1 /* 2 * Copyright (c) 2012 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 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 12 13 // TODO(Bjornv): Change the function parameter order to WebRTC code style. 14 // C version of WebRtcSpl_DownsampleFast() for generic platforms. 15 int WebRtcSpl_DownsampleFastC(const int16_t* data_in, 16 size_t data_in_length, 17 int16_t* data_out, 18 size_t data_out_length, 19 const int16_t* __restrict coefficients, 20 size_t coefficients_length, 21 int factor, 22 size_t delay) { 23 size_t i = 0; 24 size_t j = 0; 25 int32_t out_s32 = 0; 26 size_t endpos = delay + factor * (data_out_length - 1) + 1; 27 28 // Return error if any of the running conditions doesn't meet. 29 if (data_out_length == 0 || coefficients_length == 0 30 || data_in_length < endpos) { 31 return -1; 32 } 33 34 for (i = delay; i < endpos; i += factor) { 35 out_s32 = 2048; // Round value, 0.5 in Q12. 36 37 for (j = 0; j < coefficients_length; j++) { 38 out_s32 += coefficients[j] * data_in[i - j]; // Q12. 39 } 40 41 out_s32 >>= 12; // Q0. 42 43 // Saturate and store the output. 44 *data_out++ = WebRtcSpl_SatW32ToW16(out_s32); 45 } 46 47 return 0; 48 } 49
