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serge |
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/* |
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getbits |
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copyright ?-2006 by the mpg123 project - free software under the terms of the LGPL 2.1 |
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see COPYING and AUTHORS files in distribution or http://mpg123.de |
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initially written by Michael Hipp |
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*/ |
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#include "mpg123.h" |
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#if 0 |
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static void check_buffer_range(int size) |
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{ |
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int pos = (bsi.wordpointer-bsbuf) + (size>>3); |
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if( pos >= fsizeold) { |
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fprintf(stderr,"Pointer out of range (%d,%d)!\n",pos,fsizeold); |
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} |
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} |
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#endif |
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void backbits(int number_of_bits) |
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{ |
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bsi.bitindex -= number_of_bits; |
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bsi.wordpointer += (bsi.bitindex>>3); |
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bsi.bitindex &= 0x7; |
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} |
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int getbitoffset(void) |
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{ |
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return (-bsi.bitindex)&0x7; |
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} |
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int getbyte(void) |
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{ |
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#ifdef DEBUG_GETBITS |
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if(bsi.bitindex) |
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fprintf(stderr,"getbyte called unsynched!\n"); |
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#endif |
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return *bsi.wordpointer++; |
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} |
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unsigned int getbits(int number_of_bits) |
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{ |
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unsigned long rval; |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,"g%d",number_of_bits); |
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#endif |
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if(!number_of_bits) |
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return 0; |
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#if 0 |
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check_buffer_range(number_of_bits+bsi.bitindex); |
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#endif |
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{ |
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rval = bsi.wordpointer[0]; |
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rval <<= 8; |
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rval |= bsi.wordpointer[1]; |
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rval <<= 8; |
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rval |= bsi.wordpointer[2]; |
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rval <<= bsi.bitindex; |
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rval &= 0xffffff; |
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bsi.bitindex += number_of_bits; |
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rval >>= (24-number_of_bits); |
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bsi.wordpointer += (bsi.bitindex>>3); |
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bsi.bitindex &= 7; |
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} |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,":%x ",rval); |
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#endif |
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return rval; |
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} |
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unsigned int getbits_fast(int number_of_bits) |
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{ |
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unsigned int rval; |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,"g%d",number_of_bits); |
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#endif |
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#if 0 |
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check_buffer_range(number_of_bits+bsi.bitindex); |
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#endif |
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rval = (unsigned char) (bsi.wordpointer[0] << bsi.bitindex); |
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rval |= ((unsigned int) bsi.wordpointer[1]<>8; |
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rval <<= number_of_bits; |
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rval >>= 8; |
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bsi.bitindex += number_of_bits; |
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bsi.wordpointer += (bsi.bitindex>>3); |
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bsi.bitindex &= 7; |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,":%x ",rval); |
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#endif |
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return rval; |
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} |
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unsigned int get1bit(void) |
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{ |
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unsigned char rval; |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,"g%d",1); |
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#endif |
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#if 0 |
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check_buffer_range(1+bsi.bitindex); |
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#endif |
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rval = *bsi.wordpointer << bsi.bitindex; |
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bsi.bitindex++; |
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bsi.wordpointer += (bsi.bitindex>>3); |
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bsi.bitindex &= 7; |
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#ifdef DEBUG_GETBITS |
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fprintf(stderr,":%d ",rval>>7); |
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#endif |
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return rval>>7; |
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} |
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