1b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org/* 2b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * 4b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * Use of this source code is governed by a BSD-style license 5b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * that can be found in the LICENSE file in the root of the source 6b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * tree. An additional intellectual property rights grant can be found 7b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * in the file PATENTS. All contributing project authors may 8b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * be found in the AUTHORS file in the root of the source tree. 9b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org */ 10b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 11b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 12b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org/* 13b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * This file contains the function WebRtcSpl_LpcToReflCoef(). 14b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * The description header can be found in signal_processing_library.h 15b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org * 16b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org */ 17b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 18f24ac5923cbe5e806fac59a0d15e32567553ce8epbos@webrtc.org#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 19b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 20b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org#define SPL_LPC_TO_REFL_COEF_MAX_AR_MODEL_ORDER 50 21b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 22c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.orgvoid WebRtcSpl_LpcToReflCoef(int16_t* a16, int use_order, int16_t* k16) 23b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org{ 24b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org int m, k; 25c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org int32_t tmp32[SPL_LPC_TO_REFL_COEF_MAX_AR_MODEL_ORDER]; 26c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org int32_t tmp_inv_denom32; 27c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org int16_t tmp_inv_denom16; 28b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 29b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org k16[use_order - 1] = WEBRTC_SPL_LSHIFT_W16(a16[use_order], 3); //Q12<<3 => Q15 30b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org for (m = use_order - 1; m > 0; m--) 31b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org { 32b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org // (1 - k^2) in Q30 33c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org tmp_inv_denom32 = ((int32_t)1073741823) - WEBRTC_SPL_MUL_16_16(k16[m], k16[m]); 34b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org // (1 - k^2) in Q15 35c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org tmp_inv_denom16 = (int16_t)WEBRTC_SPL_RSHIFT_W32(tmp_inv_denom32, 15); 36b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 37b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org for (k = 1; k <= m; k++) 38b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org { 39b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org // tmp[k] = (a[k] - RC[m] * a[m-k+1]) / (1.0 - RC[m]*RC[m]); 40b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 41b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org // [Q12<<16 - (Q15*Q12)<<1] = [Q28 - Q28] = Q28 42c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org tmp32[k] = WEBRTC_SPL_LSHIFT_W32((int32_t)a16[k], 16) 43b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org - WEBRTC_SPL_LSHIFT_W32(WEBRTC_SPL_MUL_16_16(k16[m], a16[m-k+1]), 1); 44b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 45b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org tmp32[k] = WebRtcSpl_DivW32W16(tmp32[k], tmp_inv_denom16); //Q28/Q15 = Q13 46b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org } 47b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 48b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org for (k = 1; k < m; k++) 49b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org { 50c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org a16[k] = (int16_t)WEBRTC_SPL_RSHIFT_W32(tmp32[k], 1); //Q13>>1 => Q12 51b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org } 52b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org 53b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org tmp32[m] = WEBRTC_SPL_SAT(8191, tmp32[m], -8191); 54c49ec1327c1d956c6c889cf1f32a7f9920d76149pbos@webrtc.org k16[m - 1] = (int16_t)WEBRTC_SPL_LSHIFT_W32(tmp32[m], 2); //Q13<<2 => Q15 55b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org } 56b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org return; 57b015cbede88899f67a53fbbe581b02ce8e32794andrew@webrtc.org} 58