pctolsp3.c

g729 coding ipaddressing

#ifdef NEEDED
/**************************************************************************
*
* ROUTINE
*				pctolsp3
*
* FUNCTION
*
*				compute LSP from predictor polynomial and quantize it
*
* SYNOPSIS
*				subroutine pctolsp3(a, freq, bits, findex)
*
*	formal
*
*						data	I/O
*		name			type	type	function
*		-------------------------------------------------------------------
*		a				float	i		a-polynomial a(0)=1
*		freq			float	i/o 	lsp frequency array/
*										output quantized frequency array
*		bits			int 	i		bit allocation
*		findex			int 	o		frequency index array
*
*
***************************************************************************
*
* DESCRIPTION
*
*		Compte the LSPs using Chebyshev polynomials and then quantize.
*
*		Taken from code written by Lionel Wolovitz, PSION PLC
*
***************************************************************************
*
* CALLED BY
*
*		celp
*
* CALLS
*
*
**************************************************************************
*
* REFRENCES
*
*       Peter Kabal and Ravi Prakash Ramachandran, "The Computation of 
*       Line Spectral Frequencies Using Chebyshev Polynomials," IEEE 
*		Transactions on Acoustics, Speech, and Signal Processing, 
*		Vol. ASSP-34, No. 6, December 1986
*
**************************************************************************/

/* Extracts of code to do LSP root finding from predictor coefficients, and
   to convert back from roots to predictor coefficients.  */

static float l3lsp[MAXNO][16] =
{
  {0.01250000,	 0.02125000,   0.02812500,	 0.03125000,
   0.03500000,	 0.04250000,   0.05250000,	 0.06250000},
  {0.02625000,	 0.02937500,   0.03312500,	 0.03687500,
   0.04062500,	 0.04500000,   0.05000000,	 0.05500000,
   0.06000000,	 0.06500000,   0.07000000,	 0.07625000,
   0.08375000,	 0.09250000,   0.10125000,	 0.11000000},
  {0.05250000,	 0.05750000,   0.06250000,	 0.06750000,
   0.07312500,	 0.08000000,   0.08812500,	 0.09687500,
   0.10625000,	 0.11875000,   0.13125000,	 0.14375000,
   0.15625000,	 0.16875000,   0.18125000,	 0.19375000},
  {0.07750000,	 0.08250000,   0.09000000,	 0.09937500,
   0.11000000,	 0.12125000,   0.13500000,	 0.14625000,
   0.15875000,	 0.17125000,   0.18375000,	 0.19625000,
   0.20875000,	 0.22125000,   0.23375000,	 0.24625000},
  {0.12500000,	 0.13125000,   0.14125000,	 0.15125000,
   0.16062500,	 0.16875000,   0.17875000,	 0.18875000,
   0.19875000,	 0.20875000,   0.21875000,	 0.23125000,
   0.24375000,	 0.25625000,   0.26875000,	 0.28125000},
  {0.18375000,	 0.19625000,   0.21125000,	 0.22875000,
   0.25000000,	 0.27500000,   0.30000000,	 0.32500000},
  {0.22500000,	 0.23500000,   0.24500000,	 0.26250000,
   0.28750000,	 0.31000000,   0.33750000,	 0.36250000},
  {0.27812500,	 0.30000000,   0.31562500,	 0.33125000,
   0.35000000,	 0.36875000,   0.39375000,	 0.41875000},
  {0.34500000,	 0.36000000,   0.37500000,	 0.38750000,
   0.40000000,	 0.41375000,   0.42875000,	 0.44375000},
  {0.39875000,	 0.40875000,   0.41875000,	 0.42750000,
   0.43625000,	 0.44875000,   0.46375000,	 0.47875000}
};

static float l3table[MAXNO][17] =
{
  { 0.99691746,    0.99110012,	  0.98442723,	 0.98078609,
	0.97591778,    0.96455891,	  0.94608763,	 0.92388272,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0},
  { 0.98642983,    0.98301624,	  0.97841983,	 0.97328029,
	0.96760046,    0.96029536,	  0.95105858,	 0.94088325,
	0.92977943,    0.91775807,	  0.90483103,	 0.88741813,
	0.86471905,    0.83581413,	  0.80438365,	 0.77052259,   -2.0},
  { 0.94608763,    0.93544674,	  0.92388272,	 0.91140698,
	0.89629734,    0.87631182,	  0.85058793,	 0.82040883,
	0.78532570,    0.73433325,	  0.67881359,	 0.61910900,
	0.55558755,    0.48864087,	  0.41868168,	 0.34614129,   -2.0},
  { 0.88377046,    0.86863696,	  0.84433435,	 0.81132672,
	0.77052259,    0.72358094,	  0.66132536,	 0.60669785,
	0.54245932,    0.47487648,	  0.40436600,	 0.33136257,
	0.25631627,    0.17968976,	  0.10195545,	 0.02359258,   -2.0},
  { 0.70711856,    0.67881359,	  0.63136740,	 0.58142959,
	0.53252513,    0.48864087,	  0.43289406,	 0.37543889,
	0.31650210,    0.25631627,	  0.19511892,	 0.11756801,
	0.03929228,   -0.03922568,	 -0.11750182,	-0.19505355,   -2.0},
  { 0.40436600,    0.33136257,	  0.24110239,	 0.13315156,
	0.00003333,   -0.15639826,	 -0.30897896,	-0.45395190,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0},
  { 0.15646409,    0.09413950,	  0.03144340,	-0.07842421,
   -0.23340810,   -0.36808613,	 -0.52246020,	-0.64941130,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0},
  {-0.17575978,   -0.30897896,	 -0.40071028,	-0.48858271,
   -0.58774750,   -0.67876465,	 -0.78528443,	-0.87246873,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0},
  {-0.56204534,   -0.63738701,	 -0.70707143,	-0.76037242,
   -0.80898565,   -0.85668907,	 -0.90143037,	-0.93817086,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0},
  {-0.80434405,   -0.84006400,	 -0.87246873,	-0.89800250,
   -0.92082280,   -0.94858126,	 -0.97415943,	-0.99109125,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,
   -2.00000000,   -2.00000000,	 -2.00000000,	-2.00000000,   -2.0}
};

static void pctolsp3(float *a, float *freq, int *sbits, int *findex)
{
  int index;
  int *f, *s;
  float prev1, prev2;
  float *r, *x3, *x4, temp, temp0, temp1, temp2;
  float q[6], p[6];
  q[1] = a[1] + a[10] - 1.0;
  q[2] = a[2] + a[9] - q[1];
  q[3] = a[3] + a[8] - q[2];
  q[4] = a[4] + a[7] - q[3];
  q[5] = a[5] + a[6] - q[4];
  q[5] /= 2.0;
  p[1] = a[1] - a[10] + 1.0;
  p[2] = a[2] - a[9] + p[1];
  p[3] = a[3] - a[8] + p[2];
  p[4] = a[4] - a[7] + p[3];
  p[5] = a[5] - a[6] + p[4];
  p[5] /= 2.0;
  prev1 = 9e9;
  prev2 = 9e9;
  x3 = (&l3table[0][0]);
  x4 = (&l3lsp[0][0]);
  r = (&freq[0]);
  s = (&sbits[0]);
  f = (&findex[0]);
  index = 0;
  for (;;)
  {
	for (;;)
	{
	  /* evaluate sum polynomial (5 adds, 4 subs, 4 muls) */
	  temp = (x3[index]);
	  temp1 = 2.0*temp				 + q[1];
	  temp2 = 2.0*temp*temp1 - 1.0	 + q[2];
	  temp0 = 2.0*temp*temp2 - temp1 + q[3];
	  temp1 = 2.0*temp*temp0 - temp2 + q[4];
	  temp2 =	  temp*temp1 - temp0 + q[5];
	  /* look for sign change */
	  if ((temp2*prev1) < 0.0 || index+1 == 1<<*s)
	  {
		if (fabs(temp2) < fabs(prev1))
		  (*r++) = (x4[index]);
		else
		  (*r++) = (x4[--index]);
		if (prev1 < 0.0)
		  prev1 = 9e9;
		else
		  prev1 = (-9e9);
		*f++ = index;
		if (r < (&freq[10]))
		{
		  x3 += 17;
		  x4 += 16;
		  s++;
		  index = 0;
		  while (x4[index] < *(r-1)) index++;
		  break;
		}
		else
		  return;
	  }
	  prev1 = temp2;
	  index++;
	}
	for (;;)
	{
	  /* evaluate sum polynomial (5 adds, 4 subs, 4 muls) */
	  temp = (x3[index]);
	  temp1 = 2.0*temp				 + p[1];
	  temp2 = 2.0*temp*temp1 - 1.0	 + p[2];
	  temp0 = 2.0*temp*temp2 - temp1 + p[3];
	  temp1 = 2.0*temp*temp0 - temp2 + p[4];
	  temp2 =	  temp*temp1 - temp0 + p[5];
	  /* look for sign change */
	  if ((temp2*prev2) < 0.0 || index+1 == 1<<*s)
	  {
		if (fabs(temp2) < fabs(prev2))
		  (*r++) = (x4[index]);
		else
		  (*r++) = (x4[--index]);
		if (prev2 < 0.0)
		  prev2 = 9e9;
		else
		  prev2 = (-9e9);
		*f++ = index;
		if (r < (&freq[10]))
		{
		  x3 += 17;
		  x4 += 16;
		  s++;
		  index = 0;
		  while (x4[index] < *(r-1)) index++;
		  break;
		}
		else
		  return;
	  }
	  prev2 = temp2;
	  index++;
	}
  }
}
#endif