cannam@154: /***********************************************************************
cannam@154: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
cannam@154: Redistribution and use in source and binary forms, with or without
cannam@154: modification, are permitted provided that the following conditions
cannam@154: are met:
cannam@154: - Redistributions of source code must retain the above copyright notice,
cannam@154: this list of conditions and the following disclaimer.
cannam@154: - Redistributions in binary form must reproduce the above copyright
cannam@154: notice, this list of conditions and the following disclaimer in the
cannam@154: documentation and/or other materials provided with the distribution.
cannam@154: - Neither the name of Internet Society, IETF or IETF Trust, nor the
cannam@154: names of specific contributors, may be used to endorse or promote
cannam@154: products derived from this software without specific prior written
cannam@154: permission.
cannam@154: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
cannam@154: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
cannam@154: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
cannam@154: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
cannam@154: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
cannam@154: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
cannam@154: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
cannam@154: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
cannam@154: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
cannam@154: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
cannam@154: POSSIBILITY OF SUCH DAMAGE.
cannam@154: ***********************************************************************/
cannam@154: 
cannam@154: #ifdef HAVE_CONFIG_H
cannam@154: #include "config.h"
cannam@154: #endif
cannam@154: 
cannam@154: #include "main_FLP.h"
cannam@154: 
cannam@154: /* Autocorrelations for a warped frequency axis */
cannam@154: void silk_warped_autocorrelation_FLP(
cannam@154:     silk_float                      *corr,                              /* O    Result [order + 1]                          */
cannam@154:     const silk_float                *input,                             /* I    Input data to correlate                     */
cannam@154:     const silk_float                warping,                            /* I    Warping coefficient                         */
cannam@154:     const opus_int                  length,                             /* I    Length of input                             */
cannam@154:     const opus_int                  order                               /* I    Correlation order (even)                    */
cannam@154: )
cannam@154: {
cannam@154:     opus_int    n, i;
cannam@154:     double      tmp1, tmp2;
cannam@154:     double      state[ MAX_SHAPE_LPC_ORDER + 1 ] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
cannam@154:     double      C[     MAX_SHAPE_LPC_ORDER + 1 ] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
cannam@154: 
cannam@154:     /* Order must be even */
cannam@154:     celt_assert( ( order & 1 ) == 0 );
cannam@154: 
cannam@154:     /* Loop over samples */
cannam@154:     for( n = 0; n < length; n++ ) {
cannam@154:         tmp1 = input[ n ];
cannam@154:         /* Loop over allpass sections */
cannam@154:         for( i = 0; i < order; i += 2 ) {
cannam@154:             /* Output of allpass section */
cannam@154:             tmp2 = state[ i ] + warping * ( state[ i + 1 ] - tmp1 );
cannam@154:             state[ i ] = tmp1;
cannam@154:             C[ i ] += state[ 0 ] * tmp1;
cannam@154:             /* Output of allpass section */
cannam@154:             tmp1 = state[ i + 1 ] + warping * ( state[ i + 2 ] - tmp2 );
cannam@154:             state[ i + 1 ] = tmp2;
cannam@154:             C[ i + 1 ] += state[ 0 ] * tmp2;
cannam@154:         }
cannam@154:         state[ order ] = tmp1;
cannam@154:         C[ order ] += state[ 0 ] * tmp1;
cannam@154:     }
cannam@154: 
cannam@154:     /* Copy correlations in silk_float output format */
cannam@154:     for( i = 0; i < order + 1; i++ ) {
cannam@154:         corr[ i ] = ( silk_float )C[ i ];
cannam@154:     }
cannam@154: }