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/**
* Bitwise File Writer
* Copyright (c) 2006-2007 Justin Ruggles
*
* derived from ffmpeg/libavcodec/bitstream.h
* Common bit i/o utils
* Copyright (c) 2000, 2001 Fabrice Bellard
* Copyright (c) 2002-2004 Michael Niedermayer
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef BITIO_H
#define BITIO_H
#include "common.h"
#include <assert.h>
#include "bswap.h"
typedef struct BitWriter {
uint32_t bit_buf;
int bit_left;
uint8_t *buffer, *buf_ptr, *buf_end;
int eof;
} BitWriter;
static inline void
bitwriter_init(BitWriter *bw, void *buf, int len)
{
if(len < 0) {
len = 0;
buf = NULL;
}
bw->buffer = buf;
bw->buf_end = bw->buffer + len;
bw->buf_ptr = bw->buffer;
bw->bit_left = 32;
bw->bit_buf = 0;
bw->eof = 0;
}
static inline uint32_t
bitwriter_count(BitWriter *bw)
{
// TODO: simplify
return ((((bw->buf_ptr - bw->buffer) << 3) + 32 - bw->bit_left) + 7) >> 3;
}
static inline void
bitwriter_flush(BitWriter *bw)
{
bw->bit_buf <<= bw->bit_left;
while(bw->bit_left < 32 && !bw->eof) {
if(bw->buf_ptr >= bw->buf_end) {
bw->eof = 1;
break;
}
if(bw->buffer != NULL) {
*bw->buf_ptr = bw->bit_buf >> 24;
}
bw->buf_ptr++;
bw->bit_buf <<= 8;
bw->bit_left += 8;
}
bw->bit_left = 32;
bw->bit_buf = 0;
}
static inline void
bitwriter_writebits(BitWriter *bw, int bits, uint32_t val)
{
uint32_t bb=0;
assert(bits == 32 || val < (1U << bits));
if(bits == 0 || bw->eof) return;
if((bw->buf_ptr+3) >= bw->buf_end) {
bw->eof = 1;
return;
}
if(bits < bw->bit_left) {
bw->bit_buf = (bw->bit_buf << bits) | val;
bw->bit_left -= bits;
} else {
if(bw->bit_left == 32) {
assert(bits == 32);
bb = val;
} else {
bb = (bw->bit_buf << bw->bit_left) | (val >> (bits - bw->bit_left));
bw->bit_left += (32 - bits);
}
if(bw->buffer != NULL) {
*(uint32_t *)bw->buf_ptr = be2me_32(bb);
}
bw->buf_ptr += 4;
bw->bit_buf = val;
}
}
static inline void
bitwriter_writebits_signed(BitWriter *bw, int bits, int32_t val)
{
assert(bits >= 0 && bits <= 31);
bitwriter_writebits(bw, bits, val & ((1ULL<<bits)-1));
}
static inline void
bitwriter_write_rice_signed(BitWriter *bw, int k, int32_t val)
{
int v, q;
if(k < 0) return;
// convert signed to unsigned
v = -2*val-1;
v ^= (v>>31);
// write quotient in unary
q = (v >> k) + 1;
while(q > 31) {
bitwriter_writebits(bw, 31, 0);
q -= 31;
}
bitwriter_writebits(bw, q, 1);
// write write remainder in binary using 'k' bits
bitwriter_writebits(bw, k, v&((1<<k)-1));
}
#endif /* BITIO_H */
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