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 "webrtc/common_audio/fir_filter_neon.h" 12 13 #include <arm_neon.h> 14 #include <assert.h> 15 #include <string.h> 16 17 #include "webrtc/system_wrappers/include/aligned_malloc.h" 18 19 namespace webrtc { 20 21 FIRFilterNEON::FIRFilterNEON(const float* coefficients, 22 size_t coefficients_length, 23 size_t max_input_length) 24 : // Closest higher multiple of four. 25 coefficients_length_((coefficients_length + 3) & ~0x03), 26 state_length_(coefficients_length_ - 1), 27 coefficients_(static_cast<float*>( 28 AlignedMalloc(sizeof(float) * coefficients_length_, 16))), 29 state_(static_cast<float*>( 30 AlignedMalloc(sizeof(float) * (max_input_length + state_length_), 31 16))) { 32 // Add zeros at the end of the coefficients. 33 size_t padding = coefficients_length_ - coefficients_length; 34 memset(coefficients_.get(), 0.f, padding * sizeof(coefficients_[0])); 35 // The coefficients are reversed to compensate for the order in which the 36 // input samples are acquired (most recent last). 37 for (size_t i = 0; i < coefficients_length; ++i) { 38 coefficients_[i + padding] = coefficients[coefficients_length - i - 1]; 39 } 40 memset(state_.get(), 41 0.f, 42 (max_input_length + state_length_) * sizeof(state_[0])); 43 } 44 45 void FIRFilterNEON::Filter(const float* in, size_t length, float* out) { 46 assert(length > 0); 47 48 memcpy(&state_[state_length_], in, length * sizeof(*in)); 49 50 // Convolves the input signal |in| with the filter kernel |coefficients_| 51 // taking into account the previous state. 52 for (size_t i = 0; i < length; ++i) { 53 float* in_ptr = &state_[i]; 54 float* coef_ptr = coefficients_.get(); 55 56 float32x4_t m_sum = vmovq_n_f32(0); 57 float32x4_t m_in; 58 59 for (size_t j = 0; j < coefficients_length_; j += 4) { 60 m_in = vld1q_f32(in_ptr + j); 61 m_sum = vmlaq_f32(m_sum, m_in, vld1q_f32(coef_ptr + j)); 62 } 63 64 float32x2_t m_half = vadd_f32(vget_high_f32(m_sum), vget_low_f32(m_sum)); 65 out[i] = vget_lane_f32(vpadd_f32(m_half, m_half), 0); 66 } 67 68 // Update current state. 69 memmove(state_.get(), &state_[length], state_length_ * sizeof(state_[0])); 70 } 71 72 } // namespace webrtc 73
