Commit 109ef96a authored by Alex Converse's avatar Alex Converse Committed by Gerrit Code Review

Merge "Add a placeholder forward buffered ANS coder." into nextgenv2

parents 4914ae46 44ce6680
* Copyright (c) 2016 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.
// Buffered forward ANS writer.
// Symbols are written to the writer in forward (decode) order and serialzed
// backwards due to ANS's stack like behavior.
#include <assert.h>
#include "./vpx_config.h"
#include "vpx/vpx_integer.h"
#include "vpx_ports/mem_ops.h"
#include "vp10/common/ans.h"
#ifdef __cplusplus
extern "C" {
#endif // __cplusplus
struct buffered_ans_symbol {
uint8_t method; // one of ANS_METHOD_UABS or ANS_METHOD_RANS
// TODO(aconverse): Should be possible to write this interms of start for ABS
AnsP8 val_start; // Boolean value for ABS, start in symbol cycle for Rans
AnsP8 prob; // Probability of this symbol
struct BufAnsCoder {
struct buffered_ans_symbol *buf;
int size;
int offset;
static INLINE void buf_ans_write_init(struct BufAnsCoder *const c,
struct buffered_ans_symbol *sym_arr,
int size) {
c->buf = sym_arr;
c->size = size;
c->offset = 0;
static INLINE void buf_uabs_write(struct BufAnsCoder *const c,
uint8_t val, AnsP8 prob) {
assert(c->offset < c->size);
c->buf[c->offset].method = ANS_METHOD_UABS;
c->buf[c->offset].val_start = val;
c->buf[c->offset].prob = prob;
static INLINE void buf_rans_write(struct BufAnsCoder *const c,
const struct rans_sym *const sym) {
assert(c->offset < c->size);
c->buf[c->offset].method = ANS_METHOD_RANS;
c->buf[c->offset].val_start = sym->cum_prob;
c->buf[c->offset].prob = sym->prob;
static INLINE void buf_ans_flush(const struct BufAnsCoder *const c,
struct AnsCoder *ans) {
int offset;
for (offset = c->offset - 1; offset >= 0; --offset) {
if (c->buf[offset].method == ANS_METHOD_RANS) {
struct rans_sym sym;
sym.prob = c->buf[offset].prob;
sym.cum_prob = c->buf[offset].val_start;
rans_write(ans, &sym);
} else {
uabs_write(ans, c->buf[offset].val_start, c->buf[offset].prob);
#ifdef __cplusplus
} // extern "C"
#endif // __cplusplus
#endif // VP10_ENCODER_BUF_ANS_H_
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