runtime/js: impl CopyBytesToGo,CopyBytesToJS

runtime/js/embind/_wrap/emval.cpp

@@ -173,25 +173,13 @@ EM_VAL llgo_emval_call(EM_VAL fn, EM_VAL args[], int nargs, int kind, int *error
    return fromGenericWireType<val>(ret).release_ownership();
 }
 
-/*
-TYPEID llgo_emval_typeid_void() {
-    return take_typeid<void>();
+EM_VAL llgo_emval_memory_view_uint8(size_t length, uint8_t *data) {
+    val view{ typed_memory_view<uint8_t>(length,data) };
+    return view.release_ownership();
 }
 
-TYPEID llgo_emval_typeid_double() {
-    return take_typeid<double>();
-}
-
-TYPEID llgo_emval_typeid_string() {
-    return take_typeid<std::string>();
-}
-
-TYPEID llgo_emval_typeid_val() {
-    return take_typeid<val>();
-}
-*/
-
 void llgo_emval_dump(EM_VAL v) {
+    _emval_incref(v);
     val console = val::global("console");
     console.call<void>("log", val::take_ownership(v));
 }

runtime/js/emval.go

@@ -83,6 +83,9 @@ func emval_method_call(object Value, name *c.Char, args *Value, nargs c.Int, err
 //go:linkname emval_call C.llgo_emval_call
 func emval_call(fn Value, args *Value, nargs c.Int, kind c.Int, err *c.Int) Value
 
+//go:linkname emval_memory_view_uint8 C.llgo_emval_memory_view_uint8
+func emval_memory_view_uint8(length c.SizeT, data *c.Uint8T) Value
+
 //go:linkname emval_dump C.llgo_emval_dump
 func emval_dump(v Value)
 

runtime/js/js.go

@@ -666,7 +666,13 @@ func (e *ValueError) Error() string {
 // It panics if src is not a Uint8Array or Uint8ClampedArray.
 // It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
 func CopyBytesToGo(dst []byte, src Value) int {
-	return 0
+	if !(emval_instanceof(src, uint8Array) || emval_instanceof(src, uint8ClampedArray)) {
+		return 0
+	}
+	toCopy := src.Call("subarray", 0, len(dst))
+	view := emval_memory_view_uint8(uintptr(len(dst)), *(**byte)(unsafe.Pointer(&dst)))
+	view.Call("set", toCopy)
+	return toCopy.Length()
 	// n, ok := copyBytesToGo(dst, src.ref)
 	// runtime.KeepAlive(src)
 	// if !ok {
@@ -675,6 +681,23 @@ func CopyBytesToGo(dst []byte, src Value) int {
 	// return n
 }
 
+/*
+	// func copyBytesToGo(dst []byte, src ref) (int, bool)
+	"syscall/js.copyBytesToGo": (sp) => {
+		sp >>>= 0;
+		const dst = loadSlice(sp + 8);
+		const src = loadValue(sp + 32);
+		if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
+			this.mem.setUint8(sp + 48, 0);
+			return;
+		}
+		const toCopy = src.subarray(0, dst.length);
+		dst.set(toCopy);
+		setInt64(sp + 40, toCopy.length);
+		this.mem.setUint8(sp + 48, 1);
+	},
+*/
+
 // copyBytesToGo copies bytes from src to dst.
 //
 // Using go:noescape is safe because the dst byte slice is only used as a dst
@@ -688,7 +711,13 @@ func CopyBytesToGo(dst []byte, src Value) int {
 // It panics if dst is not a Uint8Array or Uint8ClampedArray.
 // It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
 func CopyBytesToJS(dst Value, src []byte) int {
-	return 0
+	if !(emval_instanceof(dst, uint8Array) || emval_instanceof(dst, uint8ClampedArray)) {
+		return 0
+	}
+	view := emval_memory_view_uint8(uintptr(len(src)), *(**byte)(unsafe.Pointer(&src)))
+	toCopy := view.Call("subarray", 0, dst.Length())
+	dst.Call("set", toCopy)
+	return toCopy.Length()
 	// n, ok := copyBytesToJS(dst.ref, src)
 	// runtime.KeepAlive(dst)
 	// if !ok {
@@ -697,6 +726,28 @@ func CopyBytesToJS(dst Value, src []byte) int {
 	// return n
 }
 
+/*
+	// func copyBytesToJS(dst ref, src []byte) (int, bool)
+	"syscall/js.copyBytesToJS": (sp) => {
+		sp >>>= 0;
+		const dst = loadValue(sp + 8);
+		const src = loadSlice(sp + 16);
+		if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
+			this.mem.setUint8(sp + 48, 0);
+			return;
+		}
+		const toCopy = src.subarray(0, dst.length);
+		dst.set(toCopy);
+		setInt64(sp + 40, toCopy.length);
+		this.mem.setUint8(sp + 48, 1);
+	},
+*/
+
+var (
+	uint8Array        = emval_get_global(c.Str("Uint8Array"))
+	uint8ClampedArray = emval_get_global(c.Str("Uint8ClampedArray"))
+)
+
 // copyBytesToJS copies bytes from src to dst.
 //
 // Using go:noescape is safe because the src byte slice is only used as a src