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/*
** 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;
}
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