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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: hp6k.c                                                    *
19 *                                                                       *
20 *   Description:15th order band pass 6kHz to 7kHz FIR filter        *
21 *       frequency: 4kHz   5kHz  5.5kHz  6kHz  6.5kHz  7kHz 7.5kHz 8kHz  *
22 *   dB loss:  -60dB  -45dB  -13dB   -3dB   0dB    -3dB -13dB  -45dB *
23 *                                                                   *
24 ************************************************************************/
25 
26 #include "typedef.h"
27 #include "basic_op.h"
28 #include "acelp.h"
29 #include "cnst.h"
30 
31 #define L_FIR 31
32 
33 /* filter coefficients (gain=4.0) */
34 
35 Word16 fir_6k_7k[L_FIR] =
36 {
37     -32, 47, 32, -27, -369,
38     1122, -1421, 0, 3798, -8880,
39     12349, -10984, 3548, 7766, -18001,
40     22118, -18001, 7766, 3548, -10984,
41     12349, -8880, 3798, 0, -1421,
42     1122, -369, -27, 32, 47,
43     -32
44 };
45 
46 
Init_Filt_6k_7k(Word16 mem[])47 void Init_Filt_6k_7k(Word16 mem[])         /* mem[30] */
48 {
49     Set_zero(mem, L_FIR - 1);
50     return;
51 }
52 
Filt_6k_7k(Word16 signal[],Word16 lg,Word16 mem[])53 void Filt_6k_7k(
54         Word16 signal[],                      /* input:  signal                  */
55         Word16 lg,                            /* input:  length of input         */
56         Word16 mem[]                          /* in/out: memory (size=30)        */
57            )
58 {
59     Word16 x[L_SUBFR16k + (L_FIR - 1)];
60     Word32 i, L_tmp;
61 
62     Copy(mem, x, L_FIR - 1);
63     for (i = lg - 1; i >= 0; i--)
64     {
65         x[i + L_FIR - 1] = signal[i] >> 2;                         /* gain of filter = 4 */
66     }
67     for (i = 0; i < lg; i++)
68     {
69         L_tmp =  (x[i] + x[i+ 30]) * fir_6k_7k[0];
70         L_tmp += (x[i+1] + x[i + 29]) * fir_6k_7k[1];
71         L_tmp += (x[i+2] + x[i + 28]) * fir_6k_7k[2];
72         L_tmp += (x[i+3] + x[i + 27]) * fir_6k_7k[3];
73         L_tmp += (x[i+4] + x[i + 26]) * fir_6k_7k[4];
74         L_tmp += (x[i+5] + x[i + 25]) * fir_6k_7k[5];
75         L_tmp += (x[i+6] + x[i + 24]) * fir_6k_7k[6];
76         L_tmp += (x[i+7] + x[i + 23]) * fir_6k_7k[7];
77         L_tmp += (x[i+8] + x[i + 22]) * fir_6k_7k[8];
78         L_tmp += (x[i+9] + x[i + 21]) * fir_6k_7k[9];
79         L_tmp += (x[i+10] + x[i + 20]) * fir_6k_7k[10];
80         L_tmp += (x[i+11] + x[i + 19]) * fir_6k_7k[11];
81         L_tmp += (x[i+12] + x[i + 18]) * fir_6k_7k[12];
82         L_tmp += (x[i+13] + x[i + 17]) * fir_6k_7k[13];
83         L_tmp += (x[i+14] + x[i + 16]) * fir_6k_7k[14];
84         L_tmp += (x[i+15]) * fir_6k_7k[15];
85         signal[i] = (L_tmp + 0x4000) >> 15;
86     }
87 
88     Copy(x + lg, mem, L_FIR - 1);
89 
90 }
91 
92 
93 
94