57 lines
961 B
Go
57 lines
961 B
Go
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package brotli
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/* Copyright 2010 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Write bits into a byte array. */
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type bitWriter struct {
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dst []byte
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// Data waiting to be written is the low nbits of bits.
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bits uint64
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nbits uint
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}
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func (w *bitWriter) writeBits(nb uint, b uint64) {
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w.bits |= b << w.nbits
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w.nbits += nb
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if w.nbits >= 32 {
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bits := w.bits
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w.bits >>= 32
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w.nbits -= 32
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w.dst = append(w.dst,
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byte(bits),
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byte(bits>>8),
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byte(bits>>16),
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byte(bits>>24),
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)
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}
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}
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func (w *bitWriter) writeSingleBit(bit bool) {
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if bit {
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w.writeBits(1, 1)
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} else {
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w.writeBits(1, 0)
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}
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}
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func (w *bitWriter) jumpToByteBoundary() {
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dst := w.dst
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for w.nbits != 0 {
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dst = append(dst, byte(w.bits))
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w.bits >>= 8
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if w.nbits > 8 { // Avoid underflow
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w.nbits -= 8
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} else {
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w.nbits = 0
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}
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}
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w.bits = 0
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w.dst = dst
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}
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