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