ref: 405fe6b78c3b13d2d1921f7ee745b08ce8605ed0
dir: /vpx_dsp/bitwriter.h/
/* * Copyright (c) 2010 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #ifndef VPX_DSP_BITWRITER_H_ #define VPX_DSP_BITWRITER_H_ #include "vpx_ports/mem.h" #include "vpx_dsp/prob.h" #ifdef __cplusplus extern "C" { #endif typedef struct vpx_writer { unsigned int lowvalue; unsigned int range; int count; unsigned int pos; uint8_t *buffer; } vpx_writer; void vpx_start_encode(vpx_writer *bc, uint8_t *buffer); void vpx_stop_encode(vpx_writer *bc); static INLINE void vpx_write(vpx_writer *br, int bit, int probability) { unsigned int split; int count = br->count; unsigned int range = br->range; unsigned int lowvalue = br->lowvalue; register int shift; split = 1 + (((range - 1) * probability) >> 8); range = split; if (bit) { lowvalue += split; range = br->range - split; } shift = vpx_norm[range]; range <<= shift; count += shift; if (count >= 0) { int offset = shift - count; if ((lowvalue << (offset - 1)) & 0x80000000) { int x = br->pos - 1; while (x >= 0 && br->buffer[x] == 0xff) { br->buffer[x] = 0; x--; } br->buffer[x] += 1; } br->buffer[br->pos++] = (lowvalue >> (24 - offset)); lowvalue <<= offset; shift = count; lowvalue &= 0xffffff; count -= 8; } lowvalue <<= shift; br->count = count; br->lowvalue = lowvalue; br->range = range; } static INLINE void vpx_write_bit(vpx_writer *w, int bit) { vpx_write(w, bit, 128); // vpx_prob_half } static INLINE void vpx_write_literal(vpx_writer *w, int data, int bits) { int bit; for (bit = bits - 1; bit >= 0; bit--) vpx_write_bit(w, 1 & (data >> bit)); } #define vpx_write_prob(w, v) vpx_write_literal((w), (v), 8) #ifdef __cplusplus } // extern "C" #endif #endif // VPX_DSP_BITWRITER_H_