135 lines
2.3 KiB
C
135 lines
2.3 KiB
C
/*
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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]<<bsi.bitindex)>>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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