Xash3D FWGS engine.
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/*
getbits.h - compact version of famous library mpg123
Copyright (C) 2017 Uncle Mike
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 3 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.
*/
#ifndef GETBITS_H
#define GETBITS_H
#define backbits( fr, nob ) ((void)( \
fr->bitindex -= nob, \
fr->wordpointer += (fr->bitindex>>3), \
fr->bitindex &= 0x7 ))
#define getbitoffset( fr ) ((-fr->bitindex) & 0x7)
#define getbyte( fr ) (*fr->wordpointer++)
#define skipbits( fr, nob ) fr->ultmp = ( \
fr->ultmp = fr->wordpointer[0], fr->ultmp <<= 8, fr->ultmp |= fr->wordpointer[1], \
fr->ultmp <<= 8, fr->ultmp |= fr->wordpointer[2], fr->ultmp <<= fr->bitindex, \
fr->ultmp &= 0xffffff, fr->bitindex += nob, \
fr->ultmp >>= (24-nob), fr->wordpointer += (fr->bitindex>>3), \
fr->bitindex &= 7 )
#define getbits_fast( fr, nob )( \
fr->ultmp = (byte) (fr->wordpointer[0] << fr->bitindex), \
fr->ultmp |= ((ulong)fr->wordpointer[1] << fr->bitindex) >> 8, \
fr->ultmp <<= nob, fr->ultmp >>= 8, \
fr->bitindex += nob, fr->wordpointer += (fr->bitindex >> 3), \
fr->bitindex &= 7, fr->ultmp )
#define get1bit( fr ) ( \
fr->uctmp = *fr->wordpointer << fr->bitindex, fr->bitindex++, \
fr->wordpointer += (fr->bitindex >> 3), fr->bitindex &= 7, fr->uctmp >> 7 )
static uint getbits( mpg123_handle_t *fr, int number_of_bits )
{
ulong rval;
if( (long)(fr->wordpointer-fr->bsbuf)*8
+ fr->bitindex+number_of_bits > (long)fr->framesize*8 )
return 0;
rval = fr->wordpointer[0];
rval <<= 8;
rval |= fr->wordpointer[1];
rval <<= 8;
rval |= fr->wordpointer[2];
rval <<= fr->bitindex;
rval &= 0xffffff;
fr->bitindex += number_of_bits;
rval >>= (24-number_of_bits);
fr->wordpointer += (fr->bitindex>>3);
fr->bitindex &= 7;
return rval;
}
#endif//GETBITS_H