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 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
