g729ev_main_oper_32b.c

最新的ITU-T的宽带语音编解码标准G.729.1,是对原先的G.729的最好的调整.码流输出速率可以进行自适应调整.满足未来通信要求.希望对大家有所帮助.

 |             denom_hi is a normalize number.                               |
 |             The result is in Q30.                                         |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_num                                                                  |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x0000 0000 < L_num < L_denom                         |
 |                                                                           |
 |    L_denom = denom_hi<<16 + denom_lo<<1      (DPF)                        |
 |                                                                           |
 |       denom_hi                                                            |
 |             16 bit positive normalized integer whose value falls in the   |
 |             range : 0x4000 < hi < 0x7fff                                  |
 |       denom_lo                                                            |
 |             16 bit positive integer whose value falls in the              |
 |             range : 0 < lo < 0x7fff                                       |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    L_div                                                                  |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x0000 0000 <= L_div <= 0x7fff ffff.                  |
 |             It's a Q31 value                                              |
 |                                                                           |
 |  Algorithm:                                                               |
 |                                                                           |
 |  - find = 1/L_denom.                                                      |
 |      First approximation: approx = 1 / denom_hi                           |
 |      1/L_denom = approx * (2.0 - L_denom * approx )                       |
 |                                                                           |
 |  -  result = L_num * (1/L_denom)                                          |
 |___________________________________________________________________________|
*/

Word32 Div_32(Word32 L_num, Word16 denom_hi, Word16 denom_lo)
{
  Word16    approx, hi, lo, n_hi, n_lo;
  Word32    L_32;


  /* First approximation: 1 / L_denom = 1/denom_hi */

  approx = div_s((Word16) 0x3fff, denom_hi);  /* result in Q14 */
  /* Note: 3fff = 0.5 in Q15 */

  /* 1/L_denom = approx * (2.0 - L_denom * approx) */

  L_32 = Mpy_32_16(denom_hi, denom_lo, approx); /* result in Q30 */


  L_32 = L_sub((Word32) 0x7fffffffL, L_32); /* result in Q30 */

  L_Extract(L_32, &hi, &lo);

  L_32 = Mpy_32_16(hi, lo, approx); /* = 1/L_denom in Q29 */

  /* L_num * (1/L_denom) */

  L_Extract(L_32, &hi, &lo);
  L_Extract(L_num, &n_hi, &n_lo);
  L_32 = Mpy_32(n_hi, n_lo, hi, lo);  /* result in Q29   */
  L_32 = L_shl(L_32, 2);        /* From Q29 to Q31 */

  return (L_32);
}


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : UL_add                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   32 bits addition of the two unsigned 32 bits variables (L_var1+L_var2)  |
 |   with overflow control and saturation                                    |
 |___________________________________________________________________________|
*/
UWord32 UL_add(UWord32 a, UWord32 b)
{
  UWord32   UL_var_out;

  UL_var_out = a + b;

  if ((a + b) > (UWord32) 0XffffffffL)
  {
    UL_var_out = (UWord32) 0XffffffffL;
    Overflow = 1;
  }

#if (WMOPS)
  multiCounter[currCounter].L_add++;
#endif

  return (UL_var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : UL_sub                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   32 bits substration of the two unsigned 32 bits variables               |
 |   (L_var1-L_var2) with overflow control and saturation                    |
 |___________________________________________________________________________|
*/
void UL_sub(UWord32 a, UWord32 b, UWord32 * c, UWord16 * sgn)
{
  /* the current carry is not used, nor updated... */
  if (a >= b)
  {
    *c = a - b;
    *sgn = 0;
  }
  else
  {
    *c = b - a;
    *sgn = 1;
  }
#ifdef WMOPS
  multiCounter[currCounter].L_sub++;
#endif
}


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : UL_shl                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Arithmetically shift the unsigned 32 bit input L_var1 left              |
 |   var2 positions. Zero fill the var2 LSB of the result.                   |
 |___________________________________________________________________________|
*/
UWord32 UL_shl(UWord32 a, Word16 b)
{
  UWord32   UL_var_out = 0;

  FOR(; b > 0; b--)
  {
    if (a > (UWord32) 0X7fffffffL)
    {
      Overflow = 1;
      UL_var_out = 0XffffffffL;
      break;
    }
    a *= 2;
    UL_var_out = a;
  }

#if (WMOPS)
  multiCounter[currCounter].L_shl++;
#endif

  return (UL_var_out);
}