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/*****************************************************************
* gmerlin-avdecoder - a general purpose multimedia decoding library
*
* Copyright (c) 2001 - 2012 Members of the Gmerlin project
* gmerlin-general@lists.sourceforge.net
* http://gmerlin.sourceforge.net
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
* *****************************************************************/
#include <avdec_private.h>
#include <bitstream.h>
//#define OLD_BITSTREAM
static inline void fill_cache(bgav_bitstream_t * b)
{
int i;
int bytes = sizeof(b->c);
if(b->end - b->pos < bytes)
bytes = b->end - b->pos;
b->c = 0;
for(i = 0; i < bytes; i++)
{
b->c <<= 8;
b->c |= *b->pos;
b->pos++;
}
b->bit_cache = bytes * 8;
}
void bgav_bitstream_init(bgav_bitstream_t * b, const uint8_t * pos,
int len)
{
b->pos = pos;
b->end = pos + len;
#ifdef OLD_BITSTREAM
b->c = *pos;
b->pos++;
b->bit_cache = 8;
#else
fill_cache(b);
#endif
}
int bgav_bitstream_get_long(bgav_bitstream_t * b, int64_t * ret1, int bits)
{
int bits_read = 0;
int bits_to_copy;
int64_t ret = 0;
while(bits_read < bits)
{
if(!b->bit_cache)
{
if(b->pos >= b->end)
return 0;
#ifdef OLD_BITSTREAM
b->c = *b->pos;
b->pos++;
b->bit_cache = 8;
#else
fill_cache(b);
#endif
}
bits_to_copy = bits - bits_read;
if(bits_to_copy > b->bit_cache)
bits_to_copy = b->bit_cache;
ret <<= bits_to_copy;
ret |= (b->c >> (b->bit_cache-bits_to_copy)) & (((1<<bits_to_copy)-1));
bits_read += bits_to_copy;
b->bit_cache -= bits_to_copy;
}
*ret1 = ret;
return 1;
}
int bgav_bitstream_get(bgav_bitstream_t * b, int * ret, int bits)
{
int64_t tmp;
if(!bgav_bitstream_get_long(b, &tmp, bits))
return 0;
*ret = tmp;
return 1;
}
int bgav_bitstream_get_bits(bgav_bitstream_t * b)
{
return b->bit_cache + 8 * (b->end - b->pos);
}
int bgav_bitstream_peek(bgav_bitstream_t * b, int * ret, int bits)
{
int64_t tmp = 0;
int result;
/* State is saved here */
const uint8_t * pos;
int bit_cache;
uint32_t c;
/* Save state */
pos = b->pos;
bit_cache = b->bit_cache;
c = b->c;
result = bgav_bitstream_get_long(b, &tmp, bits);
/* Restore state */
b->pos = pos;
b->bit_cache = bit_cache;
b->c = c;
*ret = tmp;
return result;
}
int bgav_bitstream_skip(bgav_bitstream_t * b, int bits)
{
int64_t tmp;
return bgav_bitstream_get_long(b, &tmp, bits);
}
/* golomb parsing */
int bgav_bitstream_get_golomb_ue(bgav_bitstream_t * b, int * ret)
{
int bits, num = 0;
while(1)
{
if(!bgav_bitstream_get(b, &bits, 1))
return 0;
if(bits)
break;
else
num++;
}
/* The variable codeNum is then assigned as follows:
codeNum = 2^leadingZeroBits - 1 + read_bits( leadingZeroBits ) */
if(!bgav_bitstream_get(b, &bits, num))
return 0;
*ret = (1 << num) - 1 + bits;
return 1;
}
int bgav_bitstream_get_golomb_se(bgav_bitstream_t * b, int * ret)
{
int ret1;
if(!bgav_bitstream_get_golomb_ue(b, &ret1))
return 0;
if(ret1 & 1)
*ret = ret1>>1;
else
*ret = -(ret1>>1);
return 1;
}
int bgav_bitstream_decode012(bgav_bitstream_t * b, int * ret)
{
int n;
if(!bgav_bitstream_get(b, &n, 1))
return 0;
if(!n)
{
*ret = 0;
return 1;
}
if(!bgav_bitstream_get(b, &n, 1))
return 0;
*ret = n + 1;
return 1;
}
int bgav_bitstream_get_unary(bgav_bitstream_t * b, int stop,
int len, int * ret)
{
int i = 0;
int tmp;
while(i < len)
{
if(!bgav_bitstream_get(b, &tmp, 1))
return 0;
if(tmp == stop)
break;
i++;
}
*ret = i;
return 1;
}
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