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: pred_lt4.c                                                *
19*                                                                      *
20*      Description: Compute the result of long term prediction with    *
21*      fractional interpolation of resolution 1/4                      *
22*      on return exc[0..L_subr-1] contains the interpolated signal     *
23*      (adaptive codebook excitation)                                  *
24*                                                                      *
25************************************************************************/
26
27#include "typedef.h"
28#include "basic_op.h"
29
30#define UP_SAMP      4
31#define L_INTERPOL2  16
32
33/* 1/4 resolution interpolation filter (-3 dB at 0.856*fs/2) in Q14 */
34
35Word16 inter4_2[4][32] =
36{
37    {0,-2,4,-2,-10,38,-88,165,-275,424,-619,871,-1207,1699,-2598,5531,14031,-2147,780,-249,
38    -16,153,-213,226,-209,175,-133,91,-55,28,-10,2},
39
40    {1,-7,19,-33,47,-52,43,-9,-60,175,-355,626,-1044,1749,-3267,10359,10359,-3267,1749,-1044,
41    626,-355,175,-60,-9,43,-52,47,-33,19, -7, 1},
42
43    {2,-10,28,-55,91,-133,175,-209,226,-213,153,-16,-249,780,-2147,14031,5531,-2598,1699,-1207,
44    871,-619,424,-275,165,-88,38,-10,-2,4,-2,0},
45
46    {1,-7,22,-49,92,-153,231,-325,431,-544,656,-762,853,-923,968,15401,968,-923,853,-762,
47    656,-544,431,-325,231,-153,92,-49,22,-7, 1, 0}
48
49};
50
51void Pred_lt4(
52        Word16 exc[],                         /* in/out: excitation buffer */
53        Word16 T0,                            /* input : integer pitch lag */
54        Word16 frac,                          /* input : fraction of lag   */
55        Word16 L_subfr                        /* input : subframe size     */
56         )
57{
58    Word16 j, k, *x;
59    Word32 L_sum;
60    Word16 *ptr, *ptr1;
61    Word16 *ptr2;
62
63    x = exc - T0;
64    frac = -frac;
65    if (frac < 0)
66    {
67        frac += UP_SAMP;
68        x--;
69    }
70    x -= 15;                                     /* x = L_INTERPOL2 - 1 */
71    k = 3 - frac;                                /* k = UP_SAMP - 1 - frac */
72
73    ptr2 = &(inter4_2[k][0]);
74    for (j = 0; j < L_subfr; j++)
75    {
76        ptr = ptr2;
77        ptr1 = x;
78        L_sum  = vo_mult32((*ptr1++), (*ptr++));
79        L_sum += vo_mult32((*ptr1++), (*ptr++));
80        L_sum += vo_mult32((*ptr1++), (*ptr++));
81        L_sum += vo_mult32((*ptr1++), (*ptr++));
82        L_sum += vo_mult32((*ptr1++), (*ptr++));
83        L_sum += vo_mult32((*ptr1++), (*ptr++));
84        L_sum += vo_mult32((*ptr1++), (*ptr++));
85        L_sum += vo_mult32((*ptr1++), (*ptr++));
86        L_sum += vo_mult32((*ptr1++), (*ptr++));
87        L_sum += vo_mult32((*ptr1++), (*ptr++));
88        L_sum += vo_mult32((*ptr1++), (*ptr++));
89        L_sum += vo_mult32((*ptr1++), (*ptr++));
90        L_sum += vo_mult32((*ptr1++), (*ptr++));
91        L_sum += vo_mult32((*ptr1++), (*ptr++));
92        L_sum += vo_mult32((*ptr1++), (*ptr++));
93        L_sum += vo_mult32((*ptr1++), (*ptr++));
94        L_sum += vo_mult32((*ptr1++), (*ptr++));
95        L_sum += vo_mult32((*ptr1++), (*ptr++));
96        L_sum += vo_mult32((*ptr1++), (*ptr++));
97        L_sum += vo_mult32((*ptr1++), (*ptr++));
98        L_sum += vo_mult32((*ptr1++), (*ptr++));
99        L_sum += vo_mult32((*ptr1++), (*ptr++));
100        L_sum += vo_mult32((*ptr1++), (*ptr++));
101        L_sum += vo_mult32((*ptr1++), (*ptr++));
102        L_sum += vo_mult32((*ptr1++), (*ptr++));
103        L_sum += vo_mult32((*ptr1++), (*ptr++));
104        L_sum += vo_mult32((*ptr1++), (*ptr++));
105        L_sum += vo_mult32((*ptr1++), (*ptr++));
106        L_sum += vo_mult32((*ptr1++), (*ptr++));
107        L_sum += vo_mult32((*ptr1++), (*ptr++));
108        L_sum += vo_mult32((*ptr1++), (*ptr++));
109        L_sum += vo_mult32((*ptr1++), (*ptr++));
110
111        L_sum = L_shl2(L_sum, 2);
112        exc[j] = extract_h(L_add(L_sum, 0x8000));
113        x++;
114    }
115
116    return;
117}
118
119
120
121