wasm: basic String operations

Signed-off-by: Xe Iaso <me@xeiaso.net>

3 files changed, 28 insertions, 0 deletions

diff --git a/wasm/malloc_other.go b/wasm/malloc_other.go
new file mode 100644
index 0000000..5d915f8
--- /dev/null
+++ b/wasm/malloc_other.go
@@ -0,0 +1,7 @@
+//go:build !wasip1
+
+package wasm
+
+func Malloc(size uint32) Buffer {
+	panic("don't call this if you're not using WASI")
+}
diff --git a/wasm/wasm.go b/wasm/wasm.go
index 88c1a11..68acd17 100644
--- a/wasm/wasm.go
+++ b/wasm/wasm.go
@@ -6,12 +6,24 @@ import (
 
 type String uint64
 
+func (value String) Address() uint32 {
+	return uint32(value >> 32)
+}
+
+func (value String) Length() uint32 {
+	return uint32((value << 32) >> 32)
+}
+
 func FromString(value string) String {
 	position := uint32(uintptr(unsafe.Pointer(unsafe.StringData(value))))
 	bytes := uint32(len(value))
 	return String(uint64(position)<<32 | uint64(bytes))
 }
 
+func (value String) String() string {
+	return unsafe.String((*byte)(unsafe.Pointer(uintptr(value.Address()))), value.Length())
+}
+
 type Buffer uint64
 
 func (buffer Buffer) Address() uint32 {
diff --git a/wasm/wasm_host.go b/wasm/wasm_host.go
index 64b8654..01c644d 100644
--- a/wasm/wasm_host.go
+++ b/wasm/wasm_host.go
@@ -21,6 +21,15 @@ func (value String) LoadBytes(module api.Module) []byte {
 	return data
 }
 
+func (value String) Store(ctx context.Context, module api.Module, data string) (String, error) {
+	buffer, err := Store(ctx, module, []byte(data))
+	if err != nil {
+		return 0, err
+	}
+
+	return String(buffer), nil
+}
+
 func (buffer Buffer) Load(module api.Module) []byte {
 	data, ok := module.Memory().Read(buffer.Address(), buffer.Length())
 	if !ok {