Chris@69: /***********************************************************************
Chris@69: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Chris@69: Redistribution and use in source and binary forms, with or without
Chris@69: modification, are permitted provided that the following conditions
Chris@69: are met:
Chris@69: - Redistributions of source code must retain the above copyright notice,
Chris@69: this list of conditions and the following disclaimer.
Chris@69: - Redistributions in binary form must reproduce the above copyright
Chris@69: notice, this list of conditions and the following disclaimer in the
Chris@69: documentation and/or other materials provided with the distribution.
Chris@69: - Neither the name of Internet Society, IETF or IETF Trust, nor the
Chris@69: names of specific contributors, may be used to endorse or promote
Chris@69: products derived from this software without specific prior written
Chris@69: permission.
Chris@69: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
Chris@69: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
Chris@69: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
Chris@69: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
Chris@69: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
Chris@69: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
Chris@69: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
Chris@69: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
Chris@69: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
Chris@69: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Chris@69: POSSIBILITY OF SUCH DAMAGE.
Chris@69: ***********************************************************************/
Chris@69: 
Chris@69: #ifdef HAVE_CONFIG_H
Chris@69: #include "config.h"
Chris@69: #endif
Chris@69: 
Chris@69: #include "main_FLP.h"
Chris@69: 
Chris@69: /* Autocorrelations for a warped frequency axis */
Chris@69: void silk_warped_autocorrelation_FLP(
Chris@69:     silk_float                      *corr,                              /* O    Result [order + 1]                          */
Chris@69:     const silk_float                *input,                             /* I    Input data to correlate                     */
Chris@69:     const silk_float                warping,                            /* I    Warping coefficient                         */
Chris@69:     const opus_int                  length,                             /* I    Length of input                             */
Chris@69:     const opus_int                  order                               /* I    Correlation order (even)                    */
Chris@69: )
Chris@69: {
Chris@69:     opus_int    n, i;
Chris@69:     double      tmp1, tmp2;
Chris@69:     double      state[ MAX_SHAPE_LPC_ORDER + 1 ] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
Chris@69:     double      C[     MAX_SHAPE_LPC_ORDER + 1 ] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
Chris@69: 
Chris@69:     /* Order must be even */
Chris@69:     celt_assert( ( order & 1 ) == 0 );
Chris@69: 
Chris@69:     /* Loop over samples */
Chris@69:     for( n = 0; n < length; n++ ) {
Chris@69:         tmp1 = input[ n ];
Chris@69:         /* Loop over allpass sections */
Chris@69:         for( i = 0; i < order; i += 2 ) {
Chris@69:             /* Output of allpass section */
Chris@69:             tmp2 = state[ i ] + warping * ( state[ i + 1 ] - tmp1 );
Chris@69:             state[ i ] = tmp1;
Chris@69:             C[ i ] += state[ 0 ] * tmp1;
Chris@69:             /* Output of allpass section */
Chris@69:             tmp1 = state[ i + 1 ] + warping * ( state[ i + 2 ] - tmp2 );
Chris@69:             state[ i + 1 ] = tmp2;
Chris@69:             C[ i + 1 ] += state[ 0 ] * tmp2;
Chris@69:         }
Chris@69:         state[ order ] = tmp1;
Chris@69:         C[ order ] += state[ 0 ] * tmp1;
Chris@69:     }
Chris@69: 
Chris@69:     /* Copy correlations in silk_float output format */
Chris@69:     for( i = 0; i < order + 1; i++ ) {
Chris@69:         corr[ i ] = ( silk_float )C[ i ];
Chris@69:     }
Chris@69: }