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/*
* Copyright (c) 2020 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_avx2.h"
#include <immintrin.h>
#include <stdint.h>
#include <string.h>
#include <xmmintrin.h>
#include "rtc_base/checks.h"
#include "rtc_base/memory/aligned_malloc.h"
namespace webrtc {
FIRFilterAVX2::FIRFilterAVX2(const float* unaligned_coefficients,
size_t unaligned_coefficients_length,
size_t max_input_length)
: // Closest higher multiple of eight.
coefficients_length_((unaligned_coefficients_length + 7) & ~0x07),
state_length_(coefficients_length_ - 1),
coefficients_(static_cast<float*>(
AlignedMalloc(sizeof(float) * coefficients_length_, 32))),
state_(static_cast<float*>(
AlignedMalloc(sizeof(float) * (max_input_length + state_length_),
32))) {
// Add zeros at the end of the coefficients.
RTC_DCHECK_GE(coefficients_length_, unaligned_coefficients_length);
size_t padding = coefficients_length_ - unaligned_coefficients_length;
memset(coefficients_.get(), 0, 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 < unaligned_coefficients_length; ++i) {
coefficients_[i + padding] =
unaligned_coefficients[unaligned_coefficients_length - i - 1];
}
memset(state_.get(), 0,
(max_input_length + state_length_) * sizeof(state_[0]));
}
FIRFilterAVX2::~FIRFilterAVX2() = default;
void FIRFilterAVX2::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();
__m256 m_sum = _mm256_setzero_ps();
__m256 m_in;
// Depending on if the pointer is aligned with 32 bytes or not it is loaded
// differently.
if (reinterpret_cast<uintptr_t>(in_ptr) & 0x1F) {
for (size_t j = 0; j < coefficients_length_; j += 8) {
m_in = _mm256_loadu_ps(in_ptr + j);
m_sum = _mm256_fmadd_ps(m_in, _mm256_load_ps(coef_ptr + j), m_sum);
}
} else {
for (size_t j = 0; j < coefficients_length_; j += 8) {
m_in = _mm256_load_ps(in_ptr + j);
m_sum = _mm256_fmadd_ps(m_in, _mm256_load_ps(coef_ptr + j), m_sum);
}
}
__m128 m128_sum = _mm_add_ps(_mm256_extractf128_ps(m_sum, 0),
_mm256_extractf128_ps(m_sum, 1));
m128_sum = _mm_add_ps(_mm_movehl_ps(m128_sum, m128_sum), m128_sum);
_mm_store_ss(out + i,
_mm_add_ss(m128_sum, _mm_shuffle_ps(m128_sum, m128_sum, 1)));
}
// Update current state.
memmove(state_.get(), &state_[length], state_length_ * sizeof(state_[0]));
}
} // namespace webrtc
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