ref: c9d5bea13e3cb7381bfa897a45d8bab4e7b767a7
dir: /silk/float/schur_FLP.c/
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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "SigProc_FLP.h"
silk_float silk_schur_FLP( /* O returns residual energy */
silk_float refl_coef[], /* O reflection coefficients (length order) */
const silk_float auto_corr[], /* I autocorrelation sequence (length order+1) */
opus_int order /* I order */
)
{
opus_int k, n;
double C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
double Ctmp1, Ctmp2, rc_tmp;
celt_assert( order >= 0 && order <= SILK_MAX_ORDER_LPC );
/* Copy correlations */
k = 0;
do {
C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ];
} while( ++k <= order );
for( k = 0; k < order; k++ ) {
/* Get reflection coefficient */
rc_tmp = -C[ k + 1 ][ 0 ] / silk_max_float( C[ 0 ][ 1 ], 1e-9f );
/* Save the output */
refl_coef[ k ] = (silk_float)rc_tmp;
/* Update correlations */
for( n = 0; n < order - k; n++ ) {
Ctmp1 = C[ n + k + 1 ][ 0 ];
Ctmp2 = C[ n ][ 1 ];
C[ n + k + 1 ][ 0 ] = Ctmp1 + Ctmp2 * rc_tmp;
C[ n ][ 1 ] = Ctmp2 + Ctmp1 * rc_tmp;
}
}
/* Return residual energy */
return (silk_float)C[ 0 ][ 1 ];
}