ref: 38464c2045ca581b2a5dfee895cabd683646f816
dir: /amr-wb/isp_az.c/
/*-----------------------------------------------------------------------*
* ISP_AZ.C *
*-----------------------------------------------------------------------*
* Compute the LPC coefficients from isp (order=M) *
*-----------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "oper_32b.h"
#include "count.h"
#include "cnst.h"
#define NC (M/2)
#define NC16k (M16k/2)
/* local function */
static void Get_isp_pol(Word16 * isp, Word32 * f, Word16 n);
static void Get_isp_pol_16kHz(Word16 * isp, Word32 * f, Word16 n);
void Isp_Az(
Word16 isp[], /* (i) Q15 : Immittance spectral pairs */
Word16 a[], /* (o) Q12 : predictor coefficients (order = M) */
Word16 m,
Word16 adaptive_scaling /* (i) 0 : adaptive scaling disabled */
/* 1 : adaptive scaling enabled */
)
{
Word16 i, j, hi, lo;
Word32 f1[NC16k + 1], f2[NC16k];
Word16 nc;
Word32 t0;
Word16 q, q_sug;
Word32 tmax;
nc = shr(m, 1);
test();
if (sub(nc, 8) > 0)
{
Get_isp_pol_16kHz(&isp[0], f1, nc);
for (i = 0; i <= nc; i++)
{
f1[i] = L_shl(f1[i], 2); move32();
}
} else
Get_isp_pol(&isp[0], f1, nc);
test();
if (sub(nc, 8) > 0)
{
Get_isp_pol_16kHz(&isp[1], f2, sub(nc, 1));
for (i = 0; i <= nc - 1; i++)
{
f2[i] = L_shl(f2[i], 2); move32();
}
} else
Get_isp_pol(&isp[1], f2, sub(nc, 1));
/*-----------------------------------------------------*
* Multiply F2(z) by (1 - z^-2) *
*-----------------------------------------------------*/
for (i = sub(nc, 1); i > 1; i--)
{
f2[i] = L_sub(f2[i], f2[i - 2]); move32(); /* f2[i] -= f2[i-2]; */
}
/*----------------------------------------------------------*
* Scale F1(z) by (1+isp[m-1]) and F2(z) by (1-isp[m-1]) *
*----------------------------------------------------------*/
for (i = 0; i < nc; i++)
{
/* f1[i] *= (1.0 + isp[M-1]); */
L_Extract(f1[i], &hi, &lo);
t0 = Mpy_32_16(hi, lo, isp[m - 1]);
f1[i] = L_add(f1[i], t0); move32();
/* f2[i] *= (1.0 - isp[M-1]); */
L_Extract(f2[i], &hi, &lo);
t0 = Mpy_32_16(hi, lo, isp[m - 1]);
f2[i] = L_sub(f2[i], t0); move32();
}
/*-----------------------------------------------------*
* A(z) = (F1(z)+F2(z))/2 *
* F1(z) is symmetric and F2(z) is antisymmetric *
*-----------------------------------------------------*/
/* a[0] = 1.0; */
a[0] = 4096; move16();
tmax = 1; move32();
for (i = 1, j = sub(m, 1); i < nc; i++, j--)
{
/* a[i] = 0.5*(f1[i] + f2[i]); */
t0 = L_add(f1[i], f2[i]); /* f1[i] + f2[i] */
tmax |= L_abs(t0); logic32();
a[i] = extract_l(L_shr_r(t0, 12)); /* from Q23 to Q12 and * 0.5 */
move16();
/* a[j] = 0.5*(f1[i] - f2[i]); */
t0 = L_sub(f1[i], f2[i]); /* f1[i] - f2[i] */
tmax |= L_abs(t0); logic32();
a[j] = extract_l(L_shr_r(t0, 12)); /* from Q23 to Q12 and * 0.5 */
move16();
}
/* rescale data if overflow has occured and reprocess the loop */
test();
if ( sub(adaptive_scaling, 1) == 0 )
q = sub(4, norm_l(tmax)); /* adaptive scaling enabled */
else
q = 0; move16(); /* adaptive scaling disabled */
test();
if (q > 0)
{
q_sug = add(12, q);
for (i = 1, j = sub(m, 1); i < nc; i++, j--)
{
/* a[i] = 0.5*(f1[i] + f2[i]); */
t0 = L_add(f1[i], f2[i]); /* f1[i] + f2[i] */
a[i] = extract_l(L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */
move16();
/* a[j] = 0.5*(f1[i] - f2[i]); */
t0 = L_sub(f1[i], f2[i]); /* f1[i] - f2[i] */
a[j] = extract_l(L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */
move16();
}
a[0] = shr(a[0], q); move16();
}
else
{
q_sug = 12; move16();
q = 0; move16();
}
/* a[NC] = 0.5*f1[NC]*(1.0 + isp[M-1]); */
L_Extract(f1[nc], &hi, &lo);
t0 = Mpy_32_16(hi, lo, isp[m - 1]);
t0 = L_add(f1[nc], t0);
a[nc] = extract_l(L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */
move16();
/* a[m] = isp[m-1]; */
a[m] = shr_r(isp[m - 1], add(3,q)); /* from Q15 to Q12 */
move16();
return;
}
/*-----------------------------------------------------------*
* procedure Get_isp_pol: *
* ~~~~~~~~~~~ *
* Find the polynomial F1(z) or F2(z) from the ISPs. *
* This is performed by expanding the product polynomials: *
* *
* F1(z) = product ( 1 - 2 isp_i z^-1 + z^-2 ) *
* i=0,2,4,6,8 *
* F2(z) = product ( 1 - 2 isp_i z^-1 + z^-2 ) *
* i=1,3,5,7 *
* *
* where isp_i are the ISPs in the cosine domain. *
*-----------------------------------------------------------*
* *
* Parameters: *
* isp[] : isp vector (cosine domaine) in Q15 *
* f[] : the coefficients of F1 or F2 in Q23 *
* n : == NC for F1(z); == NC-1 for F2(z) *
*-----------------------------------------------------------*/
static void Get_isp_pol(Word16 * isp, Word32 * f, Word16 n)
{
Word16 i, j, hi, lo;
Word32 t0;
/* All computation in Q23 */
f[0] = L_mult(4096, 1024); move32(); /* f[0] = 1.0; in Q23 */
f[1] = L_mult(isp[0], -256); move32(); /* f[1] = -2.0*isp[0] in Q23 */
f += 2; move32(); /* Advance f pointer */
isp += 2; move16(); /* Advance isp pointer */
for (i = 2; i <= n; i++)
{
*f = f[-2]; move32();
for (j = 1; j < i; j++, f--)
{
L_Extract(f[-1], &hi, &lo);
t0 = Mpy_32_16(hi, lo, *isp); /* t0 = f[-1] * isp */
t0 = L_shl(t0, 1);
*f = L_sub(*f, t0); move32(); /* *f -= t0 */
*f = L_add(*f, f[-2]); move32(); /* *f += f[-2] */
}
*f = L_msu(*f, *isp, 256); move32(); /* *f -= isp<<8 */
f += i; /* Advance f pointer */
isp += 2; /* Advance isp pointer */
}
return;
}
static void Get_isp_pol_16kHz(Word16 * isp, Word32 * f, Word16 n)
{
Word16 i, j, hi, lo;
Word32 t0;
/* All computation in Q23 */
f[0] = L_mult(4096, 256); move32(); /* f[0] = 1.0; in Q23 */
f[1] = L_mult(isp[0], -64); move32(); /* f[1] = -2.0*isp[0] in Q23 */
f += 2; move32(); /* Advance f pointer */
isp += 2; move16(); /* Advance isp pointer */
for (i = 2; i <= n; i++)
{
*f = f[-2]; move32();
for (j = 1; j < i; j++, f--)
{
L_Extract(f[-1], &hi, &lo);
t0 = Mpy_32_16(hi, lo, *isp); /* t0 = f[-1] * isp */
t0 = L_shl(t0, 1);
*f = L_sub(*f, t0); move32(); /* *f -= t0 */
*f = L_add(*f, f[-2]); move32(); /* *f += f[-2] */
}
*f = L_msu(*f, *isp, 64); move32(); /* *f -= isp<<8 */
f += i; /* Advance f pointer */
isp += 2; /* Advance isp pointer */
}
return;
}