Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2014 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 "common_audio/fir_filter_c.h" |
| 12 | |
| 13 | #include <string.h> |
Jonas Olsson | a4d8737 | 2019-07-05 19:08:33 +0200 | [diff] [blame] | 14 | |
Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 15 | #include <memory> |
| 16 | |
Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 17 | #include "rtc_base/checks.h" |
| 18 | |
| 19 | namespace webrtc { |
| 20 | |
Yves Gerey | 665174f | 2018-06-19 15:03:05 +0200 | [diff] [blame] | 21 | FIRFilterC::~FIRFilterC() {} |
Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 22 | |
| 23 | FIRFilterC::FIRFilterC(const float* coefficients, size_t coefficients_length) |
| 24 | : coefficients_length_(coefficients_length), |
| 25 | state_length_(coefficients_length - 1), |
| 26 | coefficients_(new float[coefficients_length_]), |
| 27 | state_(new float[state_length_]) { |
| 28 | for (size_t i = 0; i < coefficients_length_; ++i) { |
| 29 | coefficients_[i] = coefficients[coefficients_length_ - i - 1]; |
| 30 | } |
| 31 | memset(state_.get(), 0, state_length_ * sizeof(state_[0])); |
| 32 | } |
| 33 | |
| 34 | void FIRFilterC::Filter(const float* in, size_t length, float* out) { |
| 35 | RTC_DCHECK_GT(length, 0); |
| 36 | |
| 37 | // Convolves the input signal |in| with the filter kernel |coefficients_| |
| 38 | // taking into account the previous state. |
| 39 | for (size_t i = 0; i < length; ++i) { |
| 40 | out[i] = 0.f; |
| 41 | size_t j; |
| 42 | for (j = 0; state_length_ > i && j < state_length_ - i; ++j) { |
| 43 | out[i] += state_[i + j] * coefficients_[j]; |
| 44 | } |
| 45 | for (; j < coefficients_length_; ++j) { |
| 46 | out[i] += in[j + i - state_length_] * coefficients_[j]; |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | // Update current state. |
| 51 | if (length >= state_length_) { |
Yves Gerey | 665174f | 2018-06-19 15:03:05 +0200 | [diff] [blame] | 52 | memcpy(state_.get(), &in[length - state_length_], |
| 53 | state_length_ * sizeof(*in)); |
Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 54 | } else { |
Yves Gerey | 665174f | 2018-06-19 15:03:05 +0200 | [diff] [blame] | 55 | memmove(state_.get(), &state_[length], |
Patrik Höglund | f715c53 | 2017-11-17 11:04:15 +0100 | [diff] [blame] | 56 | (state_length_ - length) * sizeof(state_[0])); |
| 57 | memcpy(&state_[state_length_ - length], in, length * sizeof(*in)); |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | } // namespace webrtc |