compiler: disambiguate generic instances with function-local type aliases

x/tools go/ssa names instantiations using the type argument's String().
Function-local aliases like `type F = float64` therefore collide when two
callers use distinct aliases named F (Go 1.27's internal/strconv.ftoa32
and ftoa64 do exactly this). Extend localTypeArgsSuffix to detect local
aliases and include their declaration position, so the float32 and
float64 instantiations get distinct LLVM symbols.

Fixes wrong float formatting in strconv/math on Go 1.27, and adds a
regression test to testdata/localtypes.go.

Signed-off-by: deadprogram <ron@hybridgroup.com>

.github/workflows/linux.yml

@@ -209,7 +209,7 @@ jobs:
       - name: Install Node.js
         uses: actions/setup-node@v6
         with:
-          node-version: '18'
+          node-version: '22'
       - name: Install wasmtime
         uses: bytecodealliance/actions/wasmtime/setup@v1
         with:

.github/workflows/windows.yml

@@ -65,7 +65,7 @@ jobs:
         uses: actions/cache/restore@v5
         id: cache-llvm-build
         with:
-          key: llvm-build-20-windows-v4
+          key: llvm-build-20-windows-v5
           path: llvm-build
       - name: Build LLVM
         if: steps.cache-llvm-build.outputs.cache-hit != 'true'

GNUmakefile

@@ -142,6 +142,9 @@ ifeq ($(OS),Windows_NT)
 
     # PIC needs to be disabled for libclang to work.
     LLVM_OPTION += -DLLVM_ENABLE_PIC=OFF
+    # Statically link the C++ and GCC runtime into LLVM tools so they don't
+    # depend on MinGW DLLs that may not be on PATH when executed during the build.
+    LLVM_OPTION += '-DCMAKE_EXE_LINKER_FLAGS=-static-libgcc -static-libstdc++'
 
     CGO_CPPFLAGS += -DCINDEX_NO_EXPORTS
     CGO_LDFLAGS += -static -static-libgcc -static-libstdc++
@@ -304,7 +307,7 @@ wasi-cm:
 	rsync -rv --delete --exclude go.mod --exclude '*_test.go' --exclude '*_json.go' --exclude '*.md' --exclude LICENSE $(shell go list -m -f {{.Dir}} $(WASM_TOOLS_MODULE)/cm)/ ./src/internal/cm
 
 # Check for Node.js used during WASM tests.
-MIN_NODEJS_VERSION=18
+MIN_NODEJS_VERSION=22
 
 .PHONY: check-nodejs-version
 check-nodejs-version:
@@ -410,6 +413,7 @@ TEST_PACKAGES_LINUX := \
 	context \
 	crypto/aes \
 	crypto/des \
+	crypto/ecdh \
 	crypto/hmac \
 	debug/dwarf \
 	debug/plan9obj \
@@ -489,10 +493,12 @@ report-stdlib-tests-pass:
 ifeq ($(uname),Darwin)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_DARWIN)
 TEST_IOFS := true
+TEST_ENCODING_XML := true
 endif
 ifeq ($(uname),Linux)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_LINUX)
 TEST_IOFS := true
+TEST_ENCODING_XML := true
 endif
 ifeq ($(OS),Windows_NT)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_WINDOWS)
@@ -507,8 +513,11 @@ TEST_ADDITIONAL_FLAGS ?=
 .PHONY: tinygo-test
 tinygo-test:
 	@# TestExtraMethods: used by many crypto packages and uses reflect.Type.Method which is not implemented.
-	@# TestParseAndBytesRoundTrip/P256/Generic: relies on t.Skip() which is not implemented
+	@# TestParseAndBytesRoundTrip/P256/Generic: needs Goexit to run defers on wasm.
-	$(TINYGO) test $(TEST_ADDITIONAL_FLAGS) $(TEST_SKIP_FLAG) $(TEST_PACKAGES_HOST) $(TEST_PACKAGES_SLOW)
+	$(TINYGO) test $(TEST_ADDITIONAL_FLAGS) $(TEST_SKIP_FLAG) $(filter-out encoding/xml,$(TEST_PACKAGES_HOST)) $(TEST_PACKAGES_SLOW)
+ifeq ($(TEST_ENCODING_XML),true)
+	$(TINYGO) test $(TEST_ADDITIONAL_FLAGS) $(TEST_SKIP_FLAG) -stack-size=16MB encoding/xml
+endif
 	@# io/fs requires os.ReadDir, not yet supported on windows or wasi. It also
 	@# requires a large stack-size. Hence, io/fs is only run conditionally.
 	@# For more details, see the comments on issue #3143.
@@ -753,6 +762,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=xiao                examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=xiao-ble-plus       examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=rak4631             examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/dac
@@ -900,6 +911,8 @@ ifneq ($(STM32), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=stm32l0x1           examples/serial
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=stm32u031           examples/empty
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino-uno-q       examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino-uno-q       examples/serial

builder/build.go

@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"go/types"
 	"hash/crc32"
+	"maps"
 	"math/bits"
 	"os"
 	"os/exec"
@@ -137,9 +138,7 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 		if _, ok := globalValues[pkgPath]; !ok {
 			globalValues[pkgPath] = map[string]string{}
 		}
-		for k, v := range vals {
+		maps.Copy(globalValues[pkgPath], vals)
-			globalValues[pkgPath][k] = v
-		}
 	}
 
 	// Check for a libc dependency.
@@ -278,7 +277,6 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 
 	var embedFileObjects []*compileJob
 	for _, pkg := range lprogram.Sorted() {
-		pkg := pkg // necessary to avoid a race condition
 
 		var undefinedGlobals []string
 		for name := range globalValues[pkg.Pkg.Path()] {
@@ -775,7 +773,6 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 	// TODO: do this as part of building the package to be able to link the
 	// bitcode files together.
 	for _, pkg := range lprogram.Sorted() {
-		pkg := pkg
 		for _, filename := range pkg.CFiles {
 			abspath := filepath.Join(pkg.OriginalDir(), filename)
 			job := &compileJob{
@@ -842,22 +839,25 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 			}
 			ldflags = append(ldflags, "-mllvm", "-mcpu="+config.CPU())
 			ldflags = append(ldflags, "-mllvm", "-mattr="+config.Features()) // needed for MIPS softfloat
-			if config.GOOS() == "windows" {
+			switch config.LinkerFlavor() {
-				// Options for the MinGW wrapper for the lld COFF linker.
+			case "coff":
+				// Options for driving ld.lld in PE/COFF mode.
 				ldflags = append(ldflags,
 					"-Xlink=/opt:lldlto="+strconv.Itoa(speedLevel),
 					"--thinlto-cache-dir="+filepath.Join(cacheDir, "thinlto"))
-			} else if config.GOOS() == "darwin" {
+			case "darwin":
 				// Options for the ld64-compatible lld linker.
 				ldflags = append(ldflags,
 					"--lto-O"+strconv.Itoa(speedLevel),
 					"-cache_path_lto", filepath.Join(cacheDir, "thinlto"))
-			} else {
+			case "gnu":
 				// Options for the ELF linker.
 				ldflags = append(ldflags,
 					"--lto-O"+strconv.Itoa(speedLevel),
 					"--thinlto-cache-dir="+filepath.Join(cacheDir, "thinlto"),
 				)
+			default:
+				return fmt.Errorf("unknown linker flavor: %s", config.LinkerFlavor())
 			}
 			if config.CodeModel() != "default" {
 				ldflags = append(ldflags,
@@ -914,7 +914,7 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 			}
 
 			// Run wasm-opt for wasm binaries
-			if arch := strings.Split(config.Triple(), "-")[0]; arch == "wasm32" {
+			if arch, _, _ := strings.Cut(config.Triple(), "-"); arch == "wasm32" {
 				optLevel, _, _ := config.OptLevel()
 				opt := "-" + optLevel
 

builder/builder_test.go

@@ -47,7 +47,6 @@ func TestClangAttributes(t *testing.T) {
 		targetNames = append(targetNames, "esp32", "esp8266")
 	}
 	for _, targetName := range targetNames {
-		targetName := targetName
 		t.Run(targetName, func(t *testing.T) {
 			testClangAttributes(t, &compileopts.Options{Target: targetName})
 		})

builder/cc.go

@@ -281,7 +281,7 @@ func parseDepFile(s string) ([]string, error) {
 	s = strings.ReplaceAll(s, "\\\n", " ")
 
 	// Only use the first line, which is expected to begin with "deps:".
-	line := strings.SplitN(s, "\n", 2)[0]
+	line, _, _ := strings.Cut(s, "\n")
 	if !strings.HasPrefix(line, "deps:") {
 		return nil, errors.New("readDepFile: expected 'deps:' prefix")
 	}

builder/commands.go

@@ -17,7 +17,7 @@ import (
 var commands = map[string][]string{}
 
 func init() {
-	llvmMajor := strings.Split(llvm.Version, ".")[0]
+	llvmMajor, _, _ := strings.Cut(llvm.Version, ".")
 	commands["clang"] = []string{"clang-" + llvmMajor}
 	commands["ld.lld"] = []string{"ld.lld-" + llvmMajor, "ld.lld"}
 	commands["wasm-ld"] = []string{"wasm-ld-" + llvmMajor, "wasm-ld"}

builder/darwin-libsystem.go

@@ -15,7 +15,7 @@ func makeDarwinLibSystemJob(config *compileopts.Config, tmpdir string) *compileJ
 	return &compileJob{
 		description: "compile Darwin libSystem.dylib",
 		run: func(job *compileJob) (err error) {
-			arch := strings.Split(config.Triple(), "-")[0]
+			arch, _, _ := strings.Cut(config.Triple(), "-")
 			job.result = filepath.Join(tmpdir, "libSystem.dylib")
 			objpath := filepath.Join(tmpdir, "libSystem.o")
 			inpath := filepath.Join(goenv.Get("TINYGOROOT"), "lib/macos-minimal-sdk/src", arch, "libSystem.s")

builder/jobs.go

@@ -195,11 +195,11 @@ type intHeap struct {
 	sort.IntSlice
 }
 
-func (h *intHeap) Push(x interface{}) {
+func (h *intHeap) Push(x any) {
 	h.IntSlice = append(h.IntSlice, x.(int))
 }
 
-func (h *intHeap) Pop() interface{} {
+func (h *intHeap) Pop() any {
 	x := h.IntSlice[len(h.IntSlice)-1]
 	h.IntSlice = h.IntSlice[:len(h.IntSlice)-1]
 	return x

builder/library.go

@@ -232,7 +232,6 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
 	}
 	for _, path := range paths {
 		// Strip leading "../" parts off the path.
-		path := path
 		cleanpath := path
 		for strings.HasPrefix(cleanpath, "../") {
 			cleanpath = cleanpath[3:]

builder/musl.go

@@ -28,8 +28,8 @@ func buildMuslAllTypes(arch, muslDir, outputBitsDir string) error {
 		if err != nil {
 			return err
 		}
-		lines := strings.Split(string(data), "\n")
+		lines := strings.SplitSeq(string(data), "\n")
-		for _, line := range lines {
+		for line := range lines {
 			if strings.HasPrefix(line, "TYPEDEF ") {
 				matches := regexp.MustCompile(`TYPEDEF (.*) ([^ ]*);`).FindStringSubmatch(line)
 				value := matches[1]

builder/sizes_test.go

@@ -42,16 +42,15 @@ func TestBinarySize(t *testing.T) {
 	// This is a small number of very diverse targets that we want to test.
 	tests := []sizeTest{
 		// microcontrollers
-		{"hifive1b", "examples/echo", 3699, 297, 0, 2252},
+		{"hifive1b", "examples/echo", 3771, 309, 0, 2260},
-		{"microbit", "examples/serial", 2736, 356, 8, 2248},
+		{"microbit", "examples/serial", 2832, 368, 8, 2256},
-		{"wioterminal", "examples/pininterrupt", 7960, 1652, 132, 7480},
+		{"wioterminal", "examples/pininterrupt", 8065, 1663, 132, 7488},
 
 		// TODO: also check wasm. Right now this is difficult, because
 		// wasm binaries are run through wasm-opt and therefore the
 		// output varies by binaryen version.
 	}
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.target+"/"+tc.path, func(t *testing.T) {
 			t.Parallel()
 
@@ -85,7 +84,6 @@ func TestSizeFull(t *testing.T) {
 	pkgMatch := regexp.MustCompile(`^[a-z/]+$`)    // example: "internal/task"
 
 	for _, target := range tests {
-		target := target
 		t.Run(target, func(t *testing.T) {
 			t.Parallel()
 

builder/tools.go

@@ -116,7 +116,7 @@ func parseLLDErrors(text string) error {
 		// This can happen in some cases like with CGo and //go:linkname tricker.
 		if matches := regexp.MustCompile(`^ld.lld(-[0-9]+)?: error: undefined symbol: (.*)\n`).FindStringSubmatch(message); matches != nil {
 			symbolName := matches[2]
-			for _, line := range strings.Split(message, "\n") {
+			for line := range strings.SplitSeq(message, "\n") {
 				matches := regexp.MustCompile(`referenced by .* \(((.*):([0-9]+))\)`).FindStringSubmatch(line)
 				if matches != nil {
 					parsedError = true

builder/uf2.go

@@ -40,7 +40,7 @@ func convertBinToUF2(input []byte, targetAddr uint32, uf2FamilyID string) ([]byt
 	}
 	bl.SetNumBlocks(len(blocks))
 
-	for i := 0; i < len(blocks); i++ {
+	for i := range blocks {
 		bl.SetBlockNo(i)
 		bl.SetData(blocks[i])
 

cgo/cgo.go

@@ -40,7 +40,7 @@ type cgoPackage struct {
 	tokenFiles      map[string]*token.File
 	definedGlobally map[string]ast.Node
 	noescapingFuncs map[string]*noescapingFunc // #cgo noescape lines
-	anonDecls       map[interface{}]string
+	anonDecls       map[any]string
 	cflags          []string // CFlags from #cgo lines
 	ldflags         []string // LDFlags from #cgo lines
 	visitedFiles    map[string][]byte
@@ -259,7 +259,7 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 		tokenFiles:      map[string]*token.File{},
 		definedGlobally: map[string]ast.Node{},
 		noescapingFuncs: map[string]*noescapingFunc{},
-		anonDecls:       map[interface{}]string{},
+		anonDecls:       map[any]string{},
 		visitedFiles:    map[string][]byte{},
 	}
 
@@ -302,7 +302,7 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 	// Find `import "C"` C fragments in the file.
 	p.cgoHeaders = make([]string, len(files)) // combined CGo header fragment for each file
 	for i, f := range files {
-		var cgoHeader string
+		var cgoHeader strings.Builder
 		for i := 0; i < len(f.Decls); i++ {
 			decl := f.Decls[i]
 			genDecl, ok := decl.(*ast.GenDecl)
@@ -337,7 +337,8 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 			// Iterate through all parts of the CGo header. Note that every //
 			// line is a new comment.
 			position := fset.Position(genDecl.Doc.Pos())
-			fragment := fmt.Sprintf("# %d %#v\n", position.Line, position.Filename)
+			var fragment strings.Builder
+			fragment.WriteString(fmt.Sprintf("# %d %#v\n", position.Line, position.Filename))
 			for _, comment := range genDecl.Doc.List {
 				// Find all #cgo lines, extract and use their contents, and
 				// replace the lines with spaces (to preserve locations).
@@ -354,12 +355,13 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 				} else { // comment
 					c = "  " + c[2:len(c)-2]
 				}
-				fragment += c + "\n"
+				fragment.WriteString(c)
+				fragment.WriteByte('\n')
 			}
-			cgoHeader += fragment
+			cgoHeader.WriteString(fragment.String())
 		}
 
-		p.cgoHeaders[i] = cgoHeader
+		p.cgoHeaders[i] = cgoHeader.String()
 	}
 
 	// Define CFlags that will be used while parsing the package.
@@ -1217,7 +1219,7 @@ func getPos(node ast.Node) token.Pos {
 // getUnnamedDeclName creates a name (with the given prefix) for the given C
 // declaration. This is used for structs, unions, and enums that are often
 // defined without a name and used in a typedef.
-func (p *cgoPackage) getUnnamedDeclName(prefix string, itf interface{}) string {
+func (p *cgoPackage) getUnnamedDeclName(prefix string, itf any) string {
 	if name, ok := p.anonDecls[itf]; ok {
 		return name
 	}

cgo/cgo_test.go

@@ -45,7 +45,6 @@ func TestCGo(t *testing.T) {
 		"flags",
 		"const",
 	} {
-		name := name // avoid a race condition
 		t.Run(name, func(t *testing.T) {
 			// Read the AST in memory.
 			path := filepath.Join("testdata", name+".go")

cgo/libclang.go

@@ -160,7 +160,7 @@ func (f *cgoFile) readNames(fragment string, cflags []string, filename string, c
 			pos := f.getClangLocationPosition(location, unit)
 			f.addError(pos, severity+": "+spelling)
 		}
-		for i := 0; i < numDiagnostics; i++ {
+		for i := range numDiagnostics {
 			diagnostic := C.clang_getDiagnostic(unit, C.uint(i))
 			addDiagnostic(diagnostic)
 
@@ -278,7 +278,7 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 				Text:  strings.Join(doc, "\n"),
 			})
 		}
-		for i := 0; i < numArgs; i++ {
+		for i := range numArgs {
 			arg := C.tinygo_clang_Cursor_getArgument(c, C.uint(i))
 			argName := getString(C.tinygo_clang_getCursorSpelling(arg))
 			argType := C.clang_getArgType(cursorType, C.uint(i))
@@ -534,7 +534,7 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 
 // Get the precise location in the source code. Used for uniquely identifying
 // source locations.
-func (f *cgoFile) getUniqueLocationID(pos token.Pos, cursor C.GoCXCursor) interface{} {
+func (f *cgoFile) getUniqueLocationID(pos token.Pos, cursor C.GoCXCursor) any {
 	clangLocation := C.tinygo_clang_getCursorLocation(cursor)
 	var file C.CXFile
 	var line C.unsigned

cgo/sync.go

@@ -12,17 +12,17 @@ import "C"
 // C. It is useful if an API uses function pointers and you cannot pass a Go
 // pointer but only a C pointer.
 type refMap struct {
-	refs map[unsafe.Pointer]interface{}
+	refs map[unsafe.Pointer]any
 	lock sync.Mutex
 }
 
 // Put stores a value in the map. It can later be retrieved using Get. It must
 // be removed using Remove to avoid memory leaks.
-func (m *refMap) Put(v interface{}) unsafe.Pointer {
+func (m *refMap) Put(v any) unsafe.Pointer {
 	m.lock.Lock()
 	defer m.lock.Unlock()
 	if m.refs == nil {
-		m.refs = make(map[unsafe.Pointer]interface{}, 1)
+		m.refs = make(map[unsafe.Pointer]any, 1)
 	}
 	ref := C.malloc(1)
 	m.refs[ref] = v
@@ -31,7 +31,7 @@ func (m *refMap) Put(v interface{}) unsafe.Pointer {
 
 // Get returns a stored value previously inserted with Put. Use the same
 // reference as you got from Put.
-func (m *refMap) Get(ref unsafe.Pointer) interface{} {
+func (m *refMap) Get(ref unsafe.Pointer) any {
 	m.lock.Lock()
 	defer m.lock.Unlock()
 	return m.refs[ref]

compileopts/config.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -140,13 +141,7 @@ func (c *Config) GC() string {
 func (c *Config) NeedsStackObjects() bool {
 	switch c.GC() {
 	case "conservative", "custom", "precise", "boehm":
-		for _, tag := range c.BuildTags() {
+		return slices.Contains(c.BuildTags(), "tinygo.wasm")
-			if tag == "tinygo.wasm" {
-				return true
-			}
-		}
-
-		return false
 	default:
 		return false
 	}
@@ -245,7 +240,7 @@ func (c *Config) RP2040BootPatch() bool {
 // Return a canonicalized architecture name, so we don't have to deal with arm*
 // vs thumb* vs arm64.
 func CanonicalArchName(triple string) string {
-	arch := strings.Split(triple, "-")[0]
+	arch, _, _ := strings.Cut(triple, "-")
 	if arch == "arm64" {
 		return "aarch64"
 	}
@@ -466,6 +461,22 @@ func (c *Config) LDFlags() []string {
 	return ldflags
 }
 
+// LinkerFlavor returns how the configured linker should be driven.
+// Usually this is derived from GOOS, but targets may override it explicitly.
+func (c *Config) LinkerFlavor() string {
+	if c.Target.LinkerFlavor != "" {
+		return c.Target.LinkerFlavor
+	}
+	switch c.GOOS() {
+	case "windows":
+		return "coff"
+	case "darwin":
+		return "darwin"
+	default:
+		return "gnu"
+	}
+}
+
 // ExtraFiles returns the list of extra files to be built and linked with the
 // executable. This can include extra C and assembly files.
 func (c *Config) ExtraFiles() []string {

compileopts/options.go

@@ -3,6 +3,7 @@ package compileopts
 import (
 	"fmt"
 	"regexp"
+	"slices"
 	"strings"
 	"time"
 )
@@ -67,7 +68,7 @@ type Options struct {
 // Verify performs a validation on the given options, raising an error if options are not valid.
 func (o *Options) Verify() error {
 	if o.BuildMode != "" {
-		valid := isInArray(validBuildModeOptions, o.BuildMode)
+		valid := slices.Contains(validBuildModeOptions, o.BuildMode)
 		if !valid {
 			return fmt.Errorf(`invalid buildmode option '%s': valid values are %s`,
 				o.BuildMode,
@@ -75,7 +76,7 @@ func (o *Options) Verify() error {
 		}
 	}
 	if o.GC != "" {
-		valid := isInArray(validGCOptions, o.GC)
+		valid := slices.Contains(validGCOptions, o.GC)
 		if !valid {
 			return fmt.Errorf(`invalid gc option '%s': valid values are %s`,
 				o.GC,
@@ -84,7 +85,7 @@ func (o *Options) Verify() error {
 	}
 
 	if o.Scheduler != "" {
-		valid := isInArray(validSchedulerOptions, o.Scheduler)
+		valid := slices.Contains(validSchedulerOptions, o.Scheduler)
 		if !valid {
 			return fmt.Errorf(`invalid scheduler option '%s': valid values are %s`,
 				o.Scheduler,
@@ -93,7 +94,7 @@ func (o *Options) Verify() error {
 	}
 
 	if o.Serial != "" {
-		valid := isInArray(validSerialOptions, o.Serial)
+		valid := slices.Contains(validSerialOptions, o.Serial)
 		if !valid {
 			return fmt.Errorf(`invalid serial option '%s': valid values are %s`,
 				o.Serial,
@@ -102,7 +103,7 @@ func (o *Options) Verify() error {
 	}
 
 	if o.PrintSizes != "" {
-		valid := isInArray(validPrintSizeOptions, o.PrintSizes)
+		valid := slices.Contains(validPrintSizeOptions, o.PrintSizes)
 		if !valid {
 			return fmt.Errorf(`invalid size option '%s': valid values are %s`,
 				o.PrintSizes,
@@ -111,7 +112,7 @@ func (o *Options) Verify() error {
 	}
 
 	if o.PanicStrategy != "" {
-		valid := isInArray(validPanicStrategyOptions, o.PanicStrategy)
+		valid := slices.Contains(validPanicStrategyOptions, o.PanicStrategy)
 		if !valid {
 			return fmt.Errorf(`invalid panic option '%s': valid values are %s`,
 				o.PanicStrategy,
@@ -120,19 +121,10 @@ func (o *Options) Verify() error {
 	}
 
 	if o.Opt != "" {
-		if !isInArray(validOptOptions, o.Opt) {
+		if !slices.Contains(validOptOptions, o.Opt) {
 			return fmt.Errorf("invalid -opt=%s: valid values are %s", o.Opt, strings.Join(validOptOptions, ", "))
 		}
 	}
 
 	return nil
 }
-
-func isInArray(arr []string, item string) bool {
-	for _, i := range arr {
-		if i == item {
-			return true
-		}
-	}
-	return false
-}

compileopts/target.go

@@ -38,7 +38,8 @@ type TargetSpec struct {
 	Scheduler        string   `json:"scheduler,omitempty"`
 	Serial           string   `json:"serial,omitempty"` // which serial output to use (uart, usb, none)
 	Linker           string   `json:"linker,omitempty"`
-	RTLib            string   `json:"rtlib,omitempty"` // compiler runtime library (libgcc, compiler-rt)
+	LinkerFlavor     string   `json:"linker-flavor,omitempty"` // how to drive the configured linker (for example: gnu, coff, darwin)
+	RTLib            string   `json:"rtlib,omitempty"`         // compiler runtime library (libgcc, compiler-rt)
 	Libc             string   `json:"libc,omitempty"`
 	AutoStackSize    *bool    `json:"automatic-stack-size,omitempty"` // Determine stack size automatically at compile time.
 	DefaultStackSize uint64   `json:"default-stack-size,omitempty"`   // Default stack size if the size couldn't be determined at compile time.

compileopts/target_test.go

@@ -112,3 +112,52 @@ func TestOverrideProperties(t *testing.T) {
 	}
 
 }
+
+func TestConfigLinkerFlavor(t *testing.T) {
+	tests := []struct {
+		name   string
+		target *TargetSpec
+		goos   string
+		want   string
+	}{
+		{
+			name:   "default gnu",
+			target: &TargetSpec{},
+			goos:   "linux",
+			want:   "gnu",
+		},
+		{
+			name:   "default coff",
+			target: &TargetSpec{},
+			goos:   "windows",
+			want:   "coff",
+		},
+		{
+			name:   "default darwin",
+			target: &TargetSpec{},
+			goos:   "darwin",
+			want:   "darwin",
+		},
+		{
+			name: "target override",
+			target: &TargetSpec{
+				LinkerFlavor: "coff",
+			},
+			goos: "linux",
+			want: "coff",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			tc.target.GOOS = tc.goos
+			config := &Config{
+				Options: &Options{},
+				Target:  tc.target,
+			}
+			if got := config.LinkerFlavor(); got != tc.want {
+				t.Fatalf("LinkerFlavor() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}

compiler/compiler.go

@@ -90,7 +90,8 @@ type compilerContext struct {
 	astComments      map[string]*ast.CommentGroup
 	embedGlobals     map[string][]*loader.EmbedFile
 	pkg              *types.Package
-	packageDir       string // directory for this package
+	loaderPkg        *loader.Package // current package being compiled (for AST access)
+	packageDir       string          // directory for this package
 	runtimePkg       *types.Package
 	localTypeNames   typeutil.Map // *types.Named (synthetic local from generic instantiation) -> string
 }
@@ -168,7 +169,7 @@ type builder struct {
 	dilocals          map[*types.Var]llvm.Metadata
 	initInlinedAt     llvm.Metadata            // fake inlinedAt position
 	initPseudoFuncs   map[string]llvm.Metadata // fake "inlined" functions for proper init debug locations
-	allDeferFuncs     []interface{}
+	allDeferFuncs     []any
 	deferFuncs        map[*ssa.Function]int
 	deferInvokeFuncs  map[string]int
 	deferClosureFuncs map[*ssa.Function]int
@@ -298,6 +299,7 @@ func CompilePackage(moduleName string, pkg *loader.Package, ssaPkg *ssa.Package,
 	c.packageDir = pkg.OriginalDir()
 	c.embedGlobals = pkg.EmbedGlobals
 	c.pkg = pkg.Pkg
+	c.loaderPkg = pkg
 	c.runtimePkg = ssaPkg.Prog.ImportedPackage("runtime").Pkg
 	c.program = ssaPkg.Prog
 
@@ -1354,15 +1356,6 @@ func (b *builder) createFunctionStart(intrinsic bool) {
 // diagnostic.
 func (b *builder) createFunction() {
 	b.createFunctionStart(false)
-	// createFunctionStart returns early (leaving blockInfo unset) when it hits
-	// an error such as a redeclared symbol. Don't plow into the block loop and
-	// panic on an empty blockInfo — the error was already recorded.
-	if b.blockInfo == nil {
-		// TINYGO-DEBUG: surface the redeclaration collision.
-		fmt.Printf("TINYGO-DEBUG skipping fn (redeclared/errored): %s  pkg=%s\n",
-			b.fn.RelString(nil), b.fn.Pkg.Pkg.Path())
-		return
-	}
 
 	// Fill blocks with instructions.
 	for _, block := range b.fn.DomPreorder() {
@@ -2163,13 +2156,10 @@ func (c *compilerContext) maxSliceSize(elementType llvm.Type) uint64 {
 	if elementSize == 0 {
 		elementSize = 1
 	}
-	maxSize := maxPointerValue / elementSize
+	maxSize := min(
-
+		// len(slice) is an int. Make sure the length remains small enough to fit in
-	// len(slice) is an int. Make sure the length remains small enough to fit in
+		// an int.
-	// an int.
+		maxPointerValue/elementSize, maxIntegerValue)
-	if maxSize > maxIntegerValue {
-		maxSize = maxIntegerValue
-	}
 
 	return maxSize
 }

compiler/compiler_test.go

@@ -188,9 +188,9 @@ func TestCompilerErrors(t *testing.T) {
 		t.Error(err)
 	}
 	errorsFileString := strings.ReplaceAll(string(errorsFile), "\r\n", "\n")
-	for _, line := range strings.Split(errorsFileString, "\n") {
+	for line := range strings.SplitSeq(errorsFileString, "\n") {
-		if strings.HasPrefix(line, "// ERROR: ") {
+		if after, ok := strings.CutPrefix(line, "// ERROR: "); ok {
-			expectedErrors = append(expectedErrors, strings.TrimPrefix(line, "// ERROR: "))
+			expectedErrors = append(expectedErrors, after)
 		}
 	}
 

compiler/defer.go

@@ -116,8 +116,8 @@ func (b *builder) createLandingPad() {
 func (b *builder) createCheckpoint(ptr llvm.Value) llvm.Value {
 	// Construct inline assembly equivalents of setjmp.
 	// The assembly works as follows:
-	//   * All registers (both callee-saved and caller saved) are clobbered
+	//   * Registers are either clobbered or, on 386, saved for longjmp to
-	//     after the inline assembly returns.
+	//     restore if the ABI requires them to survive calls.
 	//   * The assembly stores the address just past the end of the assembly
 	//     into the jump buffer.
 	//   * The return value (eax, rax, r0, etc) is set to zero in the inline
@@ -130,8 +130,12 @@ func (b *builder) createCheckpoint(ptr llvm.Value) llvm.Value {
 		asmString = `
 xorl %eax, %eax
 movl $$1f, 4(%ebx)
+movl %ebx, 8(%ebx)
+movl %esi, 12(%ebx)
+movl %edi, 16(%ebx)
+movl %ebp, 20(%ebx)
 1:`
-		constraints = "={eax},{ebx},~{ebx},~{ecx},~{edx},~{esi},~{edi},~{ebp},~{xmm0},~{xmm1},~{xmm2},~{xmm3},~{xmm4},~{xmm5},~{xmm6},~{xmm7},~{fpsr},~{fpcr},~{flags},~{dirflag},~{memory}"
+		constraints = "={eax},{ebx},~{ecx},~{edx},~{xmm0},~{xmm1},~{xmm2},~{xmm3},~{xmm4},~{xmm5},~{xmm6},~{xmm7},~{fpsr},~{fpcr},~{flags},~{dirflag},~{memory}"
 		// This doesn't include the floating point stack because TinyGo uses
 		// newer floating point instructions.
 	case "x86_64":
@@ -669,8 +673,8 @@ func (b *builder) createRunDefers() {
 			fn := callback.Fn.(*ssa.Function)
 			valueTypes := []llvm.Type{b.uintptrType, b.dataPtrType}
 			params := fn.Signature.Params()
-			for i := 0; i < params.Len(); i++ {
+			for v := range params.Variables() {
-				valueTypes = append(valueTypes, b.getLLVMType(params.At(i).Type()))
+				valueTypes = append(valueTypes, b.getLLVMType(v.Type()))
 			}
 			valueTypes = append(valueTypes, b.dataPtrType) // closure
 			deferredCallType := b.ctx.StructType(valueTypes, false)
@@ -695,8 +699,8 @@ func (b *builder) createRunDefers() {
 
 			//Get signature from call results
 			params := callback.Type().Underlying().(*types.Signature).Params()
-			for i := 0; i < params.Len(); i++ {
+			for v := range params.Variables() {
-				valueTypes = append(valueTypes, b.getLLVMType(params.At(i).Type()))
+				valueTypes = append(valueTypes, b.getLLVMType(v.Type()))
 			}
 
 			deferredCallType := b.ctx.StructType(valueTypes, false)

compiler/func.go

@@ -81,8 +81,8 @@ func (c *compilerContext) getLLVMFunctionType(typ *types.Signature) llvm.Type {
 			paramTypes = append(paramTypes, info.llvmType)
 		}
 	}
-	for i := 0; i < typ.Params().Len(); i++ {
+	for v := range typ.Params().Variables() {
-		subType := c.getLLVMType(typ.Params().At(i).Type())
+		subType := c.getLLVMType(v.Type())
 		for _, info := range c.expandFormalParamType(subType, "", nil) {
 			paramTypes = append(paramTypes, info.llvmType)
 		}

compiler/gc.go

@@ -5,6 +5,7 @@ package compiler
 
 import (
 	"go/token"
+	"slices"
 
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
@@ -88,7 +89,7 @@ func (b *builder) trackValue(value llvm.Value) {
 			return
 		}
 		numElements := typ.StructElementTypesCount()
-		for i := 0; i < numElements; i++ {
+		for i := range numElements {
 			subValue := b.CreateExtractValue(value, i, "")
 			b.trackValue(subValue)
 		}
@@ -97,7 +98,7 @@ func (b *builder) trackValue(value llvm.Value) {
 			return
 		}
 		numElements := typ.ArrayLength()
-		for i := 0; i < numElements; i++ {
+		for i := range numElements {
 			subValue := b.CreateExtractValue(value, i, "")
 			b.trackValue(subValue)
 		}
@@ -118,12 +119,7 @@ func typeHasPointers(t llvm.Type) bool {
 	case llvm.PointerTypeKind:
 		return true
 	case llvm.StructTypeKind:
-		for _, subType := range t.StructElementTypes() {
+		return slices.ContainsFunc(t.StructElementTypes(), typeHasPointers)
-			if typeHasPointers(subType) {
-				return true
-			}
-		}
-		return false
 	case llvm.ArrayTypeKind:
 		if t.ArrayLength() == 0 {
 			return false

compiler/goroutine.go

@@ -97,7 +97,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 		funcType = b.getLLVMFunctionType(instr.Call.Value.Type().Underlying().(*types.Signature))
 		params = append(params, context, funcPtr)
 		hasContext = true
-		prefix = b.fn.RelString(nil)
+		prefix = b.getFunctionInfo(b.fn).linkName
 	}
 
 	paramBundle := b.emitPointerPack(params)
@@ -139,7 +139,7 @@ func (b *builder) createWasmExport() {
 	// Declare the exported function.
 	paramTypes := b.llvmFnType.ParamTypes()
 	exportedFnType := llvm.FunctionType(b.llvmFnType.ReturnType(), paramTypes[:len(paramTypes)-1], false)
-	exportedFn := llvm.AddFunction(b.mod, b.fn.RelString(nil)+suffix, exportedFnType)
+	exportedFn := llvm.AddFunction(b.mod, b.getFunctionInfo(b.fn).linkName+suffix, exportedFnType)
 	b.addStandardAttributes(exportedFn)
 	llvmutil.AppendToGlobal(b.mod, "llvm.used", exportedFn)
 	exportedFn.AddFunctionAttr(b.ctx.CreateStringAttribute("wasm-export-name", b.info.wasmExport))
@@ -414,7 +414,7 @@ func (c *compilerContext) createGoroutineStartWrapper(fnType llvm.Type, fn llvm.
 			// Extract parameters from the state object, and call the function
 			// that's being wrapped.
 			var callParams []llvm.Value
-			for i := 0; i < numParams; i++ {
+			for i := range numParams {
 				gep := b.CreateInBoundsGEP(stateStruct, statePtr, []llvm.Value{
 					llvm.ConstInt(b.ctx.Int32Type(), 0, false),
 					llvm.ConstInt(b.ctx.Int32Type(), uint64(i), false),

compiler/inlineasm.go

@@ -146,13 +146,14 @@ func (b *builder) emitSVCall(args []ssa.Value, pos token.Pos) (llvm.Value, error
 	llvmArgs := []llvm.Value{}
 	argTypes := []llvm.Type{}
 	asm := "svc #" + strconv.FormatUint(num, 10)
-	constraints := "={r0}"
+	var constraints strings.Builder
+	constraints.WriteString("={r0}")
 	for i, arg := range args[1:] {
 		arg = arg.(*ssa.MakeInterface).X
 		if i == 0 {
-			constraints += ",0"
+			constraints.WriteString(",0")
 		} else {
-			constraints += ",{r" + strconv.Itoa(i) + "}"
+			constraints.WriteString(",{r" + strconv.Itoa(i) + "}")
 		}
 		llvmValue := b.getValue(arg, pos)
 		llvmArgs = append(llvmArgs, llvmValue)
@@ -161,9 +162,9 @@ func (b *builder) emitSVCall(args []ssa.Value, pos token.Pos) (llvm.Value, error
 	// Implement the ARM calling convention by marking r1-r3 as
 	// clobbered. r0 is used as an output register so doesn't have to be
 	// marked as clobbered.
-	constraints += ",~{r1},~{r2},~{r3}"
+	constraints.WriteString(",~{r1},~{r2},~{r3}")
 	fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-	target := llvm.InlineAsm(fnType, asm, constraints, true, false, 0, false)
+	target := llvm.InlineAsm(fnType, asm, constraints.String(), true, false, 0, false)
 	return b.CreateCall(fnType, target, llvmArgs, ""), nil
 }
 
@@ -184,13 +185,14 @@ func (b *builder) emitSV64Call(args []ssa.Value, pos token.Pos) (llvm.Value, err
 	llvmArgs := []llvm.Value{}
 	argTypes := []llvm.Type{}
 	asm := "svc #" + strconv.FormatUint(num, 10)
-	constraints := "={x0}"
+	var constraints strings.Builder
+	constraints.WriteString("={x0}")
 	for i, arg := range args[1:] {
 		arg = arg.(*ssa.MakeInterface).X
 		if i == 0 {
-			constraints += ",0"
+			constraints.WriteString(",0")
 		} else {
-			constraints += ",{x" + strconv.Itoa(i) + "}"
+			constraints.WriteString(",{x" + strconv.Itoa(i) + "}")
 		}
 		llvmValue := b.getValue(arg, pos)
 		llvmArgs = append(llvmArgs, llvmValue)
@@ -199,9 +201,9 @@ func (b *builder) emitSV64Call(args []ssa.Value, pos token.Pos) (llvm.Value, err
 	// Implement the ARM64 calling convention by marking x1-x7 as
 	// clobbered. x0 is used as an output register so doesn't have to be
 	// marked as clobbered.
-	constraints += ",~{x1},~{x2},~{x3},~{x4},~{x5},~{x6},~{x7}"
+	constraints.WriteString(",~{x1},~{x2},~{x3},~{x4},~{x5},~{x6},~{x7}")
 	fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-	target := llvm.InlineAsm(fnType, asm, constraints, true, false, 0, false)
+	target := llvm.InlineAsm(fnType, asm, constraints.String(), true, false, 0, false)
 	return b.CreateCall(fnType, target, llvmArgs, ""), nil
 }
 

compiler/interface.go

@@ -145,8 +145,8 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 	// For a non-interface type, it returns the number of exported methods.
 	// For an interface type, it returns the number of exported and unexported methods.
 	var numMethods int
-	for i := 0; i < ms.Len(); i++ {
+	for method := range ms.Methods() {
-		if isInterface || ms.At(i).Obj().Exported() {
+		if isInterface || method.Obj().Exported() {
 			numMethods++
 		}
 	}
@@ -193,8 +193,8 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 		}
 		// Compute the method set value for types that support methods.
 		var methods []*types.Func
-		for i := 0; i < ms.Len(); i++ {
+		for method := range ms.Methods() {
-			methods = append(methods, ms.At(i).Obj().(*types.Func))
+			methods = append(methods, method.Obj().(*types.Func))
 		}
 		methodSetType := types.NewStruct([]*types.Var{
 			types.NewVar(token.NoPos, nil, "length", types.Typ[types.Uintptr]),
@@ -490,10 +490,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				c.getTypeMethodSet(typ),
 			}, typeFields...)
 		}
-		alignment := c.targetData.TypeAllocSize(c.dataPtrType)
+		alignment := max(c.targetData.TypeAllocSize(c.dataPtrType), 4)
-		if alignment < 4 {
-			alignment = 4
-		}
 		globalValue := c.ctx.ConstStruct(typeFields, false)
 		global.SetInitializer(globalValue)
 		if isLocal {
@@ -783,12 +780,12 @@ func (c *compilerContext) scanLocalTypes(ssaPkg *ssa.Package) {
 			walk(m, false)
 		case *ssa.Type:
 			mset := c.program.MethodSets.MethodSet(m.Type())
-			for i := 0; i < mset.Len(); i++ {
+			for method := range mset.Methods() {
-				walk(c.program.MethodValue(mset.At(i)), false)
+				walk(c.program.MethodValue(method), false)
 			}
 			pmset := c.program.MethodSets.MethodSet(types.NewPointer(m.Type()))
-			for i := 0; i < pmset.Len(); i++ {
+			for method := range pmset.Methods() {
-				walk(c.program.MethodValue(pmset.At(i)), false)
+				walk(c.program.MethodValue(method), false)
 			}
 		}
 	}
@@ -846,8 +843,8 @@ func (c *compilerContext) registerSyntheticLocalTypes(fn *ssa.Function) {
 				}
 			}
 			targs := t.TypeArgs()
-			for i := 0; i < targs.Len(); i++ {
+			for t := range targs.Types() {
-				visit(targs.At(i))
+				visit(t)
 			}
 			visit(t.Underlying())
 		case *types.Pointer:
@@ -862,23 +859,23 @@ func (c *compilerContext) registerSyntheticLocalTypes(fn *ssa.Function) {
 			visit(t.Key())
 			visit(t.Elem())
 		case *types.Struct:
-			for i := 0; i < t.NumFields(); i++ {
+			for field := range t.Fields() {
-				visit(t.Field(i).Type())
+				visit(field.Type())
 			}
 		case *types.Signature:
 			if p := t.Params(); p != nil {
-				for i := 0; i < p.Len(); i++ {
+				for v := range p.Variables() {
-					visit(p.At(i).Type())
+					visit(v.Type())
 				}
 			}
 			if r := t.Results(); r != nil {
-				for i := 0; i < r.Len(); i++ {
+				for v := range r.Variables() {
-					visit(r.At(i).Type())
+					visit(v.Type())
 				}
 			}
 		case *types.Tuple:
-			for i := 0; i < t.Len(); i++ {
+			for v := range t.Variables() {
-				visit(t.At(i).Type())
+				visit(v.Type())
 			}
 		case *types.Interface:
 			// A synthetic local type can be reachable only through a
@@ -887,8 +884,8 @@ func (c *compilerContext) registerSyntheticLocalTypes(fn *ssa.Function) {
 			// the interface's identifier, and the seen map breaks
 			// cycles formed by methods that mention the interface
 			// itself.
-			for i := 0; i < t.NumMethods(); i++ {
+			for method := range t.Methods() {
-				visit(t.Method(i).Type())
+				visit(method.Type())
 			}
 		}
 	}
@@ -939,8 +936,7 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 
 		// Create method set.
 		var signatures, wrappers []llvm.Value
-		for i := 0; i < ms.Len(); i++ {
+		for method := range ms.Methods() {
-			method := ms.At(i)
 			signatureGlobal := c.getMethodSignature(method.Obj().(*types.Func))
 			signatures = append(signatures, signatureGlobal)
 			fn := c.program.MethodValue(method)
@@ -1189,8 +1185,8 @@ func (c *compilerContext) getInvokeFunction(instr *ssa.CallCommon) llvm.Value {
 	if llvmFn.IsNil() {
 		sig := instr.Method.Type().(*types.Signature)
 		var paramTuple []*types.Var
-		for i := 0; i < sig.Params().Len(); i++ {
+		for v := range sig.Params().Variables() {
-			paramTuple = append(paramTuple, sig.Params().At(i))
+			paramTuple = append(paramTuple, v)
 		}
 		paramTuple = append(paramTuple, types.NewVar(token.NoPos, nil, "$typecode", types.Typ[types.UnsafePointer]))
 		llvmFnType := c.getLLVMFunctionType(types.NewSignature(sig.Recv(), types.NewTuple(paramTuple...), sig.Results(), false))
@@ -1307,34 +1303,38 @@ func methodSignature(method *types.Func) string {
 //	() string
 //	(string, int) (int, error)
 func signature(sig *types.Signature) string {
-	s := ""
+	var s strings.Builder
 	if sig.Params().Len() == 0 {
-		s += "()"
+		s.WriteString("()")
 	} else {
-		s += "("
+		s.WriteString("(")
-		for i := 0; i < sig.Params().Len(); i++ {
+		i := 0
+		for v := range sig.Params().Variables() {
 			if i > 0 {
-				s += ", "
+				s.WriteString(", ")
 			}
-			s += typestring(sig.Params().At(i).Type())
+			s.WriteString(typestring(v.Type()))
+			i++
 		}
-		s += ")"
+		s.WriteString(")")
 	}
 	if sig.Results().Len() == 0 {
 		// keep as-is
 	} else if sig.Results().Len() == 1 {
-		s += " " + typestring(sig.Results().At(0).Type())
+		s.WriteString(" " + typestring(sig.Results().At(0).Type()))
 	} else {
-		s += " ("
+		s.WriteString(" (")
-		for i := 0; i < sig.Results().Len(); i++ {
+		i := 0
+		for v := range sig.Results().Variables() {
 			if i > 0 {
-				s += ", "
+				s.WriteString(", ")
 			}
-			s += typestring(sig.Results().At(i).Type())
+			s.WriteString(typestring(v.Type()))
+			i++
 		}
-		s += ")"
+		s.WriteString(")")
 	}
-	return s
+	return s.String()
 }
 
 // typestring returns a stable (human-readable) type string for the given type

compiler/llvm.go

@@ -206,7 +206,7 @@ func (c *compilerContext) makeGlobalArray(buf []byte, name string, elementType l
 	globalType := llvm.ArrayType(elementType, len(buf))
 	global := llvm.AddGlobal(c.mod, globalType, name)
 	value := llvm.Undef(globalType)
-	for i := 0; i < len(buf); i++ {
+	for i := range buf {
 		ch := uint64(buf[i])
 		value = c.builder.CreateInsertValue(value, llvm.ConstInt(elementType, ch, false), i, "")
 	}
@@ -390,7 +390,7 @@ func (c *compilerContext) buildPointerBitmap(
 			return
 		}
 		elementSize /= ptrAlign
-		for i := 0; i < len; i++ {
+		for i := range len {
 			c.buildPointerBitmap(
 				dst,
 				ptrAlign,
@@ -417,7 +417,7 @@ func (c *compilerContext) archFamily() string {
 // features string is not one for an ARM architecture.
 func (c *compilerContext) isThumb() bool {
 	var isThumb, isNotThumb bool
-	for _, feature := range strings.Split(c.Features, ",") {
+	for feature := range strings.SplitSeq(c.Features, ",") {
 		if feature == "+thumb-mode" {
 			isThumb = true
 		}

compiler/map.go

@@ -7,6 +7,7 @@ import (
 	"go/token"
 	"go/types"
 	"golang.org/x/tools/go/ssa"
+	"strings"
 	"tinygo.org/x/go-llvm"
 )
 
@@ -293,14 +294,15 @@ func hashmapCanonicalTypeName(t types.Type) string {
 		}
 		return t.String()
 	case *types.Struct:
-		s := "struct{"
+		var s strings.Builder
+		s.WriteString("struct{")
 		for i := 0; i < t.NumFields(); i++ {
 			if i > 0 {
-				s += "; "
+				s.WriteString("; ")
 			}
-			s += hashmapCanonicalTypeName(t.Field(i).Type())
+			s.WriteString(hashmapCanonicalTypeName(t.Field(i).Type()))
 		}
-		return s + "}"
+		return s.String() + "}"
 	case *types.Array:
 		return fmt.Sprintf("[%d]%s", t.Len(), hashmapCanonicalTypeName(t.Elem()))
 	}

compiler/sizes.go

@@ -29,8 +29,7 @@ func (s *stdSizes) Alignof(T types.Type) int64 {
 		// is the largest of the values unsafe.Alignof(x.f) for each
 		// field f of x, but at least 1."
 		max := int64(1)
-		for i := 0; i < t.NumFields(); i++ {
+		for f := range t.Fields() {
-			f := t.Field(i)
 			if a := s.Alignof(f.Type()); a > max {
 				max = a
 			}

compiler/symbol.go

@@ -8,6 +8,8 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
+	"path/filepath"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -85,8 +87,8 @@ func (c *compilerContext) getFunction(fn *ssa.Function) (llvm.Type, llvm.Value)
 		retType = c.getLLVMType(fn.Signature.Results().At(0).Type())
 	} else {
 		results := make([]llvm.Type, 0, fn.Signature.Results().Len())
-		for i := 0; i < fn.Signature.Results().Len(); i++ {
+		for v := range fn.Signature.Results().Variables() {
-			results = append(results, c.getLLVMType(fn.Signature.Results().At(i).Type()))
+			results = append(results, c.getLLVMType(v.Type()))
 		}
 		retType = c.ctx.StructType(results, false)
 	}
@@ -322,6 +324,12 @@ func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
 		linkName: f.RelString(nil),
 	}
 
+	// RelString is not unique for local type arguments, so add a suffix
+	// when needed.
+	if suffix := c.localTypeArgsSuffix(f); suffix != "" {
+		info.linkName += suffix
+	}
+
 	// Check for a few runtime functions that are treated specially.
 	if info.linkName == "runtime.wasmEntryReactor" && c.BuildMode == "c-shared" {
 		info.linkName = "_initialize"
@@ -346,6 +354,42 @@ func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
 	return info
 }
 
+func (c *compilerContext) localTypeArgsSuffix(f *ssa.Function) string {
+	typeArgs := f.TypeArgs()
+	if len(typeArgs) == 0 {
+		return ""
+	}
+	var hasLocal bool
+	parts := make([]string, len(typeArgs))
+	for i, ta := range typeArgs {
+		name, isLocal := c.getTypeCodeName(ta)
+		if isLocal {
+			hasLocal = true
+		}
+		// A function-local type alias (e.g. `type F = float64` inside a
+		// function body) is invisible to getTypeCodeName because it calls
+		// types.Unalias first. Two callers that use distinct aliases with
+		// the same name (e.g. Go 1.27's internal/strconv.ftoa32 and ftoa64
+		// both declare a local `type F = ...`) then produce identical
+		// RelStrings for their shortFloat[F] instantiations and collide on
+		// mod.NamedFunction. Treat these aliases as local so the suffix
+		// disambiguates them.
+		if alias, ok := ta.(*types.Alias); ok {
+			if obj := alias.Obj(); obj.Pkg() != nil && obj.Parent() != obj.Pkg().Scope() {
+				hasLocal = true
+				pos := c.program.Fset.PositionFor(obj.Pos(), false)
+				parts[i] = fmt.Sprintf("%s$alias:%s:%d:%d", name, filepath.Base(pos.Filename), pos.Line, pos.Column)
+				continue
+			}
+		}
+		parts[i] = name
+	}
+	if !hasLocal {
+		return ""
+	}
+	return "$localtype:" + strings.Join(parts, ",")
+}
+
 // parsePragmas is used by getFunctionInfo to parse function pragmas such as
 // //export or //go:noinline.
 func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
@@ -372,6 +416,51 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 		}
 	}
 
+	// Also scan file-level //go:linkname directives. These appear as
+	// free-standing comments in *ast.File.Comments (not attached to any
+	// declaration), and are used by modern golang.org/x/sys/unix and others.
+	// Function-attached directives (above) take precedence — we only add
+	// file-level ones if no doc-comment linkname was found for this function.
+	//
+	// TODO: the hasUnsafeImport gate enforced downstream (see the
+	// //go:linkname case below) is package-level. gc enforces it per
+	// file, on the file containing the directive. For file-level
+	// linknames this is more important than for function-attached ones,
+	// because the directive can live in a file separate from the
+	// function. A stricter implementation would check whether the file
+	// returned by fileForFunc imports "unsafe", not whether any file in
+	// the package does.
+	hasFunctionLinkname := false
+	for _, comment := range pragmas {
+		if strings.HasPrefix(comment.Text, "//go:linkname ") {
+			parts := strings.Fields(comment.Text)
+			if len(parts) == 3 && parts[1] == f.Name() {
+				hasFunctionLinkname = true
+				break
+			}
+		}
+	}
+	if !hasFunctionLinkname {
+		if file := c.fileForFunc(f); file != nil {
+			for _, group := range file.Comments {
+				// Skip the function's own doc comment — already handled above.
+				if decl, ok := syntax.(*ast.FuncDecl); ok && group == decl.Doc {
+					continue
+				}
+				for _, comment := range group.List {
+					if !strings.HasPrefix(comment.Text, "//go:linkname ") {
+						continue
+					}
+					parts := strings.Fields(comment.Text)
+					if len(parts) != 3 || parts[1] != f.Name() {
+						continue
+					}
+					pragmas = append(pragmas, comment)
+				}
+			}
+		}
+	}
+
 	// Parse each pragma.
 	for _, comment := range pragmas {
 		parts := strings.Fields(comment.Text)
@@ -389,7 +478,7 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 			info.wasmName = info.linkName
 			info.exported = true
 		case "//go:interrupt":
-			if hasUnsafeImport(f.Pkg.Pkg) {
+			if slices.Contains(f.Pkg.Pkg.Imports(), types.Unsafe) {
 				info.interrupt = true
 			}
 		case "//go:wasm-module":
@@ -451,14 +540,14 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 			// This is a slightly looser requirement than what gc uses: gc
 			// requires the file to import "unsafe", not the package as a
 			// whole.
-			if hasUnsafeImport(f.Pkg.Pkg) {
+			if slices.Contains(f.Pkg.Pkg.Imports(), types.Unsafe) {
 				info.linkName = parts[2]
 			}
 		case "//go:section":
 			// Only enable go:section when the package imports "unsafe".
 			// go:section also implies go:noinline since inlining could
 			// move the code to a different section than that requested.
-			if len(parts) == 2 && hasUnsafeImport(f.Pkg.Pkg) {
+			if len(parts) == 2 && slices.Contains(f.Pkg.Pkg.Imports(), types.Unsafe) {
 				info.section = parts[1]
 				info.inline = inlineNone
 			}
@@ -467,7 +556,7 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 			// runtime functions.
 			// This is somewhat dangerous and thus only imported in packages
 			// that import unsafe.
-			if hasUnsafeImport(f.Pkg.Pkg) {
+			if slices.Contains(f.Pkg.Pkg.Imports(), types.Unsafe) {
 				info.nobounds = true
 			}
 		case "//go:noescape":
@@ -567,8 +656,8 @@ func (c *compilerContext) isValidWasmType(typ types.Type, site wasmSite) bool {
 				hasHostLayout = false // package structs added in go1.23
 			}
 		}
-		for i := 0; i < typ.NumFields(); i++ {
+		for field := range typ.Fields() {
-			ftyp := typ.Field(i).Type()
+			ftyp := field.Type()
 			if types.Unalias(ftyp).String() == "structs.HostLayout" {
 				hasHostLayout = true
 				continue
@@ -600,8 +689,8 @@ func getParams(sig *types.Signature) []*types.Var {
 	if sig.Recv() != nil {
 		params = append(params, sig.Recv())
 	}
-	for i := 0; i < sig.Params().Len(); i++ {
+	for v := range sig.Params().Variables() {
-		params = append(params, sig.Params().At(i))
+		params = append(params, v)
 	}
 	return params
 }
@@ -666,6 +755,34 @@ type globalInfo struct {
 	section  string // go:section
 }
 
+// fileForFunc returns the *ast.File that contains the declaration of f, or
+// nil if it cannot be determined. File-level pragmas are only consulted for
+// functions in the package currently being compiled — functions imported from
+// other packages have their file-level pragmas processed when those packages
+// are compiled.
+func (c *compilerContext) fileForFunc(f *ssa.Function) *ast.File {
+	if c.loaderPkg == nil || f.Pkg == nil || f.Pkg.Pkg != c.loaderPkg.Pkg {
+		return nil
+	}
+	syntax := f.Syntax()
+	if f.Origin() != nil {
+		syntax = f.Origin().Syntax()
+	}
+	if syntax == nil {
+		return nil
+	}
+	pos := syntax.Pos()
+	if !pos.IsValid() {
+		return nil
+	}
+	for _, file := range c.loaderPkg.Files {
+		if file.FileStart <= pos && pos < file.FileEnd {
+			return file
+		}
+	}
+	return nil
+}
+
 // loadASTComments loads comments on globals from the AST, for use later in the
 // program. In particular, they are required for //go:extern pragmas on globals.
 func (c *compilerContext) loadASTComments(pkg *loader.Package) {
@@ -704,10 +821,7 @@ func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
 		llvmGlobal = llvm.AddGlobal(c.mod, llvmType, info.linkName)
 
 		// Set alignment from the //go:align comment.
-		alignment := c.targetData.ABITypeAlignment(llvmType)
+		alignment := max(info.align, c.targetData.ABITypeAlignment(llvmType))
-		if info.align > alignment {
-			alignment = info.align
-		}
 		if alignment <= 0 || alignment&(alignment-1) != 0 {
 			// Check for power-of-two (or 0).
 			// See: https://stackoverflow.com/a/108360
@@ -781,7 +895,7 @@ func (info *globalInfo) parsePragmas(doc *ast.CommentGroup, c *compilerContext,
 			// This is a slightly looser requirement than what gc uses: gc
 			// requires the file to import "unsafe", not the package as a
 			// whole.
-			if hasUnsafeImport(g.Pkg.Pkg) {
+			if slices.Contains(g.Pkg.Pkg.Imports(), types.Unsafe) {
 				info.linkName = parts[2]
 			}
 		}
@@ -797,13 +911,3 @@ func getAllMethods(prog *ssa.Program, typ types.Type) []*types.Selection {
 	}
 	return methods
 }
-
-// Return true if this package imports "unsafe", false otherwise.
-func hasUnsafeImport(pkg *types.Package) bool {
-	for _, imp := range pkg.Imports() {
-		if imp == types.Unsafe {
-			return true
-		}
-	}
-	return false
-}

compiler/syscall.go

@@ -26,24 +26,25 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		argTypes := []llvm.Type{b.uintptrType}
 		// Constraints will look something like:
 		//   "={rax},0,{rdi},{rsi},{rdx},{r10},{r8},{r9},~{rcx},~{r11}"
-		constraints := "={rax},0"
+		var constraints strings.Builder
+		constraints.WriteString("={rax},0")
 		for i, arg := range call.Args[1:] {
-			constraints += "," + [...]string{
+			constraints.WriteString("," + [...]string{
 				"{rdi}",
 				"{rsi}",
 				"{rdx}",
 				"{r10}",
 				"{r8}",
 				"{r9}",
-			}[i]
+			}[i])
 			llvmValue := b.getValue(arg, getPos(call))
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		// rcx and r11 are clobbered by the syscall, so make sure they are not used
-		constraints += ",~{rcx},~{r11}"
+		constraints.WriteString(",~{rcx},~{r11}")
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-		target := llvm.InlineAsm(fnType, "syscall", constraints, true, false, llvm.InlineAsmDialectIntel, false)
+		target := llvm.InlineAsm(fnType, "syscall", constraints.String(), true, false, llvm.InlineAsmDialectIntel, false)
 		return b.CreateCall(fnType, target, args, ""), nil
 
 	case b.GOARCH == "386" && b.GOOS == "linux":
@@ -55,22 +56,23 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		argTypes := []llvm.Type{b.uintptrType}
 		// Constraints will look something like:
 		//   "={eax},0,{ebx},{ecx},{edx},{esi},{edi},{ebp}"
-		constraints := "={eax},0"
+		var constraints strings.Builder
+		constraints.WriteString("={eax},0")
 		for i, arg := range call.Args[1:] {
-			constraints += "," + [...]string{
+			constraints.WriteString("," + [...]string{
 				"{ebx}",
 				"{ecx}",
 				"{edx}",
 				"{esi}",
 				"{edi}",
 				"{ebp}",
-			}[i]
+			}[i])
 			llvmValue := b.getValue(arg, getPos(call))
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-		target := llvm.InlineAsm(fnType, "int 0x80", constraints, true, false, llvm.InlineAsmDialectIntel, false)
+		target := llvm.InlineAsm(fnType, "int 0x80", constraints.String(), true, false, llvm.InlineAsmDialectIntel, false)
 		return b.CreateCall(fnType, target, args, ""), nil
 
 	case b.GOARCH == "arm" && b.GOOS == "linux":
@@ -88,9 +90,10 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		argTypes := []llvm.Type{}
 		// Constraints will look something like:
 		//   ={r0},0,{r1},{r2},{r7},~{r3}
-		constraints := "={r0}"
+		var constraints strings.Builder
+		constraints.WriteString("={r0}")
 		for i, arg := range call.Args[1:] {
-			constraints += "," + [...]string{
+			constraints.WriteString("," + [...]string{
 				"0", // tie to output
 				"{r1}",
 				"{r2}",
@@ -98,20 +101,20 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"{r4}",
 				"{r5}",
 				"{r6}",
-			}[i]
+			}[i])
 			llvmValue := b.getValue(arg, getPos(call))
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		args = append(args, num)
 		argTypes = append(argTypes, b.uintptrType)
-		constraints += ",{r7}" // syscall number
+		constraints.WriteString(",{r7}") // syscall number
 		for i := len(call.Args) - 1; i < 4; i++ {
 			// r0-r3 get clobbered after the syscall returns
-			constraints += ",~{r" + strconv.Itoa(i) + "}"
+			constraints.WriteString(",~{r" + strconv.Itoa(i) + "}")
 		}
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0, false)
+		target := llvm.InlineAsm(fnType, "svc #0", constraints.String(), true, false, 0, false)
 		return b.CreateCall(fnType, target, args, ""), nil
 
 	case b.GOARCH == "arm64" && b.GOOS == "linux":
@@ -120,31 +123,32 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		argTypes := []llvm.Type{}
 		// Constraints will look something like:
 		//   ={x0},0,{x1},{x2},{x8},~{x3},~{x4},~{x5},~{x6},~{x7},~{x16},~{x17}
-		constraints := "={x0}"
+		var constraints strings.Builder
+		constraints.WriteString("={x0}")
 		for i, arg := range call.Args[1:] {
-			constraints += "," + [...]string{
+			constraints.WriteString("," + [...]string{
 				"0", // tie to output
 				"{x1}",
 				"{x2}",
 				"{x3}",
 				"{x4}",
 				"{x5}",
-			}[i]
+			}[i])
 			llvmValue := b.getValue(arg, getPos(call))
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		args = append(args, num)
 		argTypes = append(argTypes, b.uintptrType)
-		constraints += ",{x8}" // syscall number
+		constraints.WriteString(",{x8}") // syscall number
 		for i := len(call.Args) - 1; i < 8; i++ {
 			// x0-x7 may get clobbered during the syscall following the aarch64
 			// calling convention.
-			constraints += ",~{x" + strconv.Itoa(i) + "}"
+			constraints.WriteString(",~{x" + strconv.Itoa(i) + "}")
 		}
-		constraints += ",~{x16},~{x17}" // scratch registers
+		constraints.WriteString(",~{x16},~{x17}") // scratch registers
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
-		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0, false)
+		target := llvm.InlineAsm(fnType, "svc #0", constraints.String(), true, false, 0, false)
 		return b.CreateCall(fnType, target, args, ""), nil
 
 	case (b.GOARCH == "mips" || b.GOARCH == "mipsle") && b.GOOS == "linux":
@@ -163,7 +167,8 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		// faster and smaller code.
 		args := []llvm.Value{num}
 		argTypes := []llvm.Type{b.uintptrType}
-		constraints := "={$2},={$7},0"
+		var constraints strings.Builder
+		constraints.WriteString("={$2},={$7},0")
 		syscallParams := call.Args[1:]
 		if len(syscallParams) > 7 {
 			// There is one syscall that uses 7 parameters: sync_file_range.
@@ -172,7 +177,7 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 			syscallParams = syscallParams[:7]
 		}
 		for i, arg := range syscallParams {
-			constraints += "," + [...]string{
+			constraints.WriteString("," + [...]string{
 				"{$4}", // arg1
 				"{$5}", // arg2
 				"{$6}", // arg3
@@ -180,7 +185,7 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"r",    // arg5 on the stack
 				"r",    // arg6 on the stack
 				"r",    // arg7 on the stack
-			}[i]
+			}[i])
 			llvmValue := b.getValue(arg, getPos(call))
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
@@ -221,10 +226,10 @@ func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"addu $$sp, $$sp, 32\n" +
 				".set at\n"
 		}
-		constraints += ",~{$3},~{$4},~{$5},~{$6},~{$8},~{$9},~{$10},~{$11},~{$12},~{$13},~{$14},~{$15},~{$24},~{$25},~{hi},~{lo},~{memory}"
+		constraints.WriteString(",~{$3},~{$4},~{$5},~{$6},~{$8},~{$9},~{$10},~{$11},~{$12},~{$13},~{$14},~{$15},~{$24},~{$25},~{hi},~{lo},~{memory}")
 		returnType := b.ctx.StructType([]llvm.Type{b.uintptrType, b.uintptrType}, false)
 		fnType := llvm.FunctionType(returnType, argTypes, false)
-		target := llvm.InlineAsm(fnType, asm, constraints, true, true, 0, false)
+		target := llvm.InlineAsm(fnType, asm, constraints.String(), true, true, 0, false)
 		call := b.CreateCall(fnType, target, args, "")
 		resultCode := b.CreateExtractValue(call, 0, "") // r2
 		errorFlag := b.CreateExtractValue(call, 1, "")  // r7

compiler/testdata/pragma.go

@@ -120,3 +120,31 @@ func stillEscapes(a *int, b []int, c chan int, d *[0]byte) {
 func doesHeapAlloc() *int {
 	return new(int)
 }
+
+// Define a function in a different package using a file-level go:linkname.
+// (Same as withLinkageName1, but with the //go:linkname directive detached
+// from the function declaration — see https://github.com/tinygo-org/tinygo/issues/4395)
+func withFileLevelLinkageName1() {
+}
+
+// Import a function from a different package using a file-level go:linkname.
+// (Same as withLinkageName2, but with the //go:linkname directive detached
+// from the function declaration.)
+func withFileLevelLinkageName2()
+
+//go:linkname withFileLevelLinkageName1 somepkg.someFileLevelFunction1
+//go:linkname withFileLevelLinkageName2 somepkg.someFileLevelFunction2
+
+// File-level linkname directives can also appear between two function
+// declarations, in which case Go's AST attaches them as the doc comment
+// of the following function — even when the directive's localname refers
+// to a different function. Exercise that case: the directive below names
+// withAdjacentLinkageName, but Go will attach it to
+// sentinelAfterAdjacentLinkname's Doc. The file-level scan must find it
+// by walking comment groups regardless of which decl they're attached to.
+func withAdjacentLinkageName() {
+}
+
+//go:linkname withAdjacentLinkageName somepkg.someAdjacentFunction
+func sentinelAfterAdjacentLinkname() {
+}

compiler/testdata/pragma.ll

@@ -102,6 +102,26 @@ entry:
 ; Function Attrs: allockind("alloc,zeroed") allocsize(0)
 declare noalias nonnull ptr @runtime.alloc_noheap(i32, ptr, ptr) #9
 
+; Function Attrs: nounwind
+define hidden void @somepkg.someFileLevelFunction1(ptr %context) unnamed_addr #1 {
+entry:
+  ret void
+}
+
+declare void @somepkg.someFileLevelFunction2(ptr) #0
+
+; Function Attrs: nounwind
+define hidden void @somepkg.someAdjacentFunction(ptr %context) unnamed_addr #1 {
+entry:
+  ret void
+}
+
+; Function Attrs: nounwind
+define hidden void @main.sentinelAfterAdjacentLinkname(ptr %context) unnamed_addr #1 {
+entry:
+  ret void
+}
+
 attributes #0 = { "target-features"="+bulk-memory,+bulk-memory-opt,+call-indirect-overlong,+mutable-globals,+nontrapping-fptoint,+sign-ext,-multivalue,-reference-types" }
 attributes #1 = { nounwind "target-features"="+bulk-memory,+bulk-memory-opt,+call-indirect-overlong,+mutable-globals,+nontrapping-fptoint,+sign-ext,-multivalue,-reference-types" }
 attributes #2 = { nounwind "target-features"="+bulk-memory,+bulk-memory-opt,+call-indirect-overlong,+mutable-globals,+nontrapping-fptoint,+sign-ext,-multivalue,-reference-types" "wasm-export-name"="extern_func" }

corpus_test.go

@@ -59,7 +59,6 @@ func TestCorpus(t *testing.T) {
 	}
 
 	for _, repo := range repos {
-		repo := repo
 		name := repo.Repo
 		if repo.Tags != "" {
 			name += "(" + strings.ReplaceAll(repo.Tags, " ", "-") + ")"
@@ -132,7 +131,6 @@ func TestCorpus(t *testing.T) {
 			}
 
 			for _, dir := range repo.Subdirs {
-				dir := dir
 				t.Run(dir.Pkg, func(t *testing.T) {
 					t.Parallel()
 

diff.go

@@ -116,10 +116,7 @@ func Diff(oldName string, old []byte, newName string, new []byte) []byte {
 
 		// End chunk with common lines for context.
 		if len(ctext) > 0 {
-			n := end.x - start.x
+			n := min(end.x-start.x, C)
-			if n > C {
-				n = C
-			}
 			for _, s := range x[start.x : start.x+n] {
 				ctext = append(ctext, " "+s)
 				count.x++
@@ -234,7 +231,7 @@ func tgs(x, y []string) []pair {
 	for i := range T {
 		T[i] = n + 1
 	}
-	for i := 0; i < n; i++ {
+	for i := range n {
 		k := sort.Search(n, func(k int) bool {
 			return T[k] >= J[i]
 		})

errors_test.go

@@ -136,7 +136,7 @@ func readErrorMessages(t *testing.T, file string) string {
 	}
 
 	var errors []string
-	for _, line := range strings.Split(string(data), "\n") {
+	for line := range strings.SplitSeq(string(data), "\n") {
 		if strings.HasPrefix(line, "// ERROR: ") {
 			errors = append(errors, strings.TrimRight(line[len("// ERROR: "):], "\r\n"))
 		}

goenv/goenv.go

@@ -151,6 +151,8 @@ func Get(name string) string {
 			panic("could not find cache dir: " + err.Error())
 		}
 		return filepath.Join(dir, "tinygo")
+	case "CGO_CFLAGS":
+		return os.Getenv("CGO_CFLAGS")
 	case "CGO_ENABLED":
 		// Always enable CGo. It is required by a number of targets, including
 		// macOS and the rp2040.

interp/compiler.go

@@ -151,7 +151,7 @@ func (r *runner) compileFunction(llvmFn llvm.Value) *function {
 			case llvm.PHI:
 				inst.name = llvmInst.Name()
 				incomingCount := inst.llvmInst.IncomingCount()
-				for i := 0; i < incomingCount; i++ {
+				for i := range incomingCount {
 					incomingBB := inst.llvmInst.IncomingBlock(i)
 					incomingValue := inst.llvmInst.IncomingValue(i)
 					inst.operands = append(inst.operands,

interp/interp_test.go

@@ -22,7 +22,6 @@ func TestInterp(t *testing.T) {
 		"alloc",
 		"slicedata",
 	} {
-		name := name // make local to this closure
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 			runTest(t, "testdata/"+name)

interp/interpreter.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"math"
 	"os"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -470,7 +471,7 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				// should be returned.
 				numMethods := int(r.builder.CreateExtractValue(methodSet, 0, "").ZExtValue())
 				var method llvm.Value
-				for i := 0; i < numMethods; i++ {
+				for i := range numMethods {
 					methodSignatureAgg := r.builder.CreateExtractValue(methodSet, 1, "")
 					methodSignature := r.builder.CreateExtractValue(methodSignatureAgg, i, "")
 					if methodSignature == signature {
@@ -907,7 +908,7 @@ func (r *runner) interpretICmp(lhs, rhs value, predicate llvm.IntPredicate) bool
 func (r *runner) runAtRuntime(fn *function, inst instruction, locals []value, mem *memoryView, indent string) *Error {
 	numOperands := inst.llvmInst.OperandsCount()
 	operands := make([]llvm.Value, numOperands)
-	for i := 0; i < numOperands; i++ {
+	for i := range numOperands {
 		operand := inst.llvmInst.Operand(i)
 		if !operand.IsAInstruction().IsNil() || !operand.IsAArgument().IsNil() {
 			var err error
@@ -985,9 +986,9 @@ func (r *runner) runAtRuntime(fn *function, inst instruction, locals []value, me
 			mem.instructions = append(mem.instructions, agg)
 		}
 		result = operands[1]
-		for i := len(indices) - 1; i >= 0; i-- {
+		for i, indice := range slices.Backward(indices) {
 			agg := aggregates[i]
-			result = r.builder.CreateInsertValue(agg, result, int(indices[i]), inst.name+".insertvalue"+strconv.Itoa(i))
+			result = r.builder.CreateInsertValue(agg, result, int(indice), inst.name+".insertvalue"+strconv.Itoa(i))
 			if i != 0 { // don't add last result to mem.instructions as it will be done at the end already
 				mem.instructions = append(mem.instructions, result)
 			}

interp/memory.go

@@ -18,8 +18,10 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"maps"
 	"math"
 	"math/big"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -80,9 +82,7 @@ func (mv *memoryView) extend(sub memoryView) {
 	if mv.objects == nil && len(sub.objects) != 0 {
 		mv.objects = make(map[uint32]object)
 	}
-	for key, value := range sub.objects {
+	maps.Copy(mv.objects, sub.objects)
-		mv.objects[key] = value
-	}
 	mv.instructions = append(mv.instructions, sub.instructions...)
 }
 
@@ -90,8 +90,8 @@ func (mv *memoryView) extend(sub memoryView) {
 // created in this memoryView. Do not reuse this memoryView.
 func (mv *memoryView) revert() {
 	// Erase instructions in reverse order.
-	for i := len(mv.instructions) - 1; i >= 0; i-- {
+	for _, llvmInst := range slices.Backward(mv.instructions) {
-		llvmInst := mv.instructions[i]
+
 		if llvmInst.IsAInstruction().IsNil() {
 			// The IR builder will try to create constant versions of
 			// instructions whenever possible. If it does this, it's not an
@@ -172,7 +172,7 @@ func (mv *memoryView) markExternal(llvmValue llvm.Value, mark uint8) error {
 							continue
 						}
 						numOperands := inst.OperandsCount()
-						for i := 0; i < numOperands; i++ {
+						for i := range numOperands {
 							// Using mark '2' (which means read/write access)
 							// because this might be a store instruction.
 							err := mv.markExternal(inst.Operand(i), 2)
@@ -215,7 +215,7 @@ func (mv *memoryView) markExternal(llvmValue llvm.Value, mark uint8) error {
 			// need any marking.
 		case llvm.StructTypeKind:
 			numElements := llvmType.StructElementTypesCount()
-			for i := 0; i < numElements; i++ {
+			for i := range numElements {
 				element := mv.r.builder.CreateExtractValue(llvmValue, i, "")
 				err := mv.markExternal(element, mark)
 				if err != nil {
@@ -224,7 +224,7 @@ func (mv *memoryView) markExternal(llvmValue llvm.Value, mark uint8) error {
 			}
 		case llvm.ArrayTypeKind:
 			numElements := llvmType.ArrayLength()
-			for i := 0; i < numElements; i++ {
+			for i := range numElements {
 				element := mv.r.builder.CreateExtractValue(llvmValue, i, "")
 				err := mv.markExternal(element, mark)
 				if err != nil {
@@ -366,7 +366,7 @@ func (mv *memoryView) store(v value, p pointerValue) bool {
 		buffer := obj.buffer.asRawValue(mv.r)
 		obj.buffer = buffer
 		v := v.asRawValue(mv.r)
-		for i := uint32(0); i < valueLen; i++ {
+		for i := range valueLen {
 			buffer.buf[p.offset()+i] = v.buf[i]
 		}
 	}
@@ -392,7 +392,7 @@ type value interface {
 // literalValue contains simple integer values that don't need to be stored in a
 // buffer.
 type literalValue struct {
-	value interface{}
+	value any
 }
 
 // Make a literalValue given the number of bits.
@@ -1015,7 +1015,7 @@ func (v *rawValue) set(llvmValue llvm.Value, r *runner) {
 		if err != nil {
 			panic(err)
 		}
-		for i := uint32(0); i < ptrSize; i++ {
+		for i := range ptrSize {
 			v.buf[i] = ptr.pointer
 		}
 	} else if !llvmValue.IsAConstantExpr().IsNil() {
@@ -1056,7 +1056,7 @@ func (v *rawValue) set(llvmValue llvm.Value, r *runner) {
 				panic(err)
 			}
 			ptrValue.pointer += totalOffset
-			for i := uint32(0); i < ptrSize; i++ {
+			for i := range ptrSize {
 				v.buf[i] = ptrValue.pointer
 			}
 		case llvm.ICmp:
@@ -1113,7 +1113,7 @@ func (v *rawValue) set(llvmValue llvm.Value, r *runner) {
 			}
 		case llvm.StructTypeKind:
 			numElements := llvmType.StructElementTypesCount()
-			for i := 0; i < numElements; i++ {
+			for i := range numElements {
 				offset := r.targetData.ElementOffset(llvmType, i)
 				field := rawValue{
 					buf: v.buf[offset:],
@@ -1124,7 +1124,7 @@ func (v *rawValue) set(llvmValue llvm.Value, r *runner) {
 			numElements := llvmType.ArrayLength()
 			childType := llvmType.ElementType()
 			childTypeSize := r.targetData.TypeAllocSize(childType)
-			for i := 0; i < numElements; i++ {
+			for i := range numElements {
 				offset := i * int(childTypeSize)
 				field := rawValue{
 					buf: v.buf[offset:],

loader/loader.go

@@ -22,6 +22,7 @@ import (
 	"strings"
 	"unicode"
 
+	"github.com/google/shlex"
 	"github.com/tinygo-org/tinygo/cgo"
 	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/goenv"
@@ -506,6 +507,11 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		var initialCFlags []string
 		initialCFlags = append(initialCFlags, p.program.config.CFlags(true)...)
 		initialCFlags = append(initialCFlags, "-I"+p.Dir)
+		cgoCFlags, err := shlex.Split(goenv.Get("CGO_CFLAGS"))
+		if err != nil {
+			return nil, fmt.Errorf("failed to split CGO_CFLAGS: %w", err)
+		}
+		initialCFlags = append(initialCFlags, cgoCFlags...)
 		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.ImportPath, p.program.fset, initialCFlags, p.program.config.GOOS())
 		p.CFlags = append(initialCFlags, cflags...)
 		p.CGoHeaders = headerCode

main.go

@@ -786,15 +786,15 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 		}
 		defer func() {
 			daemon.Process.Signal(os.Interrupt)
-			var stopped uint32
+			var stopped atomic.Uint32
 			go func() {
 				time.Sleep(time.Millisecond * 100)
-				if atomic.LoadUint32(&stopped) == 0 {
+				if stopped.Load() == 0 {
 					daemon.Process.Kill()
 				}
 			}()
 			daemon.Wait()
-			atomic.StoreUint32(&stopped, 1)
+			stopped.Store(1)
 		}()
 	}
 
@@ -1046,7 +1046,7 @@ func buildAndRun(pkgName string, config *compileopts.Config, stdout io.Writer, c
 
 func touchSerialPortAt1200bps(port string) (err error) {
 	retryCount := 3
-	for i := 0; i < retryCount; i++ {
+	for range retryCount {
 		// Open port
 		p, e := serial.Open(port, &serial.Mode{BaudRate: 1200})
 		if e != nil {
@@ -1244,7 +1244,7 @@ func findFATMounts(options *compileopts.Options) ([]mountPoint, error) {
 		if err != nil {
 			return nil, fmt.Errorf("could not list mount points: %w", err)
 		}
-		for _, line := range strings.Split(string(tab), "\n") {
+		for line := range strings.SplitSeq(string(tab), "\n") {
 			fields := strings.Fields(line)
 			if len(fields) <= 2 {
 				continue
@@ -1273,7 +1273,7 @@ func findFATMounts(options *compileopts.Options) ([]mountPoint, error) {
 		}
 
 		// Extract data to convert to a []mountPoint slice.
-		for _, line := range strings.Split(out.String(), "\n") {
+		for line := range strings.SplitSeq(out.String(), "\n") {
 			words := strings.Fields(line)
 			if len(words) < 3 {
 				continue
@@ -1685,18 +1685,18 @@ func (m globalValuesFlag) String() string {
 }
 
 func (m globalValuesFlag) Set(value string) error {
-	equalsIndex := strings.IndexByte(value, '=')
+	before, after, ok := strings.Cut(value, "=")
-	if equalsIndex < 0 {
+	if !ok {
 		return errors.New("expected format pkgpath.Var=value")
 	}
-	pathAndName := value[:equalsIndex]
+	pathAndName := before
 	pointIndex := strings.LastIndexByte(pathAndName, '.')
 	if pointIndex < 0 {
 		return errors.New("expected format pkgpath.Var=value")
 	}
 	path := pathAndName[:pointIndex]
 	name := pathAndName[pointIndex+1:]
-	stringValue := value[equalsIndex+1:]
+	stringValue := after
 	if m[path] == nil {
 		m[path] = make(map[string]string)
 	}
@@ -2054,7 +2054,6 @@ func main() {
 		// This uses an additional semaphore to reduce the memory usage.
 		testSema := make(chan struct{}, cap(options.Semaphore))
 		for i, pkgName := range explicitPkgNames {
-			pkgName := pkgName
 			buf := &bufs[i]
 			testSema <- struct{}{}
 			wg.Add(1)

main_test.go

@@ -245,6 +245,21 @@ func TestBuild(t *testing.T) {
 	}
 }
 
+// TestTimerStopResetRace checks that stopping or resetting a timer while its
+// callback is running behaves correctly. It reaches into the runtime timer
+// hooks via //go:linkname and relies on the threads scheduler, which is only
+// used on these hosts.
+func TestTimerStopResetRace(t *testing.T) {
+	t.Parallel()
+
+	switch runtime.GOOS {
+	case "darwin", "linux":
+	default:
+		t.Skipf("host GOOS %s does not use the threads scheduler", runtime.GOOS)
+	}
+	runTest("timer_stop_reset_race.go", optionsFromTarget("", sema), t, nil, nil)
+}
+
 func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 	emuCheck(t, options)
 
@@ -383,7 +398,7 @@ func emuCheck(t *testing.T, options compileopts.Options) {
 		t.Fatal("failed to load target spec:", err)
 	}
 	if spec.Emulator != "" {
-		emulatorCommand := strings.SplitN(spec.Emulator, " ", 2)[0]
+		emulatorCommand, _, _ := strings.Cut(spec.Emulator, " ")
 		_, err := exec.LookPath(emulatorCommand)
 		if err != nil {
 			if errors.Is(err, exec.ErrNotFound) {
@@ -458,6 +473,12 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 		options.Directory = path
 		pkgName = "."
 	}
+	isWebAssembly := strings.HasPrefix(options.Target, "wasi") ||
+		strings.HasPrefix(options.Target, "wasm") ||
+		strings.HasPrefix(options.GOARCH, "wasm")
+	if name == "testing.go" && isWebAssembly {
+		expectedOutputPath = TESTDATA + "/testing-wasm.txt"
+	}
 
 	config, err := builder.NewConfig(&options)
 	if err != nil {
@@ -467,12 +488,18 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	// Build the test binary.
 	stdout := &bytes.Buffer{}
 	_, err = buildAndRun(pkgName, config, stdout, cmdArgs, environmentVars, 2*time.Minute, func(cmd *exec.Cmd, result builder.BuildResult) error {
+		if config.EmulatorName() == "simavr" {
+			// simavr before v1.8 wrote firmware output to stderr and loader logs
+			// to stdout, but PR #490 swapped these streams:
+			// https://github.com/buserror/simavr/pull/490
+			cmd.Stdout = stdout
+		}
 		return cmd.Run()
 	})
 	if err != nil {
 		w := &bytes.Buffer{}
 		diagnostics.CreateDiagnostics(err).WriteTo(w, "")
-		for _, line := range strings.Split(strings.TrimRight(w.String(), "\n"), "\n") {
+		for line := range strings.SplitSeq(strings.TrimRight(w.String(), "\n"), "\n") {
 			t.Log(line)
 		}
 		if stdout.Len() != 0 {
@@ -484,11 +511,7 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 
 	actual := stdout.Bytes()
 	if config.EmulatorName() == "simavr" {
-		// Strip simavr log formatting.
+		actual = cleanSimAVRTestOutput(actual)
-		actual = bytes.Replace(actual, []byte{0x1b, '[', '3', '2', 'm'}, nil, -1)
-		actual = bytes.Replace(actual, []byte{0x1b, '[', '0', 'm'}, nil, -1)
-		actual = bytes.Replace(actual, []byte{'.', '.', '\n'}, []byte{'\n'}, -1)
-		actual = bytes.Replace(actual, []byte{'\n', '.', '\n'}, []byte{'\n', '\n'}, -1)
 	}
 	if name == "testing.go" {
 		// Strip actual time.
@@ -515,6 +538,28 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	}
 }
 
+func cleanSimAVRTestOutput(output []byte) []byte {
+	output = bytes.ReplaceAll(output, []byte{0x1b, '[', '3', '2', 'm'}, nil)
+	output = bytes.ReplaceAll(output, []byte{0x1b, '[', '0', 'm'}, nil)
+	output = bytes.ReplaceAll(output, []byte{'.', '.', '\n'}, []byte{'\n'})
+	output = bytes.ReplaceAll(output, []byte{'\n', '.', '\n'}, []byte{'\n', '\n'})
+
+	var cleaned []byte
+	for _, line := range bytes.SplitAfter(output, []byte{'\n'}) {
+		trimmedLine := bytes.TrimRight(line, "\r\n")
+		if simavrLoadTextLogPattern.Match(trimmedLine) || simavrLoadBytesLogPattern.Match(trimmedLine) {
+			continue
+		}
+		cleaned = append(cleaned, line...)
+	}
+	return cleaned
+}
+
+var (
+	simavrLoadTextLogPattern  = regexp.MustCompile(`^Loaded [0-9]+ \.[A-Za-z0-9_]+( at address 0x[0-9a-fA-F]+)?$`)
+	simavrLoadBytesLogPattern = regexp.MustCompile(`^Loaded [0-9]+ bytes of [A-Za-z]+ data at (0x)?[0-9a-fA-F]+$`)
+)
+
 // Test WebAssembly files for certain properties.
 func TestWebAssembly(t *testing.T) {
 	t.Parallel()
@@ -530,7 +575,6 @@ func TestWebAssembly(t *testing.T) {
 		{name: "panic-default", target: "wasip1", imports: []string{"wasi_snapshot_preview1.fd_write", "wasi_snapshot_preview1.random_get"}},
 		{name: "panic-trap", target: "wasm-unknown", panicStrategy: "trap", imports: []string{}},
 	} {
-		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 			tmpdir := t.TempDir()
@@ -652,7 +696,6 @@ func TestWasmExport(t *testing.T) {
 	}
 
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
@@ -822,7 +865,6 @@ func TestWasmExportJS(t *testing.T) {
 		{name: "c-shared", buildMode: "c-shared"},
 	}
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 			// Build the wasm binary.
@@ -870,7 +912,6 @@ func TestWasmExit(t *testing.T) {
 		{name: "exit-1-sleep", output: "slept\nexit code: 1\n"},
 	}
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 			options := optionsFromTarget("wasm", sema)
@@ -913,6 +954,48 @@ func checkOutputData(t *testing.T, expectedOutput, actual []byte) {
 	}
 }
 
+func TestGoexitCrash(t *testing.T) {
+	t.Parallel()
+
+	options := optionsFromTarget("", sema)
+	config, err := builder.NewConfig(&options)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, tc := range []struct {
+		name string
+		want string
+	}{
+		{"main", "all goroutines are asleep - deadlock!"},
+		{"deadlock", "all goroutines are asleep - deadlock!"},
+		{"exit", "all goroutines are asleep - deadlock!"},
+		{"main-other", "all goroutines are asleep - deadlock!"},
+		{"in-panic", "all goroutines are asleep - deadlock!"},
+		{"panic", "panic: panic after Goexit"},
+		{"recovered-panic", "all goroutines are asleep - deadlock!"},
+		{"recover-before-panic", "all goroutines are asleep - deadlock!"},
+		{"recover-before-panic-loop", "all goroutines are asleep - deadlock!"},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			output := &bytes.Buffer{}
+			_, err = buildAndRun("testdata/goexit.go", config, output, []string{tc.name}, nil, time.Minute, func(cmd *exec.Cmd, result builder.BuildResult) error {
+				cmd.Stdout = nil
+				cmd.Stderr = nil
+				data, err := cmd.CombinedOutput()
+				output.Write(data)
+				return err
+			})
+			if err == nil {
+				t.Fatal("program unexpectedly exited successfully")
+			}
+			if !strings.Contains(output.String(), tc.want) {
+				t.Fatalf("output does not contain %q:\n%s", tc.want, output.String())
+			}
+		})
+	}
+}
+
 func TestTest(t *testing.T) {
 	t.Parallel()
 
@@ -945,7 +1028,6 @@ func TestTest(t *testing.T) {
 		)
 	}
 	for _, targ := range targs {
-		targ := targ
 		t.Run(targ.name, func(t *testing.T) {
 			t.Parallel()
 

src/crypto/rand/rand_baremetal.go

@@ -1,4 +1,4 @@
-//go:build nrf || (stm32 && !(stm32f103 || stm32l0x1)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3 || esp32s3 || tkey || (tinygo.riscv32 && virt)
+//go:build nrf || (stm32 && !(stm32f103 || stm32l0x1 || stm32u0)) || (sam && atsamd51) || (sam && atsame5x) || esp32c3 || esp32s3 || tkey || (tinygo.riscv32 && virt)
 
 // If you update the above build constraint, you'll probably also need to update
 // src/runtime/rand_hwrng.go.

src/crypto/tls/cipher_suites.go

@@ -0,0 +1,107 @@
+// TINYGO: cipher suite IDs and the exported CipherSuites/InsecureCipherSuites
+// descriptors, copied verbatim from the Go official implementation. TinyGo has
+// no software handshake, so only these declarations (no selection machinery)
+// are provided to satisfy callers such as google.golang.org/grpc/credentials
+// and github.com/pion/dtls that reference the cipher-suite API surface.
+
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tls
+
+// A list of cipher suite IDs that are, or have been, implemented by this
+// package.
+//
+// See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml
+const (
+	// TLS 1.0 - 1.2 cipher suites.
+	TLS_RSA_WITH_RC4_128_SHA                      uint16 = 0x0005
+	TLS_RSA_WITH_3DES_EDE_CBC_SHA                 uint16 = 0x000a
+	TLS_RSA_WITH_AES_128_CBC_SHA                  uint16 = 0x002f
+	TLS_RSA_WITH_AES_256_CBC_SHA                  uint16 = 0x0035
+	TLS_RSA_WITH_AES_128_CBC_SHA256               uint16 = 0x003c
+	TLS_RSA_WITH_AES_128_GCM_SHA256               uint16 = 0x009c
+	TLS_RSA_WITH_AES_256_GCM_SHA384               uint16 = 0x009d
+	TLS_ECDHE_ECDSA_WITH_RC4_128_SHA              uint16 = 0xc007
+	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA          uint16 = 0xc009
+	TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA          uint16 = 0xc00a
+	TLS_ECDHE_RSA_WITH_RC4_128_SHA                uint16 = 0xc011
+	TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA           uint16 = 0xc012
+	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA            uint16 = 0xc013
+	TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA            uint16 = 0xc014
+	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256       uint16 = 0xc023
+	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256         uint16 = 0xc027
+	TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256         uint16 = 0xc02f
+	TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256       uint16 = 0xc02b
+	TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384         uint16 = 0xc030
+	TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384       uint16 = 0xc02c
+	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   uint16 = 0xcca8
+	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xcca9
+
+	// TLS 1.3 cipher suites.
+	TLS_AES_128_GCM_SHA256       uint16 = 0x1301
+	TLS_AES_256_GCM_SHA384       uint16 = 0x1302
+	TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303
+
+	// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
+	// that the client is doing version fallback. See RFC 7507.
+	TLS_FALLBACK_SCSV uint16 = 0x5600
+
+	// Legacy names for the corresponding cipher suites with the correct _SHA256
+	// suffix, retained for backward compatibility.
+	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305   = TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
+	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
+)
+
+var (
+	supportedUpToTLS12 = []uint16{VersionTLS10, VersionTLS11, VersionTLS12}
+	supportedOnlyTLS12 = []uint16{VersionTLS12}
+	supportedOnlyTLS13 = []uint16{VersionTLS13}
+)
+
+// CipherSuites returns a list of cipher suites currently implemented by this
+// package, excluding those with security issues, which are returned by
+// InsecureCipherSuites.
+func CipherSuites() []*CipherSuite {
+	return []*CipherSuite{
+		{TLS_AES_128_GCM_SHA256, "TLS_AES_128_GCM_SHA256", supportedOnlyTLS13, false},
+		{TLS_AES_256_GCM_SHA384, "TLS_AES_256_GCM_SHA384", supportedOnlyTLS13, false},
+		{TLS_CHACHA20_POLY1305_SHA256, "TLS_CHACHA20_POLY1305_SHA256", supportedOnlyTLS13, false},
+
+		{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false},
+		{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, false},
+		{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false},
+		{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, false},
+		{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, false},
+		{TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, false},
+		{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, false},
+		{TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, false},
+		{TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256, "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256", supportedOnlyTLS12, false},
+		{TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256, "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256", supportedOnlyTLS12, false},
+	}
+}
+
+// InsecureCipherSuites returns a list of cipher suites currently implemented by
+// this package and which have security issues.
+//
+// Most applications should not use the cipher suites in this list, and should
+// only use those returned by CipherSuites.
+func InsecureCipherSuites() []*CipherSuite {
+	// This list includes legacy RSA kex, RC4, CBC_SHA256, and 3DES cipher
+	// suites. See cipherSuitesPreferenceOrder for details.
+	return []*CipherSuite{
+		{TLS_RSA_WITH_RC4_128_SHA, "TLS_RSA_WITH_RC4_128_SHA", supportedUpToTLS12, true},
+		{TLS_RSA_WITH_3DES_EDE_CBC_SHA, "TLS_RSA_WITH_3DES_EDE_CBC_SHA", supportedUpToTLS12, true},
+		{TLS_RSA_WITH_AES_128_CBC_SHA, "TLS_RSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, true},
+		{TLS_RSA_WITH_AES_256_CBC_SHA, "TLS_RSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, true},
+		{TLS_RSA_WITH_AES_128_CBC_SHA256, "TLS_RSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true},
+		{TLS_RSA_WITH_AES_128_GCM_SHA256, "TLS_RSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, true},
+		{TLS_RSA_WITH_AES_256_GCM_SHA384, "TLS_RSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, true},
+		{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA", supportedUpToTLS12, true},
+		{TLS_ECDHE_RSA_WITH_RC4_128_SHA, "TLS_ECDHE_RSA_WITH_RC4_128_SHA", supportedUpToTLS12, true},
+		{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA", supportedUpToTLS12, true},
+		{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true},
+		{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true},
+	}
+}

src/crypto/tls/common.go

@@ -55,6 +55,16 @@ func VersionName(version uint16) string {
 // only supports Elliptic Curve based groups. See RFC 8446, Section 4.2.7.
 type CurveID uint16
 
+const (
+	CurveP256          CurveID = 23
+	CurveP384          CurveID = 24
+	CurveP521          CurveID = 25
+	X25519             CurveID = 29
+	X25519MLKEM768     CurveID = 4588
+	SecP256r1MLKEM768  CurveID = 4587
+	SecP384r1MLKEM1024 CurveID = 4589
+)
+
 // CipherSuiteName returns the standard name for the passed cipher suite ID
 //
 // Not Implemented.
@@ -68,14 +78,42 @@ type ConnectionState struct {
 	//
 	// Minimum (empty) fields for fortio.org/log http logging and others
 	// to compile and run.
-	PeerCertificates []*x509.Certificate
+	Version                    uint16
-	CipherSuite      uint16
+	ServerName                 string
+	PeerCertificates           []*x509.Certificate
+	CipherSuite                uint16
+	NegotiatedProtocol         string
+	NegotiatedProtocolIsMutual bool // Deprecated: this value is always true.
 }
 
 // ClientAuthType declares the policy the server will follow for
 // TLS Client Authentication.
 type ClientAuthType int
 
+const (
+	// NoClientCert indicates that no client certificate should be requested
+	// during the handshake, and if any certificates are sent they will not
+	// be verified.
+	NoClientCert ClientAuthType = iota
+	// RequestClientCert indicates that a client certificate should be requested
+	// during the handshake, but does not require that the client send any
+	// certificates.
+	RequestClientCert
+	// RequireAnyClientCert indicates that a client certificate should be requested
+	// during the handshake, and that at least one certificate is required to be
+	// sent by the client, but that certificate is not required to be valid.
+	RequireAnyClientCert
+	// VerifyClientCertIfGiven indicates that a client certificate should be requested
+	// during the handshake, but does not require that the client sends a
+	// certificate. If the client does send a certificate it is required to be
+	// valid.
+	VerifyClientCertIfGiven
+	// RequireAndVerifyClientCert indicates that a client certificate should be requested
+	// during the handshake, and that at least one valid certificate is required
+	// to be sent by the client.
+	RequireAndVerifyClientCert
+)
+
 // ClientSessionCache is a cache of ClientSessionState objects that can be used
 // by a client to resume a TLS session with a given server. ClientSessionCache
 // implementations should expect to be called concurrently from different
@@ -100,6 +138,45 @@ type ClientSessionCache interface {
 // RFC 8446, Section 4.2.3.
 type SignatureScheme uint16
 
+const (
+	// RSASSA-PKCS1-v1_5 algorithms.
+	PKCS1WithSHA256 SignatureScheme = 0x0401
+	PKCS1WithSHA384 SignatureScheme = 0x0501
+	PKCS1WithSHA512 SignatureScheme = 0x0601
+
+	// RSASSA-PSS algorithms with public key OID rsaEncryption.
+	PSSWithSHA256 SignatureScheme = 0x0804
+	PSSWithSHA384 SignatureScheme = 0x0805
+	PSSWithSHA512 SignatureScheme = 0x0806
+
+	// ECDSA algorithms. Only constrained to a specific curve in TLS 1.3.
+	ECDSAWithP256AndSHA256 SignatureScheme = 0x0403
+	ECDSAWithP384AndSHA384 SignatureScheme = 0x0503
+	ECDSAWithP521AndSHA512 SignatureScheme = 0x0603
+
+	// EdDSA algorithms.
+	Ed25519 SignatureScheme = 0x0807
+
+	// Legacy signature and hash algorithms for TLS 1.2.
+	PKCS1WithSHA1 SignatureScheme = 0x0201
+	ECDSAWithSHA1 SignatureScheme = 0x0203
+)
+
+// CipherSuite is a TLS cipher suite. Note that most functions in this package
+// accept and expose cipher suite IDs instead of this type.
+type CipherSuite struct {
+	ID   uint16
+	Name string
+
+	// Supported versions is the list of TLS protocol versions that can
+	// negotiate this cipher suite.
+	SupportedVersions []uint16
+
+	// Insecure is true if the cipher suite has known security issues
+	// due to its primitives, design, or implementation.
+	Insecure bool
+}
+
 // ClientHelloInfo contains information from a ClientHello message in order to
 // guide application logic in the GetCertificate and GetConfigForClient callbacks.
 type ClientHelloInfo struct {
@@ -459,6 +536,48 @@ type Config struct {
 	autoSessionTicketKeys []ticketKey
 }
 
+// Clone returns a shallow clone of c or nil if c is nil. It is safe to clone a
+// Config that is being used concurrently by a TLS client or server.
+func (c *Config) Clone() *Config {
+	if c == nil {
+		return nil
+	}
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	return &Config{
+		Rand:                        c.Rand,
+		Time:                        c.Time,
+		Certificates:                c.Certificates,
+		NameToCertificate:           c.NameToCertificate,
+		GetCertificate:              c.GetCertificate,
+		GetClientCertificate:        c.GetClientCertificate,
+		GetConfigForClient:          c.GetConfigForClient,
+		VerifyPeerCertificate:       c.VerifyPeerCertificate,
+		VerifyConnection:            c.VerifyConnection,
+		RootCAs:                     c.RootCAs,
+		NextProtos:                  c.NextProtos,
+		ServerName:                  c.ServerName,
+		ClientAuth:                  c.ClientAuth,
+		ClientCAs:                   c.ClientCAs,
+		InsecureSkipVerify:          c.InsecureSkipVerify,
+		CipherSuites:                c.CipherSuites,
+		PreferServerCipherSuites:    c.PreferServerCipherSuites,
+		SessionTicketsDisabled:      c.SessionTicketsDisabled,
+		SessionTicketKey:            c.SessionTicketKey,
+		ClientSessionCache:          c.ClientSessionCache,
+		UnwrapSession:               c.UnwrapSession,
+		WrapSession:                 c.WrapSession,
+		MinVersion:                  c.MinVersion,
+		MaxVersion:                  c.MaxVersion,
+		CurvePreferences:            c.CurvePreferences,
+		DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled,
+		Renegotiation:               c.Renegotiation,
+		KeyLogWriter:                c.KeyLogWriter,
+		sessionTicketKeys:           c.sessionTicketKeys,
+		autoSessionTicketKeys:       c.autoSessionTicketKeys,
+	}
+}
+
 // ticketKey is the internal representation of a session ticket key.
 type ticketKey struct {
 	aesKey  [16]byte

src/crypto/tls/tls.go

@@ -20,13 +20,52 @@ import (
 	"net"
 )
 
+// Conn represents a secured connection. TINYGO: the actual TLS handshake and
+// record layer are offloaded to the network device (see net.TLSConn), so Conn
+// is a thin wrapper over an underlying net.Conn that exists to satisfy callers
+// (e.g. google.golang.org/grpc/credentials) which expect the *tls.Conn API
+// shape — ConnectionState/Handshake — that this package does not implement in
+// software.
+type Conn struct {
+	net.Conn
+}
+
+// ConnectionState returns basic TLS details about the connection. TINYGO:
+// empty; TLS is offloaded to the network device.
+func (c *Conn) ConnectionState() ConnectionState {
+	return ConnectionState{}
+}
+
+// Handshake runs the client or server handshake protocol if it has not yet been
+// run. TINYGO: no-op; the handshake is performed by the network device.
+func (c *Conn) Handshake() error {
+	return c.HandshakeContext(context.Background())
+}
+
+// HandshakeContext is the context-aware variant of Handshake. TINYGO: no-op.
+func (c *Conn) HandshakeContext(ctx context.Context) error {
+	return nil
+}
+
+// NetConn returns the underlying connection that is wrapped by c.
+func (c *Conn) NetConn() net.Conn {
+	return c.Conn
+}
+
 // Client returns a new TLS client side connection
 // using conn as the underlying transport.
 // The config cannot be nil: users must set either ServerName or
 // InsecureSkipVerify in the config.
-func Client(conn net.Conn, config *Config) *net.TLSConn {
+func Client(conn net.Conn, config *Config) *Conn {
-	panic("tls.Client() not implemented")
+	return &Conn{Conn: conn}
-	return nil
+}
+
+// Server returns a new TLS server side connection
+// using conn as the underlying transport.
+// The configuration config must be non-nil and must include
+// at least one certificate or else set GetCertificate.
+func Server(conn net.Conn, config *Config) *Conn {
+	return &Conn{Conn: conn}
 }
 
 // A listener implements a network listener (net.Listener) for TLS connections.

src/device/amd64/cpu.go

@@ -0,0 +1,74 @@
+//go:build amd64
+
+package amd64
+
+const (
+	CPUIDTimeStampCounter   = 0x15
+	CPUIDProcessorFrequency = 0x16
+)
+
+type CPUExtendedFamily uint16
+
+const (
+	CPUFamilyIntelCore CPUExtendedFamily = 6
+)
+
+//export asmPause
+func AsmPause()
+
+//export asmReadRdtsc
+func AsmReadRdtsc() uint64
+
+//export asmCpuid
+func AsmCpuid(index uint32, registerEax *uint32, registerEbx *uint32, registerEcx *uint32) int
+
+var maxCpuidIndex uint32
+var stdVendorName0 uint32
+var stdCpuid1Eax uint32
+
+func init() {
+	AsmCpuid(0, &maxCpuidIndex, &stdVendorName0, nil)
+	AsmCpuid(1, &stdCpuid1Eax, nil, nil)
+}
+
+func getExtendedCPUFamily() CPUExtendedFamily {
+	family := CPUExtendedFamily((stdCpuid1Eax >> 8) & 0x0f)
+	family += CPUExtendedFamily((stdCpuid1Eax >> 20) & 0xff)
+	return family
+}
+
+func isIntel() bool {
+	return stdVendorName0 == 0x756e6547
+}
+
+func isIntelFamilyCore() bool {
+	return isIntel() && getExtendedCPUFamily() == CPUFamilyIntelCore
+}
+
+func InternalGetPerformanceCounterFrequency() uint64 {
+	if maxCpuidIndex >= CPUIDTimeStampCounter {
+		return cpuidCoreClockCalculateTSCFrequency()
+	}
+	return 0
+}
+
+func cpuidCoreClockCalculateTSCFrequency() uint64 {
+	var eax uint32
+	var ebx uint32
+	var ecx uint32
+
+	AsmCpuid(CPUIDTimeStampCounter, &eax, &ebx, &ecx)
+	if eax == 0 || ebx == 0 {
+		return 0
+	}
+
+	coreCrystalFrequency := uint64(ecx)
+	if coreCrystalFrequency == 0 {
+		if !isIntelFamilyCore() {
+			return 0
+		}
+		coreCrystalFrequency = 24000000
+	}
+
+	return ((coreCrystalFrequency * uint64(ebx)) + (uint64(eax) / 2)) / uint64(eax)
+}

src/device/amd64/cpu_amd64.S

@@ -0,0 +1,39 @@
+.section .text
+
+.global asmPause
+asmPause:
+    pause
+    ret
+
+.global asmReadRdtsc
+asmReadRdtsc:
+    rdtsc
+    shlq  $0x20, %rdx
+    orq   %rdx, %rax
+    ret
+
+.global asmCpuid
+asmCpuid:
+    pushq  %rbx
+
+    mov    %ecx, %eax
+    pushq  %rax
+
+    pushq  %rdx
+    cpuid
+
+    test   %r9, %r9
+    jz     .SkipEcx
+    mov    %ecx, (%r9)
+.SkipEcx:
+    popq   %rcx
+    jrcxz  .SkipEax
+    mov    %eax, (%rcx)
+.SkipEax:
+    mov    %r8, %rcx
+    jrcxz  .SkipEbx
+    mov    %ebx, (%rcx)
+.SkipEbx:
+    popq   %rax
+    popq   %rbx
+    ret

src/device/uefi/arch_x86.go

@@ -0,0 +1,17 @@
+//go:build i386 || amd64
+
+package uefi
+
+import "device/amd64"
+
+func Ticks() uint64 {
+	return amd64.AsmReadRdtsc()
+}
+
+func CpuPause() {
+	amd64.AsmPause()
+}
+
+func getTSCFrequency() uint64 {
+	return amd64.InternalGetPerformanceCounterFrequency()
+}

src/device/uefi/asm_amd64.S

@@ -0,0 +1,201 @@
+.section .text
+
+.global uefiCall0
+uefiCall0:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x20, %rsp
+    callq  *%rcx
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall1
+uefiCall1:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x20, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall2
+uefiCall2:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x20, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall3
+uefiCall3:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x20, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall4
+uefiCall4:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x20, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall5
+uefiCall5:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x30, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall6
+uefiCall6:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x30, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    movq   0x40(%rbp), %r10
+    movq   %r10, 0x28(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall7
+uefiCall7:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x40, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    movq   0x40(%rbp), %r10
+    movq   %r10, 0x28(%rsp)
+    movq   0x48(%rbp), %r10
+    movq   %r10, 0x30(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall8
+uefiCall8:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x40, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    movq   0x40(%rbp), %r10
+    movq   %r10, 0x28(%rsp)
+    movq   0x48(%rbp), %r10
+    movq   %r10, 0x30(%rsp)
+    movq   0x50(%rbp), %r10
+    movq   %r10, 0x38(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall9
+uefiCall9:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x50, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    movq   0x40(%rbp), %r10
+    movq   %r10, 0x28(%rsp)
+    movq   0x48(%rbp), %r10
+    movq   %r10, 0x30(%rsp)
+    movq   0x50(%rbp), %r10
+    movq   %r10, 0x38(%rsp)
+    movq   0x58(%rbp), %r10
+    movq   %r10, 0x40(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global uefiCall10
+uefiCall10:
+    pushq  %rbp
+    movq   %rsp, %rbp
+    subq   $0x50, %rsp
+    movq   %rcx, %rax
+    movq   %rdx, %rcx
+    movq   %r8,  %rdx
+    movq   %r9,  %r8
+    movq   0x30(%rbp), %r9
+    movq   0x38(%rbp), %r10
+    movq   %r10, 0x20(%rsp)
+    movq   0x40(%rbp), %r10
+    movq   %r10, 0x28(%rsp)
+    movq   0x48(%rbp), %r10
+    movq   %r10, 0x30(%rsp)
+    movq   0x50(%rbp), %r10
+    movq   %r10, 0x38(%rsp)
+    movq   0x58(%rbp), %r10
+    movq   %r10, 0x40(%rsp)
+    movq   0x60(%rbp), %r10
+    movq   %r10, 0x48(%rsp)
+    callq  *%rax
+    movq   %rbp, %rsp
+    popq   %rbp
+    ret
+
+.global ___chkstk_ms
+___chkstk_ms:
+    ret

src/device/uefi/call.go

@@ -0,0 +1,45 @@
+package uefi
+
+//go:nosplit
+//export uefiCall0
+func UefiCall0(fn uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall1
+func UefiCall1(fn uintptr, a uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall2
+func UefiCall2(fn uintptr, a uintptr, b uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall3
+func UefiCall3(fn uintptr, a uintptr, b uintptr, c uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall4
+func UefiCall4(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall5
+func UefiCall5(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall6
+func UefiCall6(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr, f uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall7
+func UefiCall7(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr, f uintptr, g uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall8
+func UefiCall8(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr, f uintptr, g uintptr, h uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall9
+func UefiCall9(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr, f uintptr, g uintptr, h uintptr, i uintptr) EFI_STATUS
+
+//go:nosplit
+//go:export uefiCall10
+func UefiCall10(fn uintptr, a uintptr, b uintptr, c uintptr, d uintptr, e uintptr, f uintptr, g uintptr, h uintptr, i uintptr, j uintptr) EFI_STATUS

src/device/uefi/char16.go

@@ -0,0 +1,77 @@
+package uefi
+
+import (
+	"unicode/utf16"
+	"unsafe"
+)
+
+// StringToCHAR16 converts a Go string to a UTF-16 code unit slice.
+func StringToCHAR16(s string) []CHAR16 {
+	if s == "" {
+		return nil
+	}
+
+	encoded := utf16.Encode([]rune(s))
+	out := make([]CHAR16, len(encoded))
+	for i, r := range encoded {
+		out[i] = CHAR16(r)
+	}
+	return out
+}
+
+// StringToCHAR16Z converts a Go string to a NUL-terminated UTF-16 code unit slice.
+func StringToCHAR16Z(s string) []CHAR16 {
+	out := StringToCHAR16(s)
+	return append(out, 0)
+}
+
+// BytesToCHAR16 converts UTF-8 text bytes to a UTF-16 code unit slice.
+func BytesToCHAR16(b []byte) []CHAR16 {
+	return StringToCHAR16(string(b))
+}
+
+// BytesToCHAR16Z converts UTF-8 text bytes to a NUL-terminated UTF-16 code unit slice.
+func BytesToCHAR16Z(b []byte) []CHAR16 {
+	return StringToCHAR16Z(string(b))
+}
+
+// CHAR16ToString converts a UTF-16 code unit slice to a Go string.
+func CHAR16ToString(input []CHAR16) string {
+	if len(input) == 0 {
+		return ""
+	}
+
+	units := make([]uint16, len(input))
+	for i, c := range input {
+		units[i] = uint16(c)
+	}
+	return string(utf16.Decode(units))
+}
+
+// CHAR16ToBytes converts a UTF-16 code unit slice to UTF-8 text bytes.
+func CHAR16ToBytes(input []CHAR16) []byte {
+	return []byte(CHAR16ToString(input))
+}
+
+// CHAR16PtrToString converts a NUL-terminated UTF-16 string pointer to a Go string.
+func CHAR16PtrToString(input *CHAR16) string {
+	if input == nil {
+		return ""
+	}
+
+	ptr := uintptr(unsafe.Pointer(input))
+	length := 0
+	for *(*CHAR16)(unsafe.Pointer(ptr)) != 0 {
+		length++
+		ptr += 2
+	}
+	return CHAR16PtrLenToString(input, length)
+}
+
+// CHAR16PtrLenToString converts a UTF-16 string pointer with a known code unit count to a Go string.
+func CHAR16PtrLenToString(input *CHAR16, length int) string {
+	if input == nil || length <= 0 {
+		return ""
+	}
+	return CHAR16ToString(unsafe.Slice(input, length))
+}

src/device/uefi/clock.go

@@ -0,0 +1,39 @@
+//go:build uefi
+
+package uefi
+
+import "sync"
+
+var calibrateMutex sync.Mutex
+var calculatedFrequency uint64
+
+func TicksFrequency() uint64 {
+	frequency := getTSCFrequency()
+	if frequency > 0 {
+		return frequency
+	}
+
+	calibrateMutex.Lock()
+	defer calibrateMutex.Unlock()
+	if calculatedFrequency > 0 {
+		return calculatedFrequency
+	}
+
+	var event EFI_EVENT
+	var index UINTN
+	if BS().CreateEvent(EVT_TIMER, TPL_CALLBACK, nil, nil, &event) != EFI_SUCCESS {
+		return 0
+	}
+	defer BS().CloseEvent(event)
+
+	start := Ticks()
+	if BS().SetTimer(event, TimerPeriodic, 250*10000) != EFI_SUCCESS {
+		return 0
+	}
+	if BS().WaitForEvent(1, &event, &index) != EFI_SUCCESS {
+		return 0
+	}
+
+	calculatedFrequency = (Ticks() - start) * 4
+	return calculatedFrequency
+}

src/device/uefi/efidef.go

@@ -0,0 +1,66 @@
+package uefi
+
+type UINTN uintptr
+type EFI_STATUS UINTN
+type EFI_TPL UINTN
+type EFI_HANDLE uintptr
+type EFI_EVENT uintptr
+type EFI_PHYSICAL_ADDRESS uint64
+
+type CHAR16 uint16
+type BOOLEAN bool
+type VOID byte
+
+type EFI_GUID struct {
+	Data1 uint32
+	Data2 uint16
+	Data3 uint16
+	Data4 [8]byte
+}
+
+type EFI_TABLE_HEADER struct {
+	Signature  uint64
+	Revision   uint32
+	HeaderSize uint32
+	CRC32      uint32
+	Reserved   uint32
+}
+
+type EFI_ALLOCATE_TYPE int
+
+const (
+	AllocateAnyPages EFI_ALLOCATE_TYPE = iota
+	AllocateMaxAddress
+	AllocateAddress
+)
+
+type EFI_MEMORY_TYPE int
+
+const (
+	EfiReservedMemoryType EFI_MEMORY_TYPE = iota
+	EfiLoaderCode
+	EfiLoaderData
+	EfiBootServicesCode
+	EfiBootServicesData
+	EfiRuntimeServicesCode
+	EfiRuntimeServicesData
+	EfiConventionalMemory
+)
+
+type EVENT_TYPE uint32
+
+const (
+	EVT_TIMER EVENT_TYPE = 0x80000000
+)
+
+const (
+	TPL_CALLBACK EFI_TPL = 8
+)
+
+type EFI_TIMER_DELAY int
+
+const (
+	TimerCancel EFI_TIMER_DELAY = iota
+	TimerPeriodic
+	TimerRelative
+)

src/device/uefi/efistatus.go

@@ -0,0 +1,111 @@
+package uefi
+
+const (
+	uintnSize = 32 << (^uintptr(0) >> 63)
+	errorMask = 1 << uintptr(uintnSize-1)
+)
+
+const (
+	EFI_SUCCESS              EFI_STATUS = 0
+	EFI_LOAD_ERROR           EFI_STATUS = errorMask | 1
+	EFI_INVALID_PARAMETER    EFI_STATUS = errorMask | 2
+	EFI_UNSUPPORTED          EFI_STATUS = errorMask | 3
+	EFI_BAD_BUFFER_SIZE      EFI_STATUS = errorMask | 4
+	EFI_BUFFER_TOO_SMALL     EFI_STATUS = errorMask | 5
+	EFI_NOT_READY            EFI_STATUS = errorMask | 6
+	EFI_DEVICE_ERROR         EFI_STATUS = errorMask | 7
+	EFI_WRITE_PROTECTED      EFI_STATUS = errorMask | 8
+	EFI_OUT_OF_RESOURCES     EFI_STATUS = errorMask | 9
+	EFI_VOLUME_CORRUPTED     EFI_STATUS = errorMask | 10
+	EFI_VOLUME_FULL          EFI_STATUS = errorMask | 11
+	EFI_NO_MEDIA             EFI_STATUS = errorMask | 12
+	EFI_MEDIA_CHANGED        EFI_STATUS = errorMask | 13
+	EFI_NOT_FOUND            EFI_STATUS = errorMask | 14
+	EFI_ACCESS_DENIED        EFI_STATUS = errorMask | 15
+	EFI_NO_RESPONSE          EFI_STATUS = errorMask | 16
+	EFI_NO_MAPPING           EFI_STATUS = errorMask | 17
+	EFI_TIMEOUT              EFI_STATUS = errorMask | 18
+	EFI_NOT_STARTED          EFI_STATUS = errorMask | 19
+	EFI_ALREADY_STARTED      EFI_STATUS = errorMask | 20
+	EFI_ABORTED              EFI_STATUS = errorMask | 21
+	EFI_ICMP_ERROR           EFI_STATUS = errorMask | 22
+	EFI_TFTP_ERROR           EFI_STATUS = errorMask | 23
+	EFI_PROTOCOL_ERROR       EFI_STATUS = errorMask | 24
+	EFI_INCOMPATIBLE_VERSION EFI_STATUS = errorMask | 25
+	EFI_SECURITY_VIOLATION   EFI_STATUS = errorMask | 26
+	EFI_CRC_ERROR            EFI_STATUS = errorMask | 27
+	EFI_END_OF_MEDIA         EFI_STATUS = errorMask | 28
+	EFI_END_OF_FILE          EFI_STATUS = errorMask | 31
+	EFI_INVALID_LANGUAGE     EFI_STATUS = errorMask | 32
+	EFI_COMPROMISED_DATA     EFI_STATUS = errorMask | 33
+	EFI_IP_ADDRESS_CONFLICT  EFI_STATUS = errorMask | 34
+	EFI_HTTP_ERROR           EFI_STATUS = errorMask | 35
+)
+
+var errMap = map[EFI_STATUS]*Error{}
+
+var (
+	ErrLoadError           = newError(EFI_LOAD_ERROR, "image failed to load")
+	ErrInvalidParameter    = newError(EFI_INVALID_PARAMETER, "a parameter was incorrect")
+	ErrUnsupported         = newError(EFI_UNSUPPORTED, "operation not supported")
+	ErrBadBufferSize       = newError(EFI_BAD_BUFFER_SIZE, "buffer size incorrect for request")
+	ErrBufferTooSmall      = newError(EFI_BUFFER_TOO_SMALL, "buffer too small; size returned in parameter")
+	ErrNotReady            = newError(EFI_NOT_READY, "no data pending")
+	ErrDeviceError         = newError(EFI_DEVICE_ERROR, "physical device reported an error")
+	ErrWriteProtected      = newError(EFI_WRITE_PROTECTED, "device is write-protected")
+	ErrOutOfResources      = newError(EFI_OUT_OF_RESOURCES, "out of resources")
+	ErrVolumeCorrupted     = newError(EFI_VOLUME_CORRUPTED, "filesystem inconsistency detected")
+	ErrVolumeFull          = newError(EFI_VOLUME_FULL, "no more space on filesystem")
+	ErrNoMedia             = newError(EFI_NO_MEDIA, "device contains no medium")
+	ErrMediaChanged        = newError(EFI_MEDIA_CHANGED, "medium changed since last access")
+	ErrNotFound            = newError(EFI_NOT_FOUND, "item not found")
+	ErrAccessDenied        = newError(EFI_ACCESS_DENIED, "access denied")
+	ErrNoResponse          = newError(EFI_NO_RESPONSE, "server not found or no response")
+	ErrNoMapping           = newError(EFI_NO_MAPPING, "no device mapping exists")
+	ErrTimeout             = newError(EFI_TIMEOUT, "timeout expired")
+	ErrNotStarted          = newError(EFI_NOT_STARTED, "protocol not started")
+	ErrAlreadyStarted      = newError(EFI_ALREADY_STARTED, "protocol already started")
+	ErrAborted             = newError(EFI_ABORTED, "operation aborted")
+	ErrICMPError           = newError(EFI_ICMP_ERROR, "ICMP error during network operation")
+	ErrTFTPError           = newError(EFI_TFTP_ERROR, "TFTP error during network operation")
+	ErrProtocolError       = newError(EFI_PROTOCOL_ERROR, "protocol error during network operation")
+	ErrIncompatibleVersion = newError(EFI_INCOMPATIBLE_VERSION, "requested version incompatible")
+	ErrSecurityViolation   = newError(EFI_SECURITY_VIOLATION, "security violation")
+	ErrCRCError            = newError(EFI_CRC_ERROR, "CRC error detected")
+	ErrEndOfMedia          = newError(EFI_END_OF_MEDIA, "beginning or end of media reached")
+	ErrEndOfFile           = newError(EFI_END_OF_FILE, "end of file reached")
+	ErrInvalidLanguage     = newError(EFI_INVALID_LANGUAGE, "invalid language specified")
+	ErrCompromisedData     = newError(EFI_COMPROMISED_DATA, "data security status unknown or compromised")
+	ErrIPAddressConflict   = newError(EFI_IP_ADDRESS_CONFLICT, "IP address conflict detected")
+	ErrHTTPError           = newError(EFI_HTTP_ERROR, "HTTP error during network operation")
+)
+
+type Error struct {
+	code EFI_STATUS
+	msg  string
+}
+
+func newError(code EFI_STATUS, msg string) *Error {
+	err := &Error{code: code, msg: msg}
+	errMap[code] = err
+	return err
+}
+
+func (e *Error) Error() string {
+	return e.msg
+}
+
+func (e *Error) Status() EFI_STATUS {
+	return e.code
+}
+
+func StatusError(status EFI_STATUS) *Error {
+	if status == EFI_SUCCESS {
+		return nil
+	}
+	err, ok := errMap[status]
+	if !ok {
+		return newError(status, "unknown EFI error")
+	}
+	return err
+}

src/device/uefi/simple_text_out.go

@@ -0,0 +1,74 @@
+package uefi
+
+import "unsafe"
+
+func booleanArg(v BOOLEAN) uintptr {
+	if v {
+		return 1
+	}
+	return 0
+}
+
+type EFI_SIMPLE_TEXT_OUTPUT_MODE struct {
+	MaxMode       int32
+	Mode          int32
+	Attribute     int32
+	CursorColumn  int32
+	CursorRow     int32
+	CursorVisible BOOLEAN
+}
+
+type EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL struct {
+	reset             uintptr
+	outputString      uintptr
+	testString        uintptr
+	queryMode         uintptr
+	setMode           uintptr
+	setAttribute      uintptr
+	clearScreen       uintptr
+	setCursorPosition uintptr
+	enableCursor      uintptr
+	Mode              *EFI_SIMPLE_TEXT_OUTPUT_MODE
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) Reset(extendedVerification BOOLEAN) EFI_STATUS {
+	return UefiCall2(p.reset, uintptr(unsafe.Pointer(p)), booleanArg(extendedVerification))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) OutputString(s *CHAR16) EFI_STATUS {
+	return UefiCall2(p.outputString, uintptr(unsafe.Pointer(p)), uintptr(unsafe.Pointer(s)))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) TestString(s *CHAR16) EFI_STATUS {
+	return UefiCall2(p.testString, uintptr(unsafe.Pointer(p)), uintptr(unsafe.Pointer(s)))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) QueryMode(modeNumber UINTN, columns *UINTN, rows *UINTN) EFI_STATUS {
+	return UefiCall4(
+		p.queryMode,
+		uintptr(unsafe.Pointer(p)),
+		uintptr(modeNumber),
+		uintptr(unsafe.Pointer(columns)),
+		uintptr(unsafe.Pointer(rows)),
+	)
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) SetMode(modeNumber UINTN) EFI_STATUS {
+	return UefiCall2(p.setMode, uintptr(unsafe.Pointer(p)), uintptr(modeNumber))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) SetAttribute(attribute UINTN) EFI_STATUS {
+	return UefiCall2(p.setAttribute, uintptr(unsafe.Pointer(p)), uintptr(attribute))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) ClearScreen() EFI_STATUS {
+	return UefiCall1(p.clearScreen, uintptr(unsafe.Pointer(p)))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) SetCursorPosition(column UINTN, row UINTN) EFI_STATUS {
+	return UefiCall3(p.setCursorPosition, uintptr(unsafe.Pointer(p)), uintptr(column), uintptr(row))
+}
+
+func (p *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) EnableCursor(visible BOOLEAN) EFI_STATUS {
+	return UefiCall2(p.enableCursor, uintptr(unsafe.Pointer(p)), booleanArg(visible))
+}

src/device/uefi/tables.go

@@ -0,0 +1,123 @@
+package uefi
+
+import "unsafe"
+
+type EFI_RUNTIME_SERVICES struct {
+	Hdr                  EFI_TABLE_HEADER
+	getTime              uintptr
+	setTime              uintptr
+	getWakeupTime        uintptr
+	setWakeupTime        uintptr
+	setVirtualAddressMap uintptr
+	convertPointer       uintptr
+	getVariable          uintptr
+	getNextVariableName  uintptr
+	setVariable          uintptr
+	getNextHighMonoCount uintptr
+	resetSystem          uintptr
+	updateCapsule        uintptr
+	queryCapsuleCaps     uintptr
+	queryVariableInfo    uintptr
+}
+
+type EFI_BOOT_SERVICES struct {
+	Hdr                       EFI_TABLE_HEADER
+	raiseTPL                  uintptr
+	restoreTPL                uintptr
+	allocatePages             uintptr
+	freePages                 uintptr
+	getMemoryMap              uintptr
+	allocatePool              uintptr
+	freePool                  uintptr
+	createEvent               uintptr
+	setTimer                  uintptr
+	waitForEvent              uintptr
+	signalEvent               uintptr
+	closeEvent                uintptr
+	checkEvent                uintptr
+	installProtocolInterface  uintptr
+	reinstallProtocolIFace    uintptr
+	uninstallProtocolIFace    uintptr
+	handleProtocol            uintptr
+	reserved                  *VOID
+	registerProtocolNotify    uintptr
+	locateHandle              uintptr
+	locateDevicePath          uintptr
+	installConfigurationTable uintptr
+	loadImage                 uintptr
+	startImage                uintptr
+	exit                      uintptr
+	unloadImage               uintptr
+	exitBootServices          uintptr
+	getNextMonotonicCount     uintptr
+	stall                     uintptr
+	setWatchdogTimer          uintptr
+	connectController         uintptr
+	disconnectController      uintptr
+	openProtocol              uintptr
+	closeProtocol             uintptr
+	openProtocolInformation   uintptr
+	protocolsPerHandle        uintptr
+	locateHandleBuffer        uintptr
+	locateProtocol            uintptr
+}
+
+func (p *EFI_BOOT_SERVICES) AllocatePages(typ EFI_ALLOCATE_TYPE, memoryType EFI_MEMORY_TYPE, pages UINTN, memory *EFI_PHYSICAL_ADDRESS) EFI_STATUS {
+	return UefiCall4(p.allocatePages, uintptr(typ), uintptr(memoryType), uintptr(pages), uintptr(unsafe.Pointer(memory)))
+}
+
+func (p *EFI_BOOT_SERVICES) FreePages(memory EFI_PHYSICAL_ADDRESS, pages UINTN) EFI_STATUS {
+	return UefiCall2(p.freePages, uintptr(memory), uintptr(pages))
+}
+
+func (p *EFI_BOOT_SERVICES) CreateEvent(typ EVENT_TYPE, notifyTPL EFI_TPL, notifyFunction unsafe.Pointer, notifyContext unsafe.Pointer, event *EFI_EVENT) EFI_STATUS {
+	return UefiCall5(p.createEvent, uintptr(typ), uintptr(notifyTPL), uintptr(notifyFunction), uintptr(notifyContext), uintptr(unsafe.Pointer(event)))
+}
+
+func (p *EFI_BOOT_SERVICES) SetTimer(event EFI_EVENT, typ EFI_TIMER_DELAY, triggerTime uint64) EFI_STATUS {
+	return UefiCall3(p.setTimer, uintptr(event), uintptr(typ), uintptr(triggerTime))
+}
+
+func (p *EFI_BOOT_SERVICES) WaitForEvent(numberOfEvents UINTN, event *EFI_EVENT, index *UINTN) EFI_STATUS {
+	return UefiCall3(p.waitForEvent, uintptr(numberOfEvents), uintptr(unsafe.Pointer(event)), uintptr(unsafe.Pointer(index)))
+}
+
+func (p *EFI_BOOT_SERVICES) CloseEvent(event EFI_EVENT) EFI_STATUS {
+	return UefiCall1(p.closeEvent, uintptr(event))
+}
+
+func (p *EFI_BOOT_SERVICES) CheckEvent(event EFI_EVENT) EFI_STATUS {
+	return UefiCall1(p.checkEvent, uintptr(event))
+}
+
+func (p *EFI_BOOT_SERVICES) HandleProtocol(handle EFI_HANDLE, protocol *EFI_GUID, iface unsafe.Pointer) EFI_STATUS {
+	return UefiCall3(p.handleProtocol, uintptr(handle), uintptr(unsafe.Pointer(protocol)), uintptr(iface))
+}
+
+func (p *EFI_BOOT_SERVICES) LocateProtocol(protocol *EFI_GUID, registration *VOID, iface unsafe.Pointer) EFI_STATUS {
+	return UefiCall3(p.locateProtocol, uintptr(unsafe.Pointer(protocol)), uintptr(unsafe.Pointer(registration)), uintptr(iface))
+}
+
+func (p *EFI_BOOT_SERVICES) Exit(imageHandle EFI_HANDLE, exitStatus EFI_STATUS, exitDataSize UINTN, exitData *CHAR16) EFI_STATUS {
+	return UefiCall4(p.exit, uintptr(imageHandle), uintptr(exitStatus), uintptr(exitDataSize), uintptr(unsafe.Pointer(exitData)))
+}
+
+func (p *EFI_BOOT_SERVICES) SetWatchdogTimer(timeout UINTN, watchdogCode uint64, dataSize UINTN, watchdogData *CHAR16) EFI_STATUS {
+	return UefiCall4(p.setWatchdogTimer, uintptr(timeout), uintptr(watchdogCode), uintptr(dataSize), uintptr(unsafe.Pointer(watchdogData)))
+}
+
+type EFI_SYSTEM_TABLE struct {
+	Hdr                  EFI_TABLE_HEADER
+	FirmwareVendor       *CHAR16
+	FirmwareRevision     uint32
+	ConsoleInHandle      EFI_HANDLE
+	ConIn                *VOID
+	ConsoleOutHandle     EFI_HANDLE
+	ConOut               *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
+	StandardErrorHandle  EFI_HANDLE
+	StdErr               *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
+	RuntimeServices      *EFI_RUNTIME_SERVICES
+	BootServices         *EFI_BOOT_SERVICES
+	NumberOfTableEntries UINTN
+	ConfigurationTable   *VOID
+}

src/device/uefi/text_output.go

@@ -0,0 +1,41 @@
+package uefi
+
+import "errors"
+
+var errNilTextOutputProtocol = errors.New("uefi: nil simple text output protocol")
+
+type TextOutput struct {
+	proto *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
+}
+
+func NewTextOutput(proto *EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL) *TextOutput {
+	return &TextOutput{proto: proto}
+}
+
+func ConsoleOut() *TextOutput {
+	return NewTextOutput(ST().ConOut)
+}
+
+func StandardError() *TextOutput {
+	return NewTextOutput(ST().StdErr)
+}
+
+func (w *TextOutput) Write(p []byte) (int, error) {
+	if w == nil || w.proto == nil {
+		return 0, errNilTextOutputProtocol
+	}
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	buf := StringToCHAR16Z(string(p))
+	status := w.proto.OutputString(&buf[0])
+	if status != EFI_SUCCESS {
+		return 0, StatusError(status)
+	}
+	return len(p), nil
+}
+
+func (w *TextOutput) WriteString(s string) (int, error) {
+	return w.Write([]byte(s))
+}

src/device/uefi/util.go

@@ -0,0 +1,29 @@
+//go:build uefi
+
+package uefi
+
+import "unsafe"
+
+var systemTable *EFI_SYSTEM_TABLE
+var imageHandle uintptr
+
+//go:nobounds
+func Init(argImageHandle uintptr, argSystemTable uintptr) {
+	systemTable = (*EFI_SYSTEM_TABLE)(unsafe.Pointer(argSystemTable))
+	imageHandle = argImageHandle
+}
+
+func ST() *EFI_SYSTEM_TABLE {
+	return systemTable
+}
+
+func BS() *EFI_BOOT_SERVICES {
+	if systemTable == nil {
+		return nil
+	}
+	return systemTable.BootServices
+}
+
+func GetImageHandle() EFI_HANDLE {
+	return EFI_HANDLE(imageHandle)
+}

src/examples/hid-keyboard/main.go

@@ -22,6 +22,7 @@ func main() {
 	button.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 
 	kb := keyboard.Port()
+	machine.USBDev.Configure(machine.UARTConfig{}) // no-op if already init'd by serial.usb
 
 	for {
 		if !button.Get() {

src/examples/memstats/memstats.go

@@ -25,7 +25,7 @@ func main() {
 func escapesToHeap() {
 	n := rand.Intn(100)
 	println("Doing ", n, " iterations")
-	for i := 0; i < n; i++ {
+	for i := range n {
 		s := make([]byte, i)
 		_ = append(s, 42)
 	}

src/examples/test/test.go

@@ -70,7 +70,7 @@ func main() {
 	printItf(Number(3))
 	s := Stringer(thing)
 	println("Stringer.String():", s.String())
-	var itf interface{} = s
+	var itf any = s
 	println("Stringer.(*Thing).String():", itf.(Stringer).String())
 
 	// unusual calls
@@ -124,7 +124,7 @@ func strlen(s string) int {
 	return len(s)
 }
 
-func printItf(val interface{}) {
+func printItf(val any) {
 	switch val := val.(type) {
 	case Doubler:
 		println("is Doubler:", val.Double())

src/examples/usb-storage/main.go

@@ -6,8 +6,85 @@ import (
 	"time"
 )
 
+// Disk geometry.
+const (
+	sectorSize  = 512
+	diskSectors = 128 // 64 KB total
+)
+
+var diskData [diskSectors * sectorSize]byte
+
+type ramDisk struct{}
+
+func (r *ramDisk) ReadAt(p []byte, off int64) (int, error) {
+	return copy(p, diskData[off:]), nil
+}
+
+func (r *ramDisk) WriteAt(p []byte, off int64) (int, error) {
+	return copy(diskData[off:], p), nil
+}
+
+func (r *ramDisk) Size() int64                        { return int64(diskSectors * sectorSize) }
+func (r *ramDisk) WriteBlockSize() int64              { return sectorSize }
+func (r *ramDisk) EraseBlockSize() int64              { return sectorSize }
+func (r *ramDisk) EraseBlocks(start, len int64) error { return nil }
+
+func init() {
+	formatFAT12(diskData[:])
+}
+
+// formatFAT12 writes a minimal FAT12 volume boot record and FAT tables so the
+// host OS can mount the disk without reformatting.
+func formatFAT12(d []byte) {
+	// --- Sector 0: Volume Boot Record ---
+	s := d[0:]
+	s[0] = 0xEB
+	s[1] = 0x3C
+	s[2] = 0x90 // short JMP + NOP
+	copy(s[3:11], "MSDOS5.0")
+	// BPB fields (little-endian)
+	s[11] = 0x00
+	s[12] = 0x02 // bytesPerSector = 512
+	s[13] = 0x01 // sectorsPerCluster = 1
+	s[14] = 0x01
+	s[15] = 0x00 // reservedSectors = 1
+	s[16] = 0x02 // numFATs = 2
+	s[17] = 0x20
+	s[18] = 0x00 // rootEntryCount = 32
+	s[19] = 0x80
+	s[20] = 0x00 // totalSectors16 = 128
+	s[21] = 0xF8 // mediaType = fixed disk
+	s[22] = 0x01
+	s[23] = 0x00 // sectorsPerFAT = 1
+	s[24] = 0x80
+	s[25] = 0x00 // sectorsPerTrack = 128
+	s[26] = 0x01
+	s[27] = 0x00 // numHeads = 1
+	// hiddenSectors[28:32] = 0
+	// totalSectors32[32:36] = 0
+	s[38] = 0x29 // extBootSig
+	s[39] = 0x47
+	s[40] = 0x4F
+	s[41] = 0x30
+	s[42] = 0x31                  // volumeID "GO01"
+	copy(s[43:54], "TINYGO     ") // volumeLabel (11 bytes)
+	copy(s[54:62], "FAT12   ")    // fsType
+	s[510] = 0x55
+	s[511] = 0xAA // boot sector signature
+
+	// --- Sector 1: FAT1 ---
+	// Entry 0 = 0xFF8 (media byte), entry 1 = 0xFFF (EOC); all others = free.
+	d[512] = 0xF8
+	d[513] = 0xFF
+	d[514] = 0xFF
+
+	// --- Sector 2: FAT2 (identical copy) ---
+	copy(d[1024:1027], d[512:515])
+}
+
 func main() {
-	msc.Port(machine.Flash)
+	msc.Port(&ramDisk{})
+	machine.USBDev.Configure(machine.UARTConfig{})
 
 	for {
 		time.Sleep(2 * time.Second)

src/internal/bytealg/bytealg.go

@@ -45,11 +45,8 @@ func Compare(a, b []byte) int {
 // This function was copied from the Go 1.23 source tree (with runtime_cmpstring
 // manually inlined).
 func CompareString(a, b string) int {
-	l := len(a)
+	l := min(len(b), len(a))
-	if len(b) < l {
+	for i := range l {
-		l = len(b)
-	}
-	for i := 0; i < l; i++ {
 		c1, c2 := a[i], b[i]
 		if c1 < c2 {
 			return -1
@@ -170,7 +167,7 @@ const PrimeRK = 16777619
 // This function was removed in Go 1.22.
 func HashStrBytes(sep []byte) (uint32, uint32) {
 	hash := uint32(0)
-	for i := 0; i < len(sep); i++ {
+	for i := range sep {
 		hash = hash*PrimeRK + uint32(sep[i])
 	}
 	var pow, sq uint32 = 1, PrimeRK
@@ -249,7 +246,7 @@ func IndexRabinKarpBytes(s, sep []byte) int {
 	hashsep, pow := HashStrBytes(sep)
 	n := len(sep)
 	var h uint32
-	for i := 0; i < n; i++ {
+	for i := range n {
 		h = h*PrimeRK + uint32(s[i])
 	}
 	if h == hashsep && Equal(s[:n], sep) {
@@ -276,7 +273,7 @@ func IndexRabinKarp[T string | []byte](s, sep T) int {
 	hashss, pow := HashStr(sep)
 	n := len(sep)
 	var h uint32
-	for i := 0; i < n; i++ {
+	for i := range n {
 		h = h*PrimeRK + uint32(s[i])
 	}
 	if h == hashss && string(s[:n]) == string(sep) {

src/internal/cm/case.go

@@ -12,8 +12,8 @@ func CaseUnmarshaler[T ~uint8 | ~uint16 | ~uint32](cases []string) func(v *T, te
 				return &emptyTextError{}
 			}
 			s := string(text)
-			for i := 0; i < len(cases); i++ {
+			for i, c := range cases {
-				if cases[i] == s {
+				if c == s {
 					*v = T(i)
 					return nil
 				}

src/internal/task/task_asyncify.go

@@ -51,6 +51,7 @@ type stackState struct {
 // The new goroutine is immediately started.
 func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	t := &Task{}
+	addLiveTask(t)
 	t.state.initialize(fn, args, stackSize)
 	scheduleTask(t)
 }

src/internal/task/task_exit.go

@@ -0,0 +1,42 @@
+//go:build scheduler.tasks || scheduler.asyncify || scheduler.cores
+
+package task
+
+import "sync/atomic"
+
+var (
+	mainTask           *Task
+	liveTasks          uint32
+	mainExitedByGoexit uint32
+)
+
+func addLiveTask(t *Task) {
+	if mainTask == nil {
+		mainTask = t
+	}
+	atomic.AddUint32(&liveTasks, 1)
+}
+
+// Exit exits the current task because runtime.Goexit was called.
+func Exit() {
+	exit(true)
+}
+
+func exit(goexit bool) {
+	t := Current()
+	remaining := atomic.AddUint32(&liveTasks, ^uint32(0))
+	if t == mainTask {
+		if goexit {
+			if remaining == 0 {
+				runtimePanic("all goroutines are asleep - deadlock!")
+			}
+			atomic.StoreUint32(&mainExitedByGoexit, 1)
+		}
+	} else if atomic.LoadUint32(&mainExitedByGoexit) != 0 && remaining == 0 {
+		runtimePanic("all goroutines are asleep - deadlock!")
+	}
+
+	// TODO: explicitly free the stack after switching back to the scheduler.
+	Pause()
+	runtimePanic("unreachable")
+}

src/internal/task/task_stack.go

@@ -33,8 +33,7 @@ type state struct {
 
 //export tinygo_task_exit
 func taskExit() {
-	// TODO: explicitly free the stack after switching back to the scheduler.
+	exit(false)
-	Pause()
 }
 
 // initialize the state and prepare to call the specified function with the specified argument bundle.
@@ -73,6 +72,7 @@ var startTask [0]uint8
 // The new goroutine is scheduled to run later.
 func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	t := &Task{}
+	addLiveTask(t)
 	t.state.initialize(fn, args, stackSize)
 	scheduleTask(t)
 }

src/internal/task/task_threads.c

@@ -145,6 +145,11 @@ void* tinygo_task_current(void) {
     return current_task;
 }
 
+// Exit the current thread.
+void tinygo_task_exit(void) {
+    pthread_exit(NULL);
+}
+
 // Send a signal to cause the task to pause for the GC mark phase.
 void tinygo_task_send_gc_signal(pthread_t thread) {
     pthread_kill(thread, taskPauseSignal);

src/internal/task/task_threads.go

@@ -43,7 +43,9 @@ var mainTask Task
 
 // Queue of tasks (see QueueNext) that currently exist in the program.
 var activeTasks = &mainTask
+var activeTaskCount uint32 = 1
 var activeTaskLock PMutex
+var mainExitedByGoexit bool
 
 func OnSystemStack() bool {
 	runtimePanic("todo: task.OnSystemStack")
@@ -95,9 +97,6 @@ func (t *Task) Resume() {
 	t.state.pauseSem.Post()
 }
 
-// otherGoroutines is the total number of live goroutines minus one.
-var otherGoroutines uint32
-
 // Start a new OS thread.
 func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	t := &Task{}
@@ -117,7 +116,7 @@ func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	}
 	t.state.QueueNext = activeTasks
 	activeTasks = t
-	otherGoroutines++
+	activeTaskCount++
 	activeTaskLock.Unlock()
 }
 
@@ -127,6 +126,12 @@ func taskExited(t *Task) {
 		println("*** exit:", t.state.id)
 	}
 
+	if exit(t) {
+		runtimePanic("all goroutines are asleep - deadlock!")
+	}
+}
+
+func exit(t *Task) bool {
 	// Remove from the queue.
 	// TODO: this can be made more efficient by using a doubly linked list.
 	activeTaskLock.Lock()
@@ -135,16 +140,46 @@ func taskExited(t *Task) {
 		if *q == t {
 			*q = t.state.QueueNext
 			found = true
+			activeTaskCount--
 			break
 		}
 	}
-	otherGoroutines--
+	deadlocked := mainExitedByGoexit && activeTaskCount == 0
 	activeTaskLock.Unlock()
 
 	// Sanity check.
 	if !found {
 		runtimePanic("taskExited failed")
 	}
+	return deadlocked
+}
+
+func otherTasks(current *Task) uint32 {
+	if activeTaskCount == 0 {
+		return 0
+	}
+	return activeTaskCount - 1
+}
+
+// Exit exits the current task. If this is the main task and there are no other
+// goroutines, it reports a deadlock.
+func Exit() {
+	t := Current()
+	if t == &mainTask {
+		activeTaskLock.Lock()
+		noOtherTasks := otherTasks(t) == 0
+		if !noOtherTasks {
+			mainExitedByGoexit = true
+		}
+		activeTaskLock.Unlock()
+		if noOtherTasks {
+			runtimePanic("all goroutines are asleep - deadlock!")
+		}
+	}
+	if exit(t) {
+		runtimePanic("all goroutines are asleep - deadlock!")
+	}
+	tinygo_task_exit()
 }
 
 // scanWaitGroup is used to wait on until all threads have finished the current state transition.
@@ -206,7 +241,7 @@ func GCStopWorldAndScan() {
 		gcState.Store(gcStateStopped)
 
 		// Set the number of threads to wait for.
-		scanWaitGroup = initWaitGroup(otherGoroutines)
+		scanWaitGroup = initWaitGroup(otherTasks(current))
 
 		// Pause all other threads.
 		for t := activeTasks; t != nil; t = t.state.QueueNext {
@@ -242,7 +277,7 @@ func GCResumeWorld() {
 	}
 
 	// Set the wait group to track resume progress.
-	scanWaitGroup = initWaitGroup(otherGoroutines)
+	scanWaitGroup = initWaitGroup(otherTasks(Current()))
 
 	// Set the state to resumed.
 	gcState.Store(gcStateResumed)
@@ -304,6 +339,9 @@ func tinygo_task_init(t *Task, thread *threadID, numCPU *int32)
 //go:linkname tinygo_task_start tinygo_task_start
 func tinygo_task_start(fn uintptr, args unsafe.Pointer, t *Task, thread *threadID, stackTop *uintptr, stackSize uintptr) int32
 
+//go:linkname tinygo_task_exit tinygo_task_exit
+func tinygo_task_exit()
+
 // Pause the thread by sending it a signal.
 //
 //export tinygo_task_send_gc_signal

src/machine/board_xiao-ble-plus.go

@@ -0,0 +1,136 @@
+//go:build xiao_ble_plus
+
+// This file contains the pin mappings for the Seeed XIAO BLE nRF52840 [Plus, Sense Plus] boards.
+//
+// Seeed XIAO BLE is an ultra-small size, ultra-low power Bluetooth development board based on the Nordic nRF52840.
+// It features an onboard Bluetooth antenna, onboard battery charging chip, and 21*17.5mm thumb size, which makes it ideal for IoT projects.
+//
+// Seeed XIAO BLE nRF52840 Sense is a tiny Bluetooth LE development board designed for IoT and AI applications.
+// It features an onboard antenna, 6 Dof IMU, microphone, all of which make it an ideal board to run AI using TinyML and TensorFlow Lite.
+//
+// SoftDevice (s140v7) is pre-flashed on this board already.
+// See https://github.com/tinygo-org/bluetooth
+//
+// - https://www.seeedstudio.com/Seeed-XIAO-BLE-nRF52840-p-5201.html
+// - https://www.seeedstudio.com/Seeed-XIAO-BLE-Sense-nRF52840-p-5253.html
+// - https://www.seeedstudio.com/Seeed-Studio-XIAO-nRF52840-Sense-Plus-p-6360.html
+//
+// - https://wiki.seeedstudio.com/XIAO_BLE/
+// - https://github.com/Seeed-Studio/ArduinoCore-mbed/tree/master/variants/SEEED_XIAO_NRF52840_SENSE
+package machine
+
+const HasLowFrequencyCrystal = true
+
+// Digital Pins
+const (
+	D0  Pin = P0_02
+	D1  Pin = P0_03
+	D2  Pin = P0_28
+	D3  Pin = P0_29
+	D4  Pin = P0_04
+	D5  Pin = P0_05
+	D6  Pin = P1_11
+	D7  Pin = P1_12
+	D8  Pin = P1_13
+	D9  Pin = P1_14
+	D10 Pin = P1_15
+	D11 Pin = P0_15
+	D12 Pin = P0_19
+	D13 Pin = P1_01
+	D14 Pin = P0_09
+	D15 Pin = P0_10
+	D16 Pin = P0_31
+	D17 Pin = P1_03
+	D18 Pin = P1_05
+	D19 Pin = P1_07
+)
+
+// Analog pins
+const (
+	A0 Pin = P0_02
+	A1 Pin = P0_03
+	A2 Pin = P0_28
+	A3 Pin = P0_29
+	A4 Pin = P0_04
+	A5 Pin = P0_05
+)
+
+// Onboard LEDs
+const (
+	LED       = LED_CHG
+	LED1      = LED_RED
+	LED2      = LED_GREEN
+	LED3      = LED_BLUE
+	LED_CHG   = P0_17
+	LED_RED   = P0_26
+	LED_GREEN = P0_30
+	LED_BLUE  = P0_06
+)
+
+// UART pins
+const (
+	UART_RX_PIN  = P1_12
+	UART_TX_PIN  = P1_11
+	UART1_RX_PIN = P0_09
+	UART1_TX_PIN = P0_10
+)
+
+// I2C pins
+const (
+	// Defaults to internal
+	SDA_PIN = SDA1_PIN
+	SCL_PIN = SCL1_PIN
+
+	// I2C0 (external) pins
+	SDA0_PIN = P0_04
+	SCL0_PIN = P0_05
+
+	// I2C1 (internal) pins
+	SDA1_PIN = P0_07
+	SCL1_PIN = P0_27
+)
+
+// I2S pins
+const (
+	I2S_SCK_PIN = P0_19
+	I2S_WS_PIN  = P1_01
+	I2S_SD_PIN  = P0_15
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN = P1_13
+	SPI0_SDO_PIN = P1_14
+	SPI0_SDI_PIN = P1_15
+)
+
+// Peripherals
+const (
+	LSM_PWR = P1_08 // IMU (LSM6DS3TR) power
+	LSM_INT = P0_11 // IMU (LSM6DS3TR) interrupt
+
+	MIC_PWR = P1_10 // Microphone (MSM261D3526H1CPM) power
+	MIC_CLK = P1_00
+	MIC_DIN = P0_16
+)
+
+// NFC pins
+const (
+	NFC1_PIN = P0_09
+	NFC2_PIN = P0_10
+)
+
+// USB CDC identifiers
+const (
+	usb_STRING_PRODUCT      = "XIAO nRF52840 Sense"
+	usb_STRING_MANUFACTURER = "Seeed"
+)
+
+var (
+	usb_VID uint16 = 0x2886
+	usb_PID uint16 = 0x8045
+)
+
+var (
+	DefaultUART = UART0
+)

src/machine/flash.go

@@ -1,4 +1,4 @@
-//go:build esp32c3 || nrf || nrf51 || nrf52 || nrf528xx || stm32f4 || stm32l0 || stm32l4 || stm32wlx || atsamd21 || atsamd51 || atsame5x || rp2040 || rp2350
+//go:build esp32c3 || nrf || nrf51 || nrf52 || nrf528xx || stm32f4 || stm32f7 || stm32l0 || stm32l4 || stm32wlx || atsamd21 || atsamd51 || atsame5x || rp2040 || rp2350
 
 package machine
 

src/machine/machine_esp32c6_adc.go

@@ -0,0 +1,392 @@
+//go:build esp32c6
+
+package machine
+
+import (
+	"device/esp"
+	"errors"
+	"runtime/volatile"
+	"unsafe"
+)
+
+// newRegI2C returns the regI2C configured for ESP32-C6: hostID=0, drefInit=1.
+// I2C_SAR_ADC_HOSTID = 0 per soc/esp32c6/include/soc/regi2c_saradc.h.
+func newRegI2C() regI2C { return regI2C{hostID: 0, drefInit: 1} }
+
+const (
+	// ADC attenuation values for ESP32-C6 APB_SARADC.
+	// 0 dB  : ~0 .. 1.1 V
+	// 11 dB : ~0 .. 3.3 V (matches typical VDD)
+	atten0dB  = 0
+	atten11dB = 3
+)
+
+// InitADC initialises the APB_SARADC peripheral on ESP32-C6.
+// On C6 the clock/reset gating moved to PCR (not SYSTEM as on C3), and the
+// SARADC CLKM divider configuration also lives in PCR.
+func InitADC() {
+	// Reset and enable the SARADC bus clock via PCR.
+	esp.PCR.SetSARADC_CONF_SARADC_RST_EN(1)
+	esp.PCR.SetSARADC_CONF_SARADC_CLK_EN(1)
+	esp.PCR.SetSARADC_CONF_SARADC_RST_EN(0)
+
+	// Select clock source 2 (PLL_F80M), divider = 1, no fractional.
+	esp.PCR.SetSARADC_CLKM_CONF_SARADC_CLKM_SEL(2)
+	esp.PCR.SetSARADC_CLKM_CONF_SARADC_CLKM_DIV_NUM(1)
+	esp.PCR.SetSARADC_CLKM_CONF_SARADC_CLKM_DIV_B(0)
+	esp.PCR.SetSARADC_CLKM_CONF_SARADC_CLKM_DIV_A(0)
+	esp.PCR.SetSARADC_CLKM_CONF_SARADC_CLKM_EN(1)
+
+	// Power up the SAR ADC and configure FSM timing (same register layout as C3).
+	esp.APB_SARADC.SetCTRL_SARADC_XPD_SAR_FORCE(1)
+	esp.APB_SARADC.SetFSM_WAIT_SARADC_XPD_WAIT(8)
+	esp.APB_SARADC.SetFSM_WAIT_SARADC_RSTB_WAIT(8)
+	esp.APB_SARADC.SetFSM_WAIT_SARADC_STANDBY_WAIT(100)
+
+	adcSelfCalibrate()
+}
+
+// ESP32-C6 ADC pin mapping: ADC1 = GPIO0–GPIO6 (ch 0–6). There is no ADC2.
+// (The machine_esp32c6.go file defines ADC0..ADC6 as GPIO0..GPIO6.)
+func (a ADC) Configure(config ADCConfig) error {
+	if a.Pin > 6 {
+		return errors.New("invalid ADC pin for ESP32-C6")
+	}
+	a.Pin.Configure(PinConfig{Mode: PinAnalog})
+	return nil
+}
+
+// Get performs a single ADC1 conversion and returns a 16-bit value.
+// The raw 12-bit result (0..4095) is left-shifted by 4 to fill 16 bits.
+func (a ADC) Get() uint16 {
+	if a.Pin > 6 {
+		return 0
+	}
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_ATTEN(atten11dB)
+	esp.APB_SARADC.SetINT_CLR_APB_SARADC1_DONE_INT_CLR(1)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(0)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_CHANNEL(uint32(a.Pin))
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC1_ONETIME_SAMPLE(1)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(1)
+	for esp.APB_SARADC.GetINT_RAW_APB_SARADC1_DONE_INT_RAW() == 0 {
+	}
+	raw := esp.APB_SARADC.GetSAR1DATA_STATUS_APB_SARADC1_DATA()
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(0)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC1_ONETIME_SAMPLE(0)
+	return uint16(raw&0xfff) << 4
+}
+
+// ── regI2C: internal I2C-bus (LP_I2C_ANA_MST) for SAR ADC calibration ───────
+//
+// On ESP32-C6 the "REGI2C" master moved from the embedded SENS/APB_SARADC
+// controller (0x6000_E000) used on C3/S3 to the dedicated LP_I2C_ANA_MST
+// peripheral at 0x600b_2400. The SAR ADC block address and register layout
+// (DREF, ENCAL_GND, INIT_CODE) remain identical to C3.
+//
+// LP_I2C_ANA_MST.I2C0_CTRL bit layout (25-bit command field):
+//   [7:0]  = slave block address (0x69 for I2C_SAR_ADC)
+//   [15:8] = register address within the block
+//   [23:16]= write data (8 bits)
+//   [24]   = WR_CNTL: 0=read, 1=write
+//   [25]   = BUSY (read-only, set by hardware while processing)
+//
+// Source: components/esp_rom/patches/esp_rom_regi2c_esp32c6.c in esp-idf
+
+// regI2C wraps the internal I2C bus used for SAR ADC calibration registers.
+// Fields hold chip-specific parameters.
+type regI2C struct {
+	// hostID is the I2C_SAR_ADC_HOSTID (0 for ESP32-C6, matching regi2c_saradc.h).
+	hostID uint8
+	// drefInit is the DREF reference value written during calibrationInit (1 for C6).
+	drefInit uint8
+}
+
+// SAR ADC I2C register layout — identical to ESP32-C3 / ESP32-S3.
+// Source: soc/esp32c6/include/soc/regi2c_saradc.h
+const (
+	i2cSarADC = uint8(0x69)
+
+	adc1DrefAddr = uint8(0x2)
+	adc1DrefMSB  = uint8(6)
+	adc1DrefLSB  = uint8(4)
+	adc2DrefAddr = uint8(0x5)
+	adc2DrefMSB  = uint8(6)
+	adc2DrefLSB  = uint8(4)
+
+	adc1EncalGndAddr = uint8(0x7)
+	adc1EncalGndMSB  = uint8(5)
+	adc1EncalGndLSB  = uint8(5)
+	adc2EncalGndAddr = uint8(0x7)
+	adc2EncalGndMSB  = uint8(7)
+	adc2EncalGndLSB  = uint8(7)
+
+	adc1InitCodeHighAddr = uint8(0x1)
+	adc1InitCodeHighMSB  = uint8(3)
+	adc1InitCodeHighLSB  = uint8(0)
+	adc1InitCodeLowAddr  = uint8(0x0)
+	adc1InitCodeLowMSB   = uint8(7)
+	adc1InitCodeLowLSB   = uint8(0)
+	adc2InitCodeHighAddr = uint8(0x4)
+	adc2InitCodeHighMSB  = uint8(3)
+	adc2InitCodeHighLSB  = uint8(0)
+	adc2InitCodeLowAddr  = uint8(0x3)
+	adc2InitCodeLowMSB   = uint8(7)
+	adc2InitCodeLowLSB   = uint8(0)
+
+	// adcCalOffsetRange is the binary search upper bound (12-bit full scale).
+	adcCalOffsetRange = uint32(4096)
+	// adcCalMaxIterations caps binary search iterations.
+	adcCalMaxIterations = 16
+)
+
+// LP_I2C_ANA_MST I2C0_CTRL bit-field shifts (see file header comment).
+const (
+	c6SlaveIDShift = 0  // bits [7:0]
+	c6AddrShift    = 8  // bits [15:8]
+	c6DataShift    = 16 // bits [23:16]
+	c6WrCntlShift  = 24 // bit [24]
+	c6BusyBit      = uint32(1 << 25)
+
+	// c6SarI2CDeviceEn is BIT(7) in LP_I2C_ANA_MST.DEVICE_EN for I2C_SAR_ADC (0x69).
+	c6SarI2CDeviceEn = uint32(1 << 7)
+)
+
+// ANA_CONFIG / ANA_CONFIG2 register addresses and bits for the internal SAR I2C
+// domain on ESP32-C6. These differ from C3's SENS block (0x6000_E044/048).
+// Source: soc/esp32c6/include/soc/regi2c_defs.h
+const (
+	c6AnaConfigReg  = uintptr(0x600AF81C) // clear ANA_I2C_SAR_FORCE_PD (bit 18)
+	c6AnaConfig2Reg = uintptr(0x600AF820) // set   ANA_I2C_SAR_FORCE_PU  (bit 16)
+	c6SarForcePD    = uint32(1 << 18)
+	c6SarForcePU    = uint32(1 << 16)
+)
+
+// sarEnable powers up the internal SAR I2C domain and enables the LP_I2C_ANA_MST
+// clock and SAR slave device before any regI2C access.
+// Matches regi2c_ctrl_ll_i2c_saradc_enable() + regi2c_enable_block(REGI2C_SAR_I2C).
+func (r regI2C) sarEnable() {
+	cfg := (*volatile.Register32)(unsafe.Pointer(c6AnaConfigReg))
+	cfg2 := (*volatile.Register32)(unsafe.Pointer(c6AnaConfig2Reg))
+	cfg.Set(cfg.Get() &^ c6SarForcePD)
+	cfg2.Set(cfg2.Get() | c6SarForcePU)
+
+	// Enable the LP_I2C_ANA_MST master clock (MODEM_LPCON.CLK_CONF bit 2).
+	esp.MODEM_LPCON.SetCLK_CONF_CLK_I2C_MST_EN(1)
+	// Enable the master's own clock gate (LP_I2C_ANA_MST.DATE bit 28).
+	esp.LP_I2C_ANA_MST.SetDATE_LP_I2C_ANA_MAST_I2C_MAT_CLK_EN(1)
+	// Enable the SAR ADC slave device (DEVICE_EN bit 7).
+	dev := esp.LP_I2C_ANA_MST.GetDEVICE_EN_LP_I2C_ANA_MAST_I2C_DEVICE_EN()
+	esp.LP_I2C_ANA_MST.SetDEVICE_EN_LP_I2C_ANA_MAST_I2C_DEVICE_EN(dev | c6SarI2CDeviceEn)
+}
+
+// writeMask implements the REGI2C_WRITE_MASK macro for ESP32-C6 via LP_I2C_ANA_MST.
+// It reads the current byte at regAddr, updates the [msb:lsb] bitfield, and writes
+// it back. Matches esp_rom_regi2c_write_mask() in esp_rom_regi2c_esp32c6.c.
+func (r regI2C) writeMask(regAddr, msb, lsb, data uint8) {
+	ctrl := &esp.LP_I2C_ANA_MST.I2C0_CTRL
+	rdata := &esp.LP_I2C_ANA_MST.I2C0_DATA
+
+	// Issue a read command: slave_id | (reg_addr << 8), no WR_CNTL bit.
+	readCmd := (uint32(i2cSarADC) << c6SlaveIDShift) | (uint32(regAddr) << c6AddrShift)
+	volatile.StoreUint32(&ctrl.Reg, readCmd)
+	for volatile.LoadUint32(&ctrl.Reg)&c6BusyBit != 0 {
+	}
+	cur := volatile.LoadUint32(&rdata.Reg) & 0xFF
+
+	// Modify the [msb:lsb] bitfield.
+	mask := uint32(1<<(msb-lsb+1)-1) << lsb
+	cur &^= mask
+	cur |= uint32(data&(1<<(msb-lsb+1)-1)) << lsb
+
+	// Issue a write command: slave_id | (reg_addr<<8) | WR_CNTL | (data<<16).
+	writeCmd := (uint32(i2cSarADC) << c6SlaveIDShift) |
+		(uint32(regAddr) << c6AddrShift) |
+		(uint32(1) << c6WrCntlShift) |
+		((cur & 0xFF) << c6DataShift)
+	volatile.StoreUint32(&ctrl.Reg, writeCmd)
+	for volatile.LoadUint32(&ctrl.Reg)&c6BusyBit != 0 {
+	}
+}
+
+// calibrationInit sets the DREF reference for the selected ADC unit.
+func (r regI2C) calibrationInit(adcN uint8) {
+	if adcN == 0 {
+		r.writeMask(adc1DrefAddr, adc1DrefMSB, adc1DrefLSB, r.drefInit)
+	} else {
+		r.writeMask(adc2DrefAddr, adc2DrefMSB, adc2DrefLSB, r.drefInit)
+	}
+}
+
+// calibrationPrepare enables ENCAL_GND so the ADC input is shorted to ground.
+func (r regI2C) calibrationPrepare(adcN uint8) {
+	if adcN == 0 {
+		r.writeMask(adc1EncalGndAddr, adc1EncalGndMSB, adc1EncalGndLSB, 1)
+	} else {
+		r.writeMask(adc2EncalGndAddr, adc2EncalGndMSB, adc2EncalGndLSB, 1)
+	}
+}
+
+// calibrationFinish clears ENCAL_GND to reconnect the ADC input to the pad.
+func (r regI2C) calibrationFinish(adcN uint8) {
+	if adcN == 0 {
+		r.writeMask(adc1EncalGndAddr, adc1EncalGndMSB, adc1EncalGndLSB, 0)
+	} else {
+		r.writeMask(adc2EncalGndAddr, adc2EncalGndMSB, adc2EncalGndLSB, 0)
+	}
+}
+
+// setCalibrationParam writes the INIT_CODE (offset trim) for the selected ADC unit.
+func (r regI2C) setCalibrationParam(adcN uint8, param uint32) {
+	msb := uint8(param >> 8)
+	lsb := uint8(param & 0xFF)
+	if adcN == 0 {
+		r.writeMask(adc1InitCodeHighAddr, adc1InitCodeHighMSB, adc1InitCodeHighLSB, msb)
+		r.writeMask(adc1InitCodeLowAddr, adc1InitCodeLowMSB, adc1InitCodeLowLSB, lsb)
+	} else {
+		r.writeMask(adc2InitCodeHighAddr, adc2InitCodeHighMSB, adc2InitCodeHighLSB, msb)
+		r.writeMask(adc2InitCodeLowAddr, adc2InitCodeLowMSB, adc2InitCodeLowLSB, lsb)
+	}
+}
+
+// calibrateBinarySearch runs the ADC self-calibration binary search loop.
+// It performs 'iterations' rounds, drops the min/max outliers, and returns
+// the rounded mean of the remaining values. Matches adc_hal_self_calibration().
+func (r regI2C) calibrateBinarySearch(adcN uint8, iterations int, readADC func() uint32) uint32 {
+	if iterations > adcCalMaxIterations {
+		iterations = adcCalMaxIterations
+	}
+	var codeList [adcCalMaxIterations]uint32
+	var codeSum uint32
+
+	for rpt := 0; rpt < iterations; rpt++ {
+		codeH := adcCalOffsetRange
+		codeL := uint32(0)
+		chkCode := (codeH + codeL) / 2
+		r.setCalibrationParam(adcN, chkCode)
+		selfCal := readADC()
+
+		for codeH-codeL > 1 {
+			if selfCal == 0 {
+				codeH = chkCode
+			} else {
+				codeL = chkCode
+			}
+			chkCode = (codeH + codeL) / 2
+			r.setCalibrationParam(adcN, chkCode)
+			selfCal = readADC()
+			if codeH-codeL == 1 {
+				chkCode++
+				r.setCalibrationParam(adcN, chkCode)
+				selfCal = readADC()
+			}
+		}
+		codeList[rpt] = chkCode
+		codeSum += chkCode
+	}
+
+	codeMin := codeList[0]
+	codeMax := codeList[0]
+	for i := 0; i < iterations; i++ {
+		if codeList[i] < codeMin {
+			codeMin = codeList[i]
+		}
+		if codeList[i] > codeMax {
+			codeMax = codeList[i]
+		}
+	}
+	remaining := codeSum - codeMax - codeMin
+	divisor := uint32(iterations - 2)
+	finalCode := remaining / divisor
+	if remaining%divisor >= 4 {
+		finalCode++
+	}
+	return finalCode
+}
+
+// ── Self-calibration ──────────────────────────────────────────────────────────
+
+const (
+	adcCalTimesC6    = 15
+	adcCalRtcMagicC6 = uint32(0xADC1C601) // magic distinguishes C6 from C3
+	adcCalInitMinC6  = uint32(1000)
+	adcCalInitMaxC6  = uint32(4096)
+)
+
+// adcSelfCalibrate runs a self-calibration for ADC1 (the only ADC unit on C6).
+// The calibration code is cached in LP_AON scratch registers to survive sleep.
+// eFuse calibration is not used: the fields are often unprogrammed.
+func adcSelfCalibrate() {
+	reg := newRegI2C()
+	reg.sarEnable()
+
+	var adc1Code uint32
+	if saved, ok := c6RestoreFromLP(); ok {
+		adc1Code = saved
+	} else {
+		c6CalSetupADC1()
+		reg.calibrationInit(0)
+		reg.calibrationPrepare(0)
+		adc1Code = reg.calibrateBinarySearch(0, adcCalTimesC6, readADC1)
+		if adc1Code < adcCalInitMinC6 {
+			adc1Code = adcCalInitMinC6
+		}
+		if adc1Code > adcCalInitMaxC6 {
+			adc1Code = adcCalInitMaxC6
+		}
+		c6SaveToLP(adc1Code)
+		reg.calibrationFinish(0)
+	}
+
+	c6ApplyADC1Code(reg, adc1Code)
+}
+
+// c6CalSetupADC1 configures APB_SARADC for oneshot ADC1 ch0 with fixed attenuation.
+func c6CalSetupADC1() {
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_ATTEN(atten11dB)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_CHANNEL(0)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC1_ONETIME_SAMPLE(1)
+}
+
+// readADC1 performs a single ADC1 conversion and returns the raw 12-bit result.
+func readADC1() uint32 {
+	esp.APB_SARADC.SetINT_CLR_APB_SARADC1_DONE_INT_CLR(1)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(0)
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(1)
+	for esp.APB_SARADC.GetINT_RAW_APB_SARADC1_DONE_INT_RAW() == 0 {
+	}
+	raw := esp.APB_SARADC.GetSAR1DATA_STATUS_APB_SARADC1_DATA() & 0xfff
+	esp.APB_SARADC.SetONETIME_SAMPLE_SARADC_ONETIME_START(0)
+	return uint32(raw)
+}
+
+// c6RestoreFromLP reads the saved calibration code from LP_AON scratch registers.
+// On C6, LP_AON replaces the C3's RTC_CNTL for scratch storage.
+func c6RestoreFromLP() (uint32, bool) {
+	if esp.LP_AON.GetSTORE0() != adcCalRtcMagicC6 {
+		return 0, false
+	}
+	code := esp.LP_AON.GetSTORE1()
+	if code < adcCalInitMinC6 || code > adcCalInitMaxC6 {
+		return 0, false
+	}
+	return code, true
+}
+
+// c6SaveToLP stores the calibration code in LP_AON scratch registers.
+func c6SaveToLP(code uint32) {
+	if code < adcCalInitMinC6 || code > adcCalInitMaxC6 {
+		return
+	}
+	esp.LP_AON.SetSTORE0(adcCalRtcMagicC6)
+	esp.LP_AON.SetSTORE1(code)
+}
+
+// c6ApplyADC1Code sets ADC1 init code and finishes calibration.
+// ESP32-C6 has no ADC2 so only ADC1 (adcN=0) needs to be configured.
+func c6ApplyADC1Code(reg regI2C, code uint32) {
+	c6CalSetupADC1()
+	reg.calibrationInit(0)
+	reg.calibrationPrepare(0)
+	reg.setCalibrationParam(0, code)
+	reg.calibrationFinish(0)
+}

src/machine/machine_esp32s3.go

@@ -470,3 +470,41 @@ func initADCClock() {
 	esp.APB_SARADC.SetCTRL_SARADC_SAR_CLK_DIV(1)
 	esp.APB_SARADC.SetCLKM_CONF_CLK_EN(1)
 }
+
+// ReadTemperature reads the on-chip temperature sensor (TSENS) and returns
+// a value in millicelsius (°C × 1000). Uses the default measurement range
+// (offset = 0, approximately −10 °C to 80 °C, ±3 °C accuracy).
+//
+// The conversion uses the same formula as ESP-IDF with no eFuse calibration:
+//
+//	T = (0.4386 × raw − 20.52) °C
+func ReadTemperature() int32 {
+	// Enable TSENS peripheral clock.
+	esp.SENS.SetSAR_PERI_CLK_GATE_CONF_TSENS_CLK_EN(1)
+
+	// Set clock divider to default (6).
+	esp.SENS.SetSAR_TSENS_CTRL_SAR_TSENS_CLK_DIV(6)
+
+	// Power up the temperature sensor.
+	esp.SENS.SetSAR_TSENS_CTRL_SAR_TSENS_POWER_UP_FORCE(1)
+	esp.SENS.SetSAR_TSENS_CTRL2_SAR_TSENS_XPD_FORCE(1)
+	esp.SENS.SetSAR_TSENS_CTRL_SAR_TSENS_POWER_UP(1)
+
+	// Trigger a conversion.
+	esp.SENS.SetSAR_TSENS_CTRL_SAR_TSENS_DUMP_OUT(1)
+
+	// Wait for data ready.
+	for esp.SENS.GetSAR_TSENS_CTRL_SAR_TSENS_READY() == 0 {
+	}
+
+	// Read the 8-bit raw value.
+	raw := int32(esp.SENS.GetSAR_TSENS_CTRL_SAR_TSENS_OUT())
+
+	// Stop the conversion.
+	esp.SENS.SetSAR_TSENS_CTRL_SAR_TSENS_DUMP_OUT(0)
+
+	// Convert to millicelsius using the ESP-IDF integer formula (offset=0):
+	//   T_celsius     = (4386 * raw - 205200) / 10000
+	//   T_millicelsius = (4386 * raw - 205200) / 10
+	return (4386*raw - 205200) / 10
+}

src/machine/machine_stm32.go

@@ -86,6 +86,12 @@ func (p Pin) PortMaskClear() (*uint32, uint32) {
 	return &port.BSRR.Reg, 1 << (pin + 16)
 }
 
+// EnterBootloader resets the chip into the bootloader.
+// This is currently a stub for STM32, required to satisfy machine.EnterBootloader
+// called by machine/usb/cdc.
+func EnterBootloader() {
+}
+
 var deviceID [12]byte
 
 // DeviceID returns an identifier that is unique within

src/machine/machine_stm32_exti_syscfg.go

@@ -1,4 +1,4 @@
-//go:build stm32 && !stm32f1 && !stm32l5 && !stm32wlx && !stm32g0 && !stm32u5
+//go:build stm32 && !stm32f1 && !stm32l5 && !stm32wlx && !stm32g0 && !stm32u5 && !stm32u0
 
 package machine
 

src/machine/machine_stm32_gpio_reva.go

@@ -1,4 +1,4 @@
-//go:build stm32 && !stm32l4 && !stm32l5 && !stm32wlx && !stm32g0 && !stm32u5
+//go:build stm32 && !stm32l4 && !stm32l5 && !stm32wlx && !stm32g0 && !stm32u5 && !stm32u0
 
 package machine
 

src/machine/machine_stm32_i2c_revb.go

@@ -1,4 +1,4 @@
-//go:build stm32l5 || stm32f7 || stm32l4 || stm32l0 || stm32wlx || stm32g0 || stm32u5
+//go:build stm32l5 || stm32f7 || stm32l4 || stm32l0 || stm32wlx || stm32g0 || stm32u0 || stm32u5
 
 package machine
 

src/machine/machine_stm32_otgfs_usb.go

@@ -0,0 +1,828 @@
+//go:build stm32f4 || stm32f7
+
+package machine
+
+import (
+	"device/stm32"
+	"machine/usb"
+	"runtime/interrupt"
+	"runtime/volatile"
+	"unsafe"
+)
+
+// NumberOfUSBEndpoints is sized to cover TinyGo's full endpoint index space
+// (0=control, 1=CDC ACM, 2=CDC OUT, 3=CDC IN, 4=HID IN, 5=HID OUT, 6=MIDI IN, 7=MIDI OUT).
+// Physical OTG FS hardware has 4 IN + 4 OUT endpoints (0–3).
+const NumberOfUSBEndpoints = 8
+
+// Default USB identifiers; board files with USB support should override these.
+const (
+	usb_VID                 = uint16(0x239A)
+	usb_PID                 = uint16(0x0001)
+	usb_STRING_MANUFACTURER = "TinyGo"
+	usb_STRING_PRODUCT      = "STM32 USB Device"
+)
+
+// OTG FS register blocks.
+var (
+	otgDevice = (*usbDeviceRegs)(unsafe.Pointer(stm32.OTG_FS_DEVICE))
+	otgPower  = (*usbPowerRegs)(unsafe.Pointer(stm32.OTG_FS_PWRCLK))
+)
+
+// usbDeviceRegs represents the USB device-mode control block at base+0x800.
+type usbDeviceRegs struct {
+	DCFG       volatile.Register32 // 0x800
+	DCTL       volatile.Register32 // 0x804
+	DSTS       volatile.Register32 // 0x808
+	_          uint32              // 0x80C
+	DIEPMSK    volatile.Register32 // 0x810
+	DOEPMSK    volatile.Register32 // 0x814
+	DAINT      volatile.Register32 // 0x818
+	DAINTMSK   volatile.Register32 // 0x81C
+	_          [5]uint32           // 0x820 - 0x830
+	DIEPEMPMSK volatile.Register32 // 0x834
+}
+
+// usbInEndpointRegs represents the registers for a single IN endpoint at 0x900 + ep*0x20.
+type usbInEndpointRegs struct {
+	CTL   volatile.Register32 // 0x00
+	_     uint32              // 0x04
+	INT   volatile.Register32 // 0x08
+	_     uint32              // 0x0C
+	TSIZ  volatile.Register32 // 0x10
+	_     uint32              // 0x14
+	TXFST volatile.Register32 // 0x18
+	_     uint32              // 0x1C
+}
+
+// usbOutEndpointRegs represents the registers for a single OUT endpoint at 0xB00 + ep*0x20.
+type usbOutEndpointRegs struct {
+	CTL  volatile.Register32 // 0x00
+	_    uint32              // 0x04
+	INT  volatile.Register32 // 0x08
+	_    uint32              // 0x0C
+	TSIZ volatile.Register32 // 0x10
+	_    [3]uint32           // 0x14 - 0x1C
+}
+
+// usbPowerRegs represents the power and clock gating block at base+0xE00.
+type usbPowerRegs struct {
+	PCGCCTL volatile.Register32 // 0xE00
+}
+
+// otgInEP returns the IN endpoint registers for physical endpoint ep.
+func otgInEP(ep uint32) *usbInEndpointRegs {
+	return (*usbInEndpointRegs)(unsafe.Pointer(uintptr(unsafe.Pointer(stm32.OTG_FS_GLOBAL)) + 0x900 + uintptr(ep)*0x20))
+}
+
+// otgOutEP returns the OUT endpoint registers for physical endpoint ep.
+func otgOutEP(ep uint32) *usbOutEndpointRegs {
+	return (*usbOutEndpointRegs)(unsafe.Pointer(uintptr(unsafe.Pointer(stm32.OTG_FS_GLOBAL)) + 0xB00 + uintptr(ep)*0x20))
+}
+
+// otgDFIFO returns a volatile pointer to the data FIFO for physical endpoint ep.
+// DFIFO[ep] is located at 0x50001000 + ep*0x1000.
+func otgDFIFO(ep uint32) *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Pointer(uintptr(unsafe.Pointer(stm32.OTG_FS_GLOBAL)) + 0x1000 + uintptr(ep)*0x1000))
+}
+
+// DCFG bit positions and masks.
+const (
+	dcfgDSPD    = uint32(0x3) // FS PHY speed (bits [1:0] = 0b11)
+	dcfgDAD_Pos = uint32(4)   // device address field start bit
+	dcfgDAD_Msk = uint32(0x7F << 4)
+)
+
+// DCTL bits.
+const (
+	dctlSDIS   = uint32(1 << 1)  // soft disconnect
+	dctlSGINAK = uint32(1 << 7)  // set global IN NAK
+	dctlCGINAK = uint32(1 << 8)  // clear global IN NAK
+	dctlSGONAK = uint32(1 << 9)  // set global OUT NAK
+	dctlCGONAK = uint32(1 << 10) // clear global OUT NAK
+)
+
+// DSTS bits.
+const (
+	dstsSUSPSTS     = uint32(1 << 0)
+	dstsENUMSPD_Pos = uint32(1)
+	dstsENUMSPD_Msk = uint32(0x3 << 1)
+)
+
+// DIEPCTLn / DOEPCTLn bits (shared between IN and OUT endpoint control registers).
+const (
+	depctlEPENA      = uint32(1 << 31) // endpoint enable
+	depctlEPDIS      = uint32(1 << 30) // endpoint disable
+	depctlSD0PID     = uint32(1 << 28) // set DATA0 PID
+	depctlSNAK       = uint32(1 << 27) // set NAK
+	depctlCNAK       = uint32(1 << 26) // clear NAK
+	depctlSTALL      = uint32(1 << 21) // STALL handshake
+	depctlETYP_Pos   = uint32(18)      // endpoint type field start
+	depctlUSBAEP     = uint32(1 << 15) // USB active endpoint
+	depctlTXFNUM_Pos = uint32(22)      // TX FIFO number field start (IN eps only)
+	depctlMPSIZ_Pos  = uint32(0)       // max packet size field start
+)
+
+// EP0 max packet size encoding in DIEPCTL0 / DOEPCTL0 bits [1:0].
+const ep0Mps64 = uint32(0x0) // 64 bytes (FS default)
+
+// DIEPINTn / DOEPINTn bits.
+const (
+	depintXFRC = uint32(1 << 0) // transfer complete
+	depintSTUP = uint32(1 << 3) // SETUP phase done (DOEPINTn)
+)
+
+// GRXSTSP_Device PKTSTS field values.
+const (
+	rxPktstsGNAK      = uint32(0x1) // global OUT NAK
+	rxPktstsOUTData   = uint32(0x2) // OUT data packet received
+	rxPktstsOUTDone   = uint32(0x3) // OUT transfer complete
+	rxPktstsSetupDone = uint32(0x4) // SETUP transaction complete
+	rxPktstsSetupData = uint32(0x6) // SETUP data packet received (always 8 bytes)
+)
+
+// GINTSTS / GINTMSK bits (values taken from stm32f405 SVD constants).
+const (
+	gintRXFLVL  = uint32(stm32.USB_OTG_FS_GINTSTS_RXFLVL)  // 0x10
+	gintUSBRST  = uint32(stm32.USB_OTG_FS_GINTSTS_USBRST)  // 0x1000
+	gintENUMDNE = uint32(stm32.USB_OTG_FS_GINTSTS_ENUMDNE) // 0x2000
+	gintUSBSUSP = uint32(stm32.USB_OTG_FS_GINTSTS_USBSUSP) // 0x800
+	gintWKUPINT = uint32(stm32.USB_OTG_FS_GINTSTS_WKUPINT) // 0x80000000
+	gintIEPINT  = uint32(stm32.USB_OTG_FS_GINTSTS_IEPINT)  // 0x40000
+	gintOEPINT  = uint32(stm32.USB_OTG_FS_GINTSTS_OEPINT)  // 0x80000
+)
+
+// GRSTCTL bits.
+const (
+	grstCSRST      = uint32(stm32.USB_OTG_FS_GRSTCTL_CSRST)   // core soft reset
+	grstRXFFLSH    = uint32(stm32.USB_OTG_FS_GRSTCTL_RXFFLSH) // RX FIFO flush
+	grstTXFFLSH    = uint32(stm32.USB_OTG_FS_GRSTCTL_TXFFLSH) // TX FIFO flush
+	grstTXFNUM_Pos = uint32(stm32.USB_OTG_FS_GRSTCTL_TXFNUM_Pos)
+	grstAHBIDL     = uint32(stm32.USB_OTG_FS_GRSTCTL_AHBIDL) // AHB master idle
+)
+
+// FIFO size layout in 32-bit words (total budget = 320 words).
+const (
+	rxFIFODepth    = uint32(128) // shared RX FIFO
+	ep0TxFIFODepth = uint32(16)  // EP0 TX FIFO
+	ep1TxFIFODepth = uint32(64)  // EP1 TX FIFO
+	ep2TxFIFODepth = uint32(64)  // EP2 TX FIFO
+	ep3TxFIFODepth = uint32(48)  // EP3 TX FIFO
+
+	ep0TxFIFOStart = rxFIFODepth
+	ep1TxFIFOStart = ep0TxFIFOStart + ep0TxFIFODepth
+	ep2TxFIFOStart = ep1TxFIFOStart + ep1TxFIFODepth
+	ep3TxFIFOStart = ep2TxFIFOStart + ep2TxFIFODepth
+)
+
+// Driver state.
+var (
+	// sendOnEP0DATADONE tracks multi-chunk EP0 IN transfers.
+	sendOnEP0DATADONE struct {
+		ptr    *byte
+		count  int
+		offset int
+	}
+
+	// usbSetupBuf holds the 8-byte SETUP packet from the RX FIFO.
+	usbSetupBuf [8]byte
+
+	// usbRxBufLen tracks the byte count of the most recently received OUT packet
+	// per physical endpoint (index 0–3).
+	usbRxBufLen [4]uint32
+)
+
+// Configure initialises the OTG FS USB peripheral in device mode.
+// The config parameter is unused (present for interface compatibility).
+func (dev *USBDevice) Configure(config UARTConfig) {
+	if dev.initcomplete {
+		return
+	}
+
+	// ---- 1. Enable peripheral clocks ----------------------------------------
+
+	// GPIOA clock (PA11 = D-, PA12 = D+)
+	stm32.RCC.AHB1ENR.SetBits(stm32.RCC_AHB1ENR_GPIOAEN)
+	// OTG FS peripheral clock
+	stm32.RCC.AHB2ENR.SetBits(stm32.RCC_AHB2ENR_OTGFSEN)
+
+	// ---- 2. Configure GPIO pins (PA11 D-, PA12 D+) as AF, very high speed ----
+
+	for _, pin := range [2]Pin{PA11, PA12} {
+		pos := uint8(pin%16) * 2
+		port := pin.getPort()
+		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
+		port.OSPEEDR.ReplaceBits(gpioOutputSpeedVeryHigh, gpioOutputSpeedMask, pos)
+		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
+		// OTYPER remains 0 (push-pull)
+		pin.SetAltFunc(10) // AF10 = OTG FS on both F4 and F7
+	}
+
+	// ---- 3. OTG core reset --------------------------------------------------
+
+	// Wait for AHB master idle before core reset.
+	for stm32.OTG_FS_GLOBAL.GRSTCTL.Get()&grstAHBIDL == 0 {
+	}
+
+	// Core soft reset
+	stm32.OTG_FS_GLOBAL.GRSTCTL.SetBits(grstCSRST)
+	for stm32.OTG_FS_GLOBAL.GRSTCTL.HasBits(grstCSRST) {
+	}
+
+	// Wait for AHB idle again after reset
+	for stm32.OTG_FS_GLOBAL.GRSTCTL.Get()&grstAHBIDL == 0 {
+	}
+
+	// ---- 4. Force device mode, set turnaround time --------------------------
+
+	gusbcfg := stm32.OTG_FS_GLOBAL.GUSBCFG.Get()
+	gusbcfg &^= stm32.USB_OTG_FS_GUSBCFG_FHMOD |
+		stm32.USB_OTG_FS_GUSBCFG_FDMOD |
+		stm32.USB_OTG_FS_GUSBCFG_TRDT_Msk
+	gusbcfg |= stm32.USB_OTG_FS_GUSBCFG_FDMOD |
+		(9 << stm32.USB_OTG_FS_GUSBCFG_TRDT_Pos) // turnaround time = 9 for 216MHz HCLK
+	stm32.OTG_FS_GLOBAL.GUSBCFG.Set(gusbcfg)
+
+	// ---- 5. PHY / VBUS configuration (platform-specific) --------------------
+
+	initOTGFSPHY()
+
+	// ---- 6. Enable PHY clock, soft-disconnect before further init -----------
+
+	// Clear stop-clock / stop-phy-clock bits so the PHY clock runs.
+	// If a bootloader left these set, USB would hang silently.
+	otgPower.PCGCCTL.Set(0)
+
+	// Soft-disconnect now (after CSRST reset DCTL to its default connected state).
+	otgDevice.DCTL.SetBits(dctlSDIS)
+
+	// ---- 7. Configure data FIFOs --------------------------------------------
+
+	// RX FIFO (shared for all OUT + SETUP packets)
+	stm32.OTG_FS_GLOBAL.GRXFSIZ.Set(rxFIFODepth)
+
+	// EP0 TX FIFO: start = rxFIFODepth, depth = ep0TxFIFODepth
+	stm32.OTG_FS_GLOBAL.DIEPTXF0.Set(
+		(ep0TxFIFODepth << 16) | ep0TxFIFOStart,
+	)
+
+	// EP1–3 TX FIFOs
+	stm32.OTG_FS_GLOBAL.DIEPTXF1.Set(
+		(ep1TxFIFODepth << 16) | ep1TxFIFOStart,
+	)
+	stm32.OTG_FS_GLOBAL.DIEPTXF2.Set(
+		(ep2TxFIFODepth << 16) | ep2TxFIFOStart,
+	)
+	stm32.OTG_FS_GLOBAL.DIEPTXF3.Set(
+		(ep3TxFIFODepth << 16) | ep3TxFIFOStart,
+	)
+
+	// ---- 8. Flush FIFOs ----------------------------------------------------
+
+	flushRxFIFO()
+	flushTxFIFO(0x10) // flush all TX FIFOs (TXFNUM = 0x10 = all)
+
+	// ---- 9. Configure device: full-speed, no SOF output --------------------
+
+	otgDevice.DCFG.Set(dcfgDSPD) // FS PHY speed
+
+	// Clear any stale interrupts
+	stm32.OTG_FS_GLOBAL.GINTSTS.Set(0xFFFFFFFF)
+
+	// ---- 10. Enable interrupts ----------------------------------------------
+
+	stm32.OTG_FS_GLOBAL.GINTMSK.Set(
+		gintUSBRST | gintENUMDNE | gintRXFLVL | gintIEPINT | gintOEPINT |
+			gintUSBSUSP | gintWKUPINT,
+	)
+
+	// Enable device-level IN and OUT endpoint interrupt masks
+	otgDevice.DIEPMSK.Set(depintXFRC)
+	otgDevice.DOEPMSK.Set(depintXFRC | depintSTUP)
+
+	// Enable global interrupt
+	stm32.OTG_FS_GLOBAL.GAHBCFG.SetBits(stm32.USB_OTG_FS_GAHBCFG_GINT)
+
+	// ---- 11. Register and enable NVIC interrupt -----------------------------
+
+	intr := interrupt.New(stm32.IRQ_OTG_FS, handleUSBIRQ)
+	intr.SetPriority(0) // Highest priority
+	intr.Enable()
+
+	// ---- 12. Connect to host (clear soft-disconnect) -----------------------
+
+	otgDevice.DCTL.ClearBits(dctlSDIS)
+
+	dev.initcomplete = true
+}
+
+// handleUSBIRQ is the OTG FS interrupt handler, dispatching on GINTSTS bits.
+func handleUSBIRQ(intr interrupt.Interrupt) {
+	status := stm32.OTG_FS_GLOBAL.GINTSTS.Get() &
+		stm32.OTG_FS_GLOBAL.GINTMSK.Get()
+
+	if status&gintUSBSUSP != 0 {
+		stm32.OTG_FS_GLOBAL.GINTSTS.Set(gintUSBSUSP)
+		// Stop PHY clock during suspend. Only STPPCLK (bit 0); do NOT set
+		// GATEHCLK (bit 1) — that gates the AHB bus, which prevents the ISR
+		// from reading GINTSTS when WKUPINT fires.
+		otgPower.PCGCCTL.SetBits(1) // STPPCLK
+	}
+
+	if status&gintWKUPINT != 0 {
+		stm32.OTG_FS_GLOBAL.GINTSTS.Set(gintWKUPINT)
+		// Restart clocks before any endpoint activity can resume.
+		otgPower.PCGCCTL.ClearBits(1 | 2)
+	}
+
+	if status&gintUSBRST != 0 {
+		stm32.OTG_FS_GLOBAL.GINTSTS.Set(gintUSBRST)
+		otgPower.PCGCCTL.ClearBits(1 | 2) // ensure clocks running after reset-from-suspend
+		handleUSBReset()
+	}
+
+	if status&gintRXFLVL != 0 {
+		// RXFLVL is level-triggered; drain entire FIFO in a loop.
+		stm32.OTG_FS_GLOBAL.GINTMSK.ClearBits(gintRXFLVL)
+		handleRxFIFO()
+		stm32.OTG_FS_GLOBAL.GINTMSK.SetBits(gintRXFLVL)
+	}
+
+	if status&gintENUMDNE != 0 {
+		stm32.OTG_FS_GLOBAL.GINTSTS.Set(gintENUMDNE)
+		handleEnumDone()
+	}
+
+	if status&gintIEPINT != 0 {
+		handleInEndpoints()
+	}
+
+	if status&gintOEPINT != 0 {
+		handleOutEndpoints()
+	}
+}
+
+// handleUSBReset is called on USB bus reset (USBRST interrupt).
+func handleUSBReset() {
+	// Set NAK on all OUT endpoints.
+	for ep := uint32(0); ep < 4; ep++ {
+		otgOutEP(ep).CTL.SetBits(depctlSNAK)
+	}
+
+	// Flush RX and all TX FIFOs.
+	flushRxFIFO()
+	flushTxFIFO(0x10)
+
+	// Clear all endpoint interrupts.
+	otgDevice.DAINT.Set(0xFFFFFFFF)
+	otgDevice.DAINTMSK.Set(0)
+
+	// Enable EP0 IN and OUT interrupt sources.
+	otgDevice.DAINTMSK.Set((1 << 0) | (1 << 16)) // DIEP0 + DOEP0
+
+	// Re-arm EP0 OUT for up to 3 back-to-back SETUP packets.
+	armEP0Out()
+
+	// Signal upper layer: device is no longer configured.
+	usbConfiguration = 0
+	USBDev.InitEndpointComplete = false
+}
+
+// handleEnumDone is called after USB enumeration speed is detected (ENUMDNE).
+func handleEnumDone() {
+	// Activate EP0 (max packet 64, type control, TX FIFO 0).
+	ep0Ctl := ep0Mps64 | depctlUSBAEP | (0 << depctlETYP_Pos) // control type
+	otgInEP(0).CTL.SetBits(ep0Ctl)
+	otgOutEP(0).CTL.SetBits(ep0Mps64 | depctlUSBAEP)
+
+	// Clear global IN NAK so EP0 IN can send.
+	otgDevice.DCTL.SetBits(dctlCGINAK)
+}
+
+// handleRxFIFO drains the RX FIFO completely, processing each pop via GRXSTSP.
+// RXFLVL is level-triggered, so this must loop until the FIFO is empty.
+func handleRxFIFO() {
+	for stm32.OTG_FS_GLOBAL.GINTSTS.HasBits(gintRXFLVL) {
+		status := stm32.OTG_FS_GLOBAL.GRXSTSP_Device.Get()
+
+		ep := status & stm32.USB_OTG_FS_GRXSTSP_Device_EPNUM_Msk
+		bcnt := (status & stm32.USB_OTG_FS_GRXSTSP_Device_BCNT_Msk) >>
+			stm32.USB_OTG_FS_GRXSTSP_Device_BCNT_Pos
+		pktsts := (status >> stm32.USB_OTG_FS_GRXSTSP_Device_PKTSTS_Pos) & 0xF
+
+		pep := ep // GRXSTSP.EPNUM is already a physical endpoint (0–3)
+
+		switch pktsts {
+		case rxPktstsSetupData:
+			// 8-byte SETUP packet: read exactly 2 words from DFIFO[0].
+			w0 := otgDFIFO(0).Get()
+			w1 := otgDFIFO(0).Get()
+			usbSetupBuf[0] = byte(w0)
+			usbSetupBuf[1] = byte(w0 >> 8)
+			usbSetupBuf[2] = byte(w0 >> 16)
+			usbSetupBuf[3] = byte(w0 >> 24)
+			usbSetupBuf[4] = byte(w1)
+			usbSetupBuf[5] = byte(w1 >> 8)
+			usbSetupBuf[6] = byte(w1 >> 16)
+			usbSetupBuf[7] = byte(w1 >> 24)
+
+		case rxPktstsSetupDone:
+			// SETUP transaction complete: process the buffered SETUP packet.
+			setup := usb.Setup{
+				BmRequestType: usbSetupBuf[0],
+				BRequest:      usbSetupBuf[1],
+				WValueL:       usbSetupBuf[2],
+				WValueH:       usbSetupBuf[3],
+				WIndex:        uint16(usbSetupBuf[4]) | (uint16(usbSetupBuf[5]) << 8),
+				WLength:       uint16(usbSetupBuf[6]) | (uint16(usbSetupBuf[7]) << 8),
+			}
+
+			ok := false
+			if setup.BmRequestType&usb.REQUEST_TYPE == usb.REQUEST_STANDARD {
+				ok = handleStandardSetup(setup)
+			} else {
+				if setup.WIndex < uint16(len(usbSetupHandler)) &&
+					usbSetupHandler[setup.WIndex] != nil {
+					ok = usbSetupHandler[setup.WIndex](setup)
+				}
+			}
+			if !ok {
+				// Stall EP0 IN and OUT on unrecognised requests.
+				otgInEP(0).CTL.SetBits(depctlSTALL)
+				otgOutEP(0).CTL.SetBits(depctlSTALL)
+			}
+			// Re-arm EP0 OUT for the next SETUP.
+			armEP0Out()
+
+		case rxPktstsOUTData:
+			// OUT data: read bcnt bytes from DFIFO[pep] into cache buffer.
+			if bcnt > 0 && pep < 4 {
+				readFIFO(pep, bcnt)
+				usbRxBufLen[pep] = bcnt
+			}
+
+		case rxPktstsOUTDone:
+			// OUT transfer complete: nothing to do here; handled in handleOutEndpoints.
+		}
+	}
+}
+
+// readFIFO reads bcnt bytes from the shared RX FIFO (DFIFO 0) into udd_ep_out_cache_buffer[ep].
+func readFIFO(ep, bcnt uint32) {
+	buf := udd_ep_out_cache_buffer[ep][:]
+	words := (bcnt + 3) / 4
+	for i := uint32(0); i < words; i++ {
+		w := otgDFIFO(0).Get() // Always read from FIFO 0
+		b := i * 4
+		buf[b] = byte(w)
+		if b+1 < bcnt {
+			buf[b+1] = byte(w >> 8)
+		}
+		if b+2 < bcnt {
+			buf[b+2] = byte(w >> 16)
+		}
+		if b+3 < bcnt {
+			buf[b+3] = byte(w >> 24)
+		}
+	}
+}
+
+// handleInEndpoints handles IEPINT: checks each active IN endpoint for XFRC.
+func handleInEndpoints() {
+	daint := otgDevice.DAINT.Get() & 0x0000FFFF // lower 16 bits = IN EPs
+	daintmsk := otgDevice.DAINTMSK.Get() & 0x0000FFFF
+	active := daint & daintmsk
+
+	for ep := uint32(0); ep < 4; ep++ {
+		if active&(1<<ep) == 0 {
+			continue
+		}
+		diep := otgInEP(ep)
+		diepint := diep.INT.Get()
+		diepintmsk := otgDevice.DIEPMSK.Get()
+		fired := diepint & diepintmsk
+
+		if fired&depintXFRC != 0 {
+			// Clear XFRC.
+			diep.INT.Set(depintXFRC)
+
+			if ep == 0 {
+				// EP0 IN transfer complete.
+				if sendOnEP0DATADONE.ptr != nil {
+					// More data to send.
+					ptr := sendOnEP0DATADONE.ptr
+					count := sendOnEP0DATADONE.count
+					if count > usb.EndpointPacketSize {
+						sendOnEP0DATADONE.offset += usb.EndpointPacketSize
+						sendOnEP0DATADONE.ptr = &udd_ep_control_cache_buffer[sendOnEP0DATADONE.offset]
+						count = usb.EndpointPacketSize
+					}
+					sendOnEP0DATADONE.count -= count
+					sendViaEPIn(0, ptr, count)
+					if sendOnEP0DATADONE.count == 0 {
+						sendOnEP0DATADONE.ptr = nil
+						sendOnEP0DATADONE.offset = 0
+					}
+				} else {
+					// All EP0 IN data sent; arm EP0 OUT for the status ZLP from host.
+					armEP0Out()
+				}
+			} else {
+				// Non-EP0 IN: find the virtual endpoint(s) mapped to this physical EP
+				// and call the registered TX handler. Multiple virtual EPs may share
+				// a physical EP (e.g., HID_IN=4 and CDC_IN=3 both → physical 1 or 3).
+				for vep := uint32(0); vep < NumberOfUSBEndpoints; vep++ {
+					if vep == ep && usbTxHandler[vep] != nil {
+						usbTxHandler[vep]()
+					}
+				}
+			}
+		}
+
+	}
+}
+
+// handleOutEndpoints handles OEPINT: checks each active OUT endpoint for STUP / XFRC.
+func handleOutEndpoints() {
+	daint := otgDevice.DAINT.Get() >> 16 // upper 16 bits = OUT EPs
+	daintmsk := otgDevice.DAINTMSK.Get() >> 16
+	active := daint & daintmsk
+
+	for ep := uint32(0); ep < 4; ep++ {
+		if active&(1<<ep) == 0 {
+			continue
+		}
+		doep := otgOutEP(ep)
+		doepint := doep.INT.Get()
+		doepintmsk := otgDevice.DOEPMSK.Get()
+		fired := doepint & doepintmsk
+
+		if fired&depintSTUP != 0 {
+			// EP0 SETUP phase done (already processed in handleRxFIFO).
+			doep.INT.Set(depintSTUP)
+		}
+
+		if fired&depintXFRC != 0 {
+			doep.INT.Set(depintXFRC)
+			if ep > 0 {
+				buf := handleEndpointRx(ep)
+				// Find the virtual endpoint(s) mapped to this physical EP and call the RX handler.
+				for vep := uint32(0); vep < NumberOfUSBEndpoints; vep++ {
+					if vep == ep && usbRxHandler[vep] != nil {
+						if usbRxHandler[vep](buf) {
+							AckUsbOutTransfer(ep)
+						}
+						break
+					}
+				}
+			}
+		}
+	}
+}
+
+// initEndpoint configures a USB endpoint for the given type and direction.
+// MPS is hardcoded to 64 bytes; the caller (usb.go) does not pass a descriptor.
+func initEndpoint(ep, config uint32) {
+	pep := ep
+	if pep == 0 {
+		return // EP0 is always active; configured in handleEnumDone
+	}
+
+	txFIFONum := pep // TX FIFO number matches physical EP
+
+	switch config {
+	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
+		ctl := (64 << depctlMPSIZ_Pos) | depctlUSBAEP |
+			(txFIFONum << depctlTXFNUM_Pos) |
+			(3 << depctlETYP_Pos) | // interrupt type
+			depctlSD0PID
+		otgInEP(pep).CTL.Set(ctl)
+		otgDevice.DAINTMSK.SetBits(1 << pep)
+
+	case usb.ENDPOINT_TYPE_BULK | usb.EndpointIn:
+		ctl := (64 << depctlMPSIZ_Pos) | depctlUSBAEP |
+			(txFIFONum << depctlTXFNUM_Pos) |
+			(2 << depctlETYP_Pos) | // bulk type
+			depctlSD0PID
+		otgInEP(pep).CTL.Set(ctl)
+		otgDevice.DAINTMSK.SetBits(1 << pep)
+
+	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointOut:
+		ctl := uint32(64) | depctlUSBAEP | depctlSD0PID |
+			(3 << depctlETYP_Pos) // interrupt type
+		otgOutEP(pep).CTL.Set(ctl)
+		otgOutEP(pep).TSIZ.Set((1 << 19) | 64)
+		otgOutEP(pep).CTL.SetBits(depctlEPENA | depctlCNAK)
+		otgDevice.DAINTMSK.SetBits(1 << (pep + 16))
+
+	case usb.ENDPOINT_TYPE_BULK | usb.EndpointOut:
+		ctl := uint32(64) | depctlUSBAEP | depctlSD0PID |
+			(2 << depctlETYP_Pos) // bulk type
+		otgOutEP(pep).CTL.Set(ctl)
+		otgOutEP(pep).TSIZ.Set((1 << 19) | 64)
+		otgOutEP(pep).CTL.SetBits(depctlEPENA | depctlCNAK)
+		otgDevice.DAINTMSK.SetBits(1 << (pep + 16))
+
+	case usb.ENDPOINT_TYPE_CONTROL:
+		// EP0 activated in handleEnumDone.
+	}
+}
+
+// SendUSBInPacket sends data on a USB IN endpoint (interrupt or bulk).
+func SendUSBInPacket(ep uint32, data []byte) bool {
+	sendUSBPacket(ep, data)
+	return true
+}
+
+// sendUSBPacket copies data into the endpoint cache buffer then initiates the transfer.
+//
+//go:noinline
+func sendUSBPacket(ep uint32, data []byte) {
+	count := len(data)
+	var buf []byte
+	if ep == 0 {
+		buf = udd_ep_control_cache_buffer[:]
+		if count > usb.EndpointPacketSize {
+			// Large response: queue continuation via sendOnEP0DATADONE.
+			sendOnEP0DATADONE.offset = usb.EndpointPacketSize
+			sendOnEP0DATADONE.ptr = &udd_ep_control_cache_buffer[usb.EndpointPacketSize]
+			sendOnEP0DATADONE.count = count - usb.EndpointPacketSize
+			count = usb.EndpointPacketSize
+		}
+	} else {
+		pep := ep
+		buf = udd_ep_in_cache_buffer[pep][:]
+	}
+	copy(buf[:len(data)], data)
+	sendViaEPIn(ep, &buf[0], count)
+}
+
+// sendViaEPIn arms the IN endpoint and writes count bytes from ptr into the TX FIFO.
+func sendViaEPIn(ep uint32, ptr *byte, count int) {
+	pep := ep
+	diep := otgInEP(pep)
+
+	// Verify TX FIFO has enough space before writing.
+	// DTXFSTS[15:0] = INEPTFSAV: available words. Stall if insufficient.
+	if count > 0 {
+		need := uint32((count + 3) / 4)
+		avail := diep.TXFST.Get() & 0xFFFF
+		if avail < need {
+			return
+		}
+	}
+
+	// Program transfer size: 1 packet, count bytes.
+	diep.TSIZ.Set(
+		uint32(count) | (1 << 19), // XFRSIZ = count, PKTCNT = 1
+	)
+
+	// Enable endpoint and clear NAK (starts transfer).
+	diep.CTL.SetBits(depctlEPENA | depctlCNAK)
+
+	// Write bytes to FIFO in 32-bit words (last word padded if needed).
+	fifo := otgDFIFO(pep)
+	data := unsafe.Slice(ptr, count)
+	words := (count + 3) / 4
+	for i := 0; i < words; i++ {
+		b := i * 4
+		var w uint32
+		w = uint32(data[b])
+		if b+1 < count {
+			w |= uint32(data[b+1]) << 8
+		}
+		if b+2 < count {
+			w |= uint32(data[b+2]) << 16
+		}
+		if b+3 < count {
+			w |= uint32(data[b+3]) << 24
+		}
+		fifo.Set(w)
+	}
+}
+
+// SendZlp sends a zero-length packet on EP0 IN (status stage for OUT control transfers).
+func SendZlp() {
+	// PKTCNT=1, XFRSIZ=0
+	otgInEP(0).TSIZ.Set(1 << 19)
+	otgInEP(0).CTL.SetBits(depctlEPENA | depctlCNAK)
+}
+
+// handleEndpointRx returns the bytes received on the given physical endpoint.
+func handleEndpointRx(ep uint32) []byte {
+	pep := ep
+	return udd_ep_out_cache_buffer[pep][:usbRxBufLen[pep]]
+}
+
+// AckUsbOutTransfer re-arms the OUT endpoint to receive the next packet.
+func AckUsbOutTransfer(ep uint32) {
+	pep := ep
+	usbRxBufLen[pep] = 0
+	doep := otgOutEP(pep)
+	doep.TSIZ.Set(
+		(1 << 19) | 64, // PKTCNT=1, XFRSIZ=64
+	)
+	doep.CTL.SetBits(depctlEPENA | depctlCNAK)
+}
+
+// handleUSBSetAddress applies the new device address from a SET_ADDRESS request
+// and sends the status ZLP. The address is written to DCFG before the ZLP is
+// enqueued: the OTG FS core has already committed the current IN token to
+// address 0, so the ZLP goes out at the old address while the new address is
+// already in DCFG and ready for the host's next transaction.
+func handleUSBSetAddress(setup usb.Setup) bool {
+	addr := uint8(setup.WValueL) & 0x7F
+
+	dcfg := otgDevice.DCFG.Get()
+	dcfg &^= dcfgDAD_Msk
+	dcfg |= uint32(addr) << dcfgDAD_Pos
+	otgDevice.DCFG.Set(dcfg)
+
+	SendZlp()
+	return true
+}
+
+// ReceiveUSBControlPacket synchronously receives a CDC control OUT packet on EP0.
+func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error) {
+	var b [cdcLineInfoSize]byte
+
+	// Arm EP0 OUT for up to 64 bytes.
+	armEP0Out()
+
+	// Busy-wait for data to arrive. We call handleRxFIFO() manually to drain
+	// the shared RX FIFO because we are currently in an interrupt context
+	// (this is called from the setup handler) and the hardware-triggered
+	// handleRxFIFO loop is blocked waiting for us to return.
+	const timeout = 300000
+	for i := 0; i < timeout; i++ {
+		if stm32.OTG_FS_GLOBAL.GINTSTS.HasBits(gintRXFLVL) {
+			handleRxFIFO()
+		}
+		if usbRxBufLen[0] > 0 {
+			n := usbRxBufLen[0]
+			if n > cdcLineInfoSize {
+				n = cdcLineInfoSize
+			}
+			copy(b[:n], udd_ep_out_cache_buffer[0][:n])
+			usbRxBufLen[0] = 0
+			SendZlp()
+			return b, nil
+		}
+	}
+	return b, ErrUSBReadTimeout
+}
+
+// SetStallEPIn stalls an IN endpoint.
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	pep := ep
+	otgInEP(pep).CTL.SetBits(depctlSTALL)
+}
+
+// ClearStallEPIn clears the stall condition on an IN endpoint.
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	pep := ep
+	// Clear STALL and reset DATA0 PID.
+	ctl := &otgInEP(pep).CTL
+	ctl.ClearBits(depctlSTALL)
+	ctl.SetBits(depctlSD0PID)
+}
+
+// SetStallEPOut stalls an OUT endpoint.
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	pep := ep
+	otgOutEP(pep).CTL.SetBits(depctlSTALL)
+}
+
+// ClearStallEPOut clears the stall condition on an OUT endpoint.
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	pep := ep
+	ctl := &otgOutEP(pep).CTL
+	ctl.ClearBits(depctlSTALL)
+	ctl.SetBits(depctlSD0PID)
+}
+
+// armEP0Out re-arms EP0 OUT to receive the next SETUP or status ZLP from the host.
+func armEP0Out() {
+	// STUPCNT=3 (bits[30:29]=11): accept up to 3 back-to-back SETUPs.
+	// PKTCNT=1 (bit[19]):         one packet.
+	// XFRSIZ=64 (bits[6:0]):      max 64 bytes.
+	otgOutEP(0).TSIZ.Set((3 << 29) | (1 << 19) | 64)
+	otgOutEP(0).CTL.SetBits(depctlEPENA | depctlCNAK)
+}
+
+// flushTxFIFO flushes the selected TX FIFO(s).
+// txfnum: 0–3 for a specific FIFO, 0x10 to flush all TX FIFOs.
+func flushTxFIFO(txfnum uint32) {
+	stm32.OTG_FS_GLOBAL.GRSTCTL.Set(
+		grstTXFFLSH | (txfnum << grstTXFNUM_Pos),
+	)
+	for stm32.OTG_FS_GLOBAL.GRSTCTL.HasBits(grstTXFFLSH) {
+	}
+}
+
+// flushRxFIFO flushes the shared RX FIFO.
+func flushRxFIFO() {
+	stm32.OTG_FS_GLOBAL.GRSTCTL.Set(grstRXFFLSH)
+	for stm32.OTG_FS_GLOBAL.GRSTCTL.HasBits(grstRXFFLSH) {
+	}
+}

src/machine/machine_stm32_rng.go

@@ -1,4 +1,4 @@
-//go:build stm32 && !(stm32f103 || stm32l0x1 || stm32g0)
+//go:build stm32 && !(stm32f103 || stm32l0x1 || stm32g0 || stm32u0)
 
 package machine
 

src/machine/machine_stm32_spi.go

@@ -1,4 +1,4 @@
-//go:build stm32 && !stm32f7x2 && !stm32l5x2 && !stm32g0 && !stm32u5
+//go:build stm32 && !stm32f7x2 && !stm32l5x2 && !stm32g0 && !stm32u5 && !stm32u0
 
 package machine
 

src/machine/machine_stm32f4_otgfs_novbus.go

@@ -0,0 +1,12 @@
+//go:build stm32f4 && !(stm32f429 || stm32f427 || stm32f411 || stm32f407 || stm32f405 || stm32f401)
+
+package machine
+
+import "device/stm32"
+
+// initOTGFSPHY enables the STM32F4 OTG FS PHY and bypasses VBUS sensing.
+// GCCFG.PWRDWN deactivates the PHY power-down; NOVBUSSENS skips the VBUS pin
+// check so boards without PA9 connected to VBUS still enumerate.
+func initOTGFSPHY() {
+	stm32.OTG_FS_GLOBAL.GCCFG.Set(stm32.USB_OTG_FS_GCCFG_PWRDWN)
+}

src/machine/machine_stm32f4_otgfs_vbus.go

@@ -0,0 +1,15 @@
+//go:build stm32f4 && (stm32f429 || stm32f427 || stm32f411 || stm32f407 || stm32f405 || stm32f401)
+
+package machine
+
+import "device/stm32"
+
+// initOTGFSPHY enables the STM32F4 OTG FS PHY and bypasses VBUS sensing.
+// GCCFG.PWRDWN deactivates the PHY power-down; NOVBUSSENS skips the VBUS pin
+// check so boards without PA9 connected to VBUS still enumerate.
+func initOTGFSPHY() {
+	stm32.OTG_FS_GLOBAL.GCCFG.Set(
+		stm32.USB_OTG_FS_GCCFG_PWRDWN | // enable FS PHY
+			stm32.USB_OTG_FS_GCCFG_NOVBUSSENS, // bypass VBUS sensing
+	)
+}

src/machine/machine_stm32f7_flash.go

@@ -0,0 +1,10 @@
+//go:build stm32f7
+
+package machine
+
+// eraseBlockSize returns the smallest erasable unit for the STM32F7 internal
+// flash. The first sectors are 32 KB; return that as the nominal page size.
+// Flash write/erase via machine.Flash is not implemented for STM32F7; this
+// stub satisfies the flash.go interface so that BlockDevice (needed by MSC)
+// compiles on this target.
+func eraseBlockSize() int64 { return 32768 }

src/machine/machine_stm32f7_otgfs_vbus.go

@@ -0,0 +1,34 @@
+//go:build stm32f7
+
+package machine
+
+import (
+	"device/arm"
+	"device/stm32"
+)
+
+// initOTGFSPHY enables the STM32F7 OTG FS PHY and overrides B-session VBUS
+// detection via GOTGCTL so boards without VBUS sensing still enumerate.
+func initOTGFSPHY() {
+	// Enable USB voltage regulator (specific to F72x/F73x).
+	// Bit 14 in PWR_CR2 is USBREGEN.
+	stm32.PWR.CR2.SetBits(1 << 14)
+
+	// Stabilization delay for the regulator (~100us is plenty).
+	for i := 0; i < 10000; i++ {
+		arm.Asm("nop")
+	}
+
+	// Enable FS PHY.
+	stm32.OTG_FS_GLOBAL.GCCFG.SetBits(stm32.USB_OTG_FS_GCCFG_PWRDWN)
+
+	// Disable hardware VBUS detection (F7 uses VBDEN, opposite polarity to F4's NOVBUSSENS).
+	// Clearing this prevents the peripheral from gating enumeration on PA9 VBUS level.
+	stm32.OTG_FS_GLOBAL.GCCFG.ClearBits(stm32.USB_OTG_FS_GCCFG_VBDEN)
+
+	// Override B-session valid so GOTGCTL-based detection reports device connected.
+	stm32.OTG_FS_GLOBAL.GOTGCTL.SetBits(
+		stm32.USB_OTG_FS_GOTGCTL_BVALOEN | // enable B-valid override
+			stm32.USB_OTG_FS_GOTGCTL_BVALOVAL, // set B-valid = 1
+	)
+}

src/machine/machine_stm32u031.go

@@ -0,0 +1,351 @@
+//go:build stm32u031
+
+package machine
+
+import (
+	"device/stm32"
+	"runtime/interrupt"
+	"runtime/volatile"
+	"unsafe"
+)
+
+var deviceIDAddr = []uintptr{0x1FFF3E50, 0x1FFF3E54, 0x1FFF3E58}
+
+// Pin constants for all stm32u0 package sizes
+const (
+	PA0  = portA + 0
+	PA1  = portA + 1
+	PA2  = portA + 2
+	PA3  = portA + 3
+	PA4  = portA + 4
+	PA5  = portA + 5
+	PA6  = portA + 6
+	PA7  = portA + 7
+	PA8  = portA + 8
+	PA9  = portA + 9
+	PA10 = portA + 10
+	PA11 = portA + 11
+	PA12 = portA + 12
+	PA13 = portA + 13
+	PA14 = portA + 14
+	PA15 = portA + 15
+
+	PB0  = portB + 0
+	PB1  = portB + 1
+	PB2  = portB + 2
+	PB3  = portB + 3
+	PB4  = portB + 4
+	PB5  = portB + 5
+	PB6  = portB + 6
+	PB7  = portB + 7
+	PB8  = portB + 8
+	PB9  = portB + 9
+	PB10 = portB + 10
+	PB11 = portB + 11
+	PB12 = portB + 12
+	PB13 = portB + 13
+	PB14 = portB + 14
+	PB15 = portB + 15
+
+	PC0  = portC + 0
+	PC1  = portC + 1
+	PC2  = portC + 2
+	PC3  = portC + 3
+	PC4  = portC + 4
+	PC5  = portC + 5
+	PC6  = portC + 6
+	PC7  = portC + 7
+	PC8  = portC + 8
+	PC9  = portC + 9
+	PC10 = portC + 10
+	PC11 = portC + 11
+	PC12 = portC + 12
+	PC13 = portC + 13
+	PC14 = portC + 14
+	PC15 = portC + 15
+
+	PD0  = portD + 0
+	PD1  = portD + 1
+	PD2  = portD + 2
+	PD3  = portD + 3
+	PD4  = portD + 4
+	PD5  = portD + 5
+	PD6  = portD + 6
+	PD7  = portD + 7
+	PD8  = portD + 8
+	PD9  = portD + 9
+	PD10 = portD + 10
+	PD11 = portD + 11
+	PD12 = portD + 12
+	PD13 = portD + 13
+	PD14 = portD + 14
+	PD15 = portD + 15
+
+	PE0  = portE + 0
+	PE1  = portE + 1
+	PE2  = portE + 2
+	PE3  = portE + 3
+	PE4  = portE + 4
+	PE5  = portE + 5
+	PE6  = portE + 6
+	PE7  = portE + 7
+	PE8  = portE + 8
+	PE9  = portE + 9
+	PE10 = portE + 10
+	PE11 = portE + 11
+	PE12 = portE + 12
+	PE13 = portE + 13
+	PE14 = portE + 14
+	PE15 = portE + 15
+
+	PF0  = portF + 0
+	PF1  = portF + 1
+	PF2  = portF + 2
+	PF3  = portF + 3
+	PF4  = portF + 4
+	PF5  = portF + 5
+	PF6  = portF + 6
+	PF7  = portF + 7
+	PF8  = portF + 8
+	PF9  = portF + 9
+	PF10 = portF + 10
+	PF11 = portF + 11
+	PF12 = portF + 12
+	PF13 = portF + 13
+	PF14 = portF + 14
+	PF15 = portF + 15
+)
+
+func (p Pin) getPort() *stm32.GPIO_Type {
+	switch p / 16 {
+	case 0:
+		return stm32.GPIOA
+	case 1:
+		return stm32.GPIOB
+	case 2:
+		return stm32.GPIOC
+	case 3:
+		return stm32.GPIOD
+	case 4:
+		return stm32.GPIOE
+	case 5:
+		return stm32.GPIOF
+	default:
+		panic("machine: unknown port")
+	}
+}
+
+// enableClock enables the clock for this desired GPIO port.
+func (p Pin) enableClock() {
+	switch p / 16 {
+	case 0:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIOAEN)
+	case 1:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIOBEN)
+	case 2:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIOCEN)
+	case 3:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIODEN)
+	case 4:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIOEEN)
+	case 5:
+		stm32.RCC.IOPENR.SetBits(stm32.RCC_IOPENR_GPIOFEN)
+	default:
+		panic("machine: unknown port")
+	}
+}
+
+func enableAltFuncClock(bus unsafe.Pointer) {
+	switch bus {
+	case unsafe.Pointer(stm32.I2C1):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_I2C1EN)
+	case unsafe.Pointer(stm32.I2C2):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_I2C2EN)
+	case unsafe.Pointer(stm32.I2C3):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_I2C3EN)
+	case unsafe.Pointer(stm32.USART1):
+		stm32.RCC.APBENR2.SetBits(stm32.RCC_APBENR2_USART1EN)
+	case unsafe.Pointer(stm32.USART2):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_USART2EN)
+	case unsafe.Pointer(stm32.USART3):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_USART3EN)
+	case unsafe.Pointer(stm32.USART4):
+		stm32.RCC.APBENR1.SetBits(stm32.RCC_APBENR1_USART4EN)
+	}
+}
+
+var (
+	// TODO: implement output channels
+
+	TIM1 = TIM{
+		EnableRegister: &stm32.RCC.APBENR2,
+		EnableFlag:     stm32.RCC_APBENR2_TIM1EN,
+		Device:         stm32.TIM1,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM2 = TIM{
+		EnableRegister: &stm32.RCC.APBENR1,
+		EnableFlag:     stm32.RCC_APBENR1_TIM2EN,
+		Device:         stm32.TIM2,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM3 = TIM{
+		EnableRegister: &stm32.RCC.APBENR1,
+		EnableFlag:     stm32.RCC_APBENR1_TIM3EN,
+		Device:         stm32.TIM3,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM6 = TIM{
+		EnableRegister: &stm32.RCC.APBENR1,
+		EnableFlag:     stm32.RCC_APBENR1_TIM6EN,
+		Device:         stm32.TIM6,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM7 = TIM{
+		EnableRegister: &stm32.RCC.APBENR1,
+		EnableFlag:     stm32.RCC_APBENR1_TIM7EN,
+		Device:         stm32.TIM7,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM15 = TIM{
+		EnableRegister: &stm32.RCC.APBENR2,
+		EnableFlag:     stm32.RCC_APBENR2_TIM15EN,
+		Device:         stm32.TIM15,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+
+	TIM16 = TIM{
+		EnableRegister: &stm32.RCC.APBENR2,
+		EnableFlag:     stm32.RCC_APBENR2_TIM16EN,
+		Device:         stm32.TIM16,
+		Channels: [4]TimerChannel{
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+			TimerChannel{Pins: []PinFunction{}},
+		},
+		busFreq: 4e6,
+	}
+)
+
+func (t *TIM) registerUPInterrupt() interrupt.Interrupt {
+	switch t {
+	case &TIM1:
+		return interrupt.New(stm32.IRQ_TIM1_BRK_UP_TRG_COM, TIM1.handleUPInterrupt)
+	case &TIM2:
+		return interrupt.New(stm32.IRQ_TIM2, TIM2.handleUPInterrupt)
+	case &TIM3:
+		return interrupt.New(stm32.IRQ_TIM3, TIM3.handleUPInterrupt)
+	case &TIM6:
+		return interrupt.New(stm32.IRQ_TIM6_DAC_LPTIM1, TIM6.handleUPInterrupt)
+	case &TIM7:
+		return interrupt.New(stm32.IRQ_TIM7_LPTIM2, TIM7.handleUPInterrupt)
+	case &TIM15:
+		return interrupt.New(stm32.IRQ_TIM15_LPTIM3, TIM15.handleUPInterrupt)
+	case &TIM16:
+		return interrupt.New(stm32.IRQ_TIM16, TIM16.handleUPInterrupt)
+	}
+
+	return interrupt.Interrupt{}
+}
+
+func (t *TIM) registerOCInterrupt() interrupt.Interrupt {
+	switch t {
+	case &TIM1:
+		return interrupt.New(stm32.IRQ_TIM1_CC, TIM1.handleOCInterrupt)
+	case &TIM2:
+		return interrupt.New(stm32.IRQ_TIM2, TIM2.handleOCInterrupt)
+	case &TIM3:
+		return interrupt.New(stm32.IRQ_TIM3, TIM3.handleOCInterrupt)
+	case &TIM6:
+		return interrupt.New(stm32.IRQ_TIM6_DAC_LPTIM1, TIM6.handleOCInterrupt)
+	case &TIM7:
+		return interrupt.New(stm32.IRQ_TIM7_LPTIM2, TIM7.handleOCInterrupt)
+	case &TIM15:
+		return interrupt.New(stm32.IRQ_TIM15_LPTIM3, TIM15.handleOCInterrupt)
+	case &TIM16:
+		return interrupt.New(stm32.IRQ_TIM16, TIM16.handleOCInterrupt)
+	}
+
+	return interrupt.Interrupt{}
+}
+
+func (t *TIM) enableMainOutput() {
+	t.Device.BDTR.SetBits(stm32.TIM_BDTR_MOE)
+}
+
+type arrtype = uint16
+type psctype = uint16
+type arrRegType = volatile.Register16
+
+const (
+	ARR_MAX = 0x10000
+	PSC_MAX = 0x10000
+)
+
+const (
+	UART_TX_PIN = NoPin
+	UART_RX_PIN = NoPin
+)
+
+func (uart *UART) configurePins(config UARTConfig) {
+	panic("unimplemented: UART")
+}
+
+func (uart *UART) getBaudRateDivisor(baudRate uint32) uint32 {
+	panic("unimplemented: UART")
+}
+
+func (uart *UART) setRegisters() uint32 {
+	panic("unimplemented: UART")
+}
+
+const (
+	I2C0_SCL_PIN = NoPin
+	I2C0_SDA_PIN = NoPin
+)
+
+func (i2c I2C) getFreqRange(br uint32) uint32 {
+	panic("unimplemented: I2C")
+}

src/machine/spi.go

@@ -1,4 +1,4 @@
-//go:build !baremetal || atmega || attiny85 || esp32 || esp32c3 || esp32s3 || fe310 || k210 || nrf || (nxp && !mk66f18) || rp2040 || rp2350 || sam || (stm32 && !stm32f7x2 && !stm32l5x2)
+//go:build !baremetal || atmega || attiny85 || esp32 || esp32c3 || esp32s3 || fe310 || k210 || nrf || (nxp && !mk66f18) || rp2040 || rp2350 || sam || (stm32 && !stm32f7x2 && !stm32l5x2 && !stm32u0)
 
 package machine
 

src/machine/spi_tx.go

@@ -1,4 +1,4 @@
-//go:build atmega || attiny85 || fe310 || k210 || (nxp && !mk66f18) || (stm32 && !stm32f7x2 && !stm32l5x2)
+//go:build atmega || attiny85 || fe310 || k210 || (nxp && !mk66f18) || (stm32 && !stm32f7x2 && !stm32l5x2 && !stm32u0)
 
 // This file implements the SPI Tx function for targets that don't have a custom
 // (faster) implementation for it.

src/machine/usb.go

@@ -1,4 +1,4 @@
-//go:build sam || nrf52840 || rp2040 || rp2350
+//go:build sam || nrf52840 || rp2040 || rp2350 || stm32f4 || stm32f7
 
 package machine
 
@@ -184,7 +184,9 @@ func sendDescriptor(setup usb.Setup) {
 			return
 		}
 	case descriptor.TypeDeviceQualifier:
-		// skip
+		// Full-speed-only device: STALL to signal no high-speed capability (USB 2.0 §9.6.2).
+		USBDev.SetStallEPIn(0)
+		return
 	default:
 	}
 
@@ -369,6 +371,10 @@ func EnableCDC(txHandler func(), rxHandler func([]byte), setupHandler func(usb.S
 		})
 }
 
+// PhysicalEndpoint maps a virtual endpoint index to the physical endpoint number
+// used by the hardware. This is an identity mapping on all currently supported platforms.
+func PhysicalEndpoint(ep uint32) uint32 { return ep }
+
 func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointConfig, setup []usb.SetupConfig) {
 	usbDescriptor = desc
 

src/machine/usb/cdc/ring_test.go

@@ -268,7 +268,7 @@ func TestRing512_PutOversize(t *testing.T) {
 
 func TestRing512_MultiplePutPeekDiscard(t *testing.T) {
 	var r ring512
-	for i := 0; i < 2000; i++ {
+	for i := range 2000 {
 		msg := []byte(fmt.Sprintf("msg%04d", i))
 		if !r.Put(msg) {
 			t.Fatalf("Put failed at iteration %d, Free=%d, Used=%d", i, r.Free(), r.Used())
@@ -290,7 +290,7 @@ func TestRing512_HeadTailOverflow(t *testing.T) {
 		t.Fatalf("Used=%d Free=%d, want 0/512", r.Used(), r.Free())
 	}
 
-	for i := 0; i < 300; i++ {
+	for i := range 300 {
 		data := []byte{byte(i), byte(i + 1), byte(i + 2)}
 		if !r.Put(data) {
 			t.Fatalf("Put failed at iter %d (head=%d tail=%d)", i, r.head.Load(), r.tail.Load())
@@ -370,7 +370,7 @@ func TestRing512_PeekTotalEqualsUsed(t *testing.T) {
 // --- Concurrent SPSC Test ---
 
 func TestRing512_SPSC(t *testing.T) {
-	for trial := 0; trial < 20; trial++ {
+	for trial := range 20 {
 		var r ring512
 		const totalBytes = 1 << 18
 		produced := make([]byte, totalBytes)
@@ -431,7 +431,7 @@ func TestRing512_SPSCSmallChunks(t *testing.T) {
 
 	go func() {
 		defer wg.Done()
-		for i := 0; i < totalBytes; i++ {
+		for i := range totalBytes {
 			for !r.Put([]byte{byte(i)}) {
 			}
 		}
@@ -494,10 +494,7 @@ func FuzzRing512(f *testing.F) {
 
 			switch op {
 			case 0: // Put
-				size := int(arg)
+				size := min(int(arg), 512)
-				if size > 512 {
-					size = 512
-				}
 				data := make([]byte, size)
 				for j := range data {
 					data[j] = byte(j)

src/machine/usb/msc/msc.go

@@ -165,6 +165,7 @@ func (m *msc) sendCSW(status csw.Status) {
 		residue = expected - m.sentBytes
 	}
 	m.cbw.CSW(status, residue, m.cswBuf)
+	m.queuedBytes = csw.MsgLen
 	m.state = mscStateStatusSent
 	m.queuedBytes = csw.MsgLen
 	m.sendUSBPacket(m.cswBuf)

src/machine/usb/msc/setup.go

@@ -51,6 +51,7 @@ func (m *msc) handleClearFeature(setup usb.Setup, wValue uint16) bool {
 	// (b) a Clear Feature HALT to the Bulk-In endpoint (clear stall IN)
 	// (c) a Clear Feature HALT to the Bulk-Out endpoint (clear stall OUT)
 	// https://usb.org/sites/default/files/usbmassbulk_10.pdf
+
 	if m.state == mscStateNeedReset {
 		wIndex := uint8(setup.WIndex & 0x7F)
 		if wIndex == usb.MSC_ENDPOINT_IN {

src/os/file_other.go

@@ -138,6 +138,22 @@ func Symlink(oldname, newname string) error {
 	return ErrNotImplemented
 }
 
+func Chmod(name string, mode FileMode) error {
+	return ErrNotImplemented
+}
+
+func Chown(name string, uid, gid int) error {
+	return ErrNotImplemented
+}
+
+func Link(oldname, newname string) error {
+	return ErrNotImplemented
+}
+
+func (f *File) Chown(uid, gid int) error {
+	return ErrNotImplemented
+}
+
 func Readlink(name string) (string, error) {
 	return "", ErrNotImplemented
 }