diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/huff0/bitreader.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/huff0/bitreader.go | 229 |
1 files changed, 0 insertions, 229 deletions
diff --git a/vendor/github.com/klauspost/compress/huff0/bitreader.go b/vendor/github.com/klauspost/compress/huff0/bitreader.go deleted file mode 100644 index e36d9742f..000000000 --- a/vendor/github.com/klauspost/compress/huff0/bitreader.go +++ /dev/null @@ -1,229 +0,0 @@ -// Copyright 2018 Klaus Post. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. -// Based on work Copyright (c) 2013, Yann Collet, released under BSD License. - -package huff0 - -import ( - "encoding/binary" - "errors" - "fmt" - "io" -) - -// bitReader reads a bitstream in reverse. -// The last set bit indicates the start of the stream and is used -// for aligning the input. -type bitReaderBytes struct { - in []byte - off uint // next byte to read is at in[off - 1] - value uint64 - bitsRead uint8 -} - -// init initializes and resets the bit reader. -func (b *bitReaderBytes) init(in []byte) error { - if len(in) < 1 { - return errors.New("corrupt stream: too short") - } - b.in = in - b.off = uint(len(in)) - // The highest bit of the last byte indicates where to start - v := in[len(in)-1] - if v == 0 { - return errors.New("corrupt stream, did not find end of stream") - } - b.bitsRead = 64 - b.value = 0 - if len(in) >= 8 { - b.fillFastStart() - } else { - b.fill() - b.fill() - } - b.advance(8 - uint8(highBit32(uint32(v)))) - return nil -} - -// peekBitsFast requires that at least one bit is requested every time. -// There are no checks if the buffer is filled. -func (b *bitReaderBytes) peekByteFast() uint8 { - got := uint8(b.value >> 56) - return got -} - -func (b *bitReaderBytes) advance(n uint8) { - b.bitsRead += n - b.value <<= n & 63 -} - -// fillFast() will make sure at least 32 bits are available. -// There must be at least 4 bytes available. -func (b *bitReaderBytes) fillFast() { - if b.bitsRead < 32 { - return - } - - // 2 bounds checks. - v := b.in[b.off-4 : b.off] - low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) - b.value |= uint64(low) << (b.bitsRead - 32) - b.bitsRead -= 32 - b.off -= 4 -} - -// fillFastStart() assumes the bitReaderBytes is empty and there is at least 8 bytes to read. -func (b *bitReaderBytes) fillFastStart() { - // Do single re-slice to avoid bounds checks. - b.value = binary.LittleEndian.Uint64(b.in[b.off-8:]) - b.bitsRead = 0 - b.off -= 8 -} - -// fill() will make sure at least 32 bits are available. -func (b *bitReaderBytes) fill() { - if b.bitsRead < 32 { - return - } - if b.off > 4 { - v := b.in[b.off-4 : b.off] - low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) - b.value |= uint64(low) << (b.bitsRead - 32) - b.bitsRead -= 32 - b.off -= 4 - return - } - for b.off > 0 { - b.value |= uint64(b.in[b.off-1]) << (b.bitsRead - 8) - b.bitsRead -= 8 - b.off-- - } -} - -// finished returns true if all bits have been read from the bit stream. -func (b *bitReaderBytes) finished() bool { - return b.off == 0 && b.bitsRead >= 64 -} - -func (b *bitReaderBytes) remaining() uint { - return b.off*8 + uint(64-b.bitsRead) -} - -// close the bitstream and returns an error if out-of-buffer reads occurred. -func (b *bitReaderBytes) close() error { - // Release reference. - b.in = nil - if b.remaining() > 0 { - return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining()) - } - if b.bitsRead > 64 { - return io.ErrUnexpectedEOF - } - return nil -} - -// bitReaderShifted reads a bitstream in reverse. -// The last set bit indicates the start of the stream and is used -// for aligning the input. -type bitReaderShifted struct { - in []byte - off uint // next byte to read is at in[off - 1] - value uint64 - bitsRead uint8 -} - -// init initializes and resets the bit reader. -func (b *bitReaderShifted) init(in []byte) error { - if len(in) < 1 { - return errors.New("corrupt stream: too short") - } - b.in = in - b.off = uint(len(in)) - // The highest bit of the last byte indicates where to start - v := in[len(in)-1] - if v == 0 { - return errors.New("corrupt stream, did not find end of stream") - } - b.bitsRead = 64 - b.value = 0 - if len(in) >= 8 { - b.fillFastStart() - } else { - b.fill() - b.fill() - } - b.advance(8 - uint8(highBit32(uint32(v)))) - return nil -} - -// peekBitsFast requires that at least one bit is requested every time. -// There are no checks if the buffer is filled. -func (b *bitReaderShifted) peekBitsFast(n uint8) uint16 { - return uint16(b.value >> ((64 - n) & 63)) -} - -func (b *bitReaderShifted) advance(n uint8) { - b.bitsRead += n - b.value <<= n & 63 -} - -// fillFast() will make sure at least 32 bits are available. -// There must be at least 4 bytes available. -func (b *bitReaderShifted) fillFast() { - if b.bitsRead < 32 { - return - } - - // 2 bounds checks. - v := b.in[b.off-4 : b.off] - low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) - b.value |= uint64(low) << ((b.bitsRead - 32) & 63) - b.bitsRead -= 32 - b.off -= 4 -} - -// fillFastStart() assumes the bitReaderShifted is empty and there is at least 8 bytes to read. -func (b *bitReaderShifted) fillFastStart() { - // Do single re-slice to avoid bounds checks. - b.value = binary.LittleEndian.Uint64(b.in[b.off-8:]) - b.bitsRead = 0 - b.off -= 8 -} - -// fill() will make sure at least 32 bits are available. -func (b *bitReaderShifted) fill() { - if b.bitsRead < 32 { - return - } - if b.off > 4 { - v := b.in[b.off-4 : b.off] - low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) - b.value |= uint64(low) << ((b.bitsRead - 32) & 63) - b.bitsRead -= 32 - b.off -= 4 - return - } - for b.off > 0 { - b.value |= uint64(b.in[b.off-1]) << ((b.bitsRead - 8) & 63) - b.bitsRead -= 8 - b.off-- - } -} - -func (b *bitReaderShifted) remaining() uint { - return b.off*8 + uint(64-b.bitsRead) -} - -// close the bitstream and returns an error if out-of-buffer reads occurred. -func (b *bitReaderShifted) close() error { - // Release reference. - b.in = nil - if b.remaining() > 0 { - return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining()) - } - if b.bitsRead > 64 { - return io.ErrUnexpectedEOF - } - return nil -} |