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/*
** Copyright 2003-2010, VisualOn, Inc.
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
/***********************************************************************
* File: hp_wsp.c *
* Description: *
* 3nd order high pass filter with cut off frequency at 180Hz *
* 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"
/* 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)
{
Word32 i;
Word32 L_tmp;
for (i = 0; i < 6; i += 2)
{
L_tmp = ((mem[i] << 16) + (mem[i + 1]<<1));
L_tmp = L_shl(L_tmp, exp);
mem[i] = L_tmp >> 16;
mem[i + 1] = (L_tmp & 0xffff)>>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] = vo_round(L_tmp);
}
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 x0, x1, x2, x3;
Word16 y3_hi, y3_lo, y2_hi, y2_lo, y1_hi, y1_lo;
Word32 i, L_tmp;
y3_hi = mem[0];
y3_lo = mem[1];
y2_hi = mem[2];
y2_lo = mem[3];
y1_hi = mem[4];
y1_lo = mem[5];
x0 = mem[6];
x1 = mem[7];
x2 = mem[8];
for (i = 0; i < lg; i++)
{
x3 = x2;
x2 = x1;
x1 = x0;
x0 = wsp[i];
/* 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] */
L_tmp = 16384L; /* rounding to maximise precision */
L_tmp += (y1_lo * a[1])<<1;
L_tmp += (y2_lo * a[2])<<1;
L_tmp += (y3_lo * a[3])<<1;
L_tmp = L_tmp >> 15;
L_tmp += (y1_hi * a[1])<<1;
L_tmp += (y2_hi * a[2])<<1;
L_tmp += (y3_hi * a[3])<<1;
L_tmp += (x0 * b[0])<<1;
L_tmp += (x1 * b[1])<<1;
L_tmp += (x2 * b[2])<<1;
L_tmp += (x3 * b[3])<<1;
L_tmp = L_tmp << 2;
y3_hi = y2_hi;
y3_lo = y2_lo;
y2_hi = y1_hi;
y2_lo = y1_lo;
y1_hi = L_tmp >> 16;
y1_lo = (L_tmp & 0xffff) >>1;
hp_wsp[i] = (L_tmp + 0x4000)>>15;
}
mem[0] = y3_hi;
mem[1] = y3_lo;
mem[2] = y2_hi;
mem[3] = y2_lo;
mem[4] = y1_hi;
mem[5] = y1_lo;
mem[6] = x0;
mem[7] = x1;
mem[8] = x2;
return;
}
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