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/*
* Copyright (C) 2008-2013 the xine project
*
* This file is part of xine, a free video player.
*
* xine 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.
*
* xine 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
*
*/
#include <sys/types.h>
typedef struct {
const uint8_t *buffer, *start;
int offbits, length, oflow;
} bits_reader_t;
static void bits_reader_set( bits_reader_t *br, const uint8_t *buf, int len )
{
br->buffer = br->start = buf;
br->offbits = 0;
br->length = len;
br->oflow = 0;
}
static void skip_bits( bits_reader_t *br, int nbits )
{
br->offbits += nbits;
br->buffer += br->offbits / 8;
br->offbits %= 8;
if ( br->buffer > (br->start + br->length) ) {
br->oflow = 1;
}
}
static uint32_t get_bits( bits_reader_t *br, int nbits )
{
int i, nbytes;
uint32_t ret = 0;
const uint8_t *buf;
buf = br->buffer;
nbytes = (br->offbits + nbits)/8;
if ( ((br->offbits + nbits) %8 ) > 0 )
nbytes++;
if ( (buf + nbytes) > (br->start + br->length) ) {
br->oflow = 1;
return 0;
}
for ( i=0; i<nbytes; i++ )
ret += buf[i]<<((nbytes-i-1)*8);
i = (4-nbytes)*8+br->offbits;
ret = ((ret<<i)>>i)>>((nbytes*8)-nbits-br->offbits);
return ret;
}
static uint32_t read_bits( bits_reader_t *br, int nbits )
{
uint32_t ret = get_bits(br, nbits);
br->offbits += nbits;
br->buffer += br->offbits / 8;
br->offbits %= 8;
return ret;
}
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