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
