1 /*
2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 /******************************************************************
12
13 iLBC Speech Coder ANSI-C Source Code
14
15 WebRtcIlbcfix_Window32W32.c
16
17 ******************************************************************/
18
19 #include "defines.h"
20
21 /*----------------------------------------------------------------*
22 * window multiplication
23 *---------------------------------------------------------------*/
24
WebRtcIlbcfix_Window32W32(int32_t * z,int32_t * x,const int32_t * y,size_t N)25 void WebRtcIlbcfix_Window32W32(
26 int32_t *z, /* Output */
27 int32_t *x, /* Input (same domain as Output)*/
28 const int32_t *y, /* Q31 Window */
29 size_t N /* length to process */
30 ) {
31 size_t i;
32 int16_t x_low, x_hi, y_low, y_hi;
33 int16_t left_shifts;
34 int32_t temp;
35
36 left_shifts = (int16_t)WebRtcSpl_NormW32(x[0]);
37 WebRtcSpl_VectorBitShiftW32(x, N, x, (int16_t)(-left_shifts));
38
39
40 /* The double precision numbers use a special representation:
41 * w32 = hi<<16 + lo<<1
42 */
43 for (i = 0; i < N; i++) {
44 /* Extract higher bytes */
45 x_hi = (int16_t)(x[i] >> 16);
46 y_hi = (int16_t)(y[i] >> 16);
47
48 /* Extract lower bytes, defined as (w32 - hi<<16)>>1 */
49 x_low = (int16_t)((x[i] - (x_hi << 16)) >> 1);
50
51 y_low = (int16_t)((y[i] - (y_hi << 16)) >> 1);
52
53 /* Calculate z by a 32 bit multiplication using both low and high from x and y */
54 temp = ((x_hi * y_hi) << 1) + ((x_hi * y_low) >> 14);
55
56 z[i] = temp + ((x_low * y_hi) >> 14);
57 }
58
59 WebRtcSpl_VectorBitShiftW32(z, N, z, left_shifts);
60
61 return;
62 }
63