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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: pred_lt4.c *
* *
* Description: Compute the result of long term prediction with *
* fractional interpolation of resolution 1/4 *
* on return exc[0..L_subr-1] contains the interpolated signal *
* (adaptive codebook excitation) *
* *
************************************************************************/
#include "typedef.h"
#include "basic_op.h"
#define UP_SAMP 4
#define L_INTERPOL2 16
/* 1/4 resolution interpolation filter (-3 dB at 0.856*fs/2) in Q14 */
Word16 inter4_2[4][32] =
{
{0,-2,4,-2,-10,38,-88,165,-275,424,-619,871,-1207,1699,-2598,5531,14031,-2147,780,-249,
-16,153,-213,226,-209,175,-133,91,-55,28,-10,2},
{1,-7,19,-33,47,-52,43,-9,-60,175,-355,626,-1044,1749,-3267,10359,10359,-3267,1749,-1044,
626,-355,175,-60,-9,43,-52,47,-33,19, -7, 1},
{2,-10,28,-55,91,-133,175,-209,226,-213,153,-16,-249,780,-2147,14031,5531,-2598,1699,-1207,
871,-619,424,-275,165,-88,38,-10,-2,4,-2,0},
{1,-7,22,-49,92,-153,231,-325,431,-544,656,-762,853,-923,968,15401,968,-923,853,-762,
656,-544,431,-325,231,-153,92,-49,22,-7, 1, 0}
};
void Pred_lt4(
Word16 exc[], /* in/out: excitation buffer */
Word16 T0, /* input : integer pitch lag */
Word16 frac, /* input : fraction of lag */
Word16 L_subfr /* input : subframe size */
)
{
Word16 j, k, *x;
Word32 L_sum;
Word16 *ptr, *ptr1;
Word16 *ptr2;
x = exc - T0;
frac = -frac;
if (frac < 0)
{
frac += UP_SAMP;
x--;
}
x -= 15; /* x = L_INTERPOL2 - 1 */
k = 3 - frac; /* k = UP_SAMP - 1 - frac */
ptr2 = &(inter4_2[k][0]);
for (j = 0; j < L_subfr; j++)
{
ptr = ptr2;
ptr1 = x;
L_sum = vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum += vo_mult32((*ptr1++), (*ptr++));
L_sum = L_shl2(L_sum, 2);
exc[j] = extract_h(L_add(L_sum, 0x8000));
x++;
}
return;
}
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