82 lines
4.3 KiB
C
82 lines
4.3 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, (subject to the limitations in the disclaimer below)
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are permitted provided that the following conditions are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Skype Limited, nor the names of specific
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contributors, may be used to endorse or promote products derived from
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this software without specific prior written permission.
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NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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/* *
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* SKP_Silk_autocorr.c *
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* *
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* Calculates the autocorrelation *
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* The result has 29 non-zero bits for the first correlation, to leave *
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* some room for adding white noise fractions etc. *
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* *
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* Copyright 2008 (c), Skype Limited *
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* */
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#include "SKP_Silk_SigProc_FIX.h"
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/* Compute autocorrelation */
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void SKP_Silk_autocorr(
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SKP_int32 *results, /* O Result (length correlationCount) */
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SKP_int *scale, /* O Scaling of the correlation vector */
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const SKP_int16 *inputData, /* I Input data to correlate */
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const SKP_int inputDataSize, /* I Length of input */
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const SKP_int correlationCount /* I Number of correlation taps to compute */
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)
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{
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SKP_int i, lz, nRightShifts, corrCount;
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SKP_int64 corr64;
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corrCount = SKP_min_int( inputDataSize, correlationCount );
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/* compute energy (zero-lag correlation) */
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corr64 = SKP_Silk_inner_prod16_aligned_64( inputData, inputData, inputDataSize );
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/* deal with all-zero input data */
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corr64 += 1;
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/* number of leading zeros */
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lz = SKP_Silk_CLZ64( corr64 );
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/* scaling: number of right shifts applied to correlations */
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nRightShifts = 35 - lz;
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*scale = nRightShifts;
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if( nRightShifts <= 0 ) {
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results[ 0 ] = SKP_LSHIFT( (SKP_int32)SKP_CHECK_FIT32( corr64 ), -nRightShifts );
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/* compute remaining correlations based on int32 inner product */
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for( i = 1; i < corrCount; i++ ) {
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results[ i ] = SKP_LSHIFT( SKP_Silk_inner_prod_aligned( inputData, inputData + i, inputDataSize - i ), -nRightShifts );
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}
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} else {
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results[ 0 ] = (SKP_int32)SKP_CHECK_FIT32( SKP_RSHIFT64( corr64, nRightShifts ) );
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/* compute remaining correlations based on int64 inner product */
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for( i = 1; i < corrCount; i++ ) {
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results[ i ] = (SKP_int32)SKP_CHECK_FIT32( SKP_RSHIFT64( SKP_Silk_inner_prod16_aligned_64( inputData, inputData + i, inputDataSize - i ), nRightShifts ) );
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}
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}
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}
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