diff options
Diffstat (limited to 'src/pkg/compress/bzip2/bit_reader.go')
-rw-r--r-- | src/pkg/compress/bzip2/bit_reader.go | 88 |
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 -} |