Initial commit

util.go

@@ -0,0 +1,71 @@
+// Copyright 2015, David Howden
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tag
+
+import (
+	"io"
+	"io/ioutil"
+)
+
+func discardN(r io.Reader, n int64) error {
+	_, err := io.CopyN(ioutil.Discard, r, n)
+	return err
+}
+
+func getBit(b byte, n uint) bool {
+	x := byte(1 << n)
+	return (b & x) == x
+}
+
+func get7BitChunkedInt(b []byte) int {
+	var n int
+	for _, x := range b {
+		n = n << 7
+		n |= int(x)
+	}
+	return n
+}
+
+func getInt(b []byte) int {
+	var n int
+	for _, x := range b {
+		n = n << 8
+		n |= int(x)
+	}
+	return n
+}
+
+func readBytes(r io.Reader, n int) ([]byte, error) {
+	b := make([]byte, n)
+	_, err := io.ReadFull(r, b)
+	if err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+func readString(r io.Reader, n int) (string, error) {
+	b, err := readBytes(r, n)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}
+
+func readInt(r io.Reader, n int) (int, error) {
+	b, err := readBytes(r, n)
+	if err != nil {
+		return 0, err
+	}
+	return getInt(b), nil
+}
+
+func read7BitChunkedInt(r io.Reader, n int) (int, error) {
+	b, err := readBytes(r, n)
+	if err != nil {
+		return 0, err
+	}
+	return get7BitChunkedInt(b), nil
+}