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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_neon.h"
#include <arm_neon.h>
#include <string.h>
#include "rtc_base/checks.h"
#include "rtc_base/memory/aligned_malloc.h"
namespace webrtc {
FIRFilterNEON::~FIRFilterNEON() {}
FIRFilterNEON::FIRFilterNEON(const float* coefficients,
size_t coefficients_length,
size_t max_input_length)
: // Closest higher multiple of four.
coefficients_length_((coefficients_length + 3) & ~0x03),
state_length_(coefficients_length_ - 1),
coefficients_(static_cast<float*>(
AlignedMalloc(sizeof(float) * coefficients_length_, 16))),
state_(static_cast<float*>(
AlignedMalloc(sizeof(float) * (max_input_length + state_length_),
16))) {
// Add zeros at the end of the coefficients.
size_t padding = coefficients_length_ - coefficients_length;
memset(coefficients_.get(), 0.f, padding * sizeof(coefficients_[0]));
// The coefficients are reversed to compensate for the order in which the
// input samples are acquired (most recent last).
for (size_t i = 0; i < coefficients_length; ++i) {
coefficients_[i + padding] = coefficients[coefficients_length - i - 1];
}
memset(state_.get(), 0.f,
(max_input_length + state_length_) * sizeof(state_[0]));
}
void FIRFilterNEON::Filter(const float* in, size_t length, float* out) {
RTC_DCHECK_GT(length, 0);
memcpy(&state_[state_length_], in, length * sizeof(*in));
// Convolves the input signal |in| with the filter kernel |coefficients_|
// taking into account the previous state.
for (size_t i = 0; i < length; ++i) {
float* in_ptr = &state_[i];
float* coef_ptr = coefficients_.get();
float32x4_t m_sum = vmovq_n_f32(0);
float32x4_t m_in;
for (size_t j = 0; j < coefficients_length_; j += 4) {
m_in = vld1q_f32(in_ptr + j);
m_sum = vmlaq_f32(m_sum, m_in, vld1q_f32(coef_ptr + j));
}
float32x2_t m_half = vadd_f32(vget_high_f32(m_sum), vget_low_f32(m_sum));
out[i] = vget_lane_f32(vpadd_f32(m_half, m_half), 0);
}
// Update current state.
memmove(state_.get(), &state_[length], state_length_ * sizeof(state_[0]));
}
} // namespace webrtc
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