bits.c

itu-t g.729的源代码

/*
   ITU-T G.729 Speech Coder with Annex B    ANSI-C Source Code
   Version 1.3    Last modified: August 1997

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

/*****************************************************************************/
/* bit stream manipulation routines                                          */
/*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include "typedef.h"
#include "ld8k.h"
#include "tab_ld8k.h"
#include "vad.h"
#include "dtx.h"
#include "tab_dtx.h"
#include "octet.h"

/* prototypes for local functions */
static void bit2byte(Word16 para,int bitlen,unsigned char * bits,int bitpos) ;
static Word16 byte2bit(int bitlen,unsigned char * bits,int bitpos) ;
/*----------------------------------------------------------------------------
 * 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 *para,unsigned char *bits)
{
  int i;
  int bitpos = 0;
  for (i = 0;i<PRM_SIZE;i++) {
    bit2byte(*para++,bitsno[i],bits,bitpos);
    bitpos += bitsno[i];
  }
}

/*----------------------------------------------------------------------------
 * int2bin convert integer to binary and write the bits bitstream array
 *----------------------------------------------------------------------------
 */
void bit2byte(Word16 para,int bitlen,unsigned char * bits,int bitpos)
{
  int i;
  int bit = 0;
  unsigned char newbyte = 0;
 
  unsigned char *p = bits + (bitpos / 8);
  for (i = 0 ;i < bitlen; i++) {
    bit = (para >> (bitlen - i -1) ) &0x01;
    newbyte = (1 << (7 - bitpos % 8));
    if (bit == 1)
      *p |= newbyte;
    else
      *p &= ~newbyte;
    bitpos++;
    if (bitpos % 8 == 0)
      p++;
  }
}

/*----------------------------------------------------------------------------
 *  bits2prm_ld8k - converts serial received bits to  encoder parameter vector
 *----------------------------------------------------------------------------
 */
void bits2prm_ld8k(unsigned char *bits,Word16 *para)
{
  int i;
  int bitpos = 0;
  for (i = 0;i<PRM_SIZE;i++) {
    *para++ = byte2bit(bitsno[i],bits,bitpos);
    bitpos += bitsno[i];
  }
}

/*----------------------------------------------------------------------------
 * bin2int - read specified bits from bit array  and convert to integer value
 *----------------------------------------------------------------------------
 */
Word16 byte2bit(int bitlen,unsigned char * bits,int bitpos)
{
  int i;
  int bit = 0;
  Word16 newbyte = 0;
  Word16 value = 0;
 
  unsigned char *p = bits + (bitpos / 8);
  for (i = 0 ;i < bitlen; i++) {
    bit = (*p >> (7 - bitpos % 8)) &0x01;
    if (bit == 1) {
      newbyte = (1 << (bitlen - i -1));
      value |= newbyte;
    }
    bitpos++;
    if (bitpos % 8 == 0)
      p++;
  }
  return value;
}

Word16 read_frame(FILE *f_serial, Word16 *parm)
{
  Word16  i;
  Word16  serial[SERIAL_SIZE];          /* Serial stream               */

  if(fread(serial, sizeof(short), 2, f_serial) != 2) {
    return(0);
  }

  if(fread(&serial[2], sizeof(Word16), (size_t)serial[1], f_serial)
     != (size_t)serial[1]) {
    return(0);
  }

  bits2prm_ld8k(&serial[1], parm);

  /* This part was modified for version V1.3 */
  /* for speech and SID frames, the hardware detects frame erasures
     by checking if all bits are set to zero */
  /* for untransmitted frames, the hardware detects frame erasures
     by testing serial[0] */

  parm[0] = 0;           /* No frame erasure */
  if(serial[1] != 0) {
   for (i=0; i < serial[1]; i++)
     if (serial[i+2] == 0 ) parm[0] = 1;  /* frame erased     */
  }
  else if(serial[0] != SYNC_WORD) parm[0] = 1;

  if(parm[1] == 1) {
    /* check parity and put 1 in parm[5] if parity error */
    parm[5] = Check_Parity_Pitch(parm[4], parm[5]);
  }

  return(1);
}