av/media/libstagefright/codecs/amrwbenc/src/hp6k.c

/*
 ** Copyright 2003-2010, VisualOn, Inc.
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

/***********************************************************************
*       File: hp6k.c                                                    *
*                                                                       *
*   Description:15th order band pass 6kHz to 7kHz FIR filter        *
*       frequency: 4kHz   5kHz  5.5kHz  6kHz  6.5kHz  7kHz 7.5kHz 8kHz  *
*   dB loss:  -60dB  -45dB  -13dB   -3dB   0dB    -3dB -13dB  -45dB *
*                                                                   *
************************************************************************/

#include "typedef.h"
#include "basic_op.h"
#include "acelp.h"
#include "cnst.h"

#define L_FIR 31

/* filter coefficients (gain=4.0) */

Word16 fir_6k_7k[L_FIR] =
{
    -32, 47, 32, -27, -369,
    1122, -1421, 0, 3798, -8880,
    12349, -10984, 3548, 7766, -18001,
    22118, -18001, 7766, 3548, -10984,
    12349, -8880, 3798, 0, -1421,
    1122, -369, -27, 32, 47,
    -32
};


void Init_Filt_6k_7k(Word16 mem[])         /* mem[30] */
{
    Set_zero(mem, L_FIR - 1);
    return;
}

void Filt_6k_7k(
        Word16 signal[],                      /* input:  signal                  */
        Word16 lg,                            /* input:  length of input         */
        Word16 mem[]                          /* in/out: memory (size=30)        */
           )
{
    Word16 x[L_SUBFR16k + (L_FIR - 1)];
    Word32 i, L_tmp;

    Copy(mem, x, L_FIR - 1);
    for (i = lg - 1; i >= 0; i--)
    {
        x[i + L_FIR - 1] = signal[i] >> 2;                         /* gain of filter = 4 */
    }
    for (i = 0; i < lg; i++)
    {
        L_tmp =  (x[i] + x[i+ 30]) * fir_6k_7k[0];
        L_tmp += (x[i+1] + x[i + 29]) * fir_6k_7k[1];
        L_tmp += (x[i+2] + x[i + 28]) * fir_6k_7k[2];
        L_tmp += (x[i+3] + x[i + 27]) * fir_6k_7k[3];
        L_tmp += (x[i+4] + x[i + 26]) * fir_6k_7k[4];
        L_tmp += (x[i+5] + x[i + 25]) * fir_6k_7k[5];
        L_tmp += (x[i+6] + x[i + 24]) * fir_6k_7k[6];
        L_tmp += (x[i+7] + x[i + 23]) * fir_6k_7k[7];
        L_tmp += (x[i+8] + x[i + 22]) * fir_6k_7k[8];
        L_tmp += (x[i+9] + x[i + 21]) * fir_6k_7k[9];
        L_tmp += (x[i+10] + x[i + 20]) * fir_6k_7k[10];
        L_tmp += (x[i+11] + x[i + 19]) * fir_6k_7k[11];
        L_tmp += (x[i+12] + x[i + 18]) * fir_6k_7k[12];
        L_tmp += (x[i+13] + x[i + 17]) * fir_6k_7k[13];
        L_tmp += (x[i+14] + x[i + 16]) * fir_6k_7k[14];
        L_tmp += (x[i+15]) * fir_6k_7k[15];
        signal[i] = (L_tmp + 0x4000) >> 15;
    }

    Copy(x + lg, mem, L_FIR - 1);

}