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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/encoding/hex/hex.go
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Diffstat (limited to 'libgo/go/encoding/hex/hex.go')
-rw-r--r--libgo/go/encoding/hex/hex.go101
1 files changed, 101 insertions, 0 deletions
diff --git a/libgo/go/encoding/hex/hex.go b/libgo/go/encoding/hex/hex.go
new file mode 100644
index 000000000..292d917eb
--- /dev/null
+++ b/libgo/go/encoding/hex/hex.go
@@ -0,0 +1,101 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This package implements hexadecimal encoding and decoding.
+package hex
+
+import (
+ "os"
+ "strconv"
+)
+
+const hextable = "0123456789abcdef"
+
+// EncodedLen returns the length of an encoding of n source bytes.
+func EncodedLen(n int) int { return n * 2 }
+
+// Encode encodes src into EncodedLen(len(src))
+// bytes of dst. As a convenience, it returns the number
+// of bytes written to dst, but this value is always EncodedLen(len(src)).
+// Encode implements hexadecimal encoding.
+func Encode(dst, src []byte) int {
+ for i, v := range src {
+ dst[i*2] = hextable[v>>4]
+ dst[i*2+1] = hextable[v&0x0f]
+ }
+
+ return len(src) * 2
+}
+
+// OddLengthInputError results from decoding an odd length slice.
+type OddLengthInputError struct{}
+
+func (OddLengthInputError) String() string { return "odd length hex string" }
+
+// InvalidHexCharError results from finding an invalid character in a hex string.
+type InvalidHexCharError byte
+
+func (e InvalidHexCharError) String() string {
+ return "invalid hex char: " + strconv.Itoa(int(e))
+}
+
+
+func DecodedLen(x int) int { return x / 2 }
+
+// Decode decodes src into DecodedLen(len(src)) bytes, returning the actual
+// number of bytes written to dst.
+//
+// If Decode encounters invalid input, it returns an OddLengthInputError or an
+// InvalidHexCharError.
+func Decode(dst, src []byte) (int, os.Error) {
+ if len(src)%2 == 1 {
+ return 0, OddLengthInputError{}
+ }
+
+ for i := 0; i < len(src)/2; i++ {
+ a, ok := fromHexChar(src[i*2])
+ if !ok {
+ return 0, InvalidHexCharError(src[i*2])
+ }
+ b, ok := fromHexChar(src[i*2+1])
+ if !ok {
+ return 0, InvalidHexCharError(src[i*2+1])
+ }
+ dst[i] = (a << 4) | b
+ }
+
+ return len(src) / 2, nil
+}
+
+// fromHexChar converts a hex character into its value and a success flag.
+func fromHexChar(c byte) (byte, bool) {
+ switch {
+ case '0' <= c && c <= '9':
+ return c - '0', true
+ case 'a' <= c && c <= 'f':
+ return c - 'a' + 10, true
+ case 'A' <= c && c <= 'F':
+ return c - 'A' + 10, true
+ }
+
+ return 0, false
+}
+
+// EncodeToString returns the hexadecimal encoding of src.
+func EncodeToString(src []byte) string {
+ dst := make([]byte, EncodedLen(len(src)))
+ Encode(dst, src)
+ return string(dst)
+}
+
+// DecodeString returns the bytes represented by the hexadecimal string s.
+func DecodeString(s string) ([]byte, os.Error) {
+ src := []byte(s)
+ dst := make([]byte, DecodedLen(len(src)))
+ _, err := Decode(dst, src)
+ if err != nil {
+ return nil, err
+ }
+ return dst, nil
+}