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https://github.com/w23/xash3d-fwgs
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76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
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/*
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getbits.h - compact version of famous library mpg123
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Copyright (C) 2017 Uncle Mike
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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#ifndef GETBITS_H
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#define GETBITS_H
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#define backbits( fr, nob ) ((void)( \
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fr->bitindex -= nob, \
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fr->wordpointer += (fr->bitindex>>3), \
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fr->bitindex &= 0x7 ))
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#define getbitoffset( fr ) ((-fr->bitindex) & 0x7)
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#define getbyte( fr ) (*fr->wordpointer++)
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#define skipbits( fr, nob ) fr->ultmp = ( \
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fr->ultmp = fr->wordpointer[0], fr->ultmp <<= 8, fr->ultmp |= fr->wordpointer[1], \
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fr->ultmp <<= 8, fr->ultmp |= fr->wordpointer[2], fr->ultmp <<= fr->bitindex, \
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fr->ultmp &= 0xffffff, fr->bitindex += nob, \
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fr->ultmp >>= (24-nob), fr->wordpointer += (fr->bitindex>>3), \
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fr->bitindex &= 7 )
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#define getbits_fast( fr, nob )( \
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fr->ultmp = (byte) (fr->wordpointer[0] << fr->bitindex), \
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fr->ultmp |= ((ulong)fr->wordpointer[1] << fr->bitindex) >> 8, \
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fr->ultmp <<= nob, fr->ultmp >>= 8, \
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fr->bitindex += nob, fr->wordpointer += (fr->bitindex >> 3), \
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fr->bitindex &= 7, fr->ultmp )
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#define get1bit( fr ) ( \
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fr->uctmp = *fr->wordpointer << fr->bitindex, fr->bitindex++, \
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fr->wordpointer += (fr->bitindex >> 3), fr->bitindex &= 7, fr->uctmp >> 7 )
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// 24 is enough because tab13 has max. a 19 bit huffvector
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#define BITSHIFT ((sizeof(long) - 1) * 8)
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#define REFRESH_MASK \
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while( num < BITSHIFT ) { \
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mask |= ((ulong)getbyte( fr )) << (BITSHIFT - num); \
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num += 8; \
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part2remain -= 8; }
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static uint getbits( mpg123_handle_t *fr, int number_of_bits )
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{
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ulong rval;
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rval = fr->wordpointer[0];
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rval <<= 8;
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rval |= fr->wordpointer[1];
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rval <<= 8;
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rval |= fr->wordpointer[2];
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rval <<= fr->bitindex;
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rval &= 0xffffff;
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fr->bitindex += number_of_bits;
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rval >>= (24-number_of_bits);
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fr->wordpointer += (fr->bitindex>>3);
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fr->bitindex &= 7;
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return rval;
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}
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#endif//GETBITS_H
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