/*****************************************************************************
* bits.c : Bit handling helpers
*****************************************************************************
* Copyright (C) 2003 the VideoLAN team
*
* Authors: Laurent Aimar <fenrir@via.ecp.fr>
*
* 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 2.1 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, see
* <http://www.gnu.org/licenses/>.
*****************************************************************************/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include "bits.h"
#include "file/file.h"
#include "util/logging.h"
#include <stdio.h> // SEEK_*
/**
* \file
* This file defines functions, structures for handling streams of bits
*/
void bb_init( BITBUFFER *bb, const uint8_t *p_data, size_t i_data )
{
bb->p_start = p_data;
bb->p = bb->p_start;
bb->p_end = bb->p_start + i_data;
bb->i_left = 8;
}
static int _bs_read( BITSTREAM *bs)
{
int result = 0;
int64_t got;
got = file_read(bs->fp, bs->buf, BF_BUF_SIZE);
if (got <= 0 || got > BF_BUF_SIZE) {
BD_DEBUG(DBG_FILE, "_bs_read(): read error\n");
got = 0;
result = -1;
}
bs->size = (size_t)got;
bb_init(&bs->bb, bs->buf, bs->size);
return result;
}
static int _bs_read_at( BITSTREAM *bs, int64_t off )
{
if (file_seek(bs->fp, off, SEEK_SET) < 0) {
BD_DEBUG(DBG_FILE | DBG_CRIT, "bs_read(): seek failed\n");
/* no change in state. Caller _must_ check return value. */
return -1;
}
bs->pos = off;
return _bs_read(bs);
}
int bs_init( BITSTREAM *bs, BD_FILE_H *fp )
{
int64_t size = file_size(fp);;
bs->fp = fp;
bs->pos = 0;
bs->end = (size < 0) ? 0 : size;
return _bs_read(bs);
}
void bb_seek( BITBUFFER *bb, int64_t off, int whence)
{
int64_t b;
switch (whence) {
case SEEK_CUR:
off = (bb->p - bb->p_start) * 8 + off;
break;
case SEEK_END:
off = (bb->p_end - bb->p_start) * 8 - off;
break;
case SEEK_SET:
default:
break;
}
b = off >> 3;
bb->p = &bb->p_start[b];
int i_tmp = bb->i_left - (off & 0x07);
if (i_tmp <= 0) {
bb->i_left = 8 + i_tmp;
bb->p++;
} else {
bb->i_left = i_tmp;
}
}
static int _bs_seek( BITSTREAM *bs, int64_t off, int whence)
{
int result = 0;
int64_t b;
switch (whence) {
case SEEK_CUR:
off = bs->pos * 8 + (bs->bb.p - bs->bb.p_start) * 8 + off;
break;
case SEEK_END:
off = bs->end * 8 - off;
break;
case SEEK_SET:
default:
break;
}
if (off < 0) {
BD_DEBUG(DBG_FILE | DBG_CRIT, "bs_seek(): seek failed (negative offset)\n");
return -1;
}
b = off >> 3;
if (b >= bs->end)
{
int64_t pos;
if (BF_BUF_SIZE < bs->end) {
pos = bs->end - BF_BUF_SIZE;
} else {
pos = 0;
}
result = _bs_read_at(bs, pos);
bs->bb.p = bs->bb.p_end;
} else if (b < bs->pos || b >= (bs->pos + BF_BUF_SIZE)) {
result = _bs_read_at(bs, b);
} else {
b -= bs->pos;
bs->bb.p = &bs->bb.p_start[b];
bs->bb.i_left = 8 - (off & 0x07);
}
return result;
}
#if 0
void bb_seek_byte( BITBUFFER *bb, int64_t off)
{
bb_seek(bb, off << 3, SEEK_SET);
}
#endif
int bs_seek_byte( BITSTREAM *s, int64_t off)
{
return _bs_seek(s, off << 3, SEEK_SET);
}
uint32_t bb_read( BITBUFFER *bb, int i_count )
{
static const uint32_t i_mask[33] = {
0x00,
0x01, 0x03, 0x07, 0x0f,
0x1f, 0x3f, 0x7f, 0xff,
0x1ff, 0x3ff, 0x7ff, 0xfff,
0x1fff, 0x3fff, 0x7fff, 0xffff,
0x1ffff, 0x3ffff, 0x7ffff, 0xfffff,
0x1fffff, 0x3fffff, 0x7fffff, 0xffffff,
0x1ffffff, 0x3ffffff, 0x7ffffff, 0xfffffff,
0x1fffffff,0x3fffffff,0x7fffffff,0xffffffff
};
int i_shr;
uint32_t i_result = 0;
while( i_count > 0 ) {
if( bb->p >= bb->p_end ) {
break;
}
i_shr = bb->i_left - i_count;
if( i_shr >= 0 ) {
/* more in the buffer than requested */
i_result |= ( *bb->p >> i_shr )&i_mask[i_count];
bb->i_left -= i_count;
if( bb->i_left == 0 ) {
bb->p++;
bb->i_left = 8;
}
return( i_result );
} else {
/* less in the buffer than requested */
i_result |= (unsigned)(*bb->p&i_mask[bb->i_left]) << -i_shr;
i_count -= bb->i_left;
bb->p++;
bb->i_left = 8;
}
}
return( i_result );
}
uint32_t bs_read( BITSTREAM *bs, int i_count )
{
int left;
int bytes = (i_count + 7) >> 3;
if (bs->bb.p + bytes >= bs->bb.p_end) {
bs->pos = bs->pos + (bs->bb.p - bs->bb.p_start);
left = bs->bb.i_left;
file_seek(bs->fp, bs->pos, SEEK_SET);
bs->size = file_read(bs->fp, bs->buf, BF_BUF_SIZE);
bb_init(&bs->bb, bs->buf, bs->size);
bs->bb.i_left = left;
}
return bb_read(&bs->bb, i_count);
}
void bb_skip( BITBUFFER *bb, size_t i_count )
{
bb->p += i_count >> 3;
bb->i_left -= i_count & 0x07;
if( bb->i_left <= 0 ) {
bb->p++;
bb->i_left += 8;
}
}
void bs_skip( BITSTREAM *bs, size_t i_count )
{
int left;
size_t bytes = (i_count + 7) >> 3;
if (bs->bb.p + bytes >= bs->bb.p_end) {
bs->pos = bs->pos + (bs->bb.p - bs->bb.p_start);
left = bs->bb.i_left;
file_seek(bs->fp, bs->pos, SEEK_SET);
bs->size = file_read(bs->fp, bs->buf, BF_BUF_SIZE);
bb_init(&bs->bb, bs->buf, bs->size);
bs->bb.i_left = left;
}
bb_skip(&bs->bb, i_count);
}