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     11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
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     13 products derived from this software without specific prior written
     14 permission.
     15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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     18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
     19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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     24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25 POSSIBILITY OF SUCH DAMAGE.
     26 ***********************************************************************/
     27 
     28 #ifdef HAVE_CONFIG_H
     29 #include "config.h"
     30 #endif
     31 
     32 #include "main_FIX.h"
     33 
     34 #define QC  10
     35 #define QS  14
     36 
     37 /* Autocorrelations for a warped frequency axis */
     38 void silk_warped_autocorrelation_FIX(
     39           opus_int32                *corr,                                  /* O    Result [order + 1]                                                          */
     40           opus_int                  *scale,                                 /* O    Scaling of the correlation vector                                           */
     41     const opus_int16                *input,                                 /* I    Input data to correlate                                                     */
     42     const opus_int                  warping_Q16,                            /* I    Warping coefficient                                                         */
     43     const opus_int                  length,                                 /* I    Length of input                                                             */
     44     const opus_int                  order                                   /* I    Correlation order (even)                                                    */
     45 )
     46 {
     47     opus_int   n, i, lsh;
     48     opus_int32 tmp1_QS, tmp2_QS;
     49     opus_int32 state_QS[ MAX_SHAPE_LPC_ORDER + 1 ] = { 0 };
     50     opus_int64 corr_QC[  MAX_SHAPE_LPC_ORDER + 1 ] = { 0 };
     51 
     52     /* Order must be even */
     53     silk_assert( ( order & 1 ) == 0 );
     54     silk_assert( 2 * QS - QC >= 0 );
     55 
     56     /* Loop over samples */
     57     for( n = 0; n < length; n++ ) {
     58         tmp1_QS = silk_LSHIFT32( (opus_int32)input[ n ], QS );
     59         /* Loop over allpass sections */
     60         for( i = 0; i < order; i += 2 ) {
     61             /* Output of allpass section */
     62             tmp2_QS = silk_SMLAWB( state_QS[ i ], state_QS[ i + 1 ] - tmp1_QS, warping_Q16 );
     63             state_QS[ i ]  = tmp1_QS;
     64             corr_QC[  i ] += silk_RSHIFT64( silk_SMULL( tmp1_QS, state_QS[ 0 ] ), 2 * QS - QC );
     65             /* Output of allpass section */
     66             tmp1_QS = silk_SMLAWB( state_QS[ i + 1 ], state_QS[ i + 2 ] - tmp2_QS, warping_Q16 );
     67             state_QS[ i + 1 ]  = tmp2_QS;
     68             corr_QC[  i + 1 ] += silk_RSHIFT64( silk_SMULL( tmp2_QS, state_QS[ 0 ] ), 2 * QS - QC );
     69         }
     70         state_QS[ order ] = tmp1_QS;
     71         corr_QC[  order ] += silk_RSHIFT64( silk_SMULL( tmp1_QS, state_QS[ 0 ] ), 2 * QS - QC );
     72     }
     73 
     74     lsh = silk_CLZ64( corr_QC[ 0 ] ) - 35;
     75     lsh = silk_LIMIT( lsh, -12 - QC, 30 - QC );
     76     *scale = -( QC + lsh );
     77     silk_assert( *scale >= -30 && *scale <= 12 );
     78     if( lsh >= 0 ) {
     79         for( i = 0; i < order + 1; i++ ) {
     80             corr[ i ] = (opus_int32)silk_CHECK_FIT32( silk_LSHIFT64( corr_QC[ i ], lsh ) );
     81         }
     82     } else {
     83         for( i = 0; i < order + 1; i++ ) {
     84             corr[ i ] = (opus_int32)silk_CHECK_FIT32( silk_RSHIFT64( corr_QC[ i ], -lsh ) );
     85         }
     86     }
     87     silk_assert( corr_QC[ 0 ] >= 0 ); /* If breaking, decrease QC*/
     88 }
     89