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: weight_a.c *
19 * *
20 * Description:Weighting of LPC coefficients *
21 * ap[i] = a[i] * (gamma ** i) *
22 * *
23 ************************************************************************/
24
25 #include "typedef.h"
26 #include "basic_op.h"
27
Weight_a(Word16 a[],Word16 ap[],Word16 gamma,Word16 m)28 void Weight_a(
29 Word16 a[], /* (i) Q12 : a[m+1] LPC coefficients */
30 Word16 ap[], /* (o) Q12 : Spectral expanded LPC coefficients */
31 Word16 gamma, /* (i) Q15 : Spectral expansion factor. */
32 Word16 m /* (i) : LPC order. */
33 )
34 {
35 Word32 num = m - 1, fac;
36 *ap++ = *a++;
37 fac = gamma;
38 do{
39 *ap++ =(Word16)(((vo_L_mult((*a++), fac)) + 0x8000) >> 16);
40 fac = (vo_L_mult(fac, gamma) + 0x8000) >> 16;
41 }while(--num != 0);
42
43 *ap++ = (Word16)(((vo_L_mult((*a++), fac)) + 0x8000) >> 16);
44 return;
45 }
46
47
48
49