Re: [MP3 ENCODER] Assembler tweak of new quantize_xrpow

[Mathew Hendry]

Now with Takehiro's table changes; in iteration_init:

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#if (defined(__GNUC__) && defined(__i386__)) || defined (_MSC_VER)
    for (i = 0; i < PRECALC_SIZE - 1; i++)
        adj43[i] = i + 0.5 - pow(0.5 * (pow43[i] + pow43[i + 1]), 0.75);
    adj43[i] = 0.0;
#else
    for (i = 0; i < PRECALC_SIZE - 1; i++)
        adj43[i] = (i + 1) - pow(0.5 * (pow43[i] + pow43[i + 1]), 0.75);
    adj43[i] = 0.5;
#endif

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and an updated quantize_xrpow:

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#if defined(__GNUC__) && defined(__i386__)
# define XRPOW_FTOI(src, dest) \
    asm ("fistpl %0 " : "=m" (dest) : "t" (src) : "st")
#elif defined (_MSC_VER)
# define XRPOW_FTOI(src, dest) \
    do { \
      FLOAT8 src_ = (src); \
      int dest_; \
      { \
        __asm fld src_ \
        __asm fistp dest_ \
      } \
      (dest) = dest_; \
    } while (0)
#else
# define XRPOW_FTOI(src,dest) ((dest) = (int)(src))
#endif

#define QUANTFAC_OLD(rx)  0.4054
#define QUANTFAC(rx) adj43[rx]

void quantize_xrpow( FLOAT8 xr[576], int ix[576], gr_info *cod_info )
{
  /* quantize on xr^(3/4) instead of xr */
  register int j;
  FLOAT8 x,quantizerStepSize;
  FLOAT8 istep_l,istep0,istep1,istep2;
  int rx;

  quantizerStepSize = cod_info->quantizerStepSize;
  
  istep_l = pow ( 2.0, quantizerStepSize * -0.1875 );
  
  if ((cod_info->block_type==SHORT_TYPE))
    {
      istep0 = istep_l * pow(2.0,1.5* (FLOAT8) cod_info->subblock_gain[0]);
      istep1 = istep_l * pow(2.0,1.5* (FLOAT8) cod_info->subblock_gain[1]);
      istep2 = istep_l * pow(2.0,1.5* (FLOAT8) cod_info->subblock_gain[2]);
      for (j=192;j>0;j--) 
        {
          x = istep0 * *xr++;
          XRPOW_FTOI(x - .5, rx);
          XRPOW_FTOI(x + QUANTFAC(rx), *(ix++));
          x = istep1 * *xr++;
          XRPOW_FTOI(x - .5, rx);
          XRPOW_FTOI(x + QUANTFAC(rx), *(ix++));
          x = istep2 * *xr++;
          XRPOW_FTOI(x - .5, rx);
          XRPOW_FTOI(x + QUANTFAC(rx), *(ix++));
        }
    }
  else
    {
      for (j=576;j>0;j--)
        {
          x = istep_l * *xr++;
          XRPOW_FTOI(x - .5, rx);
          XRPOW_FTOI(x + QUANTFAC(rx), *(ix++));
        }
    }
}

=====

-- Mat.


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