1/* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
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
13 * express or implied.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
17 */
18/****************************************************************************************
19Portions of this file are derived from the following 3GPP standard:
20
21    3GPP TS 26.173
22    ANSI-C code for the Adaptive Multi-Rate - Wideband (AMR-WB) speech codec
23    Available from http://www.3gpp.org
24
25(C) 2007, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26Permission to distribute, modify and use this file under the standard license
27terms listed above has been obtained from the copyright holder.
28****************************************************************************************/
29/*
30------------------------------------------------------------------------------
31
32
33
34 Filename: highpass_50Hz_at_12k8.cpp
35
36     Date: 05/08/2004
37
38------------------------------------------------------------------------------
39 REVISION HISTORY
40
41
42 Description:
43
44------------------------------------------------------------------------------
45 INPUT AND OUTPUT DEFINITIONS
46
47     int16 signal[],             input signal / output is divided by 16
48     int16 lg,                   lenght of signal
49     int16 mem[]                 filter memory [6]
50
51
52------------------------------------------------------------------------------
53 FUNCTION DESCRIPTION
54
55   2nd order high pass filter with cut off frequency at 31 Hz.
56   Designed with cheby2 function in MATLAB.
57   Optimized for fixed-point to get the following frequency response:
58
59    frequency:     0Hz    14Hz  24Hz   31Hz   37Hz   41Hz   47Hz
60    dB loss:     -infdB  -15dB  -6dB   -3dB  -1.5dB  -1dB  -0.5dB
61
62  Algorithm:
63
64    y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2]
65                     + a[1]*y[i-1] + a[2]*y[i-2];
66
67    int16 b[3] = {4053, -8106, 4053};         in Q12
68    int16 a[3] = {8192, 16211, -8021};        in Q12
69
70    float -->   b[3] = {0.989501953, -1.979003906,  0.989501953};
71                a[3] = {1.000000000,  1.978881836, -0.979125977};
72
73
74------------------------------------------------------------------------------
75 REQUIREMENTS
76
77
78------------------------------------------------------------------------------
79 REFERENCES
80
81------------------------------------------------------------------------------
82 PSEUDO-CODE
83
84------------------------------------------------------------------------------
85*/
86
87
88/*----------------------------------------------------------------------------
89; INCLUDES
90----------------------------------------------------------------------------*/
91
92
93#include "pv_amr_wb_type_defs.h"
94#include "pvamrwbdecoder_basic_op.h"
95#include "pvamrwb_math_op.h"
96#include "pvamrwbdecoder_cnst.h"
97#include "pvamrwbdecoder_acelp.h"
98
99
100/*----------------------------------------------------------------------------
101; MACROS
102; Define module specific macros here
103----------------------------------------------------------------------------*/
104
105
106/*----------------------------------------------------------------------------
107; DEFINES
108; Include all pre-processor statements here. Include conditional
109; compile variables also.
110----------------------------------------------------------------------------*/
111
112/*----------------------------------------------------------------------------
113; LOCAL FUNCTION DEFINITIONS
114; Function Prototype declaration
115----------------------------------------------------------------------------*/
116
117/*----------------------------------------------------------------------------
118; LOCAL STORE/BUFFER/POINTER DEFINITIONS
119; Variable declaration - defined here and used outside this module
120----------------------------------------------------------------------------*/
121
122/*----------------------------------------------------------------------------
123; EXTERNAL FUNCTION REFERENCES
124; Declare functions defined elsewhere and referenced in this module
125----------------------------------------------------------------------------*/
126
127/*----------------------------------------------------------------------------
128; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
129; Declare variables used in this module but defined elsewhere
130----------------------------------------------------------------------------*/
131
132/*----------------------------------------------------------------------------
133; FUNCTION CODE
134----------------------------------------------------------------------------*/
135
136void highpass_50Hz_at_12k8_init(int16 mem[])
137{
138    pv_memset((void *)mem, 0, 6*sizeof(*mem));
139}
140
141/*----------------------------------------------------------------------------
142; FUNCTION CODE
143----------------------------------------------------------------------------*/
144
145void highpass_50Hz_at_12k8(
146    int16 signal[],                      /* input/output signal */
147    int16 lg,                            /* lenght of signal    */
148    int16 mem[]                          /* filter memory [6]   */
149)
150{
151    int16 i, x2;
152    int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1;
153    int32 L_tmp1;
154    int32 L_tmp2;
155    int16 *pt_sign = signal;
156
157    y2_hi = mem[0];
158    y2_lo = mem[1];
159    y1_hi = mem[2];
160    y1_lo = mem[3];
161    x0    = mem[4];
162    x1    = mem[5];
163
164
165    for (i = lg; i != 0; i--)
166    {
167
168        /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2]  */
169        /* + a[0]*y[i-1] + a[1] * y[i-2];  */
170
171        L_tmp1 = fxp_mac_16by16(y1_lo, 16211, 8192L);
172        L_tmp1 = fxp_mac_16by16(y2_lo, -8021, L_tmp1);
173        L_tmp2 = fxp_mul_16by16(y1_hi, 32422);
174        L_tmp2 = fxp_mac_16by16(y2_hi, -16042, L_tmp2);
175
176        x2 = x1;
177        x1 = x0;
178        x0 = *pt_sign;
179        L_tmp2 = fxp_mac_16by16(x2,  8106, L_tmp2);
180        L_tmp2 = fxp_mac_16by16(x1, -16212, L_tmp2);
181        L_tmp2 = fxp_mac_16by16(x0,  8106, L_tmp2);
182
183
184        L_tmp1 = ((L_tmp1 >> 14) + L_tmp2) << 2;
185
186        y2_hi = y1_hi;
187        y2_lo = y1_lo;
188        y1_hi = (int16)(L_tmp1 >> 16);
189        y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1);
190
191        /* coeff Q14 --> Q15 with saturation */
192        *(pt_sign++) = amr_wb_shl1_round(L_tmp1);
193
194    }
195
196
197    mem[0] = y2_hi;
198    mem[1] = y2_lo;
199    mem[2] = y1_hi;
200    mem[3] = y1_lo;
201    mem[4] = x0;
202    mem[5] = x1;
203
204}
205
206