add byte reader

reader/byte.go

@@ -0,0 +1,53 @@
+package reader
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+func ReadBytes(r io.Reader, size int) ([]byte, error) {
+	buf := make([]byte, size)
+
+	_, err := io.ReadFull(r, buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf, nil
+}
+
+func ReadUint8(r io.Reader) (uint8, error) {
+	b, err := ReadBytes(r, 1)
+	if err != nil {
+		return 0, err
+	}
+
+	return b[0], nil
+}
+
+func ReadUint16(r io.Reader, byteOrder binary.ByteOrder) (uint16, error) {
+	b, err := ReadBytes(r, 2)
+	if err != nil {
+		return 0, err
+	}
+
+	return byteOrder.Uint16(b), nil
+}
+
+func ReadUint32(r io.Reader, byteOrder binary.ByteOrder) (uint32, error) {
+	b, err := ReadBytes(r, 4)
+	if err != nil {
+		return 0, err
+	}
+
+	return byteOrder.Uint32(b), nil
+}
+
+func ReadUint64(r io.Reader, byteOrder binary.ByteOrder) (uint64, error) {
+	b, err := ReadBytes(r, 8)
+	if err != nil {
+		return 0, err
+	}
+
+	return byteOrder.Uint64(b), nil
+}