bits.c

关于AMR-WB+语音压缩编码的实现代码

#include "../include/amr_plus.h"
#define MASK      0x0001
/*---------------------------------------------------------------------------*
 * function:  bin2int                                                        *
 *            ~~~~~~~                                                        *
 * Read "no_of_bits" bits from the array bitstream[] and convert to integer  *
 *--------------------------------------------------------------------------*/
int bin2int(           /* output: recovered integer value              */
  int   no_of_bits,    /* input : number of bits associated with value */
  short *bitstream     /* input : address where bits are read          */
)
{
   int   value, i;
   value = 0;
   for (i = 0; i < no_of_bits; i++)	
   {
     value <<= 1;
     value += (int)((*bitstream++) & MASK);
   }
   return(value);
}
/*---------------------------------------------------------------------------*
 * function:  int2bin                                                        *
 *            ~~~~~~~                                                        *
 * Convert integer to binary and write the bits to the array bitstream[].    *
 * Most significant bits (MSB) are output first                              *
 *--------------------------------------------------------------------------*/
void int2bin(
  int   value,         /* input : value to be converted to binary      */
  int   no_of_bits,    /* input : number of bits associated with value */
  short *bitstream     /* output: address where bits are written       */
)
{
   short *pt_bitstream;
   int   i;
   pt_bitstream = bitstream + no_of_bits;
   for (i = 0; i < no_of_bits; i++)
   {
     *--pt_bitstream = (short)(value & MASK);
     value >>= 1;
   }
}