diff options
Diffstat (limited to 'third_party/libwebrtc/common_audio/fir_filter_neon.cc')
-rw-r--r-- | third_party/libwebrtc/common_audio/fir_filter_neon.cc | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/third_party/libwebrtc/common_audio/fir_filter_neon.cc b/third_party/libwebrtc/common_audio/fir_filter_neon.cc new file mode 100644 index 0000000000..346cb69f5f --- /dev/null +++ b/third_party/libwebrtc/common_audio/fir_filter_neon.cc @@ -0,0 +1,73 @@ +/* + * 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 |