Home | History | Annotate | Download | only in src
      1 /*
      2  ** Copyright 2003-2010, VisualOn, Inc.
      3  **
      4  ** Licensed under the Apache License, Version 2.0 (the "License");
      5  ** you may not use this file except in compliance with the License.
      6  ** You may obtain a copy of the License at
      7  **
      8  **     http://www.apache.org/licenses/LICENSE-2.0
      9  **
     10  ** Unless required by applicable law or agreed to in writing, software
     11  ** distributed under the License is distributed on an "AS IS" BASIS,
     12  ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  ** See the License for the specific language governing permissions and
     14  ** limitations under the License.
     15  */
     16 
     17 /***********************************************************************
     18 *       File: hp_wsp.c                                                  *
     19 *       Description:                                                    *
     20 *       3nd order high pass filter with cut off frequency at 180Hz      *
     21 * Algorithm:                                                            *
     22 *                                                                       *
     23 *  y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] + b[3]*x[i-3]           *
     24 *                   + a[1]*y[i-1] + a[2]*y[i-2] + a[3]*y[i-3];          *
     25 *                                                                       *
     26 * float a_coef[HP_ORDER]= {                                             *
     27 *    -2.64436711600664f,                                                *
     28 *    2.35087386625360f,                                                 *
     29 *   -0.70001156927424f};                                                *
     30 *                                                                       *
     31 * float b_coef[HP_ORDER+1]= {                                           *
     32 *     -0.83787057505665f,                                               *
     33 *    2.50975570071058f,                                                 *
     34 *   -2.50975570071058f,                                                 *
     35 *    0.83787057505665f};                                                *
     36 *                                                                       *
     37 *************************************************************************/
     38 
     39 #include "typedef.h"
     40 #include "basic_op.h"
     41 #include "oper_32b.h"
     42 #include "acelp.h"
     43 
     44 /* filter coefficients in Q12 */
     45 static Word16 a[4] = {8192, 21663, -19258, 5734};
     46 static Word16 b[4] = {-3432, +10280, -10280, +3432};
     47 
     48 /* Initialization of static values */
     49 void Init_Hp_wsp(Word16 mem[])
     50 {
     51 	Set_zero(mem, 9);
     52 
     53 	return;
     54 }
     55 
     56 void scale_mem_Hp_wsp(Word16 mem[], Word16 exp)
     57 {
     58 	Word32 i;
     59 	Word32 L_tmp;
     60 
     61 	for (i = 0; i < 6; i += 2)
     62 	{
     63 		L_tmp = ((mem[i] << 16) + (mem[i + 1]<<1));
     64 		L_tmp = L_shl(L_tmp, exp);
     65 		mem[i] = L_tmp >> 16;
     66 		mem[i + 1] = (L_tmp & 0xffff)>>1;
     67 	}
     68 
     69 	for (i = 6; i < 9; i++)
     70 	{
     71 		L_tmp = L_deposit_h(mem[i]);       /* x[i] */
     72 		L_tmp = L_shl(L_tmp, exp);
     73 		mem[i] = vo_round(L_tmp);
     74 	}
     75 
     76 	return;
     77 }
     78 
     79 
     80 void Hp_wsp(
     81 		Word16 wsp[],                         /* i   : wsp[]  signal       */
     82 		Word16 hp_wsp[],                      /* o   : hypass wsp[]        */
     83 		Word16 lg,                            /* i   : lenght of signal    */
     84 		Word16 mem[]                          /* i/o : filter memory [9]   */
     85 	   )
     86 {
     87 	Word16 x0, x1, x2, x3;
     88 	Word16 y3_hi, y3_lo, y2_hi, y2_lo, y1_hi, y1_lo;
     89 	Word32 i, L_tmp;
     90 
     91 	y3_hi = mem[0];
     92 	y3_lo = mem[1];
     93 	y2_hi = mem[2];
     94 	y2_lo = mem[3];
     95 	y1_hi = mem[4];
     96 	y1_lo = mem[5];
     97 	x0 = mem[6];
     98 	x1 = mem[7];
     99 	x2 = mem[8];
    100 
    101 	for (i = 0; i < lg; i++)
    102 	{
    103 		x3 = x2;
    104 		x2 = x1;
    105 		x1 = x0;
    106 		x0 = wsp[i];
    107 		/* y[i] = b[0]*x[i] + b[1]*x[i-1] + b140[2]*x[i-2] + b[3]*x[i-3]  */
    108 		/* + a[1]*y[i-1] + a[2] * y[i-2]  + a[3]*y[i-3]  */
    109 
    110 		L_tmp = 16384L;                    /* rounding to maximise precision */
    111 		L_tmp += (y1_lo * a[1])<<1;
    112 		L_tmp += (y2_lo * a[2])<<1;
    113 		L_tmp += (y3_lo * a[3])<<1;
    114 		L_tmp = L_tmp >> 15;
    115 		L_tmp += (y1_hi * a[1])<<1;
    116 		L_tmp += (y2_hi * a[2])<<1;
    117 		L_tmp += (y3_hi * a[3])<<1;
    118 		L_tmp += (x0 * b[0])<<1;
    119 		L_tmp += (x1 * b[1])<<1;
    120 		L_tmp += (x2 * b[2])<<1;
    121 		L_tmp += (x3 * b[3])<<1;
    122 
    123 		L_tmp = L_tmp << 2;
    124 
    125 		y3_hi = y2_hi;
    126 		y3_lo = y2_lo;
    127 		y2_hi = y1_hi;
    128 		y2_lo = y1_lo;
    129 		y1_hi = L_tmp >> 16;
    130 		y1_lo = (L_tmp & 0xffff) >>1;
    131 
    132 		hp_wsp[i] = (L_tmp + 0x4000)>>15;
    133 	}
    134 
    135 	mem[0] = y3_hi;
    136 	mem[1] = y3_lo;
    137 	mem[2] = y2_hi;
    138 	mem[3] = y2_lo;
    139 	mem[4] = y1_hi;
    140 	mem[5] = y1_lo;
    141 	mem[6] = x0;
    142 	mem[7] = x1;
    143 	mem[8] = x2;
    144 
    145 	return;
    146 }
    147 
    148 
    149