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Viewing changes to mpg123_artsplugin/mpg123/getbits.c

  • Committer: Bazaar Package Importer
  • Author(s): Martin Schulze
  • Date: 2003-01-22 15:00:51 UTC
  • Revision ID: james.westby@ubuntu.com-20030122150051-uihwkdoxf15mi1tn
Tags: upstream-2.2.2
Import upstream version 2.2.2

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mpg123_artsplugin/mpg123/getbits.c
 
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#include "mpg123.h"
 
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#include "common.h"
 
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void backbits(struct bitstream_info *bitbuf,int number_of_bits)
 
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{
 
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  bitbuf->bitindex    -= number_of_bits;
 
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  bitbuf->wordpointer += (bitbuf->bitindex>>3);
 
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  bitbuf->bitindex    &= 0x7;
 
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}
 
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int getbitoffset(struct bitstream_info *bitbuf) 
 
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{
 
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  return (-bitbuf->bitindex)&0x7;
 
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}
 
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int getbyte(struct bitstream_info *bitbuf)
 
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{
 
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#ifdef DEBUG_GETBITS
 
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  if(bitbuf->bitindex) 
 
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    fprintf(stderr,"getbyte called unsynched!\n");
 
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#endif
 
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  return *bitbuf->wordpointer++;
 
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}
 
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unsigned int getbits(struct bitstream_info *bitbuf,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+bitbuf->bitindex);
 
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#endif
 
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  {
 
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    rval = bitbuf->wordpointer[0];
 
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    rval <<= 8;
 
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    rval |= bitbuf->wordpointer[1];
 
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    rval <<= 8;
 
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    rval |= bitbuf->wordpointer[2];
 
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    rval <<= bitbuf->bitindex;
 
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    rval &= 0xffffff;
 
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    bitbuf->bitindex += number_of_bits;
 
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    rval >>= (24-number_of_bits);
 
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    bitbuf->wordpointer += (bitbuf->bitindex>>3);
 
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    bitbuf->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(struct bitstream_info *bitbuf,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+bitbuf->bitindex);
 
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#endif
 
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  rval =  (unsigned char) (bitbuf->wordpointer[0] << bitbuf->bitindex);
 
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  rval |= ((unsigned int) bitbuf->wordpointer[1]<<bitbuf->bitindex)>>8;
 
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  rval <<= number_of_bits;
 
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  rval >>= 8;
 
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  bitbuf->bitindex += number_of_bits;
 
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  bitbuf->wordpointer += (bitbuf->bitindex>>3);
 
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  bitbuf->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(struct bitstream_info *bitbuf)
 
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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+bitbuf->bitindex);
 
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#endif
 
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  rval = *(bitbuf->wordpointer) << bitbuf->bitindex;
 
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  bitbuf->bitindex++;
 
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  bitbuf->wordpointer += (bitbuf->bitindex>>3);
 
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  bitbuf->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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