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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#ifndef AOM_DSP_DKBOOLREADER_H_
#define AOM_DSP_DKBOOLREADER_H_
#include <assert.h>
#include <stddef.h>
#include <limits.h>
#include "./aom_config.h"
#if CONFIG_BITSTREAM_DEBUG
#include <assert.h>
#include <stdio.h>
#include "aom_util/debug_util.h"
#endif // CONFIG_BITSTREAM_DEBUG
#include "aom_ports/mem.h"
#include "aom/aomdx.h"
#include "aom/aom_integer.h"
#include "aom_dsp/prob.h"
#if CONFIG_ACCOUNTING
#include "av1/decoder/accounting.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
typedef size_t BD_VALUE;
#define BD_VALUE_SIZE ((int)sizeof(BD_VALUE) * CHAR_BIT)
// This is meant to be a large, positive constant that can still be efficiently
// loaded as an immediate (on platforms like ARM, for example).
// Even relatively modest values like 100 would work fine.
#define LOTS_OF_BITS 0x40000000
struct aom_dk_reader {
// Be careful when reordering this struct, it may impact the cache negatively.
BD_VALUE value;
unsigned int range;
int count;
const uint8_t *buffer_start;
const uint8_t *buffer_end;
const uint8_t *buffer;
aom_decrypt_cb decrypt_cb;
void *decrypt_state;
uint8_t clear_buffer[sizeof(BD_VALUE) + 1];
#if CONFIG_ACCOUNTING
Accounting *accounting;
#endif
};
int aom_dk_reader_init(struct aom_dk_reader *r, const uint8_t *buffer,
size_t size, aom_decrypt_cb decrypt_cb,
void *decrypt_state);
void aom_dk_reader_fill(struct aom_dk_reader *r);
const uint8_t *aom_dk_reader_find_end(struct aom_dk_reader *r);
static INLINE uint32_t aom_dk_reader_tell(const struct aom_dk_reader *r) {
const uint32_t bits_read =
(uint32_t)((r->buffer - r->buffer_start) * CHAR_BIT);
const int count =
(r->count < LOTS_OF_BITS) ? r->count : r->count - LOTS_OF_BITS;
assert(r->buffer >= r->buffer_start);
return bits_read - (count + CHAR_BIT);
}
/*The resolution of fractional-precision bit usage measurements, i.e.,
3 => 1/8th bits.*/
#define DK_BITRES (3)
static INLINE uint32_t aom_dk_reader_tell_frac(const struct aom_dk_reader *r) {
uint32_t num_bits;
uint32_t range;
int l;
int i;
num_bits = aom_dk_reader_tell(r) << DK_BITRES;
range = r->range;
l = 0;
for (i = DK_BITRES; i-- > 0;) {
int b;
range = range * range >> 7;
b = (int)(range >> 8);
l = l << 1 | b;
range >>= b;
}
return num_bits - l;
}
static INLINE int aom_dk_reader_has_error(struct aom_dk_reader *r) {
// Check if we have reached the end of the buffer.
//
// Variable 'count' stores the number of bits in the 'value' buffer, minus
// 8. The top byte is part of the algorithm, and the remainder is buffered
// to be shifted into it. So if count == 8, the top 16 bits of 'value' are
// occupied, 8 for the algorithm and 8 in the buffer.
//
// When reading a byte from the user's buffer, count is filled with 8 and
// one byte is filled into the value buffer. When we reach the end of the
// data, count is additionally filled with LOTS_OF_BITS. So when
// count == LOTS_OF_BITS - 1, the user's data has been exhausted.
//
// 1 if we have tried to decode bits after the end of stream was encountered.
// 0 No error.
return r->count > BD_VALUE_SIZE && r->count < LOTS_OF_BITS;
}
static INLINE int aom_dk_read(struct aom_dk_reader *r, int prob) {
unsigned int bit = 0;
BD_VALUE value;
BD_VALUE bigsplit;
int count;
unsigned int range;
unsigned int split = (r->range * prob + (256 - prob)) >> CHAR_BIT;
if (r->count < 0) aom_dk_reader_fill(r);
value = r->value;
count = r->count;
bigsplit = (BD_VALUE)split << (BD_VALUE_SIZE - CHAR_BIT);
range = split;
if (value >= bigsplit) {
range = r->range - split;
value = value - bigsplit;
bit = 1;
}
{
register int shift = aom_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
}
r->value = value;
r->count = count;
r->range = range;
#if CONFIG_BITSTREAM_DEBUG
{
int ref_bit, ref_prob;
const int queue_r = bitstream_queue_get_read();
const int frame_idx = bitstream_queue_get_frame_read();
bitstream_queue_pop(&ref_bit, &ref_prob);
if (prob != ref_prob) {
fprintf(
stderr,
"\n *** prob error, frame_idx_r %d prob %d ref_prob %d queue_r %d\n",
frame_idx, prob, ref_prob, queue_r);
assert(0);
}
if ((int)bit != ref_bit) {
fprintf(stderr, "\n *** bit error, frame_idx_r %d bit %d ref_bit %d\n",
frame_idx, bit, ref_bit);
assert(0);
}
}
#endif // CONFIG_BITSTREAM_DEBUG
return bit;
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif // AOM_DSP_DKBOOLREADER_H_
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