case p >= PC0 && p <= PC7: // port C
 		return avr.PORTC, 1 << uint8(p-portC)
-	case p >= PD0 && p <= PD7: // port D
+	default: // port D
 		return avr.PORTD, 1 << uint8(p-portD)
-	default: // port E
-		return avr.PORTE, 1 << uint8(p-portE)
 	}
 }
+
+// InitPWM initializes the registers needed for PWM.
+func InitPWM() {
+	// use waveform generation
+	avr.TCCR0A.SetBits(avr.TCCR0A_WGM00)
+
+	// set timer 0 prescale factor to 64
+	avr.TCCR0B.SetBits(avr.TCCR0B_CS01 | avr.TCCR0B_CS00)
+
+	// set timer 1 prescale factor to 64
+	avr.TCCR1B.SetBits(avr.TCCR1B_CS11)
+
+	// put timer 1 in 8-bit phase correct pwm mode
+	avr.TCCR1A.SetBits(avr.TCCR1A_WGM10)
+
+	// set timer 2 prescale factor to 64
+	avr.TCCR2B.SetBits(avr.TCCR2B_CS22)
+
+	// configure timer 2 for phase correct pwm (8-bit)
+	avr.TCCR2A.SetBits(avr.TCCR2A_WGM20)
+}
+
+// Configure configures a PWM pin for output.
+func (pwm PWM) Configure() error {
+	switch pwm.Pin / 8 {
+	case 0: // port B
+		avr.DDRB.SetBits(1 << uint8(pwm.Pin))
+	case 2: // port D
+		avr.DDRD.SetBits(1 << uint8(pwm.Pin-16))
+	}
+	return nil
+}
+
+// Set turns on the duty cycle for a PWM pin using the provided value. On the AVR this is normally a
+// 8-bit value ranging from 0 to 255.
+func (pwm PWM) Set(value uint16) {
+	value8 := uint8(value >> 8)
+	switch pwm.Pin {
+	case PD3:
+		// connect pwm to pin on timer 2, channel B
+		avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
+		avr.OCR2B.Set(value8) // set pwm duty
+	case PD5:
+		// connect pwm to pin on timer 0, channel B
+		avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
+		avr.OCR0B.Set(value8) // set pwm duty
+	case PD6:
+		// connect pwm to pin on timer 0, channel A
+		avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
+		avr.OCR0A.Set(value8) // set pwm duty
+	case PB1:
+		// connect pwm to pin on timer 1, channel A
+		avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
+		// this is a 16-bit value, but we only currently allow the low order bits to be set
+		avr.OCR1AL.Set(value8) // set pwm duty
+	case PB2:
+		// connect pwm to pin on timer 1, channel B
+		avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
+		// this is a 16-bit value, but we only currently allow the low order bits to be set
+		avr.OCR1BL.Set(value8) // set pwm duty
+	case PB3:
+		// connect pwm to pin on timer 2, channel A
+		avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
+		avr.OCR2A.Set(value8) // set pwm duty
+	default:
+		panic("Invalid PWM pin")
+	}
+}
+
+// SPI configuration
+var SPI0 = SPI{
+	spcr: avr.SPCR0,
+	spdr: avr.SPDR0,
+	spsr: avr.SPSR0,
+	sck:  PB5,
+	sdo:  PB3,
+	sdi:  PB4,
+	cs:   PB2}
+
+var SPI1 = SPI{
+	spcr: avr.SPCR1,
+	spdr: avr.SPDR1,
+	spsr: avr.SPSR1,
+	sck:  PC1,
+	sdo:  PE3,
+	sdi:  PC0,
+	cs:   PE2}
@@ -534,16 +534,16 @@ func (uart *UART) Configure(config UARTConfig) error {
 	if !ok {
 		return ErrInvalidOutputPin
 	}
-	var txPadOut uint32
+	var txPinOut uint32
 	// See table 25-9 of the datasheet (page 459) for how pads are mapped to
 	// pinout values.
 	switch txPad {
 	case 0:
-		txPadOut = 0
+		txPinOut = 0
 	case 2:
-		txPadOut = 1
+		txPinOut = 1
 	default:
-		// this should be a flow control (RTS/CTS) pin
+		// TODO: flow control (RTS/CTS)
 		return ErrInvalidOutputPin
 	}

@@ -554,35 +554,12 @@ func (uart *UART) Configure(config UARTConfig) error {
 	}
 	// As you can see in table 25-8 on page 459 of the datasheet, input pins
 	// are mapped directly.
-	rxPadOut := rxPad
+	rxPinOut := rxPad

 	// configure pins
 	config.TX.Configure(PinConfig{Mode: txPinMode})
 	config.RX.Configure(PinConfig{Mode: rxPinMode})

-	// configure RTS/CTS pins if provided
-	if config.RTS != 0 && config.CTS != 0 {
-		rtsPinMode, _, ok := findPinPadMapping(uart.SERCOM, config.RTS)
-		if !ok {
-			return ErrInvalidOutputPin
-		}
-
-		ctsPinMode, _, ok := findPinPadMapping(uart.SERCOM, config.CTS)
-		if !ok {
-			return ErrInvalidInputPin
-		}
-
-		// See table 25-9 of the datasheet (page 459) for how pads are mapped to
-		// pinout values.
-		if txPadOut == 1 {
-			return ErrInvalidOutputPin
-		}
-		txPadOut = 2
-
-		config.RTS.Configure(PinConfig{Mode: rtsPinMode})
-		config.CTS.Configure(PinConfig{Mode: ctsPinMode})
-	}
-
 	// reset SERCOM0
 	uart.Bus.CTRLA.SetBits(sam.SERCOM_USART_CTRLA_SWRST)
 	for uart.Bus.CTRLA.HasBits(sam.SERCOM_USART_CTRLA_SWRST) ||
@@ -615,8 +592,8 @@ func (uart *UART) Configure(config UARTConfig) error {
 	// set UART pads. This is not same as pins...
 	//  SERCOM_USART_CTRLA_TXPO(txPad) |
 	//   SERCOM_USART_CTRLA_RXPO(rxPad);
-	uart.Bus.CTRLA.SetBits((txPadOut << sam.SERCOM_USART_CTRLA_TXPO_Pos) |
-		(rxPadOut << sam.SERCOM_USART_CTRLA_RXPO_Pos))
+	uart.Bus.CTRLA.SetBits((txPinOut << sam.SERCOM_USART_CTRLA_TXPO_Pos) |
+		(rxPinOut << sam.SERCOM_USART_CTRLA_RXPO_Pos))

 	// Enable Transceiver and Receiver
 	//sercom->USART.CTRLB.reg |= SERCOM_USART_CTRLB_TXEN | SERCOM_USART_CTRLB_RXEN ;
@@ -683,6 +683,56 @@ func (p Pin) getPinGrouping() (uint8, uint8) {
 	return group, pin_in_group
 }

+// Static DMA channel allocation.
+// If there are a lot of DMA using peripherals, we might need to switch to
+// dynamic allocation instead.
+const (
+	dmaChannelSERCOM0 = iota
+	dmaChannelSERCOM1
+	dmaChannelSERCOM2
+	dmaChannelSERCOM3
+	dmaChannelSERCOM4
+	dmaChannelSERCOM5
+	dmaChannelSERCOM6
+	dmaChannelSERCOM7
+	dmaNumChannels
+)
+
+// DMA descriptor structure. This structure is defined by the hardware, and is
+// described by "22.9 Register Summary - SRAM" in the datasheet.
+type dmaDescriptor struct {
+	btctrl   uint16
+	btcnt    uint16
+	srcaddr  unsafe.Pointer
+	dstaddr  unsafe.Pointer
+	descaddr unsafe.Pointer
+}
+
+//go:align 16
+var dmaDescriptorSection [dmaNumChannels]dmaDescriptor
+
+//go:align 16
+var dmaDescriptorWritebackSection [dmaNumChannels]dmaDescriptor
+
+// Enable and configure the DMAC peripheral if it hasn't been enabled already.
+func enableDMAC() {
+	if !sam.DMAC.CTRL.HasBits(sam.DMAC_CTRL_DMAENABLE) {
+		// Init DMAC.
+		// First configure the clocks, then configure the DMA descriptors. Those
+		// descriptors must live in SRAM and must be aligned on a 16-byte
+		// boundary.
+		// Some examples:
+		// http://www.lucadavidian.com/2018/03/08/wifi-controlled-neo-pixels-strips/
+		// https://svn.larosterna.com/oss/trunk/arduino/zerotimer/zerodma.cpp
+		sam.MCLK.AHBMASK.SetBits(sam.MCLK_AHBMASK_DMAC_)
+		sam.DMAC.BASEADDR.Set(uint32(uintptr(unsafe.Pointer(&dmaDescriptorSection))))
+		sam.DMAC.WRBADDR.Set(uint32(uintptr(unsafe.Pointer(&dmaDescriptorWritebackSection))))
+
+		// Enable peripheral with all priorities.
+		sam.DMAC.CTRL.SetBits(sam.DMAC_CTRL_DMAENABLE | sam.DMAC_CTRL_LVLEN0 | sam.DMAC_CTRL_LVLEN1 | sam.DMAC_CTRL_LVLEN2 | sam.DMAC_CTRL_LVLEN3)
+	}
+}
+
 // InitADC initializes the ADC.
 func InitADC() {
 	// ADC Bias Calibration
@@ -1015,14 +1065,14 @@ func (uart *UART) Configure(config UARTConfig) error {
 	if !ok {
 		return ErrInvalidOutputPin
 	}
-	var txPadOut uint32
+	var txPinOut uint32
 	// See CTRLA.RXPO bits of the SERCOM USART peripheral (page 945-946) for how
 	// pads are mapped to pinout values.
 	switch txPad {
 	case 0:
-		txPadOut = 0
+		txPinOut = 0
 	default:
-		// should be flow control (RTS/CTS) pin
+		// TODO: flow control (RTS/CTS)
 		return ErrInvalidOutputPin
 	}

@@ -1033,32 +1083,12 @@ func (uart *UART) Configure(config UARTConfig) error {
 	}
 	// As you can see in the CTRLA.RXPO bits of the SERCOM USART peripheral
 	// (page 945), input pins are mapped directly.
-	rxPadOut := rxPad
+	rxPinOut := rxPad

 	// configure pins
 	config.TX.Configure(PinConfig{Mode: txPinMode})
 	config.RX.Configure(PinConfig{Mode: rxPinMode})

-	// configure RTS/CTS pins if provided
-	if config.RTS != 0 && config.CTS != 0 {
-		rtsPinMode, _, ok := findPinPadMapping(uart.SERCOM, config.RTS)
-		if !ok {
-			return ErrInvalidOutputPin
-		}
-
-		ctsPinMode, _, ok := findPinPadMapping(uart.SERCOM, config.CTS)
-		if !ok {
-			return ErrInvalidInputPin
-		}
-
-		// See CTRLA.RXPO bits of the SERCOM USART peripheral (page 945-946) for how
-		// pads are mapped to pinout values.
-		txPadOut = 2
-
-		config.RTS.Configure(PinConfig{Mode: rtsPinMode})
-		config.CTS.Configure(PinConfig{Mode: ctsPinMode})
-	}
-
 	// reset SERCOM
 	uart.Bus.CTRLA.SetBits(sam.SERCOM_USART_INT_CTRLA_SWRST)
 	for uart.Bus.CTRLA.HasBits(sam.SERCOM_USART_INT_CTRLA_SWRST) ||
@@ -1095,8 +1125,8 @@ func (uart *UART) Configure(config UARTConfig) error {
 	// set UART pads. This is not same as pins...
 	//  SERCOM_USART_CTRLA_TXPO(txPad) |
 	//   SERCOM_USART_CTRLA_RXPO(rxPad);
-	uart.Bus.CTRLA.SetBits((txPadOut << sam.SERCOM_USART_INT_CTRLA_TXPO_Pos) |
-		(rxPadOut << sam.SERCOM_USART_INT_CTRLA_RXPO_Pos))
+	uart.Bus.CTRLA.SetBits((txPinOut << sam.SERCOM_USART_INT_CTRLA_TXPO_Pos) |
+		(rxPinOut << sam.SERCOM_USART_INT_CTRLA_RXPO_Pos))

 	// Enable Transceiver and Receiver
 	//sercom->USART.CTRLB.reg |= SERCOM_USART_CTRLB_TXEN | SERCOM_USART_CTRLB_RXEN ;
@@ -1672,6 +1702,101 @@ func (spi SPI) txrx(tx, rx []byte) {
 	rx[len(rx)-1] = byte(spi.Bus.DATA.Get())
 }

+// Channel to be used for SPI transfers.
+// These channels are currently statically allocated.
+func (spi SPI) dmaTxChannel() uint8 {
+	return dmaChannelSERCOM0 + spi.SERCOM
+}
+
+// IsAsync returns whether the SPI supports async operation (usually DMA).
+//
+// It returns true on the SAM D5x chips.
+func (spi SPI) IsAsync() bool {
+	return true
+}
+
+// Start a transfer in the background.
+//
+// After this, another StartTx() or Wait() must be called. The provided byte
+// slices (tx and rx) may only be accessed again after Wait() was called.
+func (s SPI) StartTx(tx, rx []byte) error {
+	// Check whether we support doing this transfer using DMA.
+	if len(rx) != 0 {
+		return s.Tx(tx, rx)
+	}
+	if len(tx) == 0 {
+		return nil // nothing to send/receive
+	}
+	if len(tx) != int(uint16(len(tx))) {
+		// The transfer size is a 16-bit field.
+		// TODO: chain multiple transfers in some way when encountering these
+		// large buffer sizes. They're not currently implemented because
+		// transferring 64kB of data is less commonly done.
+		return s.Tx(tx, rx)
+	}
+
+	// Enable DMAC (if not already enabled).
+	enableDMAC()
+
+	// Wait until a possible previous transfer has been completed.
+	s.Wait()
+
+	// Configure the DMA channel, if it hasn't been configured already.
+	dstaddr := unsafe.Pointer(&s.Bus.DATA.Reg)
+	if dmaDescriptorSection[s.dmaTxChannel()].dstaddr != dstaddr {
+		// Configure channel descriptor.
+		dmaDescriptorSection[s.dmaTxChannel()] = dmaDescriptor{
+			btctrl: (1 << 0) | // VALID: Descriptor Valid
+				(0 << 3) | // BLOCKACT=NOACT: Block Action
+				(1 << 10) | // SRCINC: Source Address Increment Enable
+				(0 << 11) | // DSTINC: Destination Address Increment Enable
+				(1 << 12) | // STEPSEL=SRC: Step Selection
+				(0 << 13), // STEPSIZE=X1: Address Increment Step Size
+			dstaddr: dstaddr,
+		}
+
+		// Reset channel.
+		sam.DMAC.CHANNEL[s.dmaTxChannel()].CHCTRLA.ClearBits(sam.DMAC_CHANNEL_CHCTRLA_ENABLE)
+		sam.DMAC.CHANNEL[s.dmaTxChannel()].CHCTRLA.SetBits(sam.DMAC_CHANNEL_CHCTRLA_SWRST)
+
+		// Configure channel.
+		sam.DMAC.CHANNEL[s.dmaTxChannel()].CHPRILVL.Set(0)
+		sam.DMAC.CHANNEL[s.dmaTxChannel()].CHCTRLA.Set((sam.DMAC_CHANNEL_CHCTRLA_TRIGACT_BURST << sam.DMAC_CHANNEL_CHCTRLA_TRIGACT_Pos) |
+			(s.triggerSource() << sam.DMAC_CHANNEL_CHCTRLA_TRIGSRC_Pos) |
+			(sam.DMAC_CHANNEL_CHCTRLA_BURSTLEN_SINGLE << sam.DMAC_CHANNEL_CHCTRLA_BURSTLEN_Pos))
+	}
+
+	// For some reason, you have to provide the address just past the end of the
+	// array instead of the address of the array.
+	descriptor := &dmaDescriptorSection[s.dmaTxChannel()]
+	descriptor.srcaddr = unsafe.Pointer(uintptr(unsafe.Pointer(&tx[0])) + uintptr(len(tx)))
+	descriptor.btcnt = uint16(len(tx)) // beat count
+
+	// Start the transfer.
+	sam.DMAC.CHANNEL[s.dmaTxChannel()].CHCTRLA.SetBits(sam.DMAC_CHANNEL_CHCTRLA_ENABLE)
+
+	return nil
+}
+
+// Wait until all active transactions (started by StartTx) have finished. The
+// buffers provided in StartTx will be available after this method returns.
+func (spi SPI) Wait() error {
+	// Wait until the previous SPI transfer completed.
+	// This is basically the same thing as in SPI.tx.
+
+	// TODO: maybe block (and sleep) until the transfer has completed?
+
+	for !spi.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_TXC) {
+	}
+
+	// read to clear RXC register
+	for spi.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_RXC) {
+		spi.Bus.DATA.Get()
+	}
+
+	return nil
+}
+
 // The QSPI peripheral on ATSAMD51 is only available on the following pins
 const (
 	QSPI_SCK   = PB10
@@ -62,6 +62,27 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has three TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -62,6 +62,27 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0B
+	case sam.SERCOM4_SPIM:
+		return 0x0D
+	case sam.SERCOM5_SPIM:
+		return 0x0F
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -62,6 +62,27 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -76,6 +76,31 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	case sam.SERCOM6_SPIM:
+		return 0x10
+	case sam.SERCOM7_SPIM:
+		return 0x12
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -76,6 +76,31 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	case sam.SERCOM6_SPIM:
+		return 0x10
+	case sam.SERCOM7_SPIM:
+		return 0x12
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -62,6 +62,27 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -76,6 +76,31 @@ func setSERCOMClockGenerator(sercom uint8, gclk uint32) {
 	}
 }

+// DMA trigger source
+func (spi SPI) triggerSource() (tx uint32) {
+	// See TRIGSRC field of CHCTRLA register for description of these constants.
+	switch spi.Bus {
+	case sam.SERCOM0_SPIM:
+		return 0x05
+	case sam.SERCOM1_SPIM:
+		return 0x07
+	case sam.SERCOM2_SPIM:
+		return 0x09
+	case sam.SERCOM3_SPIM:
+		return 0x0A
+	case sam.SERCOM4_SPIM:
+		return 0x0C
+	case sam.SERCOM5_SPIM:
+		return 0x0E
+	case sam.SERCOM6_SPIM:
+		return 0x10
+	case sam.SERCOM7_SPIM:
+		return 0x12
+	default:
+		return 0 // should be unreachable
+	}
+}
+
 // This chip has five TCC peripherals, which have PWM as one feature.
 var (
 	TCC0 = (*TCC)(sam.TCC0)
@@ -237,13 +237,13 @@ func (p Pin) mux() *volatile.Register32 {
 	case 27:
 		return &esp.IO_MUX.GPIO27
 	case 14:
-		return &esp.IO_MUX.GPIO14
+		return &esp.IO_MUX.MTMS
 	case 12:
-		return &esp.IO_MUX.GPIO12
+		return &esp.IO_MUX.MTDI
 	case 13:
-		return &esp.IO_MUX.GPIO13
+		return &esp.IO_MUX.MTCK
 	case 15:
-		return &esp.IO_MUX.GPIO15
+		return &esp.IO_MUX.MTDO
 	case 2:
 		return &esp.IO_MUX.GPIO2
 	case 0:
@@ -255,17 +255,17 @@ func (p Pin) mux() *volatile.Register32 {
 	case 17:
 		return &esp.IO_MUX.GPIO17
 	case 9:
-		return &esp.IO_MUX.GPIO9
+		return &esp.IO_MUX.SD_DATA2
 	case 10:
-		return &esp.IO_MUX.GPIO10
+		return &esp.IO_MUX.SD_DATA3
 	case 11:
-		return &esp.IO_MUX.GPIO11
+		return &esp.IO_MUX.SD_CMD
 	case 6:
-		return &esp.IO_MUX.GPIO6
+		return &esp.IO_MUX.SD_CLK
 	case 7:
-		return &esp.IO_MUX.GPIO7
+		return &esp.IO_MUX.SD_DATA0
 	case 8:
-		return &esp.IO_MUX.GPIO8
+		return &esp.IO_MUX.SD_DATA1
 	case 5:
 		return &esp.IO_MUX.GPIO5
 	case 18:
@@ -279,9 +279,9 @@ func (p Pin) mux() *volatile.Register32 {
 	case 22:
 		return &esp.IO_MUX.GPIO22
 	case 3:
-		return &esp.IO_MUX.GPIO3
+		return &esp.IO_MUX.U0RXD
 	case 1:
-		return &esp.IO_MUX.GPIO1
+		return &esp.IO_MUX.U0TXD
 	case 23:
 		return &esp.IO_MUX.GPIO23
 	case 24:
@@ -320,8 +320,7 @@ func (uart *UART) writeByte(b byte) error {
 		// many bytes there are in the transmit buffer. Wait until there are
 		// less than 128 bytes in this buffer (the default buffer size).
 	}
-	// Write to the TX_FIFO register.
-	(*volatile.Register8)(unsafe.Add(unsafe.Pointer(uart.Bus), 0x200C0000)).Set(b)
+	uart.Bus.TX_FIFO.Set(b)
 	return nil
 }

@@ -111,10 +111,6 @@ func (p Pin) outFunc() *volatile.Register32 {
 	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(&esp.GPIO.FUNC0_OUT_SEL_CFG), uintptr(p)*4))
 }

-func (p Pin) pinReg() *volatile.Register32 {
-	return (*volatile.Register32)(unsafe.Pointer((uintptr(unsafe.Pointer(&esp.GPIO.PIN0)) + uintptr(p)*4)))
-}
-
 // inFunc returns the FUNCy_IN_SEL_CFG register used for configuring the input
 // function selection.
 func inFunc(signal uint32) *volatile.Register32 {
@@ -192,7 +188,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {

 	if callback == nil {
 		// Disable this pin interrupt
-		p.pin().ClearBits(esp.GPIO_PIN_INT_TYPE_Msk | esp.GPIO_PIN_INT_ENA_Msk)
+		p.pin().ClearBits(esp.GPIO_PIN_PIN_INT_TYPE_Msk | esp.GPIO_PIN_PIN_INT_ENA_Msk)

 		if pinCallbacks[p] != nil {
 			pinCallbacks[p] = nil
@@ -216,8 +212,8 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {
 	}

 	p.pin().Set(
-		(p.pin().Get() & ^uint32(esp.GPIO_PIN_INT_TYPE_Msk|esp.GPIO_PIN_INT_ENA_Msk)) |
-			uint32(change)<<esp.GPIO_PIN_INT_TYPE_Pos | uint32(1)<<esp.GPIO_PIN_INT_ENA_Pos)
+		(p.pin().Get() & ^uint32(esp.GPIO_PIN_PIN_INT_TYPE_Msk|esp.GPIO_PIN_PIN_INT_ENA_Msk)) |
+			uint32(change)<<esp.GPIO_PIN_PIN_INT_TYPE_Pos | uint32(1)<<esp.GPIO_PIN_PIN_INT_ENA_Pos)

 	return nil
 }
@@ -395,7 +391,7 @@ func initUARTClock(bus *esp.UART_Type, regs registerSet) {
 	// synchronize core register
 	bus.SetID_REG_UPDATE(0)
 	// enable RTC clock
-	esp.RTC_CNTL.SetCLK_CONF_DIG_CLK8M_EN(1)
+	esp.RTC_CNTL.SetRTC_CLK_CONF_DIG_CLK8M_EN(1)
 	// wait for Core Clock to ready for configuration
 	for bus.GetID_REG_UPDATE() > 0 {
 		riscv.Asm("nop")
@@ -419,7 +415,7 @@ func (uart *UART) setupPins(config UARTConfig, regs registerSet) {
 	// link TX with GPIO signal X (technical reference manual 5.10) (this is not interrupt signal!)
 	config.TX.outFunc().Set(regs.gpioMatrixSignal)
 	// link RX with GPIO signal X and route signals via GPIO matrix (GPIO_SIGn_IN_SEL 0x40)
-	inFunc(regs.gpioMatrixSignal).Set(esp.GPIO_FUNC_IN_SEL_CFG_SEL | uint32(config.RX))
+	inFunc(regs.gpioMatrixSignal).Set(esp.GPIO_FUNC_IN_SEL_CFG_SIG_IN_SEL | uint32(config.RX))
 }

 func (uart *UART) configureInterrupt(intrMapReg *volatile.Register32) { // Disable all UART interrupts
@@ -508,130 +504,3 @@ func (uart *UART) writeByte(b byte) error {
 }

 func (uart *UART) flush() {}
-
-type Serialer interface {
-	WriteByte(c byte) error
-	Write(data []byte) (n int, err error)
-	Configure(config UARTConfig) error
-	Buffered() int
-	ReadByte() (byte, error)
-	DTR() bool
-	RTS() bool
-}
-
-// USB Serial/JTAG Controller
-// See esp32-c3_technical_reference_manual_en.pdf
-// pg. 736
-type USB_DEVICE struct {
-	Bus *esp.USB_DEVICE_Type
-}
-
-var (
-	_USBCDC = &USB_DEVICE{
-		Bus: esp.USB_DEVICE,
-	}
-
-	USBCDC Serialer = _USBCDC
-)
-
-var (
-	errUSBWrongSize            = errors.New("USB: invalid write size")
-	errUSBCouldNotWriteAllData = errors.New("USB: could not write all data")
-	errUSBBufferEmpty          = errors.New("USB: read buffer empty")
-)
-
-func (usbdev *USB_DEVICE) Configure(config UARTConfig) error {
-	return nil
-}
-
-func (usbdev *USB_DEVICE) WriteByte(c byte) error {
-	if usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() == 0 {
-		return errUSBCouldNotWriteAllData
-	}
-
-	usbdev.Bus.SetEP1_RDWR_BYTE(uint32(c))
-	usbdev.flush()
-
-	return nil
-}
-
-func (usbdev *USB_DEVICE) Write(data []byte) (n int, err error) {
-	if len(data) == 0 || len(data) > 64 {
-		return 0, errUSBWrongSize
-	}
-
-	for i, c := range data {
-		if usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() == 0 {
-			if i > 0 {
-				usbdev.flush()
-			}
-
-			return i, errUSBCouldNotWriteAllData
-		}
-		usbdev.Bus.SetEP1_RDWR_BYTE(uint32(c))
-	}
-
-	usbdev.flush()
-	return len(data), nil
-}
-
-func (usbdev *USB_DEVICE) Buffered() int {
-	return int(usbdev.Bus.GetEP1_CONF_SERIAL_OUT_EP_DATA_AVAIL())
-}
-
-func (usbdev *USB_DEVICE) ReadByte() (byte, error) {
-	if usbdev.Bus.GetEP1_CONF_SERIAL_OUT_EP_DATA_AVAIL() != 0 {
-		return byte(usbdev.Bus.GetEP1_RDWR_BYTE()), nil
-	}
-
-	return 0, nil
-}
-
-func (usbdev *USB_DEVICE) DTR() bool {
-	return false
-}
-
-func (usbdev *USB_DEVICE) RTS() bool {
-	return false
-}
-
-func (usbdev *USB_DEVICE) flush() {
-	usbdev.Bus.SetEP1_CONF_WR_DONE(1)
-	for usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() == 0 {
-	}
-}
-
-// GetRNG returns 32-bit random numbers using the ESP32-C3 true random number generator,
-// Random numbers are generated based on the thermal noise in the system and the
-// asynchronous clock mismatch.
-// For maximum entropy also make sure that the SAR_ADC is enabled.
-// See esp32-c3_technical_reference_manual_en.pdf p.524
-func GetRNG() (ret uint32, err error) {
-	// ensure ADC clock is initialized
-	initADCClock()
-
-	// ensure fast RTC clock is enabled
-	if esp.RTC_CNTL.GetCLK_CONF_DIG_CLK8M_EN() == 0 {
-		esp.RTC_CNTL.SetCLK_CONF_DIG_CLK8M_EN(1)
-	}
-
-	return esp.APB_CTRL.GetRND_DATA(), nil
-}
-
-func initADCClock() {
-	if esp.APB_SARADC.GetCLKM_CONF_CLK_EN() == 1 {
-		return
-	}
-
-	// only support ADC_CTRL_CLK set to 1
-	esp.APB_SARADC.SetCLKM_CONF_CLK_SEL(1)
-
-	esp.APB_SARADC.SetCTRL_SARADC_SAR_CLK_GATED(1)
-
-	esp.APB_SARADC.SetCLKM_CONF_CLKM_DIV_NUM(15)
-	esp.APB_SARADC.SetCLKM_CONF_CLKM_DIV_B(1)
-	esp.APB_SARADC.SetCLKM_CONF_CLKM_DIV_A(0)
-
-	esp.APB_SARADC.SetCTRL_SARADC_SAR_CLK_DIV(1)
-	esp.APB_SARADC.SetCLKM_CONF_CLK_EN(1)
-}
@@ -1,353 +0,0 @@
-//go:build esp32c3 && !m5stamp_c3
-
-package machine
-
-import (
-	"device/esp"
-	"runtime/volatile"
-	"unsafe"
-)
-
-var (
-	I2C0 = &I2C{}
-)
-
-type I2C struct{}
-
-// I2CConfig is used to store config info for I2C.
-type I2CConfig struct {
-	Frequency uint32 // in Hz
-	SCL       Pin
-	SDA       Pin
-}
-
-const (
-	clkXTAL               = 0
-	clkFOSC               = 1
-	clkXTALFrequency      = uint32(40e6)
-	clkFOSCFrequency      = uint32(17.5e6)
-	i2cClkSourceFrequency = clkXTALFrequency
-	i2cClkSource          = clkXTAL
-)
-
-func (i2c *I2C) Configure(config I2CConfig) error {
-	if config.Frequency == 0 {
-		config.Frequency = 400 * KHz
-	}
-	if config.SCL == 0 {
-		config.SCL = SCL_PIN
-	}
-	if config.SDA == 0 {
-		config.SDA = SDA_PIN
-	}
-
-	i2c.initClock(config)
-	i2c.initNoiseFilter()
-	i2c.initPins(config)
-	i2c.initFrequency(config)
-	i2c.startMaster()
-	return nil
-}
-
-//go:inline
-func (i2c *I2C) initClock(config I2CConfig) {
-	// reset I2C clock
-	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(1)
-	esp.SYSTEM.SetPERIP_CLK_EN0_I2C_EXT0_CLK_EN(1)
-	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(0)
-	// disable interrupts
-	esp.I2C0.INT_ENA.ClearBits(0x3fff)
-	esp.I2C0.INT_CLR.ClearBits(0x3fff)
-
-	esp.I2C0.SetCLK_CONF_SCLK_SEL(i2cClkSource)
-	esp.I2C0.SetCLK_CONF_SCLK_ACTIVE(1)
-	esp.I2C0.SetCLK_CONF_SCLK_DIV_NUM(i2cClkSourceFrequency / (config.Frequency * 1024))
-	esp.I2C0.SetCTR_CLK_EN(1)
-}
-
-//go:inline
-func (i2c *I2C) initNoiseFilter() {
-	esp.I2C0.FILTER_CFG.Set(0x377)
-}
-
-//go:inline
-func (i2c *I2C) initPins(config I2CConfig) {
-	var muxConfig uint32
-	const function = 1 // function 1 is just GPIO
-
-	// SDA
-	muxConfig = function << esp.IO_MUX_GPIO_MCU_SEL_Pos
-	// Make this pin an input pin (always).
-	muxConfig |= esp.IO_MUX_GPIO_FUN_IE
-	// Set drive strength: 0 is lowest, 3 is highest.
-	muxConfig |= 1 << esp.IO_MUX_GPIO_FUN_DRV_Pos
-	config.SDA.mux().Set(muxConfig)
-	config.SDA.outFunc().Set(54)
-	inFunc(54).Set(uint32(esp.GPIO_FUNC_IN_SEL_CFG_SEL | config.SDA))
-	config.SDA.Set(true)
-	// Configure the pad with the given IO mux configuration.
-	config.SDA.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
-
-	esp.GPIO.ENABLE.SetBits(1 << int(config.SDA))
-	esp.I2C0.SetCTR_SDA_FORCE_OUT(1)
-
-	// SCL
-	muxConfig = function << esp.IO_MUX_GPIO_MCU_SEL_Pos
-	// Make this pin an input pin (always).
-	muxConfig |= esp.IO_MUX_GPIO_FUN_IE
-	// Set drive strength: 0 is lowest, 3 is highest.
-	muxConfig |= 1 << esp.IO_MUX_GPIO_FUN_DRV_Pos
-	config.SCL.mux().Set(muxConfig)
-	config.SCL.outFunc().Set(53)
-	inFunc(53).Set(uint32(config.SCL))
-	config.SCL.Set(true)
-	// Configure the pad with the given IO mux configuration.
-	config.SCL.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
-
-	esp.GPIO.ENABLE.SetBits(1 << int(config.SCL))
-	esp.I2C0.SetCTR_SCL_FORCE_OUT(1)
-}
-
-//go:inline
-func (i2c *I2C) initFrequency(config I2CConfig) {
-
-	clkmDiv := i2cClkSourceFrequency/(config.Frequency*1024) + 1
-	sclkFreq := i2cClkSourceFrequency / clkmDiv
-	halfCycle := sclkFreq / config.Frequency / 2
-	//SCL
-	sclLow := halfCycle
-	sclWaitHigh := uint32(0)
-	if config.Frequency > 50000 {
-		sclWaitHigh = halfCycle / 8 // compensate the time when freq > 50K
-	}
-	sclHigh := halfCycle - sclWaitHigh
-	// SDA
-	sdaHold := halfCycle / 4
-	sda_sample := halfCycle / 2
-	setup := halfCycle
-	hold := halfCycle
-
-	esp.I2C0.SetSCL_LOW_PERIOD(sclLow - 1)
-	esp.I2C0.SetSCL_HIGH_PERIOD(sclHigh)
-	esp.I2C0.SetSCL_HIGH_PERIOD_SCL_WAIT_HIGH_PERIOD(25)
-	esp.I2C0.SetSCL_RSTART_SETUP_TIME(setup)
-	esp.I2C0.SetSCL_STOP_SETUP_TIME(setup)
-	esp.I2C0.SetSCL_START_HOLD_TIME(hold - 1)
-	esp.I2C0.SetSCL_STOP_HOLD_TIME(hold - 1)
-	esp.I2C0.SetSDA_SAMPLE_TIME(sda_sample)
-	esp.I2C0.SetSDA_HOLD_TIME(sdaHold)
-}
-
-//go:inline
-func (i2c *I2C) startMaster() {
-	// FIFO mode for data
-	esp.I2C0.SetFIFO_CONF_NONFIFO_EN(0)
-	// Reset TX & RX buffers
-	esp.I2C0.SetFIFO_CONF_RX_FIFO_RST(1)
-	esp.I2C0.SetFIFO_CONF_RX_FIFO_RST(0)
-	esp.I2C0.SetFIFO_CONF_TX_FIFO_RST(1)
-	esp.I2C0.SetFIFO_CONF_TX_FIFO_RST(0)
-	// set timeout value
-	esp.I2C0.TO.Set(0x10)
-	// enable master mode
-	esp.I2C0.CTR.Set(0x113)
-	esp.I2C0.SetCTR_CONF_UPGATE(1)
-	resetMaster()
-}
-
-//go:inline
-func resetMaster() {
-	// reset FSM
-	esp.I2C0.SetCTR_FSM_RST(1)
-	// clear the bus
-	esp.I2C0.SetSCL_SP_CONF_SCL_RST_SLV_NUM(9)
-	esp.I2C0.SetSCL_SP_CONF_SCL_RST_SLV_EN(1)
-	esp.I2C0.SetSCL_STRETCH_CONF_SLAVE_SCL_STRETCH_EN(1)
-	esp.I2C0.SetCTR_CONF_UPGATE(1)
-	esp.I2C0.FILTER_CFG.Set(0x377)
-	// wait for SCL_RST_SLV_EN
-	for esp.I2C0.GetSCL_SP_CONF_SCL_RST_SLV_EN() != 0 {
-	}
-	esp.I2C0.SetSCL_SP_CONF_SCL_RST_SLV_NUM(0)
-}
-
-type i2cCommandType = uint32
-type i2cAck = uint32
-
-const (
-	i2cCMD_RSTART   i2cCommandType = 6 << 11
-	i2cCMD_WRITE    i2cCommandType = 1<<11 | 1<<8 // WRITE + ack_check_en
-	i2cCMD_READ     i2cCommandType = 3<<11 | 1<<8 // READ + ack_check_en
-	i2cCMD_READLAST i2cCommandType = 3<<11 | 5<<8 // READ + ack_check_en + NACK
-	i2cCMD_STOP     i2cCommandType = 2 << 11
-	i2cCMD_END      i2cCommandType = 4 << 11
-)
-
-type i2cCommand struct {
-	cmd  i2cCommandType
-	data []byte
-	head int
-}
-
-//go:linkname nanotime runtime.nanotime
-func nanotime() int64
-
-func (i2c *I2C) transmit(addr uint16, cmd []i2cCommand, timeoutMS int) error {
-	const intMask = esp.I2C_INT_STATUS_END_DETECT_INT_ST_Msk | esp.I2C_INT_STATUS_TRANS_COMPLETE_INT_ST_Msk | esp.I2C_INT_STATUS_TIME_OUT_INT_ST_Msk | esp.I2C_INT_STATUS_NACK_INT_ST_Msk
-	esp.I2C0.INT_CLR.SetBits(intMask)
-	esp.I2C0.INT_ENA.SetBits(intMask)
-	esp.I2C0.SetCTR_CONF_UPGATE(1)
-
-	defer func() {
-		esp.I2C0.INT_CLR.SetBits(intMask)
-		esp.I2C0.INT_ENA.ClearBits(intMask)
-	}()
-
-	timeoutNS := int64(timeoutMS) * 1000000
-	needAddress := true
-	needRestart := false
-	readLast := false
-	var readTo []byte
-	for cmdIdx, reg := 0, &esp.I2C0.COMD0; cmdIdx < len(cmd); {
-		c := &cmd[cmdIdx]
-
-		switch c.cmd {
-		case i2cCMD_RSTART:
-			reg.Set(i2cCMD_RSTART)
-			reg = nextAddress(reg)
-			cmdIdx++
-
-		case i2cCMD_WRITE:
-			count := 32
-			if needAddress {
-				needAddress = false
-				esp.I2C0.SetDATA_FIFO_RDATA((uint32(addr) & 0x7f) << 1)
-				count--
-				esp.I2C0.SLAVE_ADDR.Set(uint32(addr))
-				esp.I2C0.SetCTR_CONF_UPGATE(1)
-			}
-			for ; count > 0 && c.head < len(c.data); count, c.head = count-1, c.head+1 {
-				esp.I2C0.SetDATA_FIFO_RDATA(uint32(c.data[c.head]))
-			}
-			reg.Set(i2cCMD_WRITE | uint32(32-count))
-			reg = nextAddress(reg)
-
-			if c.head < len(c.data) {
-				reg.Set(i2cCMD_END)
-				reg = nil
-			} else {
-				cmdIdx++
-			}
-			needRestart = true
-
-		case i2cCMD_READ:
-			if needAddress {
-				needAddress = false
-				esp.I2C0.SetDATA_FIFO_RDATA((uint32(addr)&0x7f)<<1 | 1)
-				esp.I2C0.SLAVE_ADDR.Set(uint32(addr))
-				reg.Set(i2cCMD_WRITE | 1)
-				reg = nextAddress(reg)
-			}
-			if needRestart {
-				// We need to send RESTART again after i2cCMD_WRITE.
-				reg.Set(i2cCMD_RSTART)
-
-				reg = nextAddress(reg)
-				reg.Set(i2cCMD_WRITE | 1)
-
-				reg = nextAddress(reg)
-				esp.I2C0.SetDATA_FIFO_RDATA((uint32(addr)&0x7f)<<1 | 1)
-				needRestart = false
-			}
-			count := 32
-			bytes := len(c.data) - c.head
-			// Only last byte in sequence must be sent with ACK set to 1 to indicate end of data.
-			split := bytes <= count
-			if split {
-				bytes--
-			}
-			if bytes > 32 {
-				bytes = 32
-			}
-			reg.Set(i2cCMD_READ | uint32(bytes))
-			reg = nextAddress(reg)
-
-			if split {
-				readLast = true
-				reg.Set(i2cCMD_READLAST | 1)
-				reg = nextAddress(reg)
-				readTo = c.data[c.head : c.head+bytes+1] // read bytes + 1 last byte
-				cmdIdx++
-			} else {
-				reg.Set(i2cCMD_END)
-				readTo = c.data[c.head : c.head+bytes]
-				reg = nil
-			}
-
-		case i2cCMD_STOP:
-			reg.Set(i2cCMD_STOP)
-			reg = nil
-			cmdIdx++
-		}
-		if reg == nil {
-			// transmit now
-			esp.I2C0.SetCTR_CONF_UPGATE(1)
-			esp.I2C0.SetCTR_TRANS_START(1)
-			end := nanotime() + timeoutNS
-			var mask uint32
-			for mask = esp.I2C0.INT_STATUS.Get(); mask&intMask == 0; mask = esp.I2C0.INT_STATUS.Get() {
-				if nanotime() > end {
-					if readTo != nil {
-						return errI2CReadTimeout
-					}
-					return errI2CWriteTimeout
-				}
-			}
-			switch {
-			case mask&esp.I2C_INT_STATUS_NACK_INT_ST_Msk != 0 && !readLast:
-				return errI2CAckExpected
-			case mask&esp.I2C_INT_STATUS_TIME_OUT_INT_ST_Msk != 0:
-				if readTo != nil {
-					return errI2CReadTimeout
-				}
-				return errI2CWriteTimeout
-			}
-			esp.I2C0.INT_CLR.SetBits(intMask)
-			for i := 0; i < len(readTo); i++ {
-				readTo[i] = byte(esp.I2C0.GetDATA_FIFO_RDATA() & 0xff)
-				c.head++
-			}
-			readTo = nil
-			reg = &esp.I2C0.COMD0
-		}
-	}
-	return nil
-}
-
-// Tx does a single I2C transaction at the specified address.
-// It clocks out the given address, writes the bytes in w, reads back len(r)
-// bytes and stores them in r, and generates a stop condition on the bus.
-func (i2c *I2C) Tx(addr uint16, w, r []byte) (err error) {
-	// timeout in microseconds.
-	const timeout = 40 // 40ms is a reasonable time for a real-time system.
-
-	cmd := make([]i2cCommand, 0, 8)
-	cmd = append(cmd, i2cCommand{cmd: i2cCMD_RSTART})
-	if len(w) > 0 {
-		cmd = append(cmd, i2cCommand{cmd: i2cCMD_WRITE, data: w})
-	}
-	if len(r) > 0 {
-		cmd = append(cmd, i2cCommand{cmd: i2cCMD_READ, data: r})
-	}
-	cmd = append(cmd, i2cCommand{cmd: i2cCMD_STOP})
-
-	return i2c.transmit(addr, cmd, timeout)
-}
-
-func (i2c *I2C) SetBaudRate(br uint32) error {
-	return nil
-}
-
-func nextAddress(reg *volatile.Register32) *volatile.Register32 {
-	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(reg), 4))
-}
@@ -201,7 +201,7 @@ func (spi SPI) Configure(config SPIConfig) error {

 	// configure esp32c3 gpio pin matrix
 	config.SDI.Configure(PinConfig{Mode: PinInput})
-	inFunc(FSPIQ_IN_IDX).Set(esp.GPIO_FUNC_IN_SEL_CFG_SEL | uint32(config.SDI))
+	inFunc(FSPIQ_IN_IDX).Set(esp.GPIO_FUNC_IN_SEL_CFG_SIG_IN_SEL | uint32(config.SDI))
 	config.SDO.Configure(PinConfig{Mode: PinOutput})
 	config.SDO.outFunc().Set(FSPID_OUT_IDX)
 	config.SCK.Configure(PinConfig{Mode: PinOutput})
@@ -1,5 +0,0 @@
-//go:build nrf52840 && nrf52840_lfxtal_false
-
-package machine
-
-const HasLowFrequencyCrystal = false
@@ -1,5 +0,0 @@
-//go:build nrf52840 && ((nrf52840_generic && !nrf52840_lfxtal_false) || nrf52840_lfxtal_true)
-
-package machine
-
-const HasLowFrequencyCrystal = true
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Ayke van Laethem	65a059a973	samd51: add support for async SPI using DMA	2023-11-05 19:35:00 +01:00
Ayke van Laethem	cb95259adf	rp2040: add SPI DMA support	2023-11-04 16:18:45 +01:00
Ayke van Laethem	24d718fa05	machine: add dummy async SPI methods This prepares all devices for actual async SPI support.	2023-11-04 16:14:47 +01:00