| /* |
| * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #include "signal_processing_library.h" |
| |
| // TODO(Bjornv): Change the function parameter order to WebRTC code style. |
| // C version of WebRtcSpl_DownsampleFast() for generic platforms. |
| int WebRtcSpl_DownsampleFastC(const int16_t* data_in, |
| int data_in_length, |
| int16_t* data_out, |
| int data_out_length, |
| const int16_t* __restrict coefficients, |
| int coefficients_length, |
| int factor, |
| int delay) { |
| int i = 0; |
| int j = 0; |
| int32_t out_s32 = 0; |
| int endpos = delay + factor * (data_out_length - 1) + 1; |
| |
| // Return error if any of the running conditions doesn't meet. |
| if (data_out_length <= 0 || coefficients_length <= 0 |
| || data_in_length < endpos) { |
| return -1; |
| } |
| |
| for (i = delay; i < endpos; i += factor) { |
| out_s32 = 2048; // Round value, 0.5 in Q12. |
| |
| for (j = 0; j < coefficients_length; j++) { |
| out_s32 += coefficients[j] * data_in[i - j]; // Q12. |
| } |
| |
| out_s32 >>= 12; // Q0. |
| |
| // Saturate and store the output. |
| *data_out++ = WebRtcSpl_SatW32ToW16(out_s32); |
| } |
| |
| return 0; |
| } |