av/media/libstagefright/codecs/amrwbenc/src/decim54.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: decim54.c                                                 *
*                                                                      *
*      Description:Decimation of 16kHz signal to 12.8kHz           *
*                                                                      *
************************************************************************/

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

#define FAC5   5
#define DOWN_FAC  26215                    /* 4/5 in Q15 */

#define NB_COEF_DOWN  15

/* Local functions */
static void Down_samp(
        Word16 * sig,                         /* input:  signal to downsampling  */
        Word16 * sig_d,                       /* output: downsampled signal      */
        Word16 L_frame_d                      /* input:  length of output        */
        );

/* 1/5 resolution interpolation filter  (in Q14)  */
/* -1.5dB @ 6kHz, -6dB @ 6.4kHz, -10dB @ 6.6kHz, -20dB @ 6.9kHz, -25dB @ 7kHz, -55dB @ 8kHz */

static Word16 fir_down1[4][30] =
{
    {-5, 24, -50, 54, 0, -128, 294, -408, 344, 0, -647, 1505, -2379, 3034, 13107, 3034, -2379, 1505, -647, 0, 344, -408,
    294, -128, 0, 54, -50, 24, -5, 0},

    {-6, 19, -26, 0, 77, -188, 270, -233, 0, 434, -964, 1366, -1293, 0, 12254, 6575, -2746, 1030, 0, -507, 601, -441,
    198, 0, -95, 99, -58, 18, 0, -1},

    {-3, 9, 0, -41, 111, -170, 153, 0, -295, 649, -888, 770, 0, -1997, 9894, 9894, -1997, 0, 770, -888, 649, -295, 0,
    153, -170, 111, -41, 0, 9, -3},

    {-1, 0, 18, -58, 99, -95, 0, 198, -441, 601, -507, 0, 1030, -2746, 6575, 12254, 0, -1293, 1366, -964, 434, 0,
    -233, 270, -188, 77, 0, -26, 19, -6}
};

void Init_Decim_12k8(
        Word16 mem[]                          /* output: memory (2*NB_COEF_DOWN) set to zeros */
        )
{
    Set_zero(mem, 2 * NB_COEF_DOWN);
    return;
}

void Decim_12k8(
        Word16 sig16k[],                      /* input:  signal to downsampling  */
        Word16 lg,                            /* input:  length of input         */
        Word16 sig12k8[],                     /* output: decimated signal        */
        Word16 mem[]                          /* in/out: memory (2*NB_COEF_DOWN) */
           )
{
    Word16 lg_down;
    Word16 signal[L_FRAME16k + (2 * NB_COEF_DOWN)];

    Copy(mem, signal, 2 * NB_COEF_DOWN);

    Copy(sig16k, signal + (2 * NB_COEF_DOWN), lg);

    lg_down = (lg * DOWN_FAC)>>15;

    Down_samp(signal + NB_COEF_DOWN, sig12k8, lg_down);

    Copy(signal + lg, mem, 2 * NB_COEF_DOWN);

    return;
}

static void Down_samp(
        Word16 * sig,                         /* input:  signal to downsampling  */
        Word16 * sig_d,                       /* output: downsampled signal      */
        Word16 L_frame_d                      /* input:  length of output        */
        )
{
    Word32 i, j, frac, pos;
    Word16 *x, *y;
    Word32 L_sum;

    pos = 0;                                 /* position is in Q2 -> 1/4 resolution  */
    for (j = 0; j < L_frame_d; j++)
    {
        i = (pos >> 2);                   /* integer part     */
        frac = pos & 3;                   /* fractional part */
        x = sig + i - NB_COEF_DOWN + 1;
        y = (Word16 *)(fir_down1 + frac);

        L_sum = vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x++),(*y++));
        L_sum += vo_mult32((*x),(*y));

        L_sum = L_shl2(L_sum, 2);
        sig_d[j] = extract_h(L_add(L_sum, 0x8000));
        pos += FAC5;              /* pos + 5/4 */
    }
    return;
}