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7ab9b30800
Also use a vpx prefix for them. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
136 lines
3.6 KiB
C
136 lines
3.6 KiB
C
/*
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* Copyright (C) 2006 Aurelien Jacobs <aurel@gnuage.org>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Common VP5-VP9 range decoder stuff
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*/
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#ifndef AVCODEC_VPX_RAC_H
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#define AVCODEC_VPX_RAC_H
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#include <stdint.h>
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#include "config.h"
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#include "libavutil/attributes.h"
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#include "bytestream.h"
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typedef struct VPXRangeCoder {
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int high;
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int bits; /* stored negated (i.e. negative "bits" is a positive number of
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bits left) in order to eliminate a negate in cache refilling */
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const uint8_t *buffer;
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const uint8_t *end;
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unsigned int code_word;
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int end_reached;
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} VPXRangeCoder;
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extern const uint8_t ff_vpx_norm_shift[256];
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int ff_vpx_init_range_decoder(VPXRangeCoder *c, const uint8_t *buf, int buf_size);
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/**
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* returns 1 if the end of the stream has been reached, 0 otherwise.
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*/
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static av_always_inline int vpx_rac_is_end(VPXRangeCoder *c)
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{
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if (c->end <= c->buffer && c->bits >= 0)
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c->end_reached ++;
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return c->end_reached > 10;
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}
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static av_always_inline unsigned int vpx_rac_renorm(VPXRangeCoder *c)
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{
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int shift = ff_vpx_norm_shift[c->high];
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int bits = c->bits;
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unsigned int code_word = c->code_word;
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c->high <<= shift;
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code_word <<= shift;
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bits += shift;
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if(bits >= 0 && c->buffer < c->end) {
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code_word |= bytestream_get_be16(&c->buffer) << bits;
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bits -= 16;
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}
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c->bits = bits;
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return code_word;
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}
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#if ARCH_ARM
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#include "arm/vpx_arith.h"
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#elif ARCH_X86
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#include "x86/vpx_arith.h"
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#endif
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#ifndef vpx_rac_get_prob
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#define vpx_rac_get_prob vpx_rac_get_prob
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static av_always_inline int vpx_rac_get_prob(VPXRangeCoder *c, uint8_t prob)
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{
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unsigned int code_word = vpx_rac_renorm(c);
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unsigned int low = 1 + (((c->high - 1) * prob) >> 8);
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unsigned int low_shift = low << 16;
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int bit = code_word >= low_shift;
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c->high = bit ? c->high - low : low;
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c->code_word = bit ? code_word - low_shift : code_word;
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return bit;
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}
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#endif
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#ifndef vpx_rac_get_prob_branchy
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// branchy variant, to be used where there's a branch based on the bit decoded
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static av_always_inline int vpx_rac_get_prob_branchy(VPXRangeCoder *c, int prob)
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{
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unsigned long code_word = vpx_rac_renorm(c);
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unsigned low = 1 + (((c->high - 1) * prob) >> 8);
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unsigned low_shift = low << 16;
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if (code_word >= low_shift) {
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c->high -= low;
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c->code_word = code_word - low_shift;
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return 1;
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}
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c->high = low;
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c->code_word = code_word;
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return 0;
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}
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#endif
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static av_always_inline int vpx_rac_get(VPXRangeCoder *c)
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{
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unsigned int code_word = vpx_rac_renorm(c);
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/* equiprobable */
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int low = (c->high + 1) >> 1;
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unsigned int low_shift = low << 16;
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int bit = code_word >= low_shift;
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if (bit) {
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c->high -= low;
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code_word -= low_shift;
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} else {
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c->high = low;
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}
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c->code_word = code_word;
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return bit;
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}
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#endif /* AVCODEC_VPX_RAC_H */
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