817be1d214
changes prefix vp9_ to vpx_ for non codec specific functions and data structures. Change-Id: I91a21548e39bd24d2c7caaaa223ae47240bb78c8
99 lines
2.1 KiB
C
99 lines
2.1 KiB
C
/*
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* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef VPX_DSP_BITWRITER_H_
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#define VPX_DSP_BITWRITER_H_
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#include "vpx_ports/mem.h"
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#include "vpx_dsp/prob.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct vpx_writer {
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unsigned int lowvalue;
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unsigned int range;
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int count;
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unsigned int pos;
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uint8_t *buffer;
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} vpx_writer;
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void vpx_start_encode(vpx_writer *bc, uint8_t *buffer);
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void vpx_stop_encode(vpx_writer *bc);
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static INLINE void vpx_write(vpx_writer *br, int bit, int probability) {
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unsigned int split;
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int count = br->count;
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unsigned int range = br->range;
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unsigned int lowvalue = br->lowvalue;
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register unsigned int shift;
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split = 1 + (((range - 1) * probability) >> 8);
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range = split;
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if (bit) {
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lowvalue += split;
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range = br->range - split;
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}
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shift = vpx_norm[range];
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range <<= shift;
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count += shift;
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if (count >= 0) {
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int offset = shift - count;
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if ((lowvalue << (offset - 1)) & 0x80000000) {
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int x = br->pos - 1;
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while (x >= 0 && br->buffer[x] == 0xff) {
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br->buffer[x] = 0;
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x--;
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}
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br->buffer[x] += 1;
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}
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br->buffer[br->pos++] = (lowvalue >> (24 - offset));
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lowvalue <<= offset;
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shift = count;
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lowvalue &= 0xffffff;
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count -= 8;
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}
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lowvalue <<= shift;
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br->count = count;
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br->lowvalue = lowvalue;
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br->range = range;
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}
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static INLINE void vpx_write_bit(vpx_writer *w, int bit) {
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vpx_write(w, bit, 128); // vpx_prob_half
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}
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static INLINE void vpx_write_literal(vpx_writer *w, int data, int bits) {
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int bit;
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for (bit = bits - 1; bit >= 0; bit--)
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vpx_write_bit(w, 1 & (data >> bit));
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}
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#define vpx_write_prob(w, v) vpx_write_literal((w), (v), 8)
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // VPX_DSP_BITWRITER_H_
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