bits.c

使用在PC机上的g729语音压缩及编码程序

/*
   ITU-T G.729A Speech Coder    ANSI-C Source Code
   Version 1.1    Last modified: September 1996

   Copyright (c) 1996,
   AT&T, France Telecom, NTT, Universite de Sherbrooke
   All rights reserved.
*/

/*****************************************************************************/
/* bit stream manipulation routines                                          */
/*****************************************************************************/
#include "typedef.h"
#include "ld8a.h"
#include "tab_ld8a.h"

/* prototypes for local functions */
static void  int2bin(Word16 value, Word16 no_of_bits, Word16 *bitstream);
static Word16   bin2int(Word16 no_of_bits, Word16 *bitstream);

/*----------------------------------------------------------------------------
 * prm2bits_ld8k -converts encoder parameter vector into vector of serial bits
 * bits2prm_ld8k - converts serial received bits to  encoder parameter vector
 *
 * The transmitted parameters are:
 *
 *     LPC:     1st codebook           7+1 bit
 *              2nd codebook           5+5 bit
 *
 *     1st subframe:
 *          pitch period                 8 bit
 *          parity check on 1st period   1 bit
 *          codebook index1 (positions) 13 bit
 *          codebook index2 (signs)      4 bit
 *          pitch and codebook gains   4+3 bit
 *
 *     2nd subframe:
 *          pitch period (relative)      5 bit
 *          codebook index1 (positions) 13 bit
 *          codebook index2 (signs)      4 bit
 *          pitch and codebook gains   4+3 bit
 *----------------------------------------------------------------------------
 */
void prm2bits_ld8k(
 Word16   prm[],           /* input : encoded parameters  (PRM_SIZE parameters)  */
  Word16 bits[]            /* output: serial bits (SERIAL_SIZE ) bits[0] = bfi
                                    bits[1] = 80 */
)
{
   Word16 i;
   *bits++ = SYNC_WORD;     /* bit[0], at receiver this bits indicates BFI */
   *bits++ = SIZE_WORD;     /* bit[1], to be compatible with hardware      */

   for (i = 0; i < PRM_SIZE; i++)
     {
        int2bin(prm[i], bitsno[i], bits);
        bits += bitsno[i];
     }

   return;
}

/*----------------------------------------------------------------------------
 * int2bin convert integer to binary and write the bits bitstream array
 *----------------------------------------------------------------------------
 */
static void int2bin(
 Word16 value,             /* input : decimal value         */
 Word16 no_of_bits,        /* input : number of bits to use */
 Word16 *bitstream         /* output: bitstream             */
)
{
   Word16 *pt_bitstream;
   Word16   i, bit;

   pt_bitstream = bitstream + no_of_bits;

   for (i = 0; i < no_of_bits; i++)
   {
     bit = value & (Word16)0x0001;      /* get lsb */
     if (bit == 0)
         *--pt_bitstream = BIT_0;
     else
         *--pt_bitstream = BIT_1;
     value >>= 1;
   }
}

void bitstore(Word16 bits[],Word16 serialmat[])
{
	volatile Word16 i;
	volatile unsigned int value=0;

	volatile Word16 temp=0;
	Word16 *dataindex=bits+2;
	for(i=0;i<SIZE_WORD;i++)
	{
		value=(*dataindex++)==BIT_0 ? 0:1;
		temp += value<<(i%16);
		if((i+1)%16==0 && ((i+1)/16)>0)
		{
			*serialmat++=temp;
			temp=0;
		}
	}
}
		

/*----------------------------------------------------------------------------
 *  bits2prm_ld8k - converts serial received bits to  encoder parameter vector
 *----------------------------------------------------------------------------
 */
void bitrecover(Word16 serial_mat[],Word16 bitstream[])
{
	volatile Word16 value;
	volatile unsigned short valueindex=1;
	Word16 i;
	*bitstream++ = SYNC_WORD;
	*bitstream++ = SIZE_WORD;
//	value=*serial_mat++;
	for(i=0;i<SIZE_WORD;i++)
	{
		//value=*serial_mat;
		if(i%16==0)
		{
			value=*serial_mat++;
			valueindex=1;
		}
		
		*bitstream ++ = (value & valueindex)? BIT_1 : BIT_0;
		valueindex=valueindex<<1;
//		if(i%15==0 && (i/15)>0)
//		{
//			value=*serial_mat ++;
//			valueindex=1;
//		}
	}
}
void bits2prm_ld8k(
 Word16 bits[],            /* input : serial bits (80)                       */
 Word16   prm[]            /* output: decoded parameters (11 parameters)     */
)
{
   Word16 i;
   for (i = 0; i < PRM_SIZE; i++)
     {
        prm[i] = bin2int(bitsno[i], bits);
        bits  += bitsno[i];
     }

}
/*----------------------------------------------------------------------------
 * bin2int - read specified bits from bit array  and convert to integer value
 *----------------------------------------------------------------------------
 */
static Word16 bin2int(       /* output: decimal value of bit pattern */
 Word16 no_of_bits,          /* input : number of bits to read       */
 Word16 *bitstream           /* input : array containing bits        */
)
{
   Word16   value, i;
   Word16 bit;

   value = 0;
   for (i = 0; i < no_of_bits; i++)
   {
     value <<= 1;
     bit = *bitstream++;
     if (bit == BIT_1)  value += 1;
   }
   return(value);
}