868fc0b04a
This commit ports the following from aom/master: 4c46278 Add aom_reader_tell() support. b9c9935 Remove an erroneous declaration. 56c9c3b Fix ANS build. Change-Id: I59bd910f58c218c649a1de2a7b5fae0397e13cb1
113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
/*
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* Copyright (c) 2016, Alliance for Open Media. All rights reserved
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*
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* This source code is subject to the terms of the BSD 2 Clause License and
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* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
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* was not distributed with this source code in the LICENSE file, you can
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* obtain it at www.aomedia.org/license/software. If the Alliance for Open
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* Media Patent License 1.0 was not distributed with this source code in the
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* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
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*/
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#ifndef AOM_DSP_BUF_ANS_H_
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#define AOM_DSP_BUF_ANS_H_
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// Buffered forward ANS writer.
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// Symbols are written to the writer in forward (decode) order and serialized
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// backwards due to ANS's stack like behavior.
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#include <assert.h>
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#include "./aom_config.h"
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#include "aom/aom_integer.h"
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#include "aom_dsp/ans.h"
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#include "aom_dsp/answriter.h"
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#ifdef __cplusplus
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extern "C" {
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#endif // __cplusplus
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#define ANS_METHOD_UABS 0
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#define ANS_METHOD_RANS 1
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struct buffered_ans_symbol {
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unsigned int method : 1; // one of ANS_METHOD_UABS or ANS_METHOD_RANS
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// TODO(aconverse): Should be possible to write this in terms of start for ABS
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unsigned int val_start : RANS_PROB_BITS; // Boolean value for ABS
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// start in symbol cycle for Rans
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unsigned int prob : RANS_PROB_BITS; // Probability of this symbol
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};
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struct BufAnsCoder {
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struct aom_internal_error_info *error;
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struct buffered_ans_symbol *buf;
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int size;
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int offset;
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};
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void aom_buf_ans_alloc(struct BufAnsCoder *c,
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struct aom_internal_error_info *error, int size_hint);
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void aom_buf_ans_free(struct BufAnsCoder *c);
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void aom_buf_ans_grow(struct BufAnsCoder *c);
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static INLINE void buf_ans_write_reset(struct BufAnsCoder *const c) {
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c->offset = 0;
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}
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static INLINE void buf_uabs_write(struct BufAnsCoder *const c, uint8_t val,
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AnsP8 prob) {
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assert(c->offset <= c->size);
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if (c->offset == c->size) {
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aom_buf_ans_grow(c);
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}
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c->buf[c->offset].method = ANS_METHOD_UABS;
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c->buf[c->offset].val_start = val;
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c->buf[c->offset].prob = prob;
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++c->offset;
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}
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static INLINE void buf_rans_write(struct BufAnsCoder *const c,
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const struct rans_sym *const sym) {
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assert(c->offset <= c->size);
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if (c->offset == c->size) {
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aom_buf_ans_grow(c);
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}
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c->buf[c->offset].method = ANS_METHOD_RANS;
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c->buf[c->offset].val_start = sym->cum_prob;
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c->buf[c->offset].prob = sym->prob;
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++c->offset;
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}
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static INLINE void buf_ans_flush(const struct BufAnsCoder *const c,
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struct AnsCoder *ans) {
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int offset;
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for (offset = c->offset - 1; offset >= 0; --offset) {
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if (c->buf[offset].method == ANS_METHOD_RANS) {
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struct rans_sym sym;
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sym.prob = c->buf[offset].prob;
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sym.cum_prob = c->buf[offset].val_start;
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rans_write(ans, &sym);
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} else {
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uabs_write(ans, (uint8_t)c->buf[offset].val_start,
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(AnsP8)c->buf[offset].prob);
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}
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}
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}
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static INLINE void buf_uabs_write_bit(struct BufAnsCoder *c, int bit) {
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buf_uabs_write(c, bit, 128);
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}
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static INLINE void buf_uabs_write_literal(struct BufAnsCoder *c, int literal,
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int bits) {
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int bit;
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assert(bits < 31);
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for (bit = bits - 1; bit >= 0; bit--)
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buf_uabs_write_bit(c, 1 & (literal >> bit));
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}
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#ifdef __cplusplus
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} // extern "C"
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#endif // __cplusplus
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#endif // AOM_DSP_BUF_ANS_H_
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