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path: root/src/pkg/compress/bzip2/bit_reader.go
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Diffstat (limited to 'src/pkg/compress/bzip2/bit_reader.go')
-rw-r--r--src/pkg/compress/bzip2/bit_reader.go88
1 files changed, 0 insertions, 88 deletions
diff --git a/src/pkg/compress/bzip2/bit_reader.go b/src/pkg/compress/bzip2/bit_reader.go
deleted file mode 100644
index 50f0ec836..000000000
--- a/src/pkg/compress/bzip2/bit_reader.go
+++ /dev/null
@@ -1,88 +0,0 @@
-// Copyright 2011 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.
-
-package bzip2
-
-import (
- "bufio"
- "io"
- "os"
-)
-
-// bitReader wraps an io.Reader and provides the ability to read values,
-// bit-by-bit, from it. Its Read* methods don't return the usual os.Error
-// because the error handling was verbose. Instead, any error is kept and can
-// be checked afterwards.
-type bitReader struct {
- r byteReader
- n uint64
- bits uint
- err os.Error
-}
-
-// bitReader needs to read bytes from an io.Reader. We attempt to cast the
-// given io.Reader to this interface and, if it doesn't already fit, we wrap in
-// a bufio.Reader.
-type byteReader interface {
- ReadByte() (byte, os.Error)
-}
-
-func newBitReader(r io.Reader) bitReader {
- byter, ok := r.(byteReader)
- if !ok {
- byter = bufio.NewReader(r)
- }
- return bitReader{r: byter}
-}
-
-// ReadBits64 reads the given number of bits and returns them in the
-// least-significant part of a uint64. In the event of an error, it returns 0
-// and the error can be obtained by calling Error().
-func (br *bitReader) ReadBits64(bits uint) (n uint64) {
- for bits > br.bits {
- b, err := br.r.ReadByte()
- if err == os.EOF {
- err = io.ErrUnexpectedEOF
- }
- if err != nil {
- br.err = err
- return 0
- }
- br.n <<= 8
- br.n |= uint64(b)
- br.bits += 8
- }
-
- // br.n looks like this (assuming that br.bits = 14 and bits = 6):
- // Bit: 111111
- // 5432109876543210
- //
- // (6 bits, the desired output)
- // |-----|
- // V V
- // 0101101101001110
- // ^ ^
- // |------------|
- // br.bits (num valid bits)
- //
- // This the next line right shifts the desired bits into the
- // least-significant places and masks off anything above.
- n = (br.n >> (br.bits - bits)) & ((1 << bits) - 1)
- br.bits -= bits
- return
-}
-
-func (br *bitReader) ReadBits(bits uint) (n int) {
- n64 := br.ReadBits64(bits)
- return int(n64)
-}
-
-func (br *bitReader) ReadBit() bool {
- n := br.ReadBits(1)
- return n != 0
-}
-
-func (br *bitReader) Error() os.Error {
- return br.err
-}