1 /*
2 * Copyright (c) 2012 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 "common_audio/signal_processing/include/signal_processing_library.h"
12
13 #include "rtc_base/checks.h"
14 #include "rtc_base/sanitizer.h"
15
16 // TODO(Bjornv): Change the function parameter order to WebRTC code style.
17 // C version of WebRtcSpl_DownsampleFast() for generic platforms.
WebRtcSpl_DownsampleFastC(const int16_t * data_in,size_t data_in_length,int16_t * data_out,size_t data_out_length,const int16_t * __restrict coefficients,size_t coefficients_length,int factor,size_t delay)18 int WebRtcSpl_DownsampleFastC(const int16_t* data_in,
19 size_t data_in_length,
20 int16_t* data_out,
21 size_t data_out_length,
22 const int16_t* __restrict coefficients,
23 size_t coefficients_length,
24 int factor,
25 size_t delay) {
26 int16_t* const original_data_out = data_out;
27 size_t i = 0;
28 size_t j = 0;
29 int32_t out_s32 = 0;
30 size_t endpos = delay + factor * (data_out_length - 1) + 1;
31
32 // Return error if any of the running conditions doesn't meet.
33 if (data_out_length == 0 || coefficients_length == 0
34 || data_in_length < endpos) {
35 return -1;
36 }
37
38 rtc_MsanCheckInitialized(coefficients, sizeof(coefficients[0]),
39 coefficients_length);
40
41 for (i = delay; i < endpos; i += factor) {
42 out_s32 = 2048; // Round value, 0.5 in Q12.
43
44 for (j = 0; j < coefficients_length; j++) {
45 // Negative overflow is permitted here, because this is
46 // auto-regressive filters, and the state for each batch run is
47 // stored in the "negative" positions of the output vector.
48 rtc_MsanCheckInitialized(&data_in[(ptrdiff_t) i - (ptrdiff_t) j],
49 sizeof(data_in[0]), 1);
50 // out_s32 is in Q12 domain.
51 out_s32 += coefficients[j] * data_in[(ptrdiff_t) i - (ptrdiff_t) j];
52 }
53
54 out_s32 >>= 12; // Q0.
55
56 // Saturate and store the output.
57 *data_out++ = WebRtcSpl_SatW32ToW16(out_s32);
58 }
59
60 RTC_DCHECK_EQ(original_data_out + data_out_length, data_out);
61 rtc_MsanCheckInitialized(original_data_out, sizeof(original_data_out[0]),
62 data_out_length);
63
64 return 0;
65 }
66