107 строки
3.3 KiB
C
107 строки
3.3 KiB
C
/*
|
|
* 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.
|
|
*/
|
|
#include <stdlib.h>
|
|
|
|
#include "./aom_config.h"
|
|
|
|
#include "aom_dsp/dkboolreader.h"
|
|
#include "aom_dsp/prob.h"
|
|
#include "aom_dsp/aom_dsp_common.h"
|
|
#include "aom_ports/mem.h"
|
|
#include "aom_mem/aom_mem.h"
|
|
#include "aom_util/endian_inl.h"
|
|
|
|
static INLINE int aom_dk_read_bit(struct aom_dk_reader *r) {
|
|
return aom_dk_read(r, 128); // aom_prob_half
|
|
}
|
|
|
|
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) {
|
|
if (size && !buffer) {
|
|
return 1;
|
|
} else {
|
|
r->buffer_end = buffer + size;
|
|
r->buffer_start = r->buffer = buffer;
|
|
r->value = 0;
|
|
r->count = -8;
|
|
r->range = 255;
|
|
r->decrypt_cb = decrypt_cb;
|
|
r->decrypt_state = decrypt_state;
|
|
aom_dk_reader_fill(r);
|
|
return aom_dk_read_bit(r) != 0; // marker bit
|
|
}
|
|
}
|
|
|
|
void aom_dk_reader_fill(struct aom_dk_reader *r) {
|
|
const uint8_t *const buffer_end = r->buffer_end;
|
|
const uint8_t *buffer = r->buffer;
|
|
const uint8_t *buffer_start = buffer;
|
|
BD_VALUE value = r->value;
|
|
int count = r->count;
|
|
const size_t bytes_left = buffer_end - buffer;
|
|
const size_t bits_left = bytes_left * CHAR_BIT;
|
|
int shift = BD_VALUE_SIZE - CHAR_BIT - (count + CHAR_BIT);
|
|
|
|
if (r->decrypt_cb) {
|
|
size_t n = AOMMIN(sizeof(r->clear_buffer), bytes_left);
|
|
r->decrypt_cb(r->decrypt_state, buffer, r->clear_buffer, (int)n);
|
|
buffer = r->clear_buffer;
|
|
buffer_start = r->clear_buffer;
|
|
}
|
|
if (bits_left > BD_VALUE_SIZE) {
|
|
const int bits = (shift & 0xfffffff8) + CHAR_BIT;
|
|
BD_VALUE nv;
|
|
BD_VALUE big_endian_values;
|
|
memcpy(&big_endian_values, buffer, sizeof(BD_VALUE));
|
|
#if SIZE_MAX == 0xffffffffffffffffULL
|
|
big_endian_values = HToBE64(big_endian_values);
|
|
#else
|
|
big_endian_values = HToBE32(big_endian_values);
|
|
#endif
|
|
nv = big_endian_values >> (BD_VALUE_SIZE - bits);
|
|
count += bits;
|
|
buffer += (bits >> 3);
|
|
value = r->value | (nv << (shift & 0x7));
|
|
} else {
|
|
const int bits_over = (int)(shift + CHAR_BIT - bits_left);
|
|
int loop_end = 0;
|
|
if (bits_over >= 0) {
|
|
count += LOTS_OF_BITS;
|
|
loop_end = bits_over;
|
|
}
|
|
|
|
if (bits_over < 0 || bits_left) {
|
|
while (shift >= loop_end) {
|
|
count += CHAR_BIT;
|
|
value |= (BD_VALUE)*buffer++ << shift;
|
|
shift -= CHAR_BIT;
|
|
}
|
|
}
|
|
}
|
|
|
|
// NOTE: Variable 'buffer' may not relate to 'r->buffer' after decryption,
|
|
// so we increase 'r->buffer' by the amount that 'buffer' moved, rather than
|
|
// assign 'buffer' to 'r->buffer'.
|
|
r->buffer += buffer - buffer_start;
|
|
r->value = value;
|
|
r->count = count;
|
|
}
|
|
|
|
const uint8_t *aom_dk_reader_find_end(struct aom_dk_reader *r) {
|
|
// Find the end of the coded buffer
|
|
while (r->count > CHAR_BIT && r->count < BD_VALUE_SIZE) {
|
|
r->count -= CHAR_BIT;
|
|
r->buffer--;
|
|
}
|
|
return r->buffer;
|
|
}
|