ref: e80265f904b1e0e1b7f1abf37fa811aecf3aba36
dir: /amr-wb/cor_h_x.c/
/*-------------------------------------------------------------------*
* cor_h_x.C *
*-------------------------------------------------------------------*
* Compute correlation between target "x[]" and "h[]". *
* Designed for codebook search (24 pulses, 4 tracks, 4 pulses per *
* track, 16 positions in each track) to avoid saturation. *
*-------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "math_op.h"
#include "count.h"
#define L_SUBFR 64
#define NB_TRACK 4
#define STEP 4
void cor_h_x(
Word16 h[], /* (i) Q12 : impulse response of weighted synthesis filter */
Word16 x[], /* (i) Q0 : target vector */
Word16 dn[] /* (o) <12bit : correlation between target and h[] */
)
{
Word16 i, j, k;
Word32 L_tmp, y32[L_SUBFR], L_max, L_tot;
/* first keep the result on 32 bits and find absolute maximum */
L_tot = 1L; move32();
for (k = 0; k < NB_TRACK; k++)
{
L_max = 0; move32();
for (i = k; i < L_SUBFR; i += STEP)
{
L_tmp = 1L; move32(); /* 1 -> to avoid null dn[] */
for (j = i; j < L_SUBFR; j++)
L_tmp = L_mac(L_tmp, x[j], h[j - i]);
y32[i] = L_tmp; move32();
L_tmp = L_abs(L_tmp);
test();
if (L_sub(L_tmp, L_max) > (Word32) 0)
{
L_max = L_tmp; move32();
}
}
/* tot += 3*max / 8 */
L_max = L_shr(L_max, 2);
L_tot = L_add(L_tot, L_max); /* +max/4 */
L_tot = L_add(L_tot, L_shr(L_max, 1)); /* +max/8 */
}
/* Find the number of right shifts to do on y32[] so that */
/* 6.0 x sumation of max of dn[] in each track not saturate. */
j = sub(norm_l(L_tot), 4); /* 4 -> 16 x tot */
for (i = 0; i < L_SUBFR; i++)
{
dn[i] = round(L_shl(y32[i], j)); move16();
}
return;
}