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/*
* Copyright (C) 2023 Mikhail Burakov. This file is part of streamer.
*
* streamer is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* streamer is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with streamer. If not, see <https://www.gnu.org/licenses/>.
*/
#include "bitstream.h"
void BitstreamAppend(struct Bitstream* bitstream, size_t size, uint32_t bits) {
uint8_t* ptr = (uint8_t*)bitstream->data + bitstream->size / 8;
size_t vacant_bits = 8 - bitstream->size % 8;
*ptr &= ~0 << vacant_bits;
if (vacant_bits >= size) {
*ptr |= bits << (vacant_bits - size);
bitstream->size += size;
return;
}
*ptr |= bits >> (size - vacant_bits);
bitstream->size += vacant_bits;
BitstreamAppend(bitstream, size - vacant_bits, bits);
}
void BitstreamAppendUE(struct Bitstream* bitstream, uint32_t bits) {
size_t size = 0;
uint32_t dummy = ++bits;
while (dummy) {
dummy >>= 1;
size++;
}
BitstreamAppend(bitstream, size - 1, 0);
BitstreamAppend(bitstream, size, bits);
}
void BitstreamAppendSE(struct Bitstream* bitstream, int32_t bits) {
BitstreamAppendUE(
bitstream, bits <= 0 ? (uint32_t)(-2 * bits) : (uint32_t)(2 * bits - 1));
}
void BitstreamByteAlign(struct Bitstream* bitstream) {
uint8_t* ptr = (uint8_t*)bitstream->data + bitstream->size / 8;
size_t vacant_bits = 8 - bitstream->size % 8;
if (vacant_bits == 8) return;
*ptr &= ~0 << vacant_bits;
bitstream->size += vacant_bits;
}
void BitstreamInflate(struct Bitstream* bitstream,
const struct Bitstream* source) {
uint8_t* dst_data = (uint8_t*)bitstream->data + (bitstream->size + 7) / 8;
uint8_t* src_data = source->data;
size_t src_size = (source->size + 7) / 8;
if (src_size > 0) *dst_data++ = *src_data++;
if (src_size > 1) *dst_data++ = *src_data++;
for (size_t i = 2; i < src_size; i++) {
// mburakov: emulation_prevention_three_byte
if (!dst_data[-2] && !dst_data[-1] && !src_data[0]) *dst_data++ = 3;
*dst_data++ = *src_data++;
}
bitstream->size = (size_t)(dst_data - (uint8_t*)bitstream->data) * 8;
}
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