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/* * | |
* SKP_Silk_k2a.c * | |
* * | |
* Step up function, converts reflection coefficients to prediction * | |
* coefficients * | |
* * | |
* Copyright 2008 (c), Skype Limited * | |
* Date: 080103 * | |
* */ | |
#include "SKP_Silk_SigProc_FIX.h" | |
/* Step up function, converts reflection coefficients to prediction coefficients */ | |
void SKP_Silk_k2a( | |
SKP_int32 *A_Q24, /* O: Prediction coefficients [order] Q24 */ | |
const SKP_int16 *rc_Q15, /* I: Reflection coefficients [order] Q15 */ | |
const SKP_int32 order /* I: Prediction order */ | |
) | |
{ | |
SKP_int k, n; | |
SKP_int32 Atmp[ SKP_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( (SKP_int32)rc_Q15[ k ], 9 ); | |
} | |
} |