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/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
WebRtcIlbcfix_MyCorr.c
******************************************************************/
#include "modules/audio_coding/codecs/ilbc/my_corr.h"
#include "modules/audio_coding/codecs/ilbc/defines.h"
/*----------------------------------------------------------------*
* compute cross correlation between sequences
*---------------------------------------------------------------*/
void WebRtcIlbcfix_MyCorr(
int32_t* corr, /* (o) correlation of seq1 and seq2 */
const int16_t* seq1, /* (i) first sequence */
size_t dim1, /* (i) dimension first seq1 */
const int16_t* seq2, /* (i) second sequence */
size_t dim2 /* (i) dimension seq2 */
){
uint32_t max1, max2;
size_t loops;
int right_shift;
// Calculate a right shift that will let us sum dim2 pairwise products of
// values from the two sequences without overflowing an int32_t. (The +1 in
// max1 and max2 are because WebRtcSpl_MaxAbsValueW16 will return 2**15 - 1
// if the input array contains -2**15.)
max1 = WebRtcSpl_MaxAbsValueW16(seq1, dim1) + 1;
max2 = WebRtcSpl_MaxAbsValueW16(seq2, dim2) + 1;
right_shift =
(64 - 31) - WebRtcSpl_CountLeadingZeros64((max1 * max2) * (uint64_t)dim2);
if (right_shift < 0) {
right_shift = 0;
}
loops=dim1-dim2+1;
/* Calculate the cross correlations */
WebRtcSpl_CrossCorrelation(corr, seq2, seq1, dim2, loops, right_shift, 1);
return;
}
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