1 /* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
18 /****************************************************************************************
19 Portions of this file are derived from the following 3GPP standard:
22 ANSI-C code for the Adaptive Multi-Rate - Wideband (AMR-WB) speech codec
23 Available from http://www.3gpp.org
25 (C) 2007, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26 Permission to distribute, modify and use this file under the standard license
27 terms listed above has been obtained from the copyright holder.
28 ****************************************************************************************/
30 ------------------------------------------------------------------------------
34 Filename: highpass_400Hz_at_12k8.cpp
36 ------------------------------------------------------------------------------
37 INPUT AND OUTPUT DEFINITIONS
39 int16 signal[], input signal / output is divided by 16
40 int16 lg, lenght of signal
41 int16 mem[] filter memory [6]
44 ------------------------------------------------------------------------------
47 2nd order high pass filter with cut off frequency at 400 Hz.
48 Designed with cheby2 function in MATLAB.
49 Optimized for fixed-point to get the following frequency response:
51 frequency: 0Hz 100Hz 200Hz 300Hz 400Hz 630Hz 1.5kHz 3kHz
52 dB loss: -infdB -30dB -20dB -10dB -3dB +6dB +1dB 0dB
56 y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2]
57 + a[1]*y[i-1] + a[2]*y[i-2];
59 int16 b[3] = {3660, -7320, 3660}; in Q12
60 int16 a[3] = {4096, 7320, -3540}; in Q12
62 float --> b[3] = {0.893554687, -1.787109375, 0.893554687};
63 a[3] = {1.000000000, 1.787109375, -0.864257812};
66 ------------------------------------------------------------------------------
70 ------------------------------------------------------------------------------
73 ------------------------------------------------------------------------------
76 ------------------------------------------------------------------------------
80 /*----------------------------------------------------------------------------
82 ----------------------------------------------------------------------------*/
84 #include "pv_amr_wb_type_defs.h"
85 #include "pvamrwbdecoder_basic_op.h"
86 #include "pvamrwb_math_op.h"
87 #include "pvamrwbdecoder_acelp.h"
89 /*----------------------------------------------------------------------------
91 ; Define module specific macros here
92 ----------------------------------------------------------------------------*/
95 /*----------------------------------------------------------------------------
97 ; Include all pre-processor statements here. Include conditional
98 ; compile variables also.
99 ----------------------------------------------------------------------------*/
101 /*----------------------------------------------------------------------------
102 ; LOCAL FUNCTION DEFINITIONS
103 ; Function Prototype declaration
104 ----------------------------------------------------------------------------*/
106 /*----------------------------------------------------------------------------
107 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS
108 ; Variable declaration - defined here and used outside this module
109 ----------------------------------------------------------------------------*/
111 /*----------------------------------------------------------------------------
112 ; EXTERNAL FUNCTION REFERENCES
113 ; Declare functions defined elsewhere and referenced in this module
114 ----------------------------------------------------------------------------*/
116 /*----------------------------------------------------------------------------
117 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
118 ; Declare variables used in this module but defined elsewhere
119 ----------------------------------------------------------------------------*/
121 /*----------------------------------------------------------------------------
123 ----------------------------------------------------------------------------*/
124 /* Initialization of static values */
126 void highpass_400Hz_at_12k8_init(int16 mem[])
128 pv_memset((void *)mem, 0, 6*sizeof(*mem));
131 /*----------------------------------------------------------------------------
133 ----------------------------------------------------------------------------*/
135 void highpass_400Hz_at_12k8(
136 int16 signal[], /* input signal / output is divided by 16 */
137 int16 lg, /* lenght of signal */
138 int16 mem[] /* filter memory [6] */
142 int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1;
153 for (i = 0; i < lg; i++)
156 /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2] */
157 /* + a[0]*y[i-1] + a[1] * y[i-2]; */
159 L_tmp1 = fxp_mac_16by16(y1_lo, 29280, 8192L);
160 L_tmp2 = fxp_mul_16by16(y1_hi, 29280);
161 L_tmp1 = fxp_mac_16by16(y2_lo, -14160, L_tmp1);
162 L_tmp2 = fxp_mac_16by16(y2_hi, -14160, L_tmp2);
166 L_tmp2 = fxp_mac_16by16(x2, 915, L_tmp2);
167 L_tmp2 = fxp_mac_16by16(x1, -1830, L_tmp2);
168 L_tmp2 = fxp_mac_16by16(x0, 915, L_tmp2);
170 L_tmp1 = (L_tmp1 >> 13) + (L_tmp2 << 2); /* coeff Q12 --> Q13 */
174 /* signal is divided by 16 to avoid overflow in energy computation */
175 signal[i] = (int16)((L_tmp1 + 0x00008000) >> 16);
177 y1_hi = (int16)(L_tmp1 >> 16);
178 y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1);