silk/silk_k2a.c

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "silk_SigProc_FIX.h"

/* Step up function, converts reflection coefficients to prediction coefficients */
void silk_k2a(
    opus_int32            *A_Q24,                 /* O:    Prediction coefficients [order] Q24         */
    const opus_int16      *rc_Q15,                /* I:    Reflection coefficients [order] Q15         */
    const opus_int32      order                   /* I:    Prediction order                            */
)
{
    opus_int   k, n;
    opus_int32 Atmp[ SILK_MAX_ORDER_LPC ];

    for( k = 0; k < order; k++ ) {
        for( n = 0; n < k; n++ ) {
            Atmp[ n ] = A_Q24[ n ];
        }
        for( n = 0; n < k; n++ ) {
            A_Q24[ n ] = SKP_SMLAWB( A_Q24[ n ], SKP_LSHIFT( Atmp[ k - n - 1 ], 1 ), rc_Q15[ k ] );
        }
        A_Q24[ k ] = -SKP_LSHIFT( (opus_int32)rc_Q15[ k ], 9 );
    }
}