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 */ 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
