Rearranged wasm challenge utils

lib/challenge/wasm/interface/interface_tinygo.go

@@ -0,0 +1,59 @@
+//go:build tinygo
+
+package _interface
+
+// #include <stdlib.h>
+import "C"
+import (
+	"unsafe"
+)
+
+// PtrToBytes returns a byte slice from WebAssembly compatible numeric types
+// representing its pointer and length.
+func PtrToBytes(ptr uint32, size uint32) []byte {
+	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(ptr))), size)
+}
+
+// BytesToPtr returns a pointer and size pair for the given byte slice in a way
+// compatible with WebAssembly numeric types.
+// The returned pointer aliases the slice hence the slice must be kept alive
+// until ptr is no longer needed.
+func BytesToPtr(s []byte) (uint32, uint32) {
+	ptr := unsafe.Pointer(unsafe.SliceData(s))
+	return uint32(uintptr(ptr)), uint32(len(s))
+}
+
+// BytesToLeakedPtr returns a pointer and size pair for the given byte slice in a way
+// compatible with WebAssembly numeric types.
+// The pointer is not automatically managed by TinyGo hence it must be freed by the host.
+func BytesToLeakedPtr(s []byte) (uint32, uint32) {
+	size := C.ulong(len(s))
+	ptr := unsafe.Pointer(C.malloc(size))
+	copy(unsafe.Slice((*byte)(ptr), size), s)
+	return uint32(uintptr(ptr)), uint32(size)
+}
+
+// PtrToString returns a string from WebAssembly compatible numeric types
+// representing its pointer and length.
+func PtrToString(ptr uint32, size uint32) string {
+	return unsafe.String((*byte)(unsafe.Pointer(uintptr(ptr))), size)
+}
+
+// StringToPtr returns a pointer and size pair for the given string in a way
+// compatible with WebAssembly numeric types.
+// The returned pointer aliases the string hence the string must be kept alive
+// until ptr is no longer needed.
+func StringToPtr(s string) (uint32, uint32) {
+	ptr := unsafe.Pointer(unsafe.StringData(s))
+	return uint32(uintptr(ptr)), uint32(len(s))
+}
+
+// StringToLeakedPtr returns a pointer and size pair for the given string in a way
+// compatible with WebAssembly numeric types.
+// The pointer is not automatically managed by TinyGo hence it must be freed by the host.
+func StringToLeakedPtr(s string) (uint32, uint32) {
+	size := C.ulong(len(s))
+	ptr := unsafe.Pointer(C.malloc(size))
+	copy(unsafe.Slice((*byte)(ptr), size), s)
+	return uint32(uintptr(ptr)), uint32(size)
+}