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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.
*/
#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);
#if CONFIG_ACCOUNTING
r->accounting = NULL;
#endif
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 - (int)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;
}
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