ref: 012ae34cae3f152370a7c58602d8cbb841cd8aad
dir: /amr-wb/hp_wsp.c/
/*-----------------------------------------------------------------------*
* HP_WSP.C *
*-----------------------------------------------------------------------*
* *
* 3nd order high pass filter with cut off frequency at 180 Hz *
* *
* Algorithm: *
* *
* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] + b[3]*x[i-3] *
* + a[1]*y[i-1] + a[2]*y[i-2] + a[3]*y[i-3]; *
* *
* float a_coef[HP_ORDER]= { *
* -2.64436711600664f, *
* 2.35087386625360f, *
* -0.70001156927424f}; *
* *
* float b_coef[HP_ORDER+1]= { *
* -0.83787057505665f, *
* 2.50975570071058f, *
* -2.50975570071058f, *
* 0.83787057505665f}; *
* *
*-----------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "oper_32b.h"
#include "acelp.h"
#include "count.h"
/* filter coefficients in Q12 */
static Word16 a[4] = {8192, 21663, -19258, 5734};
static Word16 b[4] = {-3432, +10280, -10280, +3432};
/* Initialization of static values */
void Init_Hp_wsp(Word16 mem[])
{
Set_zero(mem, 9);
return;
}
void scale_mem_Hp_wsp(Word16 mem[], Word16 exp)
{
Word16 i;
Word32 L_tmp;
for (i = 0; i < 6; i += 2)
{
L_tmp = L_Comp(mem[i], mem[i + 1]);/* y_hi, y_lo */
L_tmp = L_shl(L_tmp, exp);
L_Extract(L_tmp, &mem[i], &mem[i + 1]);
}
for (i = 6; i < 9; i++)
{
L_tmp = L_deposit_h(mem[i]); /* x[i] */
L_tmp = L_shl(L_tmp, exp);
mem[i] = round(L_tmp); move16();
}
return;
}
void Hp_wsp(
Word16 wsp[], /* i : wsp[] signal */
Word16 hp_wsp[], /* o : hypass wsp[] */
Word16 lg, /* i : lenght of signal */
Word16 mem[] /* i/o : filter memory [9] */
)
{
Word16 i;
Word16 x0, x1, x2, x3;
Word16 y3_hi, y3_lo, y2_hi, y2_lo, y1_hi, y1_lo;
Word32 L_tmp;
y3_hi = mem[0]; move16();
y3_lo = mem[1]; move16();
y2_hi = mem[2]; move16();
y2_lo = mem[3]; move16();
y1_hi = mem[4]; move16();
y1_lo = mem[5]; move16();
x0 = mem[6]; move16();
x1 = mem[7]; move16();
x2 = mem[8]; move16();
for (i = 0; i < lg; i++)
{
x3 = x2; move16();
x2 = x1; move16();
x1 = x0; move16();
x0 = wsp[i]; move16();
/* y[i] = b[0]*x[i] + b[1]*x[i-1] + b140[2]*x[i-2] + b[3]*x[i-3] */
/* + a[1]*y[i-1] + a[2] * y[i-2] + a[3]*y[i-3] */
move32();
L_tmp = 16384L; /* rounding to maximise precision */
L_tmp = L_mac(L_tmp, y1_lo, a[1]);
L_tmp = L_mac(L_tmp, y2_lo, a[2]);
L_tmp = L_mac(L_tmp, y3_lo, a[3]);
L_tmp = L_shr(L_tmp, 15);
L_tmp = L_mac(L_tmp, y1_hi, a[1]);
L_tmp = L_mac(L_tmp, y2_hi, a[2]);
L_tmp = L_mac(L_tmp, y3_hi, a[3]);
L_tmp = L_mac(L_tmp, x0, b[0]);
L_tmp = L_mac(L_tmp, x1, b[1]);
L_tmp = L_mac(L_tmp, x2, b[2]);
L_tmp = L_mac(L_tmp, x3, b[3]);
L_tmp = L_shl(L_tmp, 2); /* coeff Q12 --> Q15 */
y3_hi = y2_hi; move16();
y3_lo = y2_lo; move16();
y2_hi = y1_hi; move16();
y2_lo = y1_lo; move16();
L_Extract(L_tmp, &y1_hi, &y1_lo);
L_tmp = L_shl(L_tmp, 1); /* coeff Q14 --> Q15 */
hp_wsp[i] = round(L_tmp); move16();
}
mem[0] = y3_hi; move16();
mem[1] = y3_lo; move16();
mem[2] = y2_hi; move16();
mem[3] = y2_lo; move16();
mem[4] = y1_hi; move16();
mem[5] = y1_lo; move16();
mem[6] = x0; move16();
mem[7] = x1; move16();
mem[8] = x2; move16();
return;
}