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 * Contains the core loop function for the lattice filter AR routine
13 * for iSAC codec.
14 *
15 */
16
17 #include "settings.h"
18 #include "signal_processing_library.h"
19 #include "typedefs.h"
20
21 /* Filter ar_g_Q0[] and ar_f_Q0[] through an AR filter with coefficients
22 * cth_Q15[] and sth_Q15[].
23 */
WebRtcIsacfix_FilterArLoop(int16_t * ar_g_Q0,int16_t * ar_f_Q0,int16_t * cth_Q15,int16_t * sth_Q15,int16_t order_coef)24 void WebRtcIsacfix_FilterArLoop(int16_t* ar_g_Q0, // Input samples
25 int16_t* ar_f_Q0, // Input samples
26 int16_t* cth_Q15, // Filter coefficients
27 int16_t* sth_Q15, // Filter coefficients
28 int16_t order_coef) { // order of the filter
29 int n = 0;
30
31 for (n = 0; n < HALF_SUBFRAMELEN - 1; n++) {
32 int k = 0;
33 int16_t tmpAR = 0;
34 int32_t tmp32 = 0;
35 int32_t tmp32_2 = 0;
36
37 tmpAR = ar_f_Q0[n + 1];
38 for (k = order_coef - 1; k >= 0; k--) {
39 tmp32 = WEBRTC_SPL_RSHIFT_W32(((WEBRTC_SPL_MUL_16_16(cth_Q15[k], tmpAR))
40 - (WEBRTC_SPL_MUL_16_16(sth_Q15[k], ar_g_Q0[k])) + 16384), 15);
41 tmp32_2 = WEBRTC_SPL_RSHIFT_W32(((WEBRTC_SPL_MUL_16_16(sth_Q15[k], tmpAR))
42 + (WEBRTC_SPL_MUL_16_16(cth_Q15[k], ar_g_Q0[k])) + 16384), 15);
43 tmpAR = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp32);
44 ar_g_Q0[k + 1] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp32_2);
45 }
46 ar_f_Q0[n + 1] = tmpAR;
47 ar_g_Q0[0] = tmpAR;
48 }
49 }
50