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/*
* Copyright (c) 2014 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 "common_audio/fir_filter_c.h"
#include <string.h>
#include <memory>
#include "common_audio/fir_filter_neon.h"
#include "common_audio/fir_filter_sse.h"
#include "rtc_base/checks.h"
namespace webrtc {
FIRFilterC::~FIRFilterC() {
}
FIRFilterC::FIRFilterC(const float* coefficients, size_t coefficients_length)
: coefficients_length_(coefficients_length),
state_length_(coefficients_length - 1),
coefficients_(new float[coefficients_length_]),
state_(new float[state_length_]) {
for (size_t i = 0; i < coefficients_length_; ++i) {
coefficients_[i] = coefficients[coefficients_length_ - i - 1];
}
memset(state_.get(), 0, state_length_ * sizeof(state_[0]));
}
void FIRFilterC::Filter(const float* in, size_t length, float* out) {
RTC_DCHECK_GT(length, 0);
// Convolves the input signal |in| with the filter kernel |coefficients_|
// taking into account the previous state.
for (size_t i = 0; i < length; ++i) {
out[i] = 0.f;
size_t j;
for (j = 0; state_length_ > i && j < state_length_ - i; ++j) {
out[i] += state_[i + j] * coefficients_[j];
}
for (; j < coefficients_length_; ++j) {
out[i] += in[j + i - state_length_] * coefficients_[j];
}
}
// Update current state.
if (length >= state_length_) {
memcpy(
state_.get(), &in[length - state_length_], state_length_ * sizeof(*in));
} else {
memmove(state_.get(),
&state_[length],
(state_length_ - length) * sizeof(state_[0]));
memcpy(&state_[state_length_ - length], in, length * sizeof(*in));
}
}
} // namespace webrtc
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