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92ea95e34a
In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC from src/webrtc to src/ (in order to preserve an healthy git history). This CL takes care of fixing header guards, #include paths, etc... NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578 Reviewed-on: https://webrtc-review.googlesource.com/1561 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19846}
65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "common_audio/signal_processing/include/signal_processing_library.h"
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#include "rtc_base/checks.h"
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size_t WebRtcSpl_AutoCorrelation(const int16_t* in_vector,
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size_t in_vector_length,
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size_t order,
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int32_t* result,
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int* scale) {
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int32_t sum = 0;
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size_t i = 0, j = 0;
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int16_t smax = 0;
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int scaling = 0;
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RTC_DCHECK_LE(order, in_vector_length);
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// Find the maximum absolute value of the samples.
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smax = WebRtcSpl_MaxAbsValueW16(in_vector, in_vector_length);
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// In order to avoid overflow when computing the sum we should scale the
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// samples so that (in_vector_length * smax * smax) will not overflow.
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if (smax == 0) {
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scaling = 0;
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} else {
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// Number of bits in the sum loop.
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int nbits = WebRtcSpl_GetSizeInBits((uint32_t)in_vector_length);
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// Number of bits to normalize smax.
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int t = WebRtcSpl_NormW32(WEBRTC_SPL_MUL(smax, smax));
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if (t > nbits) {
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scaling = 0;
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} else {
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scaling = nbits - t;
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}
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}
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// Perform the actual correlation calculation.
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for (i = 0; i < order + 1; i++) {
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sum = 0;
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/* Unroll the loop to improve performance. */
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for (j = 0; i + j + 3 < in_vector_length; j += 4) {
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sum += (in_vector[j + 0] * in_vector[i + j + 0]) >> scaling;
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sum += (in_vector[j + 1] * in_vector[i + j + 1]) >> scaling;
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sum += (in_vector[j + 2] * in_vector[i + j + 2]) >> scaling;
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sum += (in_vector[j + 3] * in_vector[i + j + 3]) >> scaling;
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}
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for (; j < in_vector_length - i; j++) {
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sum += (in_vector[j] * in_vector[i + j]) >> scaling;
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}
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*result++ = sum;
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}
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*scale = scaling;
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return order + 1;
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}
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