ref: 205443a1cccac1dcd3e9648ef53b7b7eba4e1fb8
dir: /amr-wb/syn_filt.c/
/*-------------------------------------------------------------------*
* SYN_FILT.C *
*-------------------------------------------------------------------*
* Do the synthesis filtering 1/A(z). *
*-------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "math_op.h"
#include "count.h"
#include "cnst.h"
void Syn_filt(
Word16 a[], /* (i) Q12 : a[m+1] prediction coefficients */
Word16 m, /* (i) : order of LP filter */
Word16 x[], /* (i) : input signal */
Word16 y[], /* (o) : output signal */
Word16 lg, /* (i) : size of filtering */
Word16 mem[], /* (i/o) : memory associated with this filtering. */
Word16 update /* (i) : 0=no update, 1=update of memory. */
)
{
Word16 i, j, y_buf[L_SUBFR16k + M16k], a0, s;
Word32 L_tmp;
Word16 *yy;
yy = &y_buf[0]; move16();
/* copy initial filter states into synthesis buffer */
for (i = 0; i < m; i++)
{
*yy++ = mem[i]; move16();
}
s = sub(norm_s(a[0]), 2);
a0 = shr(a[0], 1); /* input / 2 */
/* Do the filtering. */
for (i = 0; i < lg; i++)
{
L_tmp = L_mult(x[i], a0);
for (j = 1; j <= m; j++)
L_tmp = L_msu(L_tmp, a[j], yy[i - j]);
L_tmp = L_shl(L_tmp, add(3, s));
y[i] = yy[i] = round(L_tmp); move16();move16();
}
/* Update memory if required */
test();
if (update)
for (i = 0; i < m; i++)
{
mem[i] = yy[lg - m + i]; move16();
}
return;
}
void Syn_filt_32(
Word16 a[], /* (i) Q12 : a[m+1] prediction coefficients */
Word16 m, /* (i) : order of LP filter */
Word16 exc[], /* (i) Qnew: excitation (exc[i] >> Qnew) */
Word16 Qnew, /* (i) : exc scaling = 0(min) to 8(max) */
Word16 sig_hi[], /* (o) /16 : synthesis high */
Word16 sig_lo[], /* (o) /16 : synthesis low */
Word16 lg /* (i) : size of filtering */
)
{
Word16 i, j, a0, s;
Word32 L_tmp;
s = sub(norm_s(a[0]), 2);
a0 = shr(a[0], add(4, Qnew)); /* input / 16 and >>Qnew */
/* Do the filtering. */
for (i = 0; i < lg; i++)
{
L_tmp = 0; move32();
for (j = 1; j <= m; j++)
L_tmp = L_msu(L_tmp, sig_lo[i - j], a[j]);
L_tmp = L_shr(L_tmp, 16 - 4); /* -4 : sig_lo[i] << 4 */
L_tmp = L_mac(L_tmp, exc[i], a0);
for (j = 1; j <= m; j++)
L_tmp = L_msu(L_tmp, sig_hi[i - j], a[j]);
/* sig_hi = bit16 to bit31 of synthesis */
L_tmp = L_shl(L_tmp, add(3, s)); /* ai in Q12 */
sig_hi[i] = extract_h(L_tmp); move16();
/* sig_lo = bit4 to bit15 of synthesis */
L_tmp = L_shr(L_tmp, 4); /* 4 : sig_lo[i] >> 4 */
sig_lo[i] = extract_l(L_msu(L_tmp, sig_hi[i], 2048)); move16();
}
return;
}