make runtime compatible with wasm

runtime/internal/clite/syscall/dirent.go

@@ -0,0 +1,47 @@
+package syscall
+
+import (
+	"github.com/goplus/llgo/runtime/internal/clite/byteorder"
+	"github.com/goplus/llgo/runtime/internal/clite/goarch"
+)
+
+// readInt returns the size-bytes unsigned integer in native byte order at offset off.
+func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
+	if len(b) < int(off+size) {
+		return 0, false
+	}
+	if goarch.BigEndian {
+		return readIntBE(b[off:], size), true
+	}
+	return readIntLE(b[off:], size), true
+}
+
+func readIntBE(b []byte, size uintptr) uint64 {
+	switch size {
+	case 1:
+		return uint64(b[0])
+	case 2:
+		return uint64(byteorder.BEUint16(b))
+	case 4:
+		return uint64(byteorder.BEUint32(b))
+	case 8:
+		return uint64(byteorder.BEUint64(b))
+	default:
+		panic("syscall: readInt with unsupported size")
+	}
+}
+
+func readIntLE(b []byte, size uintptr) uint64 {
+	switch size {
+	case 1:
+		return uint64(b[0])
+	case 2:
+		return uint64(byteorder.LEUint16(b))
+	case 4:
+		return uint64(byteorder.LEUint32(b))
+	case 8:
+		return uint64(byteorder.LEUint64(b))
+	default:
+		panic("syscall: readInt with unsupported size")
+	}
+}