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117 lines
2.2 KiB
117 lines
2.2 KiB
15 years ago
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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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