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
19namespace webrtc {
20
21FIRFilterNEON::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
45void 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