machine: add tool to check consistency with documentation

This tool checks whether the machine package matches the documentation in https://tinygo.org/docs/reference/machine/.
runtime: make gc and scheduler asserts settable with build tags
2026-07-26 22:58:41 +00:00 · 2022-09-26 16:50:14 +02:00 · 2022-09-25 16:47:07 +02:00 · 2022-09-25 12:38:12 +02:00 · 2022-09-25 10:08:10 +02:00 · 2022-09-24 22:58:22 +02:00
138 changed files with 1699 additions and 688 deletions
@@ -118,13 +118,7 @@ jobs:
    steps:
      - test-linux:
          llvm: "14"
-  test-llvm14-go119:
-    docker:
-      - image: golang:1.19beta1-buster
-    steps:
-      - test-linux:
-          llvm: "14"
-          fmt-check: false
+    resource_class: large

 workflows:
  test-all:
@@ -132,6 +126,3 @@ workflows:
      # This tests our lowest supported versions of Go and LLVM, to make sure at
      # least the smoke tests still pass.
      - test-llvm14-go118
-      # This tests a beta version of Go. It should be removed once regular
-      # release builds are built using this version.
-      - test-llvm14-go119
@@ -16,10 +16,6 @@ jobs:
    name: build-macos
    runs-on: macos-11
    steps:
-      - name: Install Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: '1.18.1'
      - name: Install Dependencies
        shell: bash
        run: |
@@ -35,8 +31,13 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
+      - name: Install Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: '1.19'
+          cache: true
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-macos-v1
@@ -50,7 +51,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-macos-v1
@@ -68,7 +69,7 @@ jobs:
          make llvm-build
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-v4
@@ -104,23 +105,17 @@ jobs:
    name: homebrew-install
    runs-on: macos-latest
    steps:
-      - name: Install Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: '1.18'
      - name: Install LLVM
        shell: bash
        run: |
          HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@14
      - name: Checkout
        uses: actions/checkout@v2
-      - name: Cache Go
-        uses: actions/cache@v2
+      - name: Install Go
+        uses: actions/setup-go@v3
        with:
-          key: go-cache-macos-homebrew-v1-${{ hashFiles('go.mod') }}
-          path: |
-            ~/Library/Caches/go-build
-            ~/go/pkg/mod
+          go-version: '1.19'
+          cache: true
      - name: Build TinyGo
        run: go install
      - name: Check binary
@@ -18,14 +18,13 @@ jobs:
    # statically linked binary.
    runs-on: ubuntu-latest
    container:
-      image: alpine:3.16
+      image: golang:1.19-alpine
    steps:
      - name: Install apk dependencies
-        # tar: needed for actions/cache@v2
+        # tar: needed for actions/cache@v3
        # git+openssh: needed for checkout (I think?)
-        # gcompat: needed for go binary
        # ruby: needed to install fpm
-        run: apk add tar git openssh gcompat make g++ ruby
+        run: apk add tar git openssh make g++ ruby
      - name: Work around CVE-2022-24765
        # We're not on a multi-user machine, so this is safe.
        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
@@ -33,19 +32,15 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
-      - name: Install Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: '1.18.1'
      - name: Cache Go
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        with:
          key: go-cache-linux-alpine-v1-${{ hashFiles('go.mod') }}
          path: |
            ~/.cache/go-build
            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-alpine-v1
@@ -59,7 +54,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-alpine-v1
@@ -77,7 +72,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-alpine-v1
@@ -88,7 +83,7 @@ jobs:
          apk add cmake samurai python3
          make binaryen STATIC=1
      - name: Cache wasi-libc
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-linux-alpine-v1
@@ -121,9 +116,10 @@ jobs:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Install Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.18.1'
+          go-version: '1.19'
+          cache: true
      - name: Install wasmtime
        run: |
          curl https://wasmtime.dev/install.sh -sSf | bash
@@ -173,9 +169,10 @@ jobs:
              simavr \
              ninja-build
      - name: Install Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.18.1'
+          go-version: '1.19'
+          cache: true
      - name: Install Node.js
        uses: actions/setup-node@v2
        with:
@@ -184,15 +181,8 @@ jobs:
        run: |
          curl https://wasmtime.dev/install.sh -sSf | bash
          echo "$HOME/.wasmtime/bin" >> $GITHUB_PATH
-      - name: Cache Go
-        uses: actions/cache@v2
-        with:
-          key: go-cache-linux-asserts-v1-${{ hashFiles('go.mod') }}
-          path: |
-            ~/.cache/go-build
-            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-asserts-v2
@@ -206,7 +196,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-asserts-v1
@@ -222,7 +212,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-asserts-v1
@@ -231,7 +221,7 @@ jobs:
        if: steps.cache-binaryen.outputs.cache-hit != 'true'
        run: make binaryen
      - name: Cache wasi-libc
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-linux-asserts-v5
@@ -246,6 +236,8 @@ jobs:
        run: |
          make ASSERT=1
          echo "$(pwd)/build" >> $GITHUB_PATH
+      - name: Test machine package
+        run: make check-machine
      - name: Test stdlib packages
        run: make tinygo-test
      - name: Install Xtensa toolchain
@@ -279,18 +271,12 @@ jobs:
              g++-arm-linux-gnueabihf \
              libc6-dev-armhf-cross
      - name: Install Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.18.1'
-      - name: Cache Go
-        uses: actions/cache@v2
-        with:
-          key: go-cache-linux-arm-v2-${{ hashFiles('go.mod') }}
-          path: |
-            ~/.cache/go-build
-            ~/go/pkg/mod
+          go-version: '1.19'
+          cache: true
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-v2
@@ -304,7 +290,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-arm-v1
@@ -322,7 +308,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-arm-v1
@@ -385,18 +371,12 @@ jobs:
              libc6-dev-arm64-cross \
              ninja-build
      - name: Install Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
        with:
-          go-version: '1.18.1'
-      - name: Cache Go
-        uses: actions/cache@v2
-        with:
-          key: go-cache-linux-arm64-v2-${{ hashFiles('go.mod') }}
-          path: |
-            ~/.cache/go-build
-            ~/go/pkg/mod
+          go-version: '1.19'
+          cache: true
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-v1
@@ -410,7 +390,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-arm64-v1
@@ -426,7 +406,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-binaryen
        with:
          key: binaryen-linux-arm64-v1
@@ -15,10 +15,6 @@ jobs:
  build-windows:
    runs-on: windows-2022
    steps:
-      - name: Install Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: '1.18.1'
      - uses: brechtm/setup-scoop@v2
        with:
          scoop_update: 'false'
@@ -30,15 +26,13 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
-      - name: Cache Go
-        uses: actions/cache@v2
+      - name: Install Go
+        uses: actions/setup-go@v3
        with:
-          key: go-cache-windows-v1-${{ hashFiles('go.mod') }}
-          path: |
-            ~/AppData/Local/go-build
-            ~/go/pkg/mod
+          go-version: '1.19'
+          cache: true
      - name: Cache LLVM source
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-source
        with:
          key: llvm-source-14-windows-v2
@@ -52,7 +46,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-llvm-build
        with:
          key: llvm-build-14-windows-v2
@@ -69,7 +63,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v2
+        uses: actions/cache@v3
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-v4
@@ -1,5 +1,5 @@
 # tinygo-llvm stage obtains the llvm source for TinyGo
-FROM golang:1.18 AS tinygo-llvm
+FROM golang:1.19 AS tinygo-llvm

 RUN apt-get update && \
    apt-get install -y apt-utils make cmake clang-11 binutils-avr gcc-avr avr-libc ninja-build
@@ -267,6 +267,18 @@ tinygo:
 test: wasi-libc
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) test $(GOTESTFLAGS) -timeout=20m -buildmode exe -tags "byollvm osusergo" ./builder ./cgo ./compileopts ./compiler ./interp ./transform .

+# Check whether the machine package matches the documentation.
+# TODO: improve `tinygo targets` so it doesn't return these invalid targets.
+CHECK_MACHINE_EXCULDE = \
+	cortex-m-qemu \
+	particle-3rd-gen \
+	riscv-qemu \
+	riscv64-qemu \
+	rp2040 \
+	$(nil)
+check-machine:
+	$(GO) run ./tools/machinecheck $(filter-out $(CHECK_MACHINE_EXCULDE),$(shell $(TINYGO) targets))
+
 # Standard library packages that pass tests on darwin, linux, wasi, and windows, but take over a minute in wasi
 TEST_PACKAGES_SLOW = \
 	compress/bzip2 \
@@ -326,11 +338,14 @@ TEST_PACKAGES_FAST += crypto/elliptic/internal/fiat
 endif

 # archive/zip requires os.ReadAt, which is not yet supported on windows
+# compress/flate appears to hang on wasi
+# compress/lzw appears to hang on wasi
+# crypto/hmac fails on wasi, it exits with a "slice out of range" panic
 # debug/plan9obj requires os.ReadAt, which is not yet supported on windows
-# io/fs requires os.ReadDir, which is not yet supported on windows or wasi
+# io/ioutil requires os.ReadDir, which is not yet supported on windows or wasi
+# strconv requires recover() which is not yet supported on wasi
+# text/template/parse requires recover(), which is not yet supported on wasi
 # testing/fstest requires os.ReadDir, which is not yet supported on windows or wasi
-# compress/flate fails windows go 1.18, https://github.com/tinygo-org/tinygo/issues/2762
-# compress/lzw fails windows go 1.18 wasi, https://github.com/tinygo-org/tinygo/issues/2762

 # Additional standard library packages that pass tests on individual platforms
 TEST_PACKAGES_LINUX := \
@@ -340,7 +355,6 @@ TEST_PACKAGES_LINUX := \
 	crypto/hmac \
 	debug/dwarf \
 	debug/plan9obj \
-	io/fs \
 	io/ioutil \
 	strconv \
 	testing/fstest \
@@ -349,7 +363,12 @@ TEST_PACKAGES_LINUX := \
 TEST_PACKAGES_DARWIN := $(TEST_PACKAGES_LINUX)

 TEST_PACKAGES_WINDOWS := \
-	compress/lzw
+	compress/flate \
+	compress/lzw \
+	crypto/hmac \
+	strconv \
+	text/template/parse \
+	$(nil)

 # Report platforms on which each standard library package is known to pass tests
 jointmp := $(shell echo /tmp/join.$$$$)
@@ -364,12 +383,15 @@ report-stdlib-tests-pass:
 # Standard library packages that pass tests quickly on the current platform
 ifeq ($(shell uname),Darwin)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_DARWIN)
+TEST_IOFS := true
 endif
 ifeq ($(shell uname),Linux)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_LINUX)
+TEST_IOFS := true
 endif
 ifeq ($(OS),Windows_NT)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_WINDOWS)
+TEST_IOFS := false
 endif

 # Test known-working standard library packages.
@@ -377,6 +399,12 @@ endif
 .PHONY: tinygo-test
 tinygo-test:
 	$(TINYGO) test $(TEST_PACKAGES_HOST) $(TEST_PACKAGES_SLOW)
+	@# io/fs requires os.ReadDir, not yet supported on windows or wasi. It also
+	@# requires a large stack-size. Hence, io/fs is only run conditionally.
+	@# For more details, see the comments on issue #3143.
+ifeq ($(TEST_IOFS),true)
+	$(TINYGO) test -stack-size=6MB io/fs
+endif
 tinygo-test-fast:
 	$(TINYGO) test $(TEST_PACKAGES_HOST)
 tinygo-bench:
@@ -386,9 +414,9 @@ tinygo-bench-fast:

 # Same thing, except for wasi rather than the current platform.
 tinygo-test-wasi:
-	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW)
+	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW) ./tests/runtime_wasi
 tinygo-test-wasi-fast:
-	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST)
+	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) ./tests/runtime_wasi
 tinygo-bench-wasi:
 	$(TINYGO) test -target wasi -bench . $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW)
 tinygo-bench-wasi-fast:
@@ -410,6 +438,7 @@ tinygo-baremetal:
 .PHONY: smoketest
 smoketest:
 	$(TINYGO) version
+	$(TINYGO) targets > /dev/null
 	# regression test for #2892
 	cd tests/testing/recurse && ($(TINYGO) test ./... > recurse.log && cat recurse.log && test $$(wc -l < recurse.log) = 2 && rm recurse.log)
 	# compile-only platform-independent examples
@@ -519,6 +548,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-m4          examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=matrixportal-m4     examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pybadge             examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=metro-m4-airlift    examples/blinky1
@@ -585,6 +616,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-rp2040 		examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=qtpy-rp2040         examples/echo
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=macropad-rp2040 	examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=badger2040          examples/blinky1
@@ -597,7 +630,7 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=challenger-rp2040    examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=trinkey-qt2040      examples/adc_rp2040
+	$(TINYGO) build -size short -o test.hex -target=trinkey-qt2040      examples/temp
 	@$(MD5SUM) test.hex
 	# test pwm
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm
@@ -679,7 +712,9 @@ ifneq ($(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=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
@@ -687,8 +722,6 @@ endif
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=hifive1-qemu        examples/serial
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=maixbit             examples/blinky1
 	@$(MD5SUM) test.hex
 ifneq ($(WASM), 0)
@@ -66,6 +66,7 @@ The following 91 microcontroller boards are currently supported:
 * [Adafruit PyGamer](https://www.adafruit.com/product/4242)
 * [Adafruit PyPortal](https://www.adafruit.com/product/4116)
 * [Adafruit QT Py](https://www.adafruit.com/product/4600)
+* [Adafruit QT Py RP2040](https://www.adafruit.com/product/4900)
 * [Adafruit Trinket M0](https://www.adafruit.com/product/3500)
 * [Adafruit Trinkey QT2040](https://adafruit.com/product/5056)
 * [Arduino Mega 1280](https://www.arduino.cc/en/Main/arduinoBoardMega/)
@@ -124,7 +125,7 @@ The following 91 microcontroller boards are currently supported:
 * [Seeed LoRa-E5 Development Kit](https://www.seeedstudio.com/LoRa-E5-Dev-Kit-p-4868.html)
 * [Seeed Sipeed MAix BiT](https://www.seeedstudio.com/Sipeed-MAix-BiT-for-RISC-V-AI-IoT-p-2872.html)
 * [Seeed Wio Terminal](https://www.seeedstudio.com/Wio-Terminal-p-4509.html)
-* [SiFIve HiFive1 Rev B](https://www.sifive.com/boards/hifive1)
+* [SiFIve HiFive1 Rev B](https://www.sifive.com/boards/hifive1-rev-b)
 * [Sparkfun Thing Plus RP2040](https://www.sparkfun.com/products/17745)
 * [ST Micro "Nucleo" F103RB](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
 * [ST Micro "Nucleo" F722ZE](https://www.st.com/en/evaluation-tools/nucleo-f722ze.html)
@@ -178,7 +178,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil

 		Scheduler:          config.Scheduler(),
 		AutomaticStackSize: config.AutomaticStackSize(),
-		DefaultStackSize:   config.Target.DefaultStackSize,
+		DefaultStackSize:   config.StackSize(),
 		NeedsStackObjects:  config.NeedsStackObjects(),
 		Debug:              true,
 	}
@@ -32,6 +32,7 @@ type cgoPackage struct {
 	errors          []error
 	currentDir      string // current working directory
 	packageDir      string // full path to the package to process
+	importPath      string
 	fset            *token.FileSet
 	tokenFiles      map[string]*token.File
 	definedGlobally map[string]ast.Node
@@ -39,12 +40,15 @@ type cgoPackage struct {
 	cflags          []string // CFlags from #cgo lines
 	ldflags         []string // LDFlags from #cgo lines
 	visitedFiles    map[string][]byte
+	cgoHeaders      []string
 }

 // cgoFile holds information only for a single Go file (with one or more
 // `import "C"` statements).
 type cgoFile struct {
 	*cgoPackage
+	file    *ast.File
+	index   int
 	defined map[string]ast.Node
 	names   map[string]clangCursor
 }
@@ -158,9 +162,10 @@ 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 string, fset *token.FileSet, cflags []string, clangHeaders string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
+func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cflags []string, clangHeaders string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
 	p := &cgoPackage{
 		currentDir:      dir,
+		importPath:      importPath,
 		fset:            fset,
 		tokenFiles:      map[string]*token.File{},
 		definedGlobally: map[string]ast.Node{},
@@ -210,13 +215,13 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		}
 	}
 	// Patch some types, for example *C.char in C.CString.
-	cf := p.newCGoFile()
+	cf := p.newCGoFile(nil, -1) // dummy *cgoFile for the walker
 	astutil.Apply(p.generated, func(cursor *astutil.Cursor) bool {
 		return cf.walker(cursor, nil)
 	}, nil)

 	// Find `import "C"` C fragments in the file.
-	cgoHeaders := make([]string, len(files)) // combined CGo header fragment for each file
+	p.cgoHeaders = make([]string, len(files)) // combined CGo header fragment for each file
 	for i, f := range files {
 		var cgoHeader string
 		for i := 0; i < len(f.Decls); i++ {
@@ -275,7 +280,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 			cgoHeader += fragment
 		}

-		cgoHeaders[i] = cgoHeader
+		p.cgoHeaders[i] = cgoHeader
 	}

 	// Define CFlags that will be used while parsing the package.
@@ -289,7 +294,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	}

 	// Retrieve types such as C.int, C.longlong, etc from C.
-	p.newCGoFile().readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
+	p.newCGoFile(nil, -1).readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
 		gen := &ast.GenDecl{
 			TokPos: token.NoPos,
 			Tok:    token.TYPE,
@@ -303,8 +308,8 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string

 	// Process CGo imports for each file.
 	for i, f := range files {
-		cf := p.newCGoFile()
-		cf.readNames(cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
+		cf := p.newCGoFile(f, i)
+		cf.readNames(p.cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
 			for _, name := range builtinAliases {
 				// Names such as C.int should not be obtained from C.
 				// This works around an issue in picolibc that has `#define int`
@@ -320,12 +325,14 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	// Print the newly generated in-memory AST, for debugging.
 	//ast.Print(fset, p.generated)

-	return p.generated, 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() *cgoFile {
+func (p *cgoPackage) newCGoFile(file *ast.File, index int) *cgoFile {
 	return &cgoFile{
 		cgoPackage: p,
+		file:       file,
+		index:      index,
 		defined:    make(map[string]ast.Node),
 		names:      make(map[string]clangCursor),
 	}
@@ -1117,8 +1124,11 @@ func (f *cgoFile) getASTDeclName(name string, found clangCursor, iscall bool) st
 		return alias
 	}
 	node := f.getASTDeclNode(name, found, iscall)
-	if _, ok := node.(*ast.FuncDecl); ok && !iscall {
-		return "C." + name + "$funcaddr"
+	if node, ok := node.(*ast.FuncDecl); ok {
+		if !iscall {
+			return node.Name.Name + "$funcaddr"
+		}
+		return node.Name.Name
 	}
 	return "C." + name
 }
@@ -1142,7 +1152,7 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			// Original cgo reports an error like
 			//   cgo: inconsistent definitions for C.myint
 			// which is far less helpful.
-			f.addError(getPos(node), "defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
+			f.addError(getPos(node), name+" defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
 		}
 		f.defined[name] = node
 		return node
@@ -1150,11 +1160,39 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as

 	// The declaration has no AST node. Create it now.
 	f.defined[name] = nil
-	node, elaboratedType := f.createASTNode(name, found)
+	node, extra := f.createASTNode(name, found)
 	f.defined[name] = node
-	f.definedGlobally[name] = node
 	switch node := node.(type) {
 	case *ast.FuncDecl:
+		if strings.HasPrefix(node.Doc.List[0].Text, "//export _Cgo_static_") {
+			// Static function. Only accessible in the current Go file.
+			globalName := strings.TrimPrefix(node.Doc.List[0].Text, "//export ")
+			// Make an alias. Normally this is done using the alias function
+			// attribute, but MacOS for some reason doesn't support this (even
+			// though the linker has support for aliases in the form of N_INDR).
+			// Therefore, create an actual function for MacOS.
+			var params []string
+			for _, param := range node.Type.Params.List {
+				params = append(params, param.Names[0].Name)
+			}
+			callInst := fmt.Sprintf("%s(%s);", name, strings.Join(params, ", "))
+			if node.Type.Results != nil {
+				callInst = "return " + callInst
+			}
+			aliasDeclaration := fmt.Sprintf(`
+#ifdef __APPLE__
+%s {
+	%s
+}
+#else
+extern __typeof(%s) %s __attribute__((alias(%#v)));
+#endif
+`, extra.(string), callInst, name, globalName, name)
+			f.cgoHeaders[f.index] += "\n\n" + aliasDeclaration
+		} else {
+			// Regular (non-static) function.
+			f.definedGlobally[name] = node
+		}
 		f.generated.Decls = append(f.generated.Decls, node)
 		// Also add a declaration like the following:
 		//   var C.foo$funcaddr unsafe.Pointer
@@ -1162,7 +1200,7 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			Tok: token.VAR,
 			Specs: []ast.Spec{
 				&ast.ValueSpec{
-					Names: []*ast.Ident{{Name: "C." + name + "$funcaddr"}},
+					Names: []*ast.Ident{{Name: node.Name.Name + "$funcaddr"}},
 					Type: &ast.SelectorExpr{
 						X:   &ast.Ident{Name: "unsafe"},
 						Sel: &ast.Ident{Name: "Pointer"},
@@ -1171,8 +1209,10 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			},
 		})
 	case *ast.GenDecl:
+		f.definedGlobally[name] = node
 		f.generated.Decls = append(f.generated.Decls, node)
 	case *ast.TypeSpec:
+		f.definedGlobally[name] = node
 		f.generated.Decls = append(f.generated.Decls, &ast.GenDecl{
 			Tok:   token.TYPE,
 			Specs: []ast.Spec{node},
@@ -1186,7 +1226,8 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as

 	// If this is a struct or union it may need bitfields or union accessor
 	// methods.
-	if elaboratedType != nil {
+	switch elaboratedType := extra.(type) {
+	case *elaboratedTypeInfo:
 		// Add struct bitfields.
 		for _, bitfield := range elaboratedType.bitfields {
 			f.createBitfieldGetter(bitfield, "C."+name)
@@ -48,7 +48,7 @@ func TestCGo(t *testing.T) {
 			}

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

 			// Check the AST for type errors.
 			var typecheckErrors []error
@@ -4,7 +4,9 @@ package cgo
 // modification. It does not touch the AST itself.

 import (
+	"crypto/sha256"
 	"crypto/sha512"
+	"encoding/hex"
 	"fmt"
 	"go/ast"
 	"go/scanner"
@@ -43,6 +45,8 @@ typedef struct {
 GoCXCursor tinygo_clang_getTranslationUnitCursor(CXTranslationUnit tu);
 unsigned tinygo_clang_visitChildren(GoCXCursor parent, CXCursorVisitor visitor, CXClientData client_data);
 CXString tinygo_clang_getCursorSpelling(GoCXCursor c);
+CXString tinygo_clang_getCursorPrettyPrinted(GoCXCursor c, CXPrintingPolicy Policy);
+CXPrintingPolicy tinygo_clang_getCursorPrintingPolicy(GoCXCursor c);
 enum CXCursorKind tinygo_clang_getCursorKind(GoCXCursor c);
 CXType tinygo_clang_getCursorType(GoCXCursor c);
 GoCXCursor tinygo_clang_getTypeDeclaration(CXType t);
@@ -50,6 +54,7 @@ CXType tinygo_clang_getTypedefDeclUnderlyingType(GoCXCursor c);
 CXType tinygo_clang_getCursorResultType(GoCXCursor c);
 int tinygo_clang_Cursor_getNumArguments(GoCXCursor c);
 GoCXCursor tinygo_clang_Cursor_getArgument(GoCXCursor c, unsigned i);
+enum CX_StorageClass tinygo_clang_Cursor_getStorageClass(GoCXCursor c);
 CXSourceLocation tinygo_clang_getCursorLocation(GoCXCursor c);
 CXSourceRange tinygo_clang_getCursorExtent(GoCXCursor c);
 CXTranslationUnit tinygo_clang_Cursor_getTranslationUnit(GoCXCursor c);
@@ -189,7 +194,7 @@ func (f *cgoFile) readNames(fragment string, cflags []string, filename string, c

 // Convert the AST node under the given Clang cursor to a Go AST node and return
 // it.
-func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaboratedTypeInfo) {
+func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 	kind := C.tinygo_clang_getCursorKind(c)
 	pos := f.getCursorPosition(c)
 	switch kind {
@@ -200,19 +205,43 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaborat
 			Kind: ast.Fun,
 			Name: "C." + name,
 		}
+		exportName := name
+		localName := name
+		var stringSignature string
+		if C.tinygo_clang_Cursor_getStorageClass(c) == C.CX_SC_Static {
+			// A static function is assigned a globally unique symbol name based
+			// on the file path (like _Cgo_static_2d09198adbf58f4f4655_foo) and
+			// has a different Go name in the form of C.foo!symbols.go instead
+			// of just C.foo.
+			path := f.importPath + "/" + filepath.Base(f.fset.File(f.file.Pos()).Name())
+			staticIDBuf := sha256.Sum256([]byte(path))
+			staticID := hex.EncodeToString(staticIDBuf[:10])
+			exportName = "_Cgo_static_" + staticID + "_" + name
+			localName = name + "!" + filepath.Base(path)
+
+			// Create a signature. This is necessary for MacOS to forward the
+			// call, because MacOS doesn't support aliases like ELF and PE do.
+			// (There is N_INDR but __attribute__((alias("..."))) doesn't work).
+			policy := C.tinygo_clang_getCursorPrintingPolicy(c)
+			defer C.clang_PrintingPolicy_dispose(policy)
+			C.clang_PrintingPolicy_setProperty(policy, C.CXPrintingPolicy_TerseOutput, 1)
+			stringSignature = getString(C.tinygo_clang_getCursorPrettyPrinted(c, policy))
+			stringSignature = strings.Replace(stringSignature, " "+name+"(", " "+exportName+"(", 1)
+			stringSignature = strings.TrimPrefix(stringSignature, "static ")
+		}
 		args := make([]*ast.Field, numArgs)
 		decl := &ast.FuncDecl{
 			Doc: &ast.CommentGroup{
 				List: []*ast.Comment{
 					{
 						Slash: pos - 1,
-						Text:  "//export " + name,
+						Text:  "//export " + exportName,
 					},
 				},
 			},
 			Name: &ast.Ident{
 				NamePos: pos,
-				Name:    "C." + name,
+				Name:    "C." + localName,
 				Obj:     obj,
 			},
 			Type: &ast.FuncType{
@@ -263,7 +292,7 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaborat
 			}
 		}
 		obj.Decl = decl
-		return decl, nil
+		return decl, stringSignature
 	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
 		typ := f.makeASTRecordType(c, pos)
 		typeName := "C." + name
@@ -17,6 +17,14 @@ CXString tinygo_clang_getCursorSpelling(CXCursor c) {
 	return clang_getCursorSpelling(c);
 }

+CXString tinygo_clang_getCursorPrettyPrinted(CXCursor c, CXPrintingPolicy policy) {
+	return clang_getCursorPrettyPrinted(c, policy);
+}
+
+CXPrintingPolicy tinygo_clang_getCursorPrintingPolicy(CXCursor c) {
+	return clang_getCursorPrintingPolicy(c);
+}
+
 enum CXCursorKind tinygo_clang_getCursorKind(CXCursor c) {
 	return clang_getCursorKind(c);
 }
@@ -45,6 +53,10 @@ CXCursor tinygo_clang_Cursor_getArgument(CXCursor c, unsigned i) {
 	return clang_Cursor_getArgument(c, i);
 }

+enum CX_StorageClass tinygo_clang_Cursor_getStorageClass(CXCursor c) {
+	return clang_Cursor_getStorageClass(c);
+}
+
 CXSourceLocation tinygo_clang_getCursorLocation(CXCursor c) {
 	return clang_getCursorLocation(c);
 }
@@ -5,6 +5,7 @@ package main
 int foo(int a, int b);
 void variadic0();
 void variadic2(int x, int y, ...);
+static void staticfunc(int x);

 // Global variable signatures.
 extern int someValue;
@@ -16,6 +17,7 @@ func accessFunctions() {
 	C.foo(3, 4)
 	C.variadic0()
 	C.variadic2(3, 5)
+	C.staticfunc(3)
 }

 func accessGlobals() {
@@ -55,5 +55,10 @@ func C.variadic2(x C.int, y C.int)

 var C.variadic2$funcaddr unsafe.Pointer

+//export _Cgo_static_173c95a79b6df1980521_staticfunc
+func C.staticfunc!symbols.go(x C.int)
+
+var C.staticfunc!symbols.go$funcaddr unsafe.Pointer
+
 //go:extern someValue
 var C.someValue C.int
@@ -175,6 +175,15 @@ func (c *Config) AutomaticStackSize() bool {
 	return false
 }

+// StackSize returns the default stack size to be used for goroutines, if the
+// stack size could not be determined automatically at compile time.
+func (c *Config) StackSize() uint64 {
+	if c.Options.StackSize != 0 {
+		return c.Options.StackSize
+	}
+	return c.Target.DefaultStackSize
+}
+
 // UseThinLTO returns whether ThinLTO should be used for the given target. Some
 // targets (such as wasm) are not yet supported.
 // We should try and remove as many exceptions as possible in the future, so
@@ -457,7 +466,14 @@ func (c *Config) OpenOCDConfiguration() (args []string, err error) {
 		args = append(args, "-c", cmd)
 	}
 	if c.Target.OpenOCDTransport != "" {
-		args = append(args, "-c", "transport select "+c.Target.OpenOCDTransport)
+		transport := c.Target.OpenOCDTransport
+		if transport == "swd" {
+			switch openocdInterface {
+			case "stlink-dap":
+				transport = "dapdirect_swd"
+			}
+		}
+		args = append(args, "-c", "transport select "+transport)
 	}
 	args = append(args, "-f", "target/"+c.Target.OpenOCDTarget+".cfg")
 	return args, nil
@@ -28,6 +28,7 @@ type Options struct {
 	GC              string
 	PanicStrategy   string
 	Scheduler       string
+	StackSize       uint64 // goroutine stack size (if none could be automatically determined)
 	Serial          string
 	Work            bool // -work flag to print temporary build directory
 	InterpTimeout   time.Duration
@@ -49,6 +50,8 @@ type Options struct {
 	LLVMFeatures    string
 	Directory       string
 	PrintJSON       bool
+	Monitor         bool
+	BaudRate        int
 }

 // Verify performs a validation on the given options, raising an error if options are not valid.
@@ -65,7 +65,7 @@ type TargetSpec struct {
 }

 // overrideProperties overrides all properties that are set in child into itself using reflection.
-func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
+func (spec *TargetSpec) overrideProperties(child *TargetSpec) error {
 	specType := reflect.TypeOf(spec).Elem()
 	specValue := reflect.ValueOf(spec).Elem()
 	childValue := reflect.ValueOf(child).Elem()
@@ -95,14 +95,15 @@ func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
 				for j := i + 1; j < dst.Len(); j++ {
 					w := dst.Index(j).String()
 					if v == w {
-						panic("duplicate value '" + v + "' in field : " + field.Name)
+						return fmt.Errorf("duplicate value '%s' in field %s", v, field.Name)
 					}
 				}
 			}
 		default:
-			panic("unknown field type : " + kind.String())
+			return fmt.Errorf("unknown field type: %s", kind)
 		}
 	}
+	return nil
 }

 // load reads a target specification from the JSON in the given io.Reader. It
@@ -117,10 +118,10 @@ func (spec *TargetSpec) load(r io.Reader) error {
 }

 // loadFromGivenStr loads the TargetSpec from the given string that could be:
-// - targets/ directory inside the compiler sources
-// - a relative or absolute path to custom (project specific) target specification .json file;
-//   the Inherits[] could contain the files from target folder (ex. stm32f4disco)
-//   as well as path to custom files (ex. myAwesomeProject.json)
+//   - targets/ directory inside the compiler sources
+//   - a relative or absolute path to custom (project specific) target specification .json file;
+//     the Inherits[] could contain the files from target folder (ex. stm32f4disco)
+//     as well as path to custom files (ex. myAwesomeProject.json)
 func (spec *TargetSpec) loadFromGivenStr(str string) error {
 	path := ""
 	if strings.HasSuffix(str, ".json") {
@@ -150,11 +151,17 @@ func (spec *TargetSpec) resolveInherits() error {
 		if err != nil {
 			return err
 		}
-		newSpec.overrideProperties(subtarget)
+		err = newSpec.overrideProperties(subtarget)
+		if err != nil {
+			return err
+		}
 	}

 	// When all properties are loaded, make sure they are properly inherited.
-	newSpec.overrideProperties(spec)
+	err := newSpec.overrideProperties(spec)
+	if err != nil {
+		return err
+	}
 	*spec = *newSpec

 	return nil
@@ -221,7 +228,7 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 	// it includes all parents as specified in the "inherits" key.
 	err = spec.resolveInherits()
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%s : %w", options.Target, err)
 	}

 	if spec.Scheduler == "asyncify" {
@@ -79,7 +79,7 @@ func TestCompiler(t *testing.T) {
 				RelocationModel:    config.RelocationModel(),
 				Scheduler:          config.Scheduler(),
 				AutomaticStackSize: config.AutomaticStackSize(),
-				DefaultStackSize:   config.Target.DefaultStackSize,
+				DefaultStackSize:   config.StackSize(),
 				NeedsStackObjects:  config.NeedsStackObjects(),
 			}
 			machine, err := NewTargetMachine(compilerConfig)
@@ -163,18 +163,20 @@ func (c *compilerContext) getFunction(fn *ssa.Function) llvm.Value {
 	// External/exported functions may not retain pointer values.
 	// https://golang.org/cmd/cgo/#hdr-Passing_pointers
 	if info.exported {
-		// Set the wasm-import-module attribute if the function's module is set.
-		if info.module != "" {
-
+		if c.archFamily() == "wasm32" {
 			// We need to add the wasm-import-module and the wasm-import-name
-			wasmImportModuleAttr := c.ctx.CreateStringAttribute("wasm-import-module", info.module)
-			llvmFn.AddFunctionAttr(wasmImportModuleAttr)
-
-			// Add the Wasm Import Name, if we are a named wasm import
-			if info.importName != "" {
-				wasmImportNameAttr := c.ctx.CreateStringAttribute("wasm-import-name", info.importName)
-				llvmFn.AddFunctionAttr(wasmImportNameAttr)
+			// attributes.
+			module := info.module
+			if module == "" {
+				module = "env"
 			}
+			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-module", module))
+
+			name := info.importName
+			if name == "" {
+				name = info.linkName
+			}
+			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-name", name))
 		}
 		nocaptureKind := llvm.AttributeKindID("nocapture")
 		nocapture := c.ctx.CreateEnumAttribute(nocaptureKind, 0)
@@ -62,7 +62,7 @@ declare void @main.undefinedFunctionNotInSection(i8*) #0

 attributes #0 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #1 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" }
+attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" "wasm-import-module"="env" "wasm-import-name"="extern_func" }
 attributes #3 = { inlinehint nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #4 = { noinline nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #5 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" }
+attributes #5 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" "wasm-import-module"="env" "wasm-import-name"="exportedFunctionInSection" }
@@ -9,8 +9,10 @@ require (
 	github.com/chromedp/chromedp v0.7.6
 	github.com/gofrs/flock v0.8.1
 	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
+	github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf
 	github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892
 	github.com/mattn/go-colorable v0.1.8
+	github.com/mattn/go-tty v0.0.4
 	go.bug.st/serial v1.3.5
 	golang.org/x/sys v0.0.0-20220829200755-d48e67d00261
 	golang.org/x/tools v0.1.11
@@ -12,7 +12,6 @@ github.com/chromedp/sysutil v1.0.0/go.mod h1:kgWmDdq8fTzXYcKIBqIYvRRTnYb9aNS9moA
 github.com/creack/goselect v0.1.2 h1:2DNy14+JPjRBgPzAd1thbQp4BSIihxcBf0IXhQXDRa0=
 github.com/creack/goselect v0.1.2/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
 github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
 github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
@@ -23,44 +22,47 @@ github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
 github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
+github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf h1:FtEj8sfIcaaBfAKrE1Cwb61YDtYq9JxChK1c7AKce7s=
+github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf/go.mod h1:yrqSXGoD/4EKfF26AOGzscPOgTTJcyAwM2rpixWT+t4=
 github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
 github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
 github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892 h1:6J+qramlHVLmiBOgRiBOnQkno8uprqG6YFFQTt6uYIw=
 github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
+github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-colorable v0.1.8 h1:c1ghPdyEDarC70ftn0y+A/Ee++9zz8ljHG1b13eJ0s8=
 github.com/mattn/go-colorable v0.1.8/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
+github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcMEpPG5Rm84=
 github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+github.com/mattn/go-runewidth v0.0.7/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
+github.com/mattn/go-tty v0.0.4 h1:NVikla9X8MN0SQAqCYzpGyXv0jY7MNl3HOWD2dkle7E=
+github.com/mattn/go-tty v0.0.4/go.mod h1:u5GGXBtZU6RQoKV8gY5W6UhMudbR5vXnUe7j3pxse28=
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5 h1:1SoBaSPudixRecmlHXb/GxmaD3fLMtHIDN13QujwQuc=
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5/go.mod h1:nZgzbfBr3hhjoZnS66nKrHmduYNpc34ny7RK4z5/HM0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
-github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-go.bug.st/serial v1.1.3 h1:YEBxJa9pKS9Wdg46B/jiaKbvvbUrjhZZZITfJHEJhaE=
-go.bug.st/serial v1.1.3/go.mod h1:8TT7u/SwwNIpJ8QaG4s+HTjFt9ReXs2cdOU7ZEk50Dk=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 go.bug.st/serial v1.3.5 h1:k50SqGZCnHZ2MiBQgzccXWG+kd/XpOs1jUljpDDKzaE=
 go.bug.st/serial v1.3.5/go.mod h1:z8CesKorE90Qr/oRSJiEuvzYRKol9r/anJZEb5kt304=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+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=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200909081042-eff7692f9009/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 v0.0.0-20220114195835-da31bd327af9 h1:XfKQ4OlFl8okEOr5UvAqFRVj8pY/4yfcXrddB8qAbU0=
-golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220829200755-d48e67d00261 h1:v6hYoSR9T5oet+pMXwUWkbiVqx/63mlHjefrHmxwfeY=
 golang.org/x/sys v0.0.0-20220829200755-d48e67d00261/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/tools v0.1.11 h1:loJ25fNOEhSXfHrpoGj91eCUThwdNX6u24rO1xnNteY=
 golang.org/x/tools v0.1.11/go.mod h1:SgwaegtQh8clINPpECJMqnxLv9I09HLqnW3RMqW0CA4=
 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 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 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 v0.0.0-20220802112859-5bb0b77907a7 h1:nSLR52mUw7DPQQVA3ZJFH63zjU4ME84fKiin6mdnYWc=
 tinygo.org/x/go-llvm v0.0.0-20220802112859-5bb0b77907a7/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
@@ -369,6 +369,11 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				nBytes := uint32(operands[3].Uint())
 				dstObj := mem.getWritable(dst.index())
 				dstBuf := dstObj.buffer.asRawValue(r)
+				if mem.get(src.index()).buffer == nil {
+					// Looks like the source buffer is not defined.
+					// This can happen with //extern or //go:embed.
+					return nil, mem, r.errorAt(inst, errUnsupportedRuntimeInst)
+				}
 				srcBuf := mem.get(src.index()).buffer.asRawValue(r)
 				copy(dstBuf.buf[dst.offset():dst.offset()+nBytes], srcBuf.buf[src.offset():])
 				dstObj.buffer = dstBuf
@@ -440,7 +440,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		var initialCFlags []string
 		initialCFlags = append(initialCFlags, p.program.config.CFlags()...)
 		initialCFlags = append(initialCFlags, "-I"+p.Dir)
-		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.program.fset, initialCFlags, p.program.clangHeaders)
+		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.ImportPath, p.program.fset, initialCFlags, p.program.clangHeaders)
 		p.CFlags = append(initialCFlags, cflags...)
 		p.CGoHeaders = headerCode
 		for path, hash := range accessedFiles {
@@ -26,6 +26,7 @@ import (
 	"time"

 	"github.com/google/shlex"
+	"github.com/inhies/go-bytesize"
 	"github.com/mattn/go-colorable"
 	"github.com/tinygo-org/tinygo/builder"
 	"github.com/tinygo-org/tinygo/compileopts"
@@ -243,17 +244,36 @@ func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options
 		// Tests are always run in the package directory.
 		cmd.Dir = result.MainDir

-		// Wasmtime needs a few extra flags to work.
+		// wasmtime is the default emulator used for `-target=wasi`. wasmtime
+		// is a WebAssembly runtime CLI with WASI enabled by default. However,
+		// only stdio are allowed by default. For example, while STDOUT routes
+		// to the host, other files don't. It also does not inherit environment
+		// variables from the host. Some tests read testdata files, often from
+		// outside the package directory. Other tests require temporary
+		// writeable directories. We allow this by adding wasmtime flags below.
 		if config.EmulatorName() == "wasmtime" {
-			// Add directories to the module root, but skip the current working
-			// directory which is already added by buildAndRun.
+			// At this point, The current working directory is at the package
+			// directory. Ex. $GOROOT/src/compress/flate for compress/flate.
+			// buildAndRun has already added arguments for wasmtime, that allow
+			// read-access to files such as "testdata/huffman-zero.in".
+			//
+			// Ex. main(.wasm) --dir=. -- -test.v
+
+			// Below adds additional wasmtime flags in case a test reads files
+			// outside its directory, like "../testdata/e.txt". This allows any
+			// relative directory up to the module root, even if the test never
+			// reads any files.
+			//
+			// Ex. --dir=.. --dir=../.. --dir=../../..
 			dirs := dirsToModuleRoot(result.MainDir, result.ModuleRoot)
 			var args []string
 			for _, d := range dirs[1:] {
 				args = append(args, "--dir="+d)
 			}

-			// create a new temp directory just for this run, announce it to os.TempDir() via TMPDIR
+			// Some tests create temp directories using os.MkdirTemp or via
+			// t.TempDir(). Create a writeable directory and map it to the
+			// default tempDir environment variable: TMPDIR.
 			tmpdir, err := os.MkdirTemp("", "tinygotmp")
 			if err != nil {
 				return fmt.Errorf("failed to create temporary directory: %w", err)
@@ -262,7 +282,8 @@ func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options
 			// TODO: add option to not delete temp dir for debugging?
 			defer os.RemoveAll(tmpdir)

-			// Insert new argments at the front of the command line argments.
+			// The below re-organizes the arguments so that the current
+			// directory is added last.
 			args = append(args, cmd.Args[1:]...)
 			cmd.Args = append(cmd.Args[:1:1], args...)
 		}
@@ -402,7 +423,6 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
-			return nil
 		case "msd":
 			switch fileExt {
 			case ".uf2":
@@ -410,13 +430,11 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 				if err != nil {
 					return &commandError{"failed to flash", result.Binary, err}
 				}
-				return nil
 			case ".hex":
 				err := flashHexUsingMSD(config.Target.FlashVolume, result.Binary, config.Options)
 				if err != nil {
 					return &commandError{"failed to flash", result.Binary, err}
 				}
-				return nil
 			default:
 				return errors.New("mass storage device flashing currently only supports uf2 and hex")
 			}
@@ -437,7 +455,6 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
-			return nil
 		case "bmp":
 			gdb, err := config.Target.LookupGDB()
 			if err != nil {
@@ -456,10 +473,13 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
-			return nil
 		default:
 			return fmt.Errorf("unknown flash method: %s", flashMethod)
 		}
+		if options.Monitor {
+			return Monitor("", options)
+		}
+		return nil
 	})
 }

@@ -978,7 +998,8 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 			preferredPortIDs = append(preferredPortIDs, [2]uint16{uint16(vid), uint16(pid)})
 		}

-		var primaryPorts []string // ports picked from preferred USB VID/PID
+		var primaryPorts []string   // ports picked from preferred USB VID/PID
+		var secondaryPorts []string // other ports (as a fallback)
 		for _, p := range portsList {
 			if !p.IsUSB {
 				continue
@@ -1000,6 +1021,8 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 					continue
 				}
 			}
+
+			secondaryPorts = append(secondaryPorts, p.Name)
 		}
 		if len(primaryPorts) == 1 {
 			// There is exactly one match in the set of preferred ports. Use
@@ -1011,18 +1034,10 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 			// one device of the same type are connected (e.g. two Arduino
 			// Unos).
 			ports = primaryPorts
-		}
-
-		if len(ports) == 0 {
-			// fallback
-			switch runtime.GOOS {
-			case "darwin":
-				ports, err = filepath.Glob("/dev/cu.usb*")
-			case "linux":
-				ports, err = filepath.Glob("/dev/ttyACM*")
-			case "windows":
-				ports, err = serial.GetPortsList()
-			}
+		} else {
+			// No preferred ports found. Fall back to other serial ports
+			// available in the system.
+			ports = secondaryPorts
 		}
 	default:
 		return "", errors.New("unable to search for a default USB device to be flashed on this OS")
@@ -1037,7 +1052,9 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 	}

 	if len(portCandidates) == 0 {
-		if len(ports) == 1 {
+		if len(usbInterfaces) > 0 {
+			return "", errors.New("unable to search for a default USB device - use -port flag, available ports are " + strings.Join(ports, ", "))
+		} else if len(ports) == 1 {
 			return ports[0], nil
 		} else {
 			return "", errors.New("multiple serial ports available - use -port flag, available ports are " + strings.Join(ports, ", "))
@@ -1102,6 +1119,7 @@ func usage(command string) {
 		fmt.Fprintln(os.Stderr, "  flash:   compile and flash to the device")
 		fmt.Fprintln(os.Stderr, "  gdb:     run/flash and immediately enter GDB")
 		fmt.Fprintln(os.Stderr, "  lldb:    run/flash and immediately enter LLDB")
+		fmt.Fprintln(os.Stderr, "  monitor: open communication port")
 		fmt.Fprintln(os.Stderr, "  env:     list environment variables used during build")
 		fmt.Fprintln(os.Stderr, "  list:    run go list using the TinyGo root")
 		fmt.Fprintln(os.Stderr, "  clean:   empty cache directory ("+goenv.Get("GOCACHE")+")")
@@ -1298,6 +1316,12 @@ func main() {
 	var tags buildutil.TagsFlag
 	flag.Var(&tags, "tags", "a space-separated list of extra build tags")
 	target := flag.String("target", "", "chip/board name or JSON target specification file")
+	var stackSize uint64
+	flag.Func("stack-size", "goroutine stack size (if unknown at compile time)", func(s string) error {
+		size, err := bytesize.Parse(s)
+		stackSize = uint64(size)
+		return err
+	})
 	printSize := flag.String("size", "", "print sizes (none, short, full)")
 	printStacks := flag.Bool("print-stacks", false, "print stack sizes of goroutines")
 	printAllocsString := flag.String("print-allocs", "", "regular expression of functions for which heap allocations should be printed")
@@ -1312,6 +1336,8 @@ func main() {
 	wasmAbi := flag.String("wasm-abi", "", "WebAssembly ABI conventions: js (no i64 params) or generic")
 	llvmFeatures := flag.String("llvm-features", "", "comma separated LLVM features to enable")
 	cpuprofile := flag.String("cpuprofile", "", "cpuprofile output")
+	monitor := flag.Bool("monitor", false, "enable serial monitor")
+	baudrate := flag.Int("baudrate", 115200, "baudrate of serial monitor")

 	var flagJSON, flagDeps, flagTest bool
 	if command == "help" || command == "list" || command == "info" || command == "build" {
@@ -1378,6 +1404,7 @@ func main() {
 		GOARCH:          goenv.Get("GOARCH"),
 		GOARM:           goenv.Get("GOARM"),
 		Target:          *target,
+		StackSize:       stackSize,
 		Opt:             *opt,
 		GC:              *gc,
 		PanicStrategy:   *panicStrategy,
@@ -1400,6 +1427,8 @@ func main() {
 		OpenOCDCommands: ocdCommands,
 		LLVMFeatures:    *llvmFeatures,
 		PrintJSON:       flagJSON,
+		Monitor:         *monitor,
+		BaudRate:        *baudrate,
 	}
 	if *printCommands {
 		options.PrintCommands = printCommand
@@ -1590,6 +1619,9 @@ func main() {
 			fmt.Println("FAIL")
 			os.Exit(1)
 		}
+	case "monitor":
+		err := Monitor(*port, options)
+		handleCompilerError(err)
 	case "targets":
 		dir := filepath.Join(goenv.Get("TINYGOROOT"), "targets")
 		entries, err := ioutil.ReadDir(dir)
@@ -0,0 +1,106 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"time"
+
+	"github.com/mattn/go-tty"
+	"github.com/tinygo-org/tinygo/builder"
+	"github.com/tinygo-org/tinygo/compileopts"
+	"go.bug.st/serial"
+)
+
+// Monitor connects to the given port and reads/writes the serial port.
+func Monitor(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
+	}
+	defer tty.Close()
+
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, os.Interrupt)
+	defer signal.Stop(sig)
+
+	go func() {
+		<-sig
+		tty.Close()
+		os.Exit(0)
+	}()
+
+	fmt.Printf("Connected to %s. Press Ctrl-C to exit.\n", port)
+
+	errCh := make(chan error, 1)
+
+	go func() {
+		buf := make([]byte, 100*1024)
+		for {
+			n, err := p.Read(buf)
+			if err != nil {
+				errCh <- fmt.Errorf("read error: %w", err)
+				return
+			}
+
+			if n == 0 {
+				continue
+			}
+			fmt.Printf("%v", string(buf[:n]))
+		}
+	}()
+
+	go func() {
+		for {
+			r, err := tty.ReadRune()
+			if err != nil {
+				errCh <- err
+				return
+			}
+			if r == 0 {
+				continue
+			}
+			p.Write([]byte(string(r)))
+		}
+	}()
+
+	return <-errCh
+}
@@ -1,5 +1,5 @@
-//go:build stm32 || (sam && atsamd51) || (sam && atsame5x)
-// +build stm32 sam,atsamd51 sam,atsame5x
+//go:build nrf || stm32 || (sam && atsamd51) || (sam && atsame5x)
+// +build nrf stm32 sam,atsamd51 sam,atsame5x

 package rand

@@ -1,49 +0,0 @@
-// Reads multiple rp2040 ADC channels concurrently. Including the internal temperature sensor
-
-package main
-
-import (
-	"fmt"
-	"machine"
-	"time"
-)
-
-type celsius float32
-
-func (c celsius) String() string {
-	return fmt.Sprintf("%4.1f℃", c)
-}
-
-// rp2040 ADC is 12 bits. Reading are shifted <<4 to fill the 16-bit range.
-var adcReading [3]uint16
-
-func readADC(a machine.ADC, w time.Duration, i int) {
-	for {
-		adcReading[i] = a.Get()
-		time.Sleep(w)
-	}
-}
-
-func main() {
-	machine.InitADC()
-	a0 := machine.ADC{machine.ADC0} // GPIO26 input
-	a1 := machine.ADC{machine.ADC1} // GPIO27 input
-	a2 := machine.ADC{machine.ADC2} // GPIO28 input
-	t := machine.ADC_TEMP_SENSOR    // Internal Temperature sensor
-	// Configure sets the GPIOs to PinAnalog mode
-	a0.Configure(machine.ADCConfig{})
-	a1.Configure(machine.ADCConfig{})
-	a2.Configure(machine.ADCConfig{})
-	// Configure powers on the temperature sensor
-	t.Configure(machine.ADCConfig{})
-
-	// Safe to read concurrently
-	go readADC(a0, 10*time.Millisecond, 0)
-	go readADC(a1, 17*time.Millisecond, 1)
-	go readADC(a2, 29*time.Millisecond, 2)
-
-	for {
-		fmt.Printf("ADC0: %5d ADC1: %5d ADC2: %5d Temp: %v\n\r", adcReading[0], adcReading[1], adcReading[2], celsius(float32(t.ReadTemperature())/1000))
-		time.Sleep(1000 * time.Millisecond)
-	}
-}
@@ -0,0 +1,23 @@
+// Read the internal temperature sensor of the chip.
+
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+)
+
+type celsius float32
+
+func (c celsius) String() string {
+	return fmt.Sprintf("%4.1f℃", c)
+}
+
+func main() {
+	for {
+		temp := celsius(float32(machine.ReadTemperature()) / 1000)
+		println("temperature:", temp.String())
+		time.Sleep(time.Second)
+	}
+}
@@ -21,12 +21,14 @@ $ tinygo build -o ./wasm.wasm -target wasm ./main/main.go
 This creates a `wasm.wasm` file, which we can load in JavaScript and execute in
 a browser.

-This examples folder contains two examples that can be built using `make`:
-
-```bash
-$ make export
-```
+Next, choose which example you want to use:
+* [callback](callback): Defines and configures callbacks in Wasm.
+* [export](export): Defines callbacks in Wasm, but configures them in JavaScript.
+* [invoke](invoke): Invokes a function defined in JavaScript from Wasm.
+* [main](main): Prints a message to the JavaScript console from Wasm.
+* [slices](slices): Splits an Array defined in JavaScript from Wasm.

+Let's say you chose [main](main), you'd build it like so:
 ```bash
 $ make main
 ```
@@ -42,12 +44,8 @@ Serving ./html on http://localhost:8080

 Use your web browser to visit http://localhost:8080.

-* The wasm "export" example displays a simple math equation using HTML, with
-the result calculated dynamically using WebAssembly.  Changing any of the
-values on the left hand side triggers the exported wasm `update` function to
-recalculate the result.
-* The wasm "main" example uses `println` to write to your browser JavaScript
-console. You may need to open the browser development tools console to see it.
+* Tip: Open the browser development tools (e.g. Right-click, Inspect in
+  FireFox) to see console output.

 ## How it works

@@ -8,10 +8,12 @@ import (
 var a, b int

 func main() {
+	wait := make(chan struct{}, 0)
 	document := js.Global().Get("document")
 	document.Call("getElementById", "a").Set("oninput", updater(&a))
 	document.Call("getElementById", "b").Set("oninput", updater(&b))
 	update()
+	<-wait
 }

 func updater(n *int) js.Func {
@@ -2,12 +2,16 @@

 .functype start_unwind (i32) -> ()
 .import_module start_unwind, asyncify
+.import_name start_unwind, start_unwind
 .functype stop_unwind () -> ()
 .import_module stop_unwind, asyncify
+.import_name stop_unwind, stop_unwind
 .functype start_rewind (i32) -> ()
 .import_module start_rewind, asyncify
+.import_name start_rewind, start_rewind
 .functype stop_rewind () -> ()
 .import_module stop_rewind, asyncify
+.import_name stop_rewind, stop_rewind

 .global  tinygo_unwind
 .hidden  tinygo_unwind
@@ -1,5 +1,8 @@
 // Windows on amd64 has a slightly different ABI than other (*nix) systems.
 // Therefore, assembly functions need to be tweaked slightly.
+//
+// The calling convention is described here:
+// https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170

 .section .text.tinygo_startTask,"ax"
 .global  tinygo_startTask
@@ -17,8 +20,9 @@ tinygo_startTask:
    // Branch to the "goroutine start" function.
    callq *%r12

-    // After return, exit this goroutine. This is a tail call.
-    jmp tinygo_pause
+    // After return, exit this goroutine.
+    // This has to be a call, not a jump, to keep the stack correctly aligned.
+    callq tinygo_pause

 .global tinygo_swapTask
 .section .text.tinygo_swapTask,"ax"
@@ -35,6 +39,17 @@ tinygo_swapTask:
    pushq %rsi
    pushq %rdi
    pushq %rbp
+    sub   $160, %rsp
+    movaps  %xmm6, 144(%rsp)
+    movaps  %xmm7, 128(%rsp)
+    movaps  %xmm8, 112(%rsp)
+    movaps  %xmm9,  96(%rsp)
+    movaps  %xmm10, 80(%rsp)
+    movaps  %xmm11, 64(%rsp)
+    movaps  %xmm12, 48(%rsp)
+    movaps  %xmm13, 32(%rsp)
+    movaps  %xmm14, 16(%rsp)
+    movaps  %xmm15,  0(%rsp)
    pushq %rbx

    // Save the current stack pointer in oldStack.
@@ -45,6 +60,17 @@ tinygo_swapTask:

    // Load saved register from the new stack.
    popq %rbx
+    movaps 0(%rsp),   %xmm15
+    movaps 16(%rsp),  %xmm14
+    movaps 32(%rsp),  %xmm13
+    movaps 48(%rsp),  %xmm12
+    movaps 64(%rsp),  %xmm11
+    movaps 80(%rsp),  %xmm10
+    movaps 96(%rsp),  %xmm9
+    movaps 112(%rsp), %xmm8
+    movaps 128(%rsp), %xmm7
+    movaps 144(%rsp), %xmm6
+    add   $160, %rsp
    popq %rbp
    popq %rdi
    popq %rsi
@@ -13,15 +13,34 @@ var systemStack uintptr
 // calleeSavedRegs is the list of registers that must be saved and restored when
 // switching between tasks. Also see task_stack_amd64_windows.S that relies on
 // the exact layout of this struct.
+// The calling convention is described here:
+// https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170
+// Most importantly, these are the registers we need to save/restore:
+//
+// > The x64 ABI considers registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14,
+// > R15, and XMM6-XMM15 nonvolatile. They must be saved and restored by a
+// > function that uses them.
 type calleeSavedRegs struct {
-	rbx uintptr
-	rbp uintptr
-	rdi uintptr
-	rsi uintptr
-	r12 uintptr
-	r13 uintptr
-	r14 uintptr
-	r15 uintptr
+	// Note: rbx is placed here so that the stack is correctly aligned when
+	// loading/storing the xmm registers.
+	rbx   uintptr
+	xmm15 [2]uint64
+	xmm14 [2]uint64
+	xmm13 [2]uint64
+	xmm12 [2]uint64
+	xmm11 [2]uint64
+	xmm10 [2]uint64
+	xmm9  [2]uint64
+	xmm8  [2]uint64
+	xmm7  [2]uint64
+	xmm6  [2]uint64
+	rbp   uintptr
+	rdi   uintptr
+	rsi   uintptr
+	r12   uintptr
+	r13   uintptr
+	r14   uintptr
+	r15   uintptr

 	pc uintptr
 }
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135

 // GPIO Pins - Digital Low
 const (
@@ -12,9 +12,9 @@ const (

 const (
 	PB0 = portB + 0
-	PB1 = portB + 1
-	PB2 = portB + 2
-	PB3 = portB + 3
+	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
@@ -30,9 +30,9 @@ const (
 	PD0 = portD + 0
 	PD1 = portD + 1
 	PD2 = portD + 2
-	PD3 = portD + 3
+	PD3 = portD + 3 // peripherals: Timer2 channel B
 	PD4 = portD + 4
-	PD5 = portD + 5
-	PD6 = portD + 6
+	PD5 = portD + 5 // peripherals: Timer0 channel B
+	PD6 = portD + 6 // peripherals: Timer0 channel A
 	PD7 = portD + 7
 )
@@ -10,38 +10,38 @@ func CPUFrequency() uint32 {

 // Hardware pins
 const (
-	PA00 Pin = 0
-	PA01 Pin = 1
+	PA00 Pin = 0 // peripherals: TCC2 channel 0
+	PA01 Pin = 1 // peripherals: TCC2 channel 1
 	PA02 Pin = 2
 	PA03 Pin = 3
-	PA04 Pin = 4
-	PA05 Pin = 5
-	PA06 Pin = 6
-	PA07 Pin = 7
-	PA08 Pin = 8
-	PA09 Pin = 9
-	PA10 Pin = 10
-	PA11 Pin = 11
-	PA12 Pin = 12
-	PA13 Pin = 13
-	PA14 Pin = 14
-	PA15 Pin = 15
-	PA16 Pin = 16
-	PA17 Pin = 17
-	PA18 Pin = 18
-	PA19 Pin = 19
-	PA20 Pin = 20
-	PA21 Pin = 21
-	PA22 Pin = 22
-	PA23 Pin = 23
-	PA24 Pin = 24
-	PA25 Pin = 25
+	PA04 Pin = 4  // peripherals: TCC0 channel 0
+	PA05 Pin = 5  // peripherals: TCC0 channel 1
+	PA06 Pin = 6  // peripherals: TCC1 channel 0
+	PA07 Pin = 7  // peripherals: TCC1 channel 1
+	PA08 Pin = 8  // peripherals: TCC0 channel 0, TCC1 channel 2
+	PA09 Pin = 9  // peripherals: TCC0 channel 1, TCC1 channel 3
+	PA10 Pin = 10 // peripherals: TCC1 channel 0, TCC0 channel 2
+	PA11 Pin = 11 // peripherals: TCC1 channel 1, TCC0 channel 3
+	PA12 Pin = 12 // peripherals: TCC2 channel 0, TCC0 channel 2
+	PA13 Pin = 13 // peripherals: TCC2 channel 1, TCC0 channel 3
+	PA14 Pin = 14 // peripherals: TCC0 channel 0
+	PA15 Pin = 15 // peripherals: TCC0 channel 1
+	PA16 Pin = 16 // peripherals: TCC2 channel 0, TCC0 channel 2
+	PA17 Pin = 17 // peripherals: TCC2 channel 1, TCC0 channel 3
+	PA18 Pin = 18 // peripherals: TCC0 channel 2
+	PA19 Pin = 19 // peripherals: TCC0 channel 3
+	PA20 Pin = 20 // peripherals: TCC0 channel 2
+	PA21 Pin = 21 // peripherals: TCC0 channel 3
+	PA22 Pin = 22 // peripherals: TCC0 channel 0
+	PA23 Pin = 23 // peripherals: TCC0 channel 1
+	PA24 Pin = 24 // peripherals: TCC1 channel 2
+	PA25 Pin = 25 // peripherals: TCC1 channel 3
 	PA26 Pin = 26
 	PA27 Pin = 27
 	PA28 Pin = 28
 	PA29 Pin = 29
-	PA30 Pin = 30
-	PA31 Pin = 31
+	PA30 Pin = 30 // peripherals: TCC1 channel 0
+	PA31 Pin = 31 // peripherals: TCC1 channel 1
 	PB00 Pin = 32
 	PB01 Pin = 33
 	PB02 Pin = 34
@@ -52,14 +52,14 @@ const (
 	PB07 Pin = 39
 	PB08 Pin = 40
 	PB09 Pin = 41
-	PB10 Pin = 42
-	PB11 Pin = 43
-	PB12 Pin = 44
-	PB13 Pin = 45
+	PB10 Pin = 42 // peripherals: TCC0 channel 0
+	PB11 Pin = 43 // peripherals: TCC0 channel 1
+	PB12 Pin = 44 // peripherals: TCC0 channel 2
+	PB13 Pin = 45 // peripherals: TCC0 channel 3
 	PB14 Pin = 46
 	PB15 Pin = 47
-	PB16 Pin = 48
-	PB17 Pin = 49
+	PB16 Pin = 48 // peripherals: TCC0 channel 0
+	PB17 Pin = 49 // peripherals: TCC0 channel 1
 	PB18 Pin = 50
 	PB19 Pin = 51
 	PB20 Pin = 52
@@ -72,6 +72,6 @@ const (
 	PB27 Pin = 59
 	PB28 Pin = 60
 	PB29 Pin = 61
-	PB30 Pin = 62
-	PB31 Pin = 63
+	PB30 Pin = 62 // peripherals: TCC0 channel 0, TCC1 channel 2
+	PB31 Pin = 63 // peripherals: TCC0 channel 1, TCC1 channel 3
 )
@@ -8,7 +8,7 @@ import (
 )

 // Definition for compatibility, but not used
-const RESET_MAGIC_VALUE = 0x00000000
+const resetMagicValue = 0x00000000

 const (
 	LED    = PC18
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -8,7 +8,7 @@ import (
 )

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -245,7 +245,7 @@ const (

 // Other peripheral constants
 const (
-	RESET_MAGIC_VALUE = 0xF01669EF // Used to reset into bootloader
+	resetMagicValue = 0xF01669EF // Used to reset into bootloader
 )

 // USB CDC pins
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xF01669EF
+const resetMagicValue = 0xF01669EF

 // Digital pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135

 // Note: On the P1AM-100, pins D8, D9, D10, A3, and A4 are used for
 // communication with the base controller.
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -0,0 +1,119 @@
+//go:build qtpy_rp2040
+// +build qtpy_rp2040
+
+package machine
+
+import (
+	"device/rp"
+	"runtime/interrupt"
+)
+
+// Onboard crystal oscillator frequency, in MHz.
+const xoscFreq = 12 // MHz
+
+// GPIO Pins
+const (
+	SDA  = GPIO24
+	SCL  = GPIO25
+	TX   = GPIO20
+	MO   = GPIO3
+	MOSI = GPIO3
+	MI   = GPIO4
+	MISO = GPIO4
+	SCK  = GPIO6
+	RX   = GPIO5
+
+	QT_SCL1 = GPIO23
+	QT_SDA1 = GPIO22
+)
+
+// Analog pins
+const (
+	A0 = GPIO29
+	A1 = GPIO28
+	A2 = GPIO27
+	A3 = GPIO26
+)
+
+const (
+	NEOPIXEL       = GPIO12
+	WS2812         = GPIO12
+	NEOPIXEL_POWER = GPIO11
+)
+
+// I2C Pins.
+const (
+	I2C0_SDA_PIN = GPIO24
+	I2C0_SCL_PIN = GPIO25
+
+	I2C1_SDA_PIN = GPIO26
+	I2C1_SCL_PIN = GPIO27
+
+	I2C1_QT_SDA_PIN = GPIO22
+	I2C1_QT_SCL_PIN = GPIO23
+
+	SDA_PIN = GPIO24
+	SCL_PIN = GPIO25
+)
+
+// SPI default pins
+const (
+	// Default Serial Clock Bus 0 for SPI communications
+	SPI0_SCK_PIN = GPIO6
+	// Default Serial Out Bus 0 for SPI communications
+	SPI0_SDO_PIN = GPIO3 // Tx
+	// Default Serial In Bus 0 for SPI communications
+	SPI0_SDI_PIN = GPIO4 // Rx
+	SPI0_CS      = GPIO5
+
+	// Default Serial Clock Bus 1 for SPI communications
+	SPI1_SCK_PIN = GPIO26
+	// Default Serial Out Bus 1 for SPI communications
+	SPI1_SDO_PIN = GPIO27 // Tx
+	// Default Serial In Bus 1 for SPI communications
+	SPI1_SDI_PIN = GPIO24 // Rx
+	SPI1_CS      = GPIO25
+)
+
+// UART pins
+const (
+	UART0_TX_PIN = GPIO28
+	UART0_RX_PIN = GPIO29
+	UART1_TX_PIN = GPIO20
+	UART1_RX_PIN = GPIO5
+	UART_TX_PIN  = UART0_TX_PIN
+	UART_RX_PIN  = UART0_RX_PIN
+)
+
+// UART on the RP2040
+var (
+	UART0  = &_UART0
+	_UART0 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    rp.UART0,
+	}
+
+	UART1  = &_UART1
+	_UART1 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    rp.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)
+}
+
+// USB identifiers
+const (
+	usb_STRING_PRODUCT      = "QT Py RP2040"
+	usb_STRING_MANUFACTURER = "Adafruit"
+)
+
+var (
+	usb_VID uint16 = 0x239A
+	usb_PID uint16 = 0x80F7
+)
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 const (
 	ADC0 = A0
@@ -104,7 +104,7 @@ const (

 var (
 	usb_VID uint16 = 0x2886
-	usb_PID uint16 = 0x0045
+	usb_PID uint16 = 0x8045
 )

 var (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef

 // GPIO Pins
 const (
@@ -8,6 +8,8 @@ import (
 )

 // TWI_FREQ is the I2C bus speed. Normally either 100 kHz, or 400 kHz for high-speed bus.
+//
+// Deprecated: use 100 * machine.KHz or 400 * machine.KHz instead.
 const (
 	TWI_FREQ_100KHZ = 100000
 	TWI_FREQ_400KHZ = 400000
@@ -18,6 +18,13 @@ var (
 // particular chip but instead runs in WebAssembly for example.
 const Device = deviceName

+// Generic constants.
+const (
+	KHz = 1000
+	MHz = 1000_000
+	GHz = 1000_000_000
+)
+
 // PinMode sets the direction and pull mode of the pin. For example, PinOutput
 // sets the pin as an output and PinInputPullup sets the pin as an input with a
 // pull-up.
@@ -26,7 +26,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}

 	// Activate internal pullups for twi.
@@ -38,10 +38,10 @@ const (
 	PB1 = portB + 1
 	PB2 = portB + 2
 	PB3 = portB + 3
-	PB4 = portB + 4
-	PB5 = portB + 5
-	PB6 = portB + 6
-	PB7 = portB + 7
+	PB4 = portB + 4 // peripherals: Timer2 channel A
+	PB5 = portB + 5 // peripherals: Timer1 channel A
+	PB6 = portB + 6 // peripherals: Timer1 channel B
+	PB7 = portB + 7 // peripherals: Timer0 channel A
 	PC0 = portC + 0
 	PC1 = portC + 1
 	PC2 = portC + 2
@@ -57,9 +57,9 @@ const (
 	PD7 = portD + 7
 	PE0 = portE + 0
 	PE1 = portE + 1
-	PE3 = portE + 3
-	PE4 = portE + 4
-	PE5 = portE + 5
+	PE3 = portE + 3 // peripherals: Timer3 channel A
+	PE4 = portE + 4 // peripherals: Timer3 channel B
+	PE5 = portE + 5 // peripherals: Timer3 channel C
 	PE6 = portE + 6
 	PF0 = portF + 0
 	PF1 = portF + 1
@@ -72,13 +72,13 @@ const (
 	PG0 = portG + 0
 	PG1 = portG + 1
 	PG2 = portG + 2
-	PG5 = portG + 5
+	PG5 = portG + 5 // peripherals: Timer0 channel B
 	PH0 = portH + 0
 	PH1 = portH + 1
-	PH3 = portH + 3
-	PH4 = portH + 4
-	PH5 = portH + 5
-	PH6 = portH + 6
+	PH3 = portH + 3 // peripherals: Timer4 channel A
+	PH4 = portH + 4 // peripherals: Timer4 channel B
+	PH5 = portH + 5 // peripherals: Timer4 channel C
+	PH6 = portH + 6 // peripherals: Timer0 channel B
 	PJ0 = portJ + 0
 	PJ1 = portJ + 1
 	PK0 = portK + 0
@@ -92,9 +92,9 @@ const (
 	PL0 = portL + 0
 	PL1 = portL + 1
 	PL2 = portL + 2
-	PL3 = portL + 3
-	PL4 = portL + 4
-	PL5 = portL + 5
+	PL3 = portL + 3 // peripherals: Timer5 channel A
+	PL4 = portL + 4 // peripherals: Timer5 channel B
+	PL5 = portL + 5 // peripherals: Timer5 channel C
 	PL6 = portL + 6
 	PL7 = portL + 7
 )
@@ -10,7 +10,6 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
-	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -677,7 +676,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 	if config.SDA == 0 && config.SCL == 0 {
 		config.SDA = SDA_PIN
@@ -1274,10 +1273,6 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 	return byte(spi.Bus.DATA.Get()), nil
 }

-var (
-	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
-)
-
 // Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
 // interface, there must always be the same number of bytes written as bytes read.
 // The Tx method knows about this, and offers a few different ways of calling it.
@@ -1740,7 +1735,7 @@ func EnterBootloader() {

 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = RESET_MAGIC_VALUE
+	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = resetMagicValue

 	arm.SystemReset()
 }
@@ -10,7 +10,6 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
-	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -78,86 +77,86 @@ const (
 	PA05 Pin = 5
 	PA06 Pin = 6
 	PA07 Pin = 7
-	PA08 Pin = 8
-	PA09 Pin = 9
-	PA10 Pin = 10
-	PA11 Pin = 11
-	PA12 Pin = 12
-	PA13 Pin = 13
-	PA14 Pin = 14
-	PA15 Pin = 15
-	PA16 Pin = 16
-	PA17 Pin = 17
-	PA18 Pin = 18
-	PA19 Pin = 19
-	PA20 Pin = 20
-	PA21 Pin = 21
-	PA22 Pin = 22
-	PA23 Pin = 23
-	PA24 Pin = 24
-	PA25 Pin = 25
+	PA08 Pin = 8  // peripherals: TCC0 channel 0, TCC1 channel 4
+	PA09 Pin = 9  // peripherals: TCC0 channel 1, TCC1 channel 5
+	PA10 Pin = 10 // peripherals: TCC0 channel 2, TCC1 channel 6
+	PA11 Pin = 11 // peripherals: TCC0 channel 3, TCC1 channel 7
+	PA12 Pin = 12 // peripherals: TCC0 channel 6, TCC1 channel 2
+	PA13 Pin = 13 // peripherals: TCC0 channel 7, TCC1 channel 3
+	PA14 Pin = 14 // peripherals: TCC2 channel 0, TCC1 channel 2
+	PA15 Pin = 15 // peripherals: TCC2 channel 1, TCC1 channel 3
+	PA16 Pin = 16 // peripherals: TCC1 channel 0, TCC0 channel 4
+	PA17 Pin = 17 // peripherals: TCC1 channel 1, TCC0 channel 5
+	PA18 Pin = 18 // peripherals: TCC1 channel 2, TCC0 channel 6
+	PA19 Pin = 19 // peripherals: TCC1 channel 3, TCC0 channel 7
+	PA20 Pin = 20 // peripherals: TCC1 channel 4, TCC0 channel 0
+	PA21 Pin = 21 // peripherals: TCC1 channel 5, TCC0 channel 1
+	PA22 Pin = 22 // peripherals: TCC1 channel 6, TCC0 channel 2
+	PA23 Pin = 23 // peripherals: TCC1 channel 7, TCC0 channel 3
+	PA24 Pin = 24 // peripherals: TCC2 channel 2
+	PA25 Pin = 25 // peripherals: TCC2 channel 3
 	PA26 Pin = 26
 	PA27 Pin = 27
 	PA28 Pin = 28
 	PA29 Pin = 29
-	PA30 Pin = 30
-	PA31 Pin = 31
+	PA30 Pin = 30 // peripherals: TCC2 channel 0
+	PA31 Pin = 31 // peripherals: TCC2 channel 1
 	PB00 Pin = 32
 	PB01 Pin = 33
-	PB02 Pin = 34
-	PB03 Pin = 35
+	PB02 Pin = 34 // peripherals: TCC2 channel 2
+	PB03 Pin = 35 // peripherals: TCC2 channel 3
 	PB04 Pin = 36
 	PB05 Pin = 37
 	PB06 Pin = 38
 	PB07 Pin = 39
 	PB08 Pin = 40
 	PB09 Pin = 41
-	PB10 Pin = 42
-	PB11 Pin = 43
-	PB12 Pin = 44
-	PB13 Pin = 45
-	PB14 Pin = 46
-	PB15 Pin = 47
-	PB16 Pin = 48
-	PB17 Pin = 49
-	PB18 Pin = 50
-	PB19 Pin = 51
-	PB20 Pin = 52
-	PB21 Pin = 53
+	PB10 Pin = 42 // peripherals: TCC0 channel 4, TCC1 channel 0
+	PB11 Pin = 43 // peripherals: TCC0 channel 5, TCC1 channel 1
+	PB12 Pin = 44 // peripherals: TCC3 channel 0, TCC0 channel 0
+	PB13 Pin = 45 // peripherals: TCC3 channel 1, TCC0 channel 1
+	PB14 Pin = 46 // peripherals: TCC4 channel 0, TCC0 channel 2
+	PB15 Pin = 47 // peripherals: TCC4 channel 1, TCC0 channel 3
+	PB16 Pin = 48 // peripherals: TCC3 channel 0, TCC0 channel 4
+	PB17 Pin = 49 // peripherals: TCC3 channel 1, TCC0 channel 5
+	PB18 Pin = 50 // peripherals: TCC1 channel 0
+	PB19 Pin = 51 // peripherals: TCC1 channel 1
+	PB20 Pin = 52 // peripherals: TCC1 channel 2
+	PB21 Pin = 53 // peripherals: TCC1 channel 3
 	PB22 Pin = 54
 	PB23 Pin = 55
 	PB24 Pin = 56
 	PB25 Pin = 57
-	PB26 Pin = 58
-	PB27 Pin = 59
-	PB28 Pin = 60
-	PB29 Pin = 61
-	PB30 Pin = 62
-	PB31 Pin = 63
+	PB26 Pin = 58 // peripherals: TCC1 channel 2
+	PB27 Pin = 59 // peripherals: TCC1 channel 3
+	PB28 Pin = 60 // peripherals: TCC1 channel 4
+	PB29 Pin = 61 // peripherals: TCC1 channel 5
+	PB30 Pin = 62 // peripherals: TCC4 channel 0, TCC0 channel 6
+	PB31 Pin = 63 // peripherals: TCC4 channel 1, TCC0 channel 7
 	PC00 Pin = 64
 	PC01 Pin = 65
 	PC02 Pin = 66
 	PC03 Pin = 67
-	PC04 Pin = 68
-	PC05 Pin = 69
+	PC04 Pin = 68 // peripherals: TCC0 channel 0
+	PC05 Pin = 69 // peripherals: TCC0 channel 1
 	PC06 Pin = 70
 	PC07 Pin = 71
 	PC08 Pin = 72
 	PC09 Pin = 73
-	PC10 Pin = 74
-	PC11 Pin = 75
-	PC12 Pin = 76
-	PC13 Pin = 77
-	PC14 Pin = 78
-	PC15 Pin = 79
-	PC16 Pin = 80
-	PC17 Pin = 81
-	PC18 Pin = 82
-	PC19 Pin = 83
-	PC20 Pin = 84
-	PC21 Pin = 85
-	PC22 Pin = 86
-	PC23 Pin = 87
+	PC10 Pin = 74 // peripherals: TCC0 channel 0, TCC1 channel 4
+	PC11 Pin = 75 // peripherals: TCC0 channel 1, TCC1 channel 5
+	PC12 Pin = 76 // peripherals: TCC0 channel 2, TCC1 channel 6
+	PC13 Pin = 77 // peripherals: TCC0 channel 3, TCC1 channel 7
+	PC14 Pin = 78 // peripherals: TCC0 channel 4, TCC1 channel 0
+	PC15 Pin = 79 // peripherals: TCC0 channel 5, TCC1 channel 1
+	PC16 Pin = 80 // peripherals: TCC0 channel 0
+	PC17 Pin = 81 // peripherals: TCC0 channel 1
+	PC18 Pin = 82 // peripherals: TCC0 channel 2
+	PC19 Pin = 83 // peripherals: TCC0 channel 3
+	PC20 Pin = 84 // peripherals: TCC0 channel 4
+	PC21 Pin = 85 // peripherals: TCC0 channel 5
+	PC22 Pin = 86 // peripherals: TCC0 channel 6
+	PC23 Pin = 87 // peripherals: TCC0 channel 7
 	PC24 Pin = 88
 	PC25 Pin = 89
 	PC26 Pin = 90
@@ -174,20 +173,20 @@ const (
 	PD05 Pin = 101
 	PD06 Pin = 102
 	PD07 Pin = 103
-	PD08 Pin = 104
-	PD09 Pin = 105
-	PD10 Pin = 106
-	PD11 Pin = 107
-	PD12 Pin = 108
-	PD13 Pin = 109
+	PD08 Pin = 104 // peripherals: TCC0 channel 1
+	PD09 Pin = 105 // peripherals: TCC0 channel 2
+	PD10 Pin = 106 // peripherals: TCC0 channel 3
+	PD11 Pin = 107 // peripherals: TCC0 channel 4
+	PD12 Pin = 108 // peripherals: TCC0 channel 5
+	PD13 Pin = 109 // peripherals: TCC0 channel 6
 	PD14 Pin = 110
 	PD15 Pin = 111
 	PD16 Pin = 112
 	PD17 Pin = 113
 	PD18 Pin = 114
 	PD19 Pin = 115
-	PD20 Pin = 116
-	PD21 Pin = 117
+	PD20 Pin = 116 // peripherals: TCC1 channel 0
+	PD21 Pin = 117 // peripherals: TCC1 channel 1
 	PD22 Pin = 118
 	PD23 Pin = 119
 	PD24 Pin = 120
@@ -1151,7 +1150,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}

 	// Use default I2C pins if not set.
@@ -1527,10 +1526,6 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 	return byte(spi.Bus.DATA.Get()), nil
 }

-var (
-	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
-)
-
 // Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
 // interface, there must always be the same number of bytes written as bytes read.
 // The Tx method knows about this, and offers a few different ways of calling it.
@@ -1980,7 +1975,7 @@ func EnterBootloader() {

 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = RESET_MAGIC_VALUE
+	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = resetMagicValue

 	arm.SystemReset()
 }
@@ -59,12 +59,9 @@ type PinChange uint8

 // Pin change interrupt constants for SetInterrupt.
 const (
-	PinNoInterrupt PinChange = iota
-	PinRising
+	PinRising PinChange = iota + 1
 	PinFalling
 	PinToggle
-	PinLowLevel
-	PinHighLevel
 )

 // Configure this pin with the given configuration.
@@ -190,7 +187,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {
 		return ErrInvalidInputPin
 	}

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

@@ -264,15 +261,6 @@ type UART struct {
 	DataOverflowDetected bool // set when data overflow detected in UART FIFO buffer or RingBuffer
 }

-type UARTStopBits int
-
-const (
-	UARTStopBits_Default UARTStopBits = iota
-	UARTStopBits_1
-	UARTStopBits_1_5
-	UARTStopBits_2
-)
-
 const (
 	defaultDataBits = 8
 	defaultStopBit  = 1
@@ -231,7 +231,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 	var i2cClockFrequency uint32 = 32000000
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}

 	if config.SDA == 0 && config.SCL == 0 {
@@ -23,11 +23,17 @@ type PinChange uint8
 // Pin modes.
 const (
 	PinInput PinMode = iota
-	PinInputPullUp
-	PinInputPullDown
+	PinInputPullup
+	PinInputPulldown
 	PinOutput
 )

+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
+)
+
 // FPIOA internal pull resistors.
 const (
 	fpioaPullNone fpioaPullMode = iota
@@ -89,10 +95,10 @@ func (p Pin) Configure(config PinConfig) {
 	case PinInput:
 		p.setFPIOAIOPull(fpioaPullNone)
 		input = true
-	case PinInputPullUp:
+	case PinInputPullup:
 		p.setFPIOAIOPull(fpioaPullUp)
 		input = true
-	case PinInputPullDown:
+	case PinInputPulldown:
 		p.setFPIOAIOPull(fpioaPullDown)
 		input = true
 	case PinOutput:
@@ -517,7 +523,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {

 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}

 	if config.SDA == 0 && config.SCL == 0 {
@@ -21,8 +21,8 @@ func CPUFrequency() uint32 {
 const (
 	// GPIO
 	PinInput PinMode = iota
-	PinInputPullUp
-	PinInputPullDown
+	PinInputPullup
+	PinInputPulldown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable
@@ -45,12 +45,16 @@ const (
 	PinModeI2CSCL
 )

+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
+)
+
 type PinChange uint8

 const (
-	PinLow PinChange = iota
-	PinHigh
-	PinRising
+	PinRising PinChange = iota + 2
 	PinFalling
 	PinToggle
 )
@@ -259,11 +263,11 @@ func (p Pin) Configure(config PinConfig) {
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7))

-	case PinInputPullUp:
+	case PinInputPullup:
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7) | pke | pue | pup(3) | hys)

-	case PinInputPullDown:
+	case PinInputPulldown:
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7) | pke | pue | hys)

@@ -387,7 +391,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
 	mask := p.getMask()
 	if nil != callback {
 		switch change {
-		case PinLow, PinHigh, PinRising, PinFalling:
+		case PinRising, PinFalling:
 			gpio.EDGE_SEL.ClearBits(mask)
 			var reg *volatile.Register32
 			var pos uint8
@@ -746,7 +750,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 	switch config.Mode {

 	// GPIO
-	case PinInput, PinInputPullUp, PinInputPullDown,
+	case PinInput, PinInputPullup, PinInputPulldown,
 		PinOutput, PinOutputOpenDrain, PinDisable:
 		mode := uint32(0x5) // GPIO is always alternate function 5
 		if forcePath {
@@ -10,15 +10,6 @@ import (
 	"errors"
 )

-const (
-	TWI_FREQ_BUS     = 24000000        // LPI2C root clock is on 24 MHz OSC
-	TWI_FREQ_100KHZ  = 100000          // StandardMode (100 kHz)
-	TWI_FREQ_400KHZ  = 400000          // FastMode (400 kHz)
-	TWI_FREQ_1MHZ    = 1000000         // FastModePlus (1 MHz)
-	TWI_FREQ_5MHZ    = 5000000         // UltraFastMode (5 MHz)
-	TWI_FREQ_DEFAULT = TWI_FREQ_100KHZ // default to StandardMode (100 kHz)
-)
-
 var (
 	errI2CWriteTimeout       = errors.New("I2C timeout during write")
 	errI2CReadTimeout        = errors.New("I2C timeout during read")
@@ -174,7 +165,7 @@ func (i2c *I2C) Configure(config I2CConfig) {

 	freq := config.Frequency
 	if 0 == freq {
-		freq = TWI_FREQ_DEFAULT
+		freq = 100 * KHz
 	}

 	// reset clock and registers, and enable LPI2C module interface
@@ -305,7 +296,7 @@ func (i2c *I2C) setFrequency(freq uint32) {
 	wasEnabled := i2c.Bus.MCR.HasBits(nxp.LPI2C_MCR_MEN)
 	i2c.Bus.MCR.ClearBits(nxp.LPI2C_MCR_MEN)

-	// baud rate = (TWI_FREQ_BUS/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
+	// baud rate = (24MHz/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
 	// assume: CLKLO=2*CLKHI, SETHOLD=CLKHI, DATAVD=CLKHI/2
 	for pre := uint32(1); pre <= 128; pre *= 2 {
 		if bestError == 0 {
@@ -314,9 +305,9 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		for clkHi := uint32(1); clkHi < 32; clkHi++ {
 			var absError, rate uint32
 			if clkHi == 1 {
-				rate = (TWI_FREQ_BUS / pre) / (1 + 3 + 2 + 2/pre)
+				rate = (24 * MHz / pre) / (1 + 3 + 2 + 2/pre)
 			} else {
-				rate = (TWI_FREQ_BUS / pre) / (3*clkHi + 2 + 2/pre)
+				rate = (24 * MHz / pre) / (3*clkHi + 2 + 2/pre)
 			}
 			if freq > rate {
 				absError = freq - rate
@@ -370,15 +361,15 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		mcfgr2, mcfgr3 uint32
 	)
 	const i2cClockStretchTimeout = 15000 // microseconds
-	if freq >= TWI_FREQ_5MHZ {
+	if freq >= 5*MHz {
 		// I2C UltraFastMode 5 MHz
 		mcfgr2 = 0 // disable glitch filters and timeout for UltraFastMode
 		mcfgr3 = 0 //
-	} else if freq >= TWI_FREQ_1MHZ {
+	} else if freq >= 1*MHz {
 		// I2C FastModePlus 1 MHz
 		mcfgr2 = filtsda(1) | filtscl(1) | busidle(2400) // 100us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
-	} else if freq >= TWI_FREQ_400KHZ {
+	} else if freq >= 400*KHz {
 		// I2C FastMode 400 kHz
 		mcfgr2 = filtsda(2) | filtscl(2) | busidle(3600) // 150us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
@@ -159,8 +159,8 @@ func (uart *UART) Disable() {
 		uart.Bus.CTRL.ClearBits(nxp.LPUART_CTRL_TE | nxp.LPUART_CTRL_RE)

 		// put pins back into GPIO mode
-		uart.rx.Configure(PinConfig{Mode: PinInputPullUp})
-		uart.tx.Configure(PinConfig{Mode: PinInputPullUp})
+		uart.rx.Configure(PinConfig{Mode: PinInputPullup})
+		uart.tx.Configure(PinConfig{Mode: PinInputPullup})
 	}
 	uart.configured = false
 }
@@ -5,15 +5,10 @@ package machine

 import (
 	"device/nrf"
-	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )

-var (
-	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
-)
-
 const deviceName = nrf.Device

 const (
@@ -230,7 +225,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {

 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 	// Default I2C pins if not set.
 	if config.SDA == 0 && config.SCL == 0 {
@@ -253,7 +248,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 		(nrf.GPIO_PIN_CNF_DRIVE_S0D1 << nrf.GPIO_PIN_CNF_DRIVE_Pos) |
 		(nrf.GPIO_PIN_CNF_SENSE_Disabled << nrf.GPIO_PIN_CNF_SENSE_Pos))

-	if config.Frequency == TWI_FREQ_400KHZ {
+	if config.Frequency >= 400*KHz {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K400)
 	} else {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K100)
@@ -350,3 +345,41 @@ func (i2c *I2C) readByte() (byte, error) {
 	i2c.Bus.EVENTS_RXDREADY.Set(0)
 	return byte(i2c.Bus.RXD.Get()), nil
 }
+
+var rngStarted = false
+
+// GetRNG returns 32 bits of non-deterministic random data based on internal thermal noise.
+// According to Nordic's documentation, the random output is suitable for cryptographic purposes.
+func GetRNG() (ret uint32, err error) {
+	// There's no apparent way to check the status of the RNG peripheral's task, so simply start it
+	// to avoid deadlocking while waiting for output.
+	if !rngStarted {
+		nrf.RNG.TASKS_START.Set(1)
+		nrf.RNG.SetCONFIG_DERCEN(nrf.RNG_CONFIG_DERCEN_Enabled)
+		rngStarted = true
+	}
+
+	// The RNG returns one byte at a time, so stack up four bytes into a single uint32 for return.
+	for i := 0; i < 4; i++ {
+		// Wait for data to be ready.
+		for nrf.RNG.EVENTS_VALRDY.Get() == 0 {
+		}
+		// Append random byte to output.
+		ret = (ret << 8) ^ nrf.RNG.GetVALUE()
+		// Unset the EVENTS_VALRDY register to avoid reading the same random output twice.
+		nrf.RNG.EVENTS_VALRDY.Set(0)
+	}
+
+	return ret, nil
+}
+
+// ReadTemperature reads the silicon die temperature of the chip. The return
+// value is in milli-celsius.
+func ReadTemperature() int32 {
+	nrf.TEMP.TASKS_START.Set(1)
+	for nrf.TEMP.EVENTS_DATARDY.Get() == 0 {
+	}
+	temp := int32(nrf.TEMP.TEMP.Get()) * 250 // the returned value is in units of 0.25°C
+	nrf.TEMP.EVENTS_DATARDY.Set(0)
+	return temp
+}
@@ -9,16 +9,16 @@ import (
 )

 const (
-	DFU_MAGIC_SERIAL_ONLY_RESET = 0x4e
-	DFU_MAGIC_UF2_RESET         = 0x57
-	DFU_MAGIC_OTA_RESET         = 0xA8
+	dfuMagicSerialOnlyReset = 0x4e
+	dfuMagicUF2Reset        = 0x57
+	dfuMagicOTAReset        = 0xA8
 )

 // EnterSerialBootloader resets the chip into the serial bootloader. After
 // reset, it can be flashed using serial/nrfutil.
 func EnterSerialBootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_SERIAL_ONLY_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicSerialOnlyReset)
 	arm.SystemReset()
 }

@@ -26,7 +26,7 @@ func EnterSerialBootloader() {
 // can be flashed via nrfutil or by copying a UF2 file to the mass storage device
 func EnterUF2Bootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_UF2_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicUF2Reset)
 	arm.SystemReset()
 }

@@ -34,6 +34,6 @@ func EnterUF2Bootloader() {
 // flashed via an OTA update
 func EnterOTABootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_OTA_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicOTAReset)
 	arm.SystemReset()
 }
@@ -42,13 +42,19 @@ const deviceName = nxp.Device

 const (
 	PinInput PinMode = iota
-	PinInputPullUp
-	PinInputPullDown
+	PinInputPullup
+	PinInputPulldown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable
 )

+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
+)
+
 const (
 	PA00 Pin = iota
 	PA01
@@ -223,11 +229,11 @@ func (p Pin) Configure(config PinConfig) {
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos))

-	case PinInputPullUp:
+	case PinInputPullup:
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos) | nxp.PORT_PCR0_PE | nxp.PORT_PCR0_PS)

-	case PinInputPullDown:
+	case PinInputPulldown:
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos) | nxp.PORT_PCR0_PE)

@@ -203,8 +203,8 @@ func (u *UART) Disable() {
 	u.C2.Set(0)

 	// reconfigure pin
-	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullUp})
-	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullUp})
+	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullup})
+	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullup})

 	// clear flags
 	u.S1.Get()
@@ -11,36 +11,36 @@ const deviceName = rp.Device

 const (
 	// GPIO pins
-	GPIO0  Pin = 0
-	GPIO1  Pin = 1
-	GPIO2  Pin = 2
-	GPIO3  Pin = 3
-	GPIO4  Pin = 4
-	GPIO5  Pin = 5
-	GPIO6  Pin = 6
-	GPIO7  Pin = 7
-	GPIO8  Pin = 8
-	GPIO9  Pin = 9
-	GPIO10 Pin = 10
-	GPIO11 Pin = 11
-	GPIO12 Pin = 12
-	GPIO13 Pin = 13
-	GPIO14 Pin = 14
-	GPIO15 Pin = 15
-	GPIO16 Pin = 16
-	GPIO17 Pin = 17
-	GPIO18 Pin = 18
-	GPIO19 Pin = 19
-	GPIO20 Pin = 20
-	GPIO21 Pin = 21
-	GPIO22 Pin = 22
-	GPIO23 Pin = 23
-	GPIO24 Pin = 24
-	GPIO25 Pin = 25
-	GPIO26 Pin = 26
-	GPIO27 Pin = 27
-	GPIO28 Pin = 28
-	GPIO29 Pin = 29
+	GPIO0  Pin = 0  // peripherals: PWM0 channel A
+	GPIO1  Pin = 1  // peripherals: PWM0 channel B
+	GPIO2  Pin = 2  // peripherals: PWM1 channel A
+	GPIO3  Pin = 3  // peripherals: PWM1 channel B
+	GPIO4  Pin = 4  // peripherals: PWM2 channel A
+	GPIO5  Pin = 5  // peripherals: PWM2 channel B
+	GPIO6  Pin = 6  // peripherals: PWM3 channel A
+	GPIO7  Pin = 7  // peripherals: PWM3 channel B
+	GPIO8  Pin = 8  // peripherals: PWM4 channel A
+	GPIO9  Pin = 9  // peripherals: PWM4 channel B
+	GPIO10 Pin = 10 // peripherals: PWM5 channel A
+	GPIO11 Pin = 11 // peripherals: PWM5 channel B
+	GPIO12 Pin = 12 // peripherals: PWM6 channel A
+	GPIO13 Pin = 13 // peripherals: PWM6 channel B
+	GPIO14 Pin = 14 // peripherals: PWM7 channel A
+	GPIO15 Pin = 15 // peripherals: PWM7 channel B
+	GPIO16 Pin = 16 // peripherals: PWM0 channel A
+	GPIO17 Pin = 17 // peripherals: PWM0 channel B
+	GPIO18 Pin = 18 // peripherals: PWM1 channel A
+	GPIO19 Pin = 19 // peripherals: PWM1 channel B
+	GPIO20 Pin = 20 // peripherals: PWM2 channel A
+	GPIO21 Pin = 21 // peripherals: PWM2 channel B
+	GPIO22 Pin = 22 // peripherals: PWM3 channel A
+	GPIO23 Pin = 23 // peripherals: PWM3 channel B
+	GPIO24 Pin = 24 // peripherals: PWM4 channel A
+	GPIO25 Pin = 25 // peripherals: PWM4 channel B
+	GPIO26 Pin = 26 // peripherals: PWM5 channel A
+	GPIO27 Pin = 27 // peripherals: PWM5 channel B
+	GPIO28 Pin = 28 // peripherals: PWM6 channel A
+	GPIO29 Pin = 29 // peripherals: PWM6 channel B

 	// Analog pins
 	ADC0 Pin = GPIO26
@@ -17,8 +17,8 @@ const (
 	adc0_CH ADCChannel = iota
 	adc1_CH
 	adc2_CH
-	adc3_CH         // Note: GPIO29 not broken out on pico board
-	ADC_TEMP_SENSOR // Internal temperature sensor channel
+	adc3_CH       // Note: GPIO29 not broken out on pico board
+	adcTempSensor // Internal temperature sensor channel
 )

 // Used to serialise ADC sampling
@@ -75,19 +75,17 @@ func (a ADC) GetADCChannel() (c ADCChannel, err error) {
 	return c, err
 }

-// Configure sets the channel's associated pin to analog input mode or powers on the temperature sensor for ADC_TEMP_SENSOR.
+// Configure sets the channel's associated pin to analog input mode.
 // The powered on temperature sensor increases ADC_AVDD current by approximately 40 μA.
 func (c ADCChannel) Configure(config ADCConfig) error {
 	if config.Reference != 0 {
 		adcAref = config.Reference
 	}
-	if p, err := c.Pin(); err == nil {
-		p.Configure(PinConfig{Mode: PinAnalog})
-	}
-	if c == ADC_TEMP_SENSOR {
-		// Enable temperature sensor bias source
-		rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
+	p, err := c.Pin()
+	if err != nil {
+		return err
 	}
+	p.Configure(PinConfig{Mode: PinAnalog})
 	return nil
 }

@@ -112,13 +110,16 @@ func (c ADCChannel) getVoltage() uint32 {
 }

 // ReadTemperature does a one-shot sample of the internal temperature sensor and returns a milli-celsius reading.
-// Only works on the ADC_TEMP_SENSOR channel. aka AINSEL=4. Other channels will return 0
-func (c ADCChannel) ReadTemperature() (millicelsius uint32) {
-	if c != ADC_TEMP_SENSOR {
-		return
+func ReadTemperature() (millicelsius int32) {
+	if rp.ADC.CS.Get()&rp.ADC_CS_EN == 0 {
+		InitADC()
 	}
+
+	// Enable temperature sensor bias source
+	rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
+
 	// T = 27 - (ADC_voltage - 0.706)/0.001721
-	return (27000<<16 - (c.getVoltage()-706<<16)*581) >> 16
+	return (27000<<16 - (int32(adcTempSensor.getVoltage())-706<<16)*581) >> 16
 }

 // waitForReady spins waiting for the ADC peripheral to become ready.
@@ -10,11 +10,6 @@ import (
 	"unsafe"
 )

-const (
-	KHz = 1000
-	MHz = 1000000
-)
-
 func CPUFrequency() uint32 {
 	return 125 * MHz
 }
@@ -226,12 +226,8 @@ type PinChange uint8

 // Pin change interrupt constants for SetInterrupt.
 const (
-	// PinLevelLow triggers whenever pin is at a low (around 0V) logic level.
-	PinLevelLow PinChange = 1 << iota
-	// PinLevelLow triggers whenever pin is at a high (around 3V) logic level.
-	PinLevelHigh
 	// Edge falling
-	PinFalling
+	PinFalling PinChange = 4 << iota
 	// Edge rising
 	PinRising
 )
@@ -0,0 +1,42 @@
+//go:build rp2040
+// +build rp2040
+
+// Implementation based on code located here:
+// https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_lwip/random.c
+
+package machine
+
+import (
+	"device/rp"
+)
+
+const numberOfCycles = 32
+
+// GetRNG returns 32 bits of semi-random data based on ring oscillator.
+//
+// Unlike some other implementations of GetRNG, these random numbers are not
+// cryptographically secure and must not be used for cryptographic operations
+// (nonces, etc).
+func GetRNG() (uint32, error) {
+	var val uint32
+	for i := 0; i < 4; i++ {
+		val = (val << 8) | uint32(roscRandByte())
+	}
+	return val, nil
+}
+
+var randomByte uint8
+
+func roscRandByte() uint8 {
+	var poly uint8
+	for i := 0; i < numberOfCycles; i++ {
+		if randomByte&0x80 != 0 {
+			poly = 0x35
+		} else {
+			poly = 0
+		}
+		randomByte = ((randomByte << 1) | uint8(rp.ROSC.GetRANDOMBIT()) ^ poly)
+		// TODO: delay a little because the random bit is a little slow
+	}
+	return randomByte
+}
@@ -38,10 +38,9 @@ type SPIConfig struct {
 }

 var (
-	ErrLSBNotSupported    = errors.New("SPI LSB unsupported on PL022")
-	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
-	ErrSPITimeout         = errors.New("SPI timeout")
-	ErrSPIBaud            = errors.New("SPI baud too low or above 66.5Mhz")
+	ErrLSBNotSupported = errors.New("SPI LSB unsupported on PL022")
+	ErrSPITimeout      = errors.New("SPI timeout")
+	ErrSPIBaud         = errors.New("SPI baud too low or above 66.5Mhz")
 )

 type SPI struct {
@@ -137,7 +137,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {

 	// default to 100 kHz (Sm, standard mode) if no frequency is set
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}

 	// configure I2C input clock
@@ -1,5 +1,5 @@
-//go:build !baremetal || (stm32 && !stm32f7x2 && !stm32l5x2) || fe310 || k210 || (nxp && !mk66f18) || atmega
-// +build !baremetal stm32,!stm32f7x2,!stm32l5x2 fe310 k210 nxp,!mk66f18 atmega
+//go:build !baremetal || atmega || esp32 || fe310 || k210 || nrf || (nxp && !mk66f18) || rp2040 || sam || (stm32 && !stm32f7x2 && !stm32l5x2)
+// +build !baremetal atmega esp32 fe310 k210 nrf nxp,!mk66f18 rp2040 sam stm32,!stm32f7x2,!stm32l5x2

 package machine

@@ -17,58 +17,3 @@ var (
 	ErrTxInvalidSliceSize      = errors.New("SPI write and read slices must be same size")
 	errSPIInvalidMachineConfig = errors.New("SPI port was not configured properly by the machine")
 )
-
-// Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
-// interface, there must always be the same number of bytes written as bytes read.
-// The Tx method knows about this, and offers a few different ways of calling it.
-//
-// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
-// Note that the tx and rx buffers must be the same size:
-//
-//	spi.Tx(tx, rx)
-//
-// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
-// until all the bytes in the command packet have been received:
-//
-//	spi.Tx(tx, nil)
-//
-// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
-//
-//	spi.Tx(nil, rx)
-func (spi SPI) Tx(w, r []byte) error {
-	var err error
-
-	switch {
-	case w == nil:
-		// read only, so write zero and read a result.
-		for i := range r {
-			r[i], err = spi.Transfer(0)
-			if err != nil {
-				return err
-			}
-		}
-	case r == nil:
-		// write only
-		for _, b := range w {
-			_, err = spi.Transfer(b)
-			if err != nil {
-				return err
-			}
-		}
-
-	default:
-		// write/read
-		if len(w) != len(r) {
-			return ErrTxInvalidSliceSize
-		}
-
-		for i, b := range w {
-			r[i], err = spi.Transfer(b)
-			if err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}
@@ -0,0 +1,62 @@
+//go:build !baremetal || atmega || fe310 || k210 || (nxp && !mk66f18) || (stm32 && !stm32f7x2 && !stm32l5x2)
+// +build !baremetal atmega fe310 k210 nxp,!mk66f18 stm32,!stm32f7x2,!stm32l5x2
+
+// This file implements the SPI Tx function for targets that don't have a custom
+// (faster) implementation for it.
+
+package machine
+
+// Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
+// interface, there must always be the same number of bytes written as bytes read.
+// The Tx method knows about this, and offers a few different ways of calling it.
+//
+// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
+// Note that the tx and rx buffers must be the same size:
+//
+//	spi.Tx(tx, rx)
+//
+// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
+// until all the bytes in the command packet have been received:
+//
+//	spi.Tx(tx, nil)
+//
+// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
+//
+//	spi.Tx(nil, rx)
+func (spi SPI) Tx(w, r []byte) error {
+	var err error
+
+	switch {
+	case w == nil:
+		// read only, so write zero and read a result.
+		for i := range r {
+			r[i], err = spi.Transfer(0)
+			if err != nil {
+				return err
+			}
+		}
+	case r == nil:
+		// write only
+		for _, b := range w {
+			_, err = spi.Transfer(b)
+			if err != nil {
+				return err
+			}
+		}
+
+	default:
+		// write/read
+		if len(w) != len(r) {
+			return ErrTxInvalidSliceSize
+		}
+
+		for i, b := range w {
+			r[i], err = spi.Transfer(b)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
@@ -8,20 +8,20 @@ import "errors"
 var errUARTBufferEmpty = errors.New("UART buffer empty")

 // UARTParity is the parity setting to be used for UART communication.
-type UARTParity int
+type UARTParity uint8

 const (
 	// ParityNone means to not use any parity checking. This is
 	// the most common setting.
-	ParityNone UARTParity = 0
+	ParityNone UARTParity = iota

 	// ParityEven means to expect that the total number of 1 bits sent
 	// should be an even number.
-	ParityEven UARTParity = 1
+	ParityEven

 	// ParityOdd means to expect that the total number of 1 bits sent
 	// should be an odd number.
-	ParityOdd UARTParity = 2
+	ParityOdd
 )

 // To implement the UART interface for a board, you must declare a concrete type as follows:
@@ -20,21 +20,46 @@ var heapStartSymbol [0]byte
 //go:extern __global_base
 var globalsStartSymbol [0]byte

+const (
+	// wasmMemoryIndex is always zero until the multi-memory feature is used.
+	//
+	// See https://github.com/WebAssembly/multi-memory
+	wasmMemoryIndex = 0
+
+	// wasmPageSize is the size of a page in WebAssembly's 32-bit memory. This
+	// is also its only unit of change.
+	//
+	// See https://www.w3.org/TR/wasm-core-1/#page-size
+	wasmPageSize = 64 * 1024
+)
+
+// wasm_memory_size invokes the "memory.size" instruction, which returns the
+// current size to the memory at the given index (always wasmMemoryIndex), in
+// pages.
+//
 //export llvm.wasm.memory.size.i32
 func wasm_memory_size(index int32) int32

+// wasm_memory_grow invokes the "memory.grow" instruction, which attempts to
+// increase the size of the memory at the given index (always wasmMemoryIndex),
+// by the delta (in pages). This returns the previous size on success of -1 on
+// failure.
+//
 //export llvm.wasm.memory.grow.i32
 func wasm_memory_grow(index int32, delta int32) int32

 var (
-	heapStart    = uintptr(unsafe.Pointer(&heapStartSymbol))
-	heapEnd      = uintptr(wasm_memory_size(0) * wasmPageSize)
+	// heapStart is the current memory offset which starts the heap. The heap
+	// extends from this offset until heapEnd (exclusive).
+	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
+
+	// heapEnd is the current memory length in bytes.
+	heapEnd = uintptr(wasm_memory_size(wasmMemoryIndex) * wasmPageSize)
+
 	globalsStart = uintptr(unsafe.Pointer(&globalsStartSymbol))
 	globalsEnd   = uintptr(unsafe.Pointer(&heapStartSymbol))
 )

-const wasmPageSize = 64 * 1024
-
 func align(ptr uintptr) uintptr {
 	// Align to 16, which is the alignment of max_align_t:
 	// https://godbolt.org/z/dYqTsWrGq
@@ -48,44 +73,67 @@ func getCurrentStackPointer() uintptr
 // otherwise.
 func growHeap() bool {
 	// Grow memory by the available size, which means the heap size is doubled.
-	memorySize := wasm_memory_size(0)
-	result := wasm_memory_grow(0, memorySize)
+	memorySize := wasm_memory_size(wasmMemoryIndex)
+	result := wasm_memory_grow(wasmMemoryIndex, memorySize)
 	if result == -1 {
 		// Grow failed.
 		return false
 	}

-	setHeapEnd(uintptr(wasm_memory_size(0) * wasmPageSize))
+	setHeapEnd(uintptr(wasm_memory_size(wasmMemoryIndex) * wasmPageSize))

 	// Heap has grown successfully.
 	return true
 }

-// The below functions override the default allocator of wasi-libc.
-// Most functions are defined but unimplemented to make sure that if there is
-// any code using them, they will get an error instead of (incorrectly) using
-// the wasi-libc dlmalloc heap implementation instead. If they are needed by any
-// program, they can certainly be implemented.
+// The below functions override the default allocator of wasi-libc. This ensures
+// code linked from other languages can allocate memory without colliding with
+// our GC allocations.
+
+var allocs = make(map[uintptr][]byte)

 //export malloc
 func libc_malloc(size uintptr) unsafe.Pointer {
-	return alloc(size, nil)
+	buf := make([]byte, size)
+	ptr := unsafe.Pointer(&buf[0])
+	allocs[uintptr(ptr)] = buf
+	return ptr
 }

 //export free
 func libc_free(ptr unsafe.Pointer) {
-	free(ptr)
+	if ptr == nil {
+		return
+	}
+	if _, ok := allocs[uintptr(ptr)]; ok {
+		delete(allocs, uintptr(ptr))
+	} else {
+		panic("free: invalid pointer")
+	}
 }

 //export calloc
 func libc_calloc(nmemb, size uintptr) unsafe.Pointer {
-	// Note: we could be even more correct here and check that nmemb * size
-	// doesn't overflow. However the current implementation should normally work
-	// fine.
-	return alloc(nmemb*size, nil)
+	// No difference between calloc and malloc.
+	return libc_malloc(nmemb * size)
 }

 //export realloc
-func libc_realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
-	return realloc(ptr, size)
+func libc_realloc(oldPtr unsafe.Pointer, size uintptr) unsafe.Pointer {
+	// It's hard to optimize this to expand the current buffer with our GC, but
+	// it is theoretically possible. For now, just always allocate fresh.
+	buf := make([]byte, size)
+
+	if oldPtr != nil {
+		if oldBuf, ok := allocs[uintptr(oldPtr)]; ok {
+			copy(buf, oldBuf)
+			delete(allocs, uintptr(oldPtr))
+		} else {
+			panic("realloc: invalid pointer")
+		}
+	}
+
+	ptr := unsafe.Pointer(&buf[0])
+	allocs[uintptr(ptr)] = buf
+	return ptr
 }
@@ -0,0 +1,9 @@
+//go:build runtime_asserts
+
+package runtime
+
+// enable assertions for the garbage collector
+const gcAsserts = true
+
+// enable asserts for the scheduler
+const schedulerAsserts = true
@@ -0,0 +1,9 @@
+//go:build !runtime_asserts
+
+package runtime
+
+// disable assertions for the garbage collector
+const gcAsserts = false
+
+// disable assertions for the scheduler
+const schedulerAsserts = false
@@ -25,7 +25,9 @@ package runtime
 // heapStart..metadataStart.
 //
 // More information:
+// https://aykevl.nl/2020/09/gc-tinygo
 // https://github.com/micropython/micropython/wiki/Memory-Manager
+// https://github.com/micropython/micropython/blob/master/py/gc.c
 // "The Garbage Collection Handbook" by Richard Jones, Antony Hosking, Eliot
 // Moss.

@@ -35,11 +37,7 @@ import (
 	"unsafe"
 )

-// Set gcDebug to true to print debug information.
-const (
-	gcDebug   = false   // print debug info
-	gcAsserts = gcDebug // perform sanity checks
-)
+const gcDebug = false

 // Some globals + constants for the entire GC.

@@ -288,7 +286,14 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 				// could be found. Run a garbage collection cycle to reclaim
 				// free memory and try again.
 				heapScanCount = 2
-				GC()
+				freeBytes := runGC()
+				heapSize := uintptr(metadataStart) - heapStart
+				if freeBytes < heapSize/3 {
+					// Ensure there is at least 33% headroom.
+					// This percentage was arbitrarily chosen, and may need to
+					// be tuned in the future.
+					growHeap()
+				}
 			} else {
 				// Even after garbage collection, no free memory could be found.
 				// Try to increase heap size.
@@ -379,6 +384,13 @@ func free(ptr unsafe.Pointer) {

 // GC performs a garbage collection cycle.
 func GC() {
+	runGC()
+}
+
+// runGC performs a garbage colleciton cycle. It is the internal implementation
+// of the runtime.GC() function. The difference is that it returns the number of
+// free bytes in the heap after the GC is finished.
+func runGC() (freeBytes uintptr) {
 	if gcDebug {
 		println("running collection cycle...")
 	}
@@ -420,12 +432,14 @@ func GC() {

 	// Sweep phase: free all non-marked objects and unmark marked objects for
 	// the next collection cycle.
-	sweep()
+	freeBytes = sweep()

 	// Show how much has been sweeped, for debugging.
 	if gcDebug {
 		dumpHeap()
 	}
+
+	return
 }

 // markRoots reads all pointers from start to end (exclusive) and if they look
@@ -568,7 +582,8 @@ func markRoot(addr, root uintptr) {
 }

 // Sweep goes through all memory and frees unmarked memory.
-func sweep() {
+// It returns how many bytes are free in the heap after the sweep.
+func sweep() (freeBytes uintptr) {
 	freeCurrentObject := false
 	for block := gcBlock(0); block < endBlock; block++ {
 		switch block.state() {
@@ -577,11 +592,13 @@ func sweep() {
 			block.markFree()
 			freeCurrentObject = true
 			gcFrees++
+			freeBytes += bytesPerBlock
 		case blockStateTail:
 			if freeCurrentObject {
 				// This is a tail object following an unmarked head.
 				// Free it now.
 				block.markFree()
+				freeBytes += bytesPerBlock
 			}
 		case blockStateMark:
 			// This is a marked object. The next tail blocks must not be freed,
@@ -589,8 +606,11 @@ func sweep() {
 			// collect this object if it is unreferenced then.
 			block.unmark()
 			freeCurrentObject = false
+		case blockStateFree:
+			freeBytes += bytesPerBlock
 		}
 	}
+	return
 }

 // looksLikePointer returns whether this could be a pointer. Currently, it
@@ -11,8 +11,6 @@ import (
 	"unsafe"
 )

-const gcAsserts = false // perform sanity checks
-
 // Ever-incrementing pointer: no memory is freed.
 var heapptr = heapStart

@@ -11,8 +11,6 @@ import (
 	"unsafe"
 )

-const gcAsserts = false // perform sanity checks
-
 var gcTotalAlloc uint64 // for runtime.MemStats
 var gcMallocs uint64
 var gcFrees uint64
@@ -10,8 +10,7 @@ import (

 var ErrUnimplemented = errors.New("runtime/pprof: unimplemented")

-type Profile struct {
-}
+type Profile struct{}

 func StartCPUProfile(w io.Writer) error {
 	return nil
@@ -28,6 +27,18 @@ func Lookup(name string) *Profile {
 	return nil
 }

+func (p *Profile) Name() string {
+	return ""
+}
+
+func (p *Profile) Count() int {
+	return 0
+}
+
 func (p *Profile) WriteTo(w io.Writer, debug int) error {
 	return ErrUnimplemented
 }
+
+func Profiles() []*Profile {
+	return nil
+}
@@ -0,0 +1,13 @@
+// Stubs for the runtime/trace package
+package trace
+
+import (
+	"errors"
+	"io"
+)
+
+func Start(w io.Writer) error {
+	return errors.New("not implemented")
+}
+
+func Stop() {}
@@ -34,6 +34,17 @@ func (m *Map) LoadOrStore(key, value interface{}) (actual interface{}, loaded bo
 	return value, false
 }

+func (m *Map) LoadAndDelete(key interface{}) (value interface{}, loaded bool) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	value, ok := m.m[key]
+	if !ok {
+		return nil, false
+	}
+	delete(m.m, key)
+	return value, true
+}
+
 func (m *Map) Store(key, value interface{}) {
 	m.lock.Lock()
 	defer m.lock.Unlock()
@@ -0,0 +1,19 @@
+package sync_test
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestMapLoadAndDelete(t *testing.T) {
+	var sm sync.Map
+	sm.Store("present", "value")
+
+	if v, ok := sm.LoadAndDelete("present"); !ok || v != "value" {
+		t.Errorf("LoadAndDelete returned %v, %v, want value, true", v, ok)
+	}
+
+	if v, ok := sm.LoadAndDelete("absent"); ok || v != nil {
+		t.Errorf("LoadAndDelete returned %v, %v, want nil, false", v, ok)
+	}
+}
@@ -1,6 +1,6 @@
 {
    "inherits": ["nrf52840", "nrf52840-s140v6-uf2"],
    "build-tags": ["circuitplay_bluefruit"],
-    "serial-port": ["acm:239a:8045", "acm:239a:45"],
+    "serial-port": ["acm:239a:8045"],
    "msd-volume-name": "CPLAYBTBOOT"
 }
@@ -3,7 +3,7 @@
    "build-tags": ["circuitplay_express"],
    "flash-1200-bps-reset": "true",
    "flash-method": "msd",
-    "serial-port": ["acm:239a:8018", "acm:239a:18"],
+    "serial-port": ["acm:239a:8018"],
    "msd-volume-name": "CPLAYBOOT",
    "msd-firmware-name": "firmware.uf2"
 }
@@ -1,6 +1,6 @@
 {
    "inherits": ["nrf52840", "nrf52840-s140v6-uf2"],
    "build-tags": ["clue_alpha"],
-    "serial-port": ["acm:239a:8072", "acm:239a:0072", "acm:239a:0071", "acm:239a:8071"],
+    "serial-port": ["acm:239a:8072", "acm:239a:8071"],
    "msd-volume-name": "CLUEBOOT"
 }
@@ -1,5 +1,5 @@
 {
 	"inherits": ["esp32c3"],
-	"build-tags": ["esp32c312f", "esp32c3", "esp"]
+	"build-tags": ["esp32c312f"]
 }

--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Ayke van Laethem	df8add7b60	machine: add tool to check consistency with documentation This tool checks whether the machine package matches the documentation in https://tinygo.org/docs/reference/machine/.	2022-09-26 16:50:14 +02:00
Damian Gryski	fca2de21b1	runtime: make gc and scheduler asserts settable with build tags	2022-09-25 16:47:07 +02:00
Ayke van Laethem	107b1c2906	machine: do not expose RESET_MAGIC_VALUE This is a constant for internal use only, but was (unintentionally?) exported. In addition, it doesn't follow the Go naming convention. This change simply renames the constant so that it is unexported.	2022-09-25 12:38:12 +02:00
deadprogram	2409bbef69	build: set circleci resource class to large for CI build Signed-off-by: deadprogram <ron@hybridgroup.com>	2022-09-25 10:08:10 +02:00
Ayke van Laethem	8b078a9e8f	machine: remove level triggered pin interrupts This removes level-triggered interrupts. While working on https://github.com/tinygo-org/tinygo/pull/3170, I found these level triggered interrupt constants. Apart from them being inconsistent with each other (PinLowLevel vs PinLevelLow) I don't think they are actually used anywhere. In addition, I removed the PinNoInterrupt constant on the esp32c3. This makes the esp32c3 pass the tests in #3170. I looked into level-triggered interrupts and I really couldn't find a good justification for them: - They were added to the esp32c3 and the rp2040 together with other pin interrupt types, meaning they were probably just added because the chip supports the feature and not because they were actually needed. - Level interrupts aren't supported in TinyGo for any other chip, and I haven't seen anybody ask for this feature. - They aren't supported in the nrf series chips _at all_, and with a quick search I found only very little demand for them in general. - I tried to see whether there is any good use case for them, but I couldn't really find one (where an edge triggered interrupt wouldn't work just as well). If there is one where level triggered interrupts are a real advantage over edge triggered interrupts, please let me know. Of course, we shouldn't remove a feature lightly. But in this case, I can't think of an advantage of having this feature. I can think of downsides: more maintenance and having to specify their behavior in the machine package documentation. In general, I would like to keep the machine package clean and only support things that have a proven use case.	2022-09-24 22:58:22 +02:00
sago35	9e24441978	main: allow setting the baud rate for serial monitors (#3190 ) * main: allow setting the baud rate for serial monitors with default baudrate of 115200 bps	2022-09-24 19:09:41 +02:00
Ayke van Laethem	1e6c14b3e4	ci: build TinyGo using Go 1.19 We've supported Go 1.19 for a while now, let's actually use it in CI.	2022-09-24 13:22:38 +02:00
Crypt Keeper	25f6be1488	build: makes CI choose latest Go 1.18.x (#3143 ) * build: makes CI choose latest Go 1.18.x	2022-09-24 10:14:18 +02:00
Ayke van Laethem	9a9106a297	esp32c3: remove unused UARTStopBits constants	2022-09-21 18:16:29 +02:00
Ayke van Laethem	a68f7e4ce3	nrf: add ReadTemperature method Similar to the rp2040, the nrf has an on-board temperature sensor. The main reason why I added this function was to show how this new API is more general and can be used on multiple chips.	2022-09-21 08:26:56 +02:00
Ayke van Laethem	70b3ece6ec	rp2040: add machine.ReadTemperature Replace ADCChannel.ReadTemperature() with a simple ReadTemperature function. Not all chips will have a temperature sensor that is read by sampling an ADC channel. The replacement ReadTemperature is simpler and more generic to other chip families. This breaks chips that were relying on the previous ReadTemperature method. I hope it won't break a lot of existing code. If it does, a fallback can be added.	2022-09-21 08:26:56 +02:00
Ayke van Laethem	86ea216e7d	machine: move SPI Tx function into separate file This makes the code a bit cleaner because ErrTxInvalidSliceSize isn't redefined in every file that uses SPI and Mode0/Mode1/Mode2/Mode3 is defined for every target that uses SPI.	2022-09-21 06:52:42 +02:00
Ayke van Laethem	5a92c35536	main: restore support for flashing Espressif chips This reverts commit `303410d3fc` and also removes the unnecessary fallback.	2022-09-20 23:03:07 +02:00
Ayke van Laethem	7513fa2c96	machine: add KHz, MHz, GHz constants, deprecate TWI_FREQ_* constants There are two main issues with these constants: * They don't follow the Go naming convention. * They call themselves "TWI", while it makes a lot more sense to refer to the actual name which is I2C (or I²C). I have not removed them but just deprecated them. Perhaps we can remove them when we move towards version 1.0.	2022-09-20 21:00:17 +02:00
Ayke van Laethem	bc946f346d	machine: rename PinInputPullUp/PinInputPullDown Some targets used capital PullUp/PullDown, while the documented standard is Pullup/Pulldown. This commit fixes this mismatch, while preserving compatibility with aliases that are marked deprecated.	2022-09-20 05:45:53 +02:00
Ayke van Laethem	6e6666519c	go mod tidy	2022-09-19 20:14:09 +02:00
Ayke van Laethem	cecae8084c	nrf52840: do not export DFU_MAGIC_* constants These constants are for internal use only, so should not have been exported. In addition, they didn't follow the Go naming convention before this change.	2022-09-19 07:41:46 +02:00
Ayke van Laethem	9720ccacbb	machine: improve UARTParity slightly There are only 3 possible values, so a uint8 seems more appropriate. Also, there is no reason to use specific numbers over a simple enumeration.	2022-09-18 21:30:30 +02:00
Damian Gryski	a5aa777c7b	src/runtime: add a few more docs about the garbage collector	2022-09-18 15:19:11 +02:00
sago35	aca1ad187d	targets: remove usbpid of bootloader For more information, see https://github.com/tinygo-org/tinygo/pull/3168	2022-09-17 11:00:31 +02:00
sago35	5a41ed6329	xiao-ble: fix usbpid	2022-09-17 07:25:41 +02:00
Ayke van Laethem	91e9c84d85	nrf: make GetRNG available to all chips All nrf chips have a cryptographically secure RNG on board. Therefore, I've made the code more portable so that it works on all nrf chips. I did remove a number of exported functions. I am of the opinion that these should only be made available once we have an agreed upon API for multiple chips. People who want to have greater control over the RNG should use the device/nrf package directly instead. I have also changed the behavior to always enable digital error correction. Enabling it seems like a more conservative (and secure) default to me. Again, people who would like to have it disabled can use the device/nrf package directly.	2022-09-17 06:08:54 +02:00
sago35	4af530f238	wioterminal: remove serial-port setting of bootloader	2022-09-16 20:12:47 +02:00
Ayke van Laethem	d3863f337d	rp2040: do not use GetRNG in crypto/rand The crypto/rand package is used for sensitive cryptographic operations. Do not use the rp2040 RNG for this purpose, because it's not strong enough for cryptography. I think it is _possible_ to make use of the RP2040 RNG to create cryptographically secure pseudo-random numbers, but it needs some entropy calculation and secure hashing (blake2s or so) to make them truly unpredictable.	2022-09-16 14:48:41 +02:00
Ayke van Laethem	5551ec7a1e	cgo: implement support for static functions	2022-09-16 14:05:17 +02:00
Ayke van Laethem	91104b2f27	runtime: ensure some headroom for the GC to run The GC was originally designed for systems with a fixed amount of memory, like baremetal systems. Therefore, it just used what it could and ran a GC cycle when out of memory. Other systems (like Linux or WebAssembly) are different. In those systems, it is possible to grow the amount of memory on demand. But the GC only actually grew the heap when it was really out of memory, not when it was getting very close to being out of memory. This patch fixes this by ensuring there is at least 33% headroom for the GC. This means that programs can allocate around 50% more than what was live in the last GC cycle. It should fix a performance cliff when a program is almost, but not entirely, out of memory and the GC has to run almost every heap allocation.	2022-09-16 11:11:50 +02:00
sago35	80f38e8449	main: add serial port monitoring functionality Co-authored-by: Ayke <aykevanlaethem@gmail.com>	2022-09-16 09:28:03 +02:00
Adrian Cole	22893c5180	wasm: documents memory constants This documents memory constants. Somewhere, we should document what the default memory size is (seems 2 pages so 128KB), as that determines the initial heap size (which is a portion of that). Signed-off-by: Adrian Cole <adrian@tetrate.io>	2022-09-16 07:32:43 +02:00
Ayke van Laethem	9e4e182615	interp: fix reading from external global This fixes https://github.com/tinygo-org/tinygo/issues/3020.	2022-09-15 19:07:04 +02:00
Ayke van Laethem	5f96d2b784	all: add flag for setting the goroutine stack size This is helpful in some cases where the default stack size isn't big enough.	2022-09-15 12:43:51 +02:00
Ayke van Laethem	bd1d93b705	go mod tidy	2022-09-15 12:43:51 +02:00
Anuraag Agrawal	03d1c44265	wasm,wasi: make sure buffers returned by malloc are not freed until f… (#3148 ) * wasm,wasi: make sure buffers returned by malloc are not freed until free is called	2022-09-15 09:14:39 +02:00
Adrian Cole	dc0346d968	wasi: adds more details about why wasmtime flags are added Signed-off-by: Adrian Cole <adrian@tetrate.io>	2022-09-14 19:52:04 +02:00
Ayke van Laethem	dadae95448	ci: use the Go Alpine image for building the release binary This fixes https://github.com/tinygo-org/tinygo/issues/3146 by using a prebuilt Docker image. I don't remember why I used `setup-go` but probably to make it faster (setup-go usually uses cached binaries).	2022-09-14 15:43:14 +02:00
sago35	f5fc2fc072	main: add support for stlink-dap programmer	2022-09-14 14:58:31 +02:00
Matt Schultz	4ba76a5df9	machine/nrf52840: implement RNG peripheral operation	2022-09-12 09:54:51 +02:00
deadprogram	ea1e08f53f	machine/rp2040: implement semi-random RNG based on ROSC based on pico-sdk Signed-off-by: deadprogram <ron@hybridgroup.com>	2022-09-10 10:47:48 +02:00
Adrian Cole	bba0dc9575	build: uses setup-go@v3 to simplify cache config This updates to setup-go@v3 which is the only updated version (v2 last updated in feb), and employs its cache to simplify workflow configuration. Notably, we can't do this for Alpine until #3146 Signed-off-by: Adrian Cole <adrian@tetrate.io>	2022-09-09 21:48:51 +02:00
Isaac Rodman	617c7586fe	Remove unconnected simple LED pin from qtpy-rp2040	2022-09-09 11:05:12 +02:00
Isaac Rodman	7366d5e185	Set default-stack-size to 4096, and remove NEOPIXELS pluralization for qtpy-rp2040	2022-09-09 11:05:12 +02:00
Adrian Cole	96e3ecd949	build: updates to actions/cache@v3 v2 has bugs and hasn't had a release since last November. See https://github.com/actions/cache/releases Signed-off-by: Adrian Cole <adrian@tetrate.io>	2022-09-08 16:27:40 +02:00
Ayke van Laethem	8bbfb1ee68	wasm: do not allow undefined symbols --allow-undefined can be a problem: it allows compiling code that will fail when loaded. This change makes sure that if some symbols are undefined, they are reported as an error by the linker. Previously, people could get away with importing a function that was not defined, like this: func add(int a, int b) int func test() { println(add(3, 5)) } This was always unintended but mostly worked. With this change, it isn't possible anymore. Now every function needs to be marked with //export explicitly: //export add func add(int a, int b) int func test() { println(add(3, 5)) } As before, functions will be placed in the `env` module with the name set from the `//export` tag. This can be overridden with `//go:import-module`: //go:import-module math //export add func add(int a, int b) int func test() { println(add(3, 5)) } For the syscall/js package, I needed to give a list of symbols that are undefined. This list is based on the JavaScript functions defined in targets/wasm_exec.js.	2022-09-08 08:25:27 +02:00
Adrian Cole	07cdcc61f7	examples: adds summary of wasm examples and fixes callback bug This adds a summary of each wasm example, as before it was a bit unclear how to do so. This also fixes the callback example which was broken. Fixes #2568 Signed-off-by: Adrian Cole <adrian@tetrate.io>	2022-09-07 13:31:21 +02:00
Ayke van Laethem	4ca9b34133	machine: add PWM peripheral comments to pins These comments will be used in a change to the tinygo.org documentation.	2022-09-05 18:56:34 +02:00
Patricio Whittingslow	d5e4b16911	add github.com/soypat/mu8 to corpus.yaml	2022-09-04 09:42:49 +02:00
sago35	fd05254683	Update compileopts/target.go Co-authored-by: Ayke <aykevanlaethem@gmail.com>	2022-09-03 11:50:41 +02:00
sago35	c579e7e509	Update compileopts/target.go Co-authored-by: Ayke <aykevanlaethem@gmail.com>	2022-09-03 11:50:41 +02:00
sago35	d463528a72	smoketest: add test to run `tinygo targets`	2022-09-03 11:50:41 +02:00
sago35	49b0086f8f	main: improve error handling when loading target/*.json	2022-09-03 11:50:41 +02:00
Yurii Soldak	d7814ff50b	targets: fix build tag duplicates and add missing targets to smoke test	2022-09-03 08:31:27 +02:00
Ayke van Laethem	02160aa8d8	windows: run more tests where supported I found that some packages do in fact run on Windows, so I've added them where possible. I've also updated the description of which packages fail tests and why.	2022-09-02 20:04:28 +02:00
Ayke van Laethem	c199dd03c7	windows: save and restore xmm registers when switching goroutines This is required according to the Windows x64 calling convention: https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170#callercallee-saved-registers We didn't do this, and this didn't appear to cause any problems. But we should do it anyway for correctness.	2022-09-02 18:47:00 +02:00
Ayke van Laethem	472aecf07a	targets: remove hifive1-qemu target This target was added purely for running tests, and it is currently unused. When I try to use it, it causes runtime exceptions. The replacement riscv-qemu is much better behaved. This doesn't drop support for any actual hardware, the HiFive 1 B will remain supported.	2022-09-02 16:35:05 +02:00
Isaac Rodman	09350e5719	Add qtpy-rp2040 to TinyGo v0.25.0	2022-09-02 15:06:37 +02:00
Tim Schaub	623dd6a815	sync: implement map.LoadAndDelete	2022-09-02 11:48:01 +02:00
Joe Shaw	e09bd5abb3	runtime/pprof, runtime/trace: stub some additional functions These are necessary to import some parts of the net/http package.	2022-09-02 10:37:50 +02:00