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.h"
12
13 #include <assert.h>
14 #include <string.h>
15
16 #include "webrtc/base/scoped_ptr.h"
17 #include "webrtc/common_audio/fir_filter_neon.h"
18 #include "webrtc/common_audio/fir_filter_sse.h"
19 #include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
20
21 namespace webrtc {
22
23 class FIRFilterC : public FIRFilter {
24 public:
25 FIRFilterC(const float* coefficients,
26 size_t coefficients_length);
27
28 void Filter(const float* in, size_t length, float* out) override;
29
30 private:
31 size_t coefficients_length_;
32 size_t state_length_;
33 rtc::scoped_ptr<float[]> coefficients_;
34 rtc::scoped_ptr<float[]> state_;
35 };
36
Create(const float * coefficients,size_t coefficients_length,size_t max_input_length)37 FIRFilter* FIRFilter::Create(const float* coefficients,
38 size_t coefficients_length,
39 size_t max_input_length) {
40 if (!coefficients || coefficients_length <= 0 || max_input_length <= 0) {
41 assert(false);
42 return NULL;
43 }
44
45 FIRFilter* filter = NULL;
46 // If we know the minimum architecture at compile time, avoid CPU detection.
47 #if defined(WEBRTC_ARCH_X86_FAMILY)
48 #if defined(__SSE2__)
49 filter =
50 new FIRFilterSSE2(coefficients, coefficients_length, max_input_length);
51 #else
52 // x86 CPU detection required.
53 if (WebRtc_GetCPUInfo(kSSE2)) {
54 filter =
55 new FIRFilterSSE2(coefficients, coefficients_length, max_input_length);
56 } else {
57 filter = new FIRFilterC(coefficients, coefficients_length);
58 }
59 #endif
60 #elif defined(WEBRTC_HAS_NEON)
61 filter =
62 new FIRFilterNEON(coefficients, coefficients_length, max_input_length);
63 #elif defined(WEBRTC_DETECT_NEON)
64 if (WebRtc_GetCPUFeaturesARM() & kCPUFeatureNEON) {
65 filter =
66 new FIRFilterNEON(coefficients, coefficients_length, max_input_length);
67 } else {
68 filter = new FIRFilterC(coefficients, coefficients_length);
69 }
70 #else
71 filter = new FIRFilterC(coefficients, coefficients_length);
72 #endif
73
74 return filter;
75 }
76
FIRFilterC(const float * coefficients,size_t coefficients_length)77 FIRFilterC::FIRFilterC(const float* coefficients, size_t coefficients_length)
78 : coefficients_length_(coefficients_length),
79 state_length_(coefficients_length - 1),
80 coefficients_(new float[coefficients_length_]),
81 state_(new float[state_length_]) {
82 for (size_t i = 0; i < coefficients_length_; ++i) {
83 coefficients_[i] = coefficients[coefficients_length_ - i - 1];
84 }
85 memset(state_.get(), 0, state_length_ * sizeof(state_[0]));
86 }
87
Filter(const float * in,size_t length,float * out)88 void FIRFilterC::Filter(const float* in, size_t length, float* out) {
89 assert(length > 0);
90
91 // Convolves the input signal |in| with the filter kernel |coefficients_|
92 // taking into account the previous state.
93 for (size_t i = 0; i < length; ++i) {
94 out[i] = 0.f;
95 size_t j;
96 for (j = 0; state_length_ > i && j < state_length_ - i; ++j) {
97 out[i] += state_[i + j] * coefficients_[j];
98 }
99 for (; j < coefficients_length_; ++j) {
100 out[i] += in[j + i - state_length_] * coefficients_[j];
101 }
102 }
103
104 // Update current state.
105 if (length >= state_length_) {
106 memcpy(
107 state_.get(), &in[length - state_length_], state_length_ * sizeof(*in));
108 } else {
109 memmove(state_.get(),
110 &state_[length],
111 (state_length_ - length) * sizeof(state_[0]));
112 memcpy(&state_[state_length_ - length], in, length * sizeof(*in));
113 }
114 }
115
116 } // namespace webrtc
117