/* Uses SMULL(), available on armv4 */ opus_int32 silk_schur64( /* O returns residual energy */ opus_int32 rc_Q16[], /* O Reflection coefficients [order] Q16 */ const opus_int32 c[], /* I Correlations [order+1] */ opus_int32 order /* I Prediction order */ ) { opus_int k, n; opus_int32 C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ]; opus_int32 Ctmp1_Q30, Ctmp2_Q30, rc_tmp_Q31; silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 ); /* Check for invalid input */ if( c[ 0 ] <= 0 ) { silk_memset( rc_Q16, 0, order * sizeof( opus_int32 ) ); return 0; } for( k = 0; k < order + 1; k++ ) { C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ]; } for( k = 0; k < order; k++ ) { /* Check that we won't be getting an unstable rc, otherwise stop here. */ if (silk_abs_int32(C[ k + 1 ][ 0 ]) >= C[ 0 ][ 1 ]) { if ( C[ k + 1 ][ 0 ] > 0 ) { rc_Q16[ k ] = -SILK_FIX_CONST( .99f, 16 ); } else { rc_Q16[ k ] = SILK_FIX_CONST( .99f, 16 ); } k++; break; } /* Get reflection coefficient: divide two Q30 values and get result in Q31 */ rc_tmp_Q31 = silk_DIV32_varQ( -C[ k + 1 ][ 0 ], C[ 0 ][ 1 ], 31 ); /* Save the output */ rc_Q16[ k ] = silk_RSHIFT_ROUND( rc_tmp_Q31, 15 ); /* Update correlations */ for( n = 0; n < order - k; n++ ) { Ctmp1_Q30 = C[ n + k + 1 ][ 0 ]; Ctmp2_Q30 = C[ n ][ 1 ]; /* Multiply and add the highest int32 */ C[ n + k + 1 ][ 0 ] = Ctmp1_Q30 + silk_SMMUL( silk_LSHIFT( Ctmp2_Q30, 1 ), rc_tmp_Q31 ); C[ n ][ 1 ] = Ctmp2_Q30 + silk_SMMUL( silk_LSHIFT( Ctmp1_Q30, 1 ), rc_tmp_Q31 ); } } for(; k < order; k++ ) { rc_Q16[ k ] = 0; } return silk_max_32( 1, C[ 0 ][ 1 ] ); }
/* uses SMLAWB(), requiring armv5E and higher. */ opus_int32 silk_schur( /* O Returns residual energy */ opus_int16 *rc_Q15, /* O reflection coefficients [order] Q15 */ const opus_int32 *c, /* I correlations [order+1] */ const opus_int32 order /* I prediction order */ ) { opus_int k, n, lz; opus_int32 C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ]; opus_int32 Ctmp1, Ctmp2, rc_tmp_Q15; silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 ); /* Get number of leading zeros */ lz = silk_CLZ32( c[ 0 ] ); /* Copy correlations and adjust level to Q30 */ if( lz < 2 ) { /* lz must be 1, so shift one to the right */ for( k = 0; k < order + 1; k++ ) { C[ k ][ 0 ] = C[ k ][ 1 ] = silk_RSHIFT( c[ k ], 1 ); } } else if( lz > 2 ) { /* Shift to the left */ lz -= 2; for( k = 0; k < order + 1; k++ ) { C[ k ][ 0 ] = C[ k ][ 1 ] = silk_LSHIFT( c[ k ], lz ); } } else { /* No need to shift */ for( k = 0; k < order + 1; k++ ) { C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ]; } } for( k = 0; k < order; k++ ) { /* Check that we won't be getting an unstable rc, otherwise stop here. */ if (silk_abs_int32(C[ k + 1 ][ 0 ]) >= C[ 0 ][ 1 ]) { if ( C[ k + 1 ][ 0 ] > 0 ) { rc_Q15[ k ] = -SILK_FIX_CONST( .99f, 15 ); } else { rc_Q15[ k ] = SILK_FIX_CONST( .99f, 15 ); } k++; break; } /* Get reflection coefficient */ rc_tmp_Q15 = -silk_DIV32_16( C[ k + 1 ][ 0 ], silk_max_32( silk_RSHIFT( C[ 0 ][ 1 ], 15 ), 1 ) ); /* Clip (shouldn't happen for properly conditioned inputs) */ rc_tmp_Q15 = silk_SAT16( rc_tmp_Q15 ); /* Store */ rc_Q15[ k ] = (opus_int16)rc_tmp_Q15; /* Update correlations */ for( n = 0; n < order - k; n++ ) { Ctmp1 = C[ n + k + 1 ][ 0 ]; Ctmp2 = C[ n ][ 1 ]; C[ n + k + 1 ][ 0 ] = silk_SMLAWB( Ctmp1, silk_LSHIFT( Ctmp2, 1 ), rc_tmp_Q15 ); C[ n ][ 1 ] = silk_SMLAWB( Ctmp2, silk_LSHIFT( Ctmp1, 1 ), rc_tmp_Q15 ); } } for(; k < order; k++ ) { rc_Q15[ k ] = 0; } /* return residual energy */ return silk_max_32( 1, C[ 0 ][ 1 ] ); }
/* amplitude of monic warped coefficients by using bandwidth expansion on the true coefficients */ static inline void limit_warped_coefs( opus_int32 *coefs_syn_Q24, opus_int32 *coefs_ana_Q24, opus_int lambda_Q16, opus_int32 limit_Q24, opus_int order ) { opus_int i, iter, ind = 0; opus_int32 tmp, maxabs_Q24, chirp_Q16, gain_syn_Q16, gain_ana_Q16; opus_int32 nom_Q16, den_Q24; /* Convert to monic coefficients */ lambda_Q16 = -lambda_Q16; for( i = order - 1; i > 0; i-- ) { coefs_syn_Q24[ i - 1 ] = silk_SMLAWB( coefs_syn_Q24[ i - 1 ], coefs_syn_Q24[ i ], lambda_Q16 ); coefs_ana_Q24[ i - 1 ] = silk_SMLAWB( coefs_ana_Q24[ i - 1 ], coefs_ana_Q24[ i ], lambda_Q16 ); } lambda_Q16 = -lambda_Q16; nom_Q16 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 16 ), -lambda_Q16, lambda_Q16 ); den_Q24 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 24 ), coefs_syn_Q24[ 0 ], lambda_Q16 ); gain_syn_Q16 = silk_DIV32_varQ( nom_Q16, den_Q24, 24 ); den_Q24 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 24 ), coefs_ana_Q24[ 0 ], lambda_Q16 ); gain_ana_Q16 = silk_DIV32_varQ( nom_Q16, den_Q24, 24 ); for( i = 0; i < order; i++ ) { coefs_syn_Q24[ i ] = silk_SMULWW( gain_syn_Q16, coefs_syn_Q24[ i ] ); coefs_ana_Q24[ i ] = silk_SMULWW( gain_ana_Q16, coefs_ana_Q24[ i ] ); } for( iter = 0; iter < 10; iter++ ) { /* Find maximum absolute value */ maxabs_Q24 = -1; for( i = 0; i < order; i++ ) { tmp = silk_max( silk_abs_int32( coefs_syn_Q24[ i ] ), silk_abs_int32( coefs_ana_Q24[ i ] ) ); if( tmp > maxabs_Q24 ) { maxabs_Q24 = tmp; ind = i; } } if( maxabs_Q24 <= limit_Q24 ) { /* Coefficients are within range - done */ return; } /* Convert back to true warped coefficients */ for( i = 1; i < order; i++ ) { coefs_syn_Q24[ i - 1 ] = silk_SMLAWB( coefs_syn_Q24[ i - 1 ], coefs_syn_Q24[ i ], lambda_Q16 ); coefs_ana_Q24[ i - 1 ] = silk_SMLAWB( coefs_ana_Q24[ i - 1 ], coefs_ana_Q24[ i ], lambda_Q16 ); } gain_syn_Q16 = silk_INVERSE32_varQ( gain_syn_Q16, 32 ); gain_ana_Q16 = silk_INVERSE32_varQ( gain_ana_Q16, 32 ); for( i = 0; i < order; i++ ) { coefs_syn_Q24[ i ] = silk_SMULWW( gain_syn_Q16, coefs_syn_Q24[ i ] ); coefs_ana_Q24[ i ] = silk_SMULWW( gain_ana_Q16, coefs_ana_Q24[ i ] ); } /* Apply bandwidth expansion */ chirp_Q16 = SILK_FIX_CONST( 0.99, 16 ) - silk_DIV32_varQ( silk_SMULWB( maxabs_Q24 - limit_Q24, silk_SMLABB( SILK_FIX_CONST( 0.8, 10 ), SILK_FIX_CONST( 0.1, 10 ), iter ) ), silk_MUL( maxabs_Q24, ind + 1 ), 22 ); silk_bwexpander_32( coefs_syn_Q24, order, chirp_Q16 ); silk_bwexpander_32( coefs_ana_Q24, order, chirp_Q16 ); /* Convert to monic warped coefficients */ lambda_Q16 = -lambda_Q16; for( i = order - 1; i > 0; i-- ) { coefs_syn_Q24[ i - 1 ] = silk_SMLAWB( coefs_syn_Q24[ i - 1 ], coefs_syn_Q24[ i ], lambda_Q16 ); coefs_ana_Q24[ i - 1 ] = silk_SMLAWB( coefs_ana_Q24[ i - 1 ], coefs_ana_Q24[ i ], lambda_Q16 ); } lambda_Q16 = -lambda_Q16; nom_Q16 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 16 ), -lambda_Q16, lambda_Q16 ); den_Q24 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 24 ), coefs_syn_Q24[ 0 ], lambda_Q16 ); gain_syn_Q16 = silk_DIV32_varQ( nom_Q16, den_Q24, 24 ); den_Q24 = silk_SMLAWB( SILK_FIX_CONST( 1.0, 24 ), coefs_ana_Q24[ 0 ], lambda_Q16 ); gain_ana_Q16 = silk_DIV32_varQ( nom_Q16, den_Q24, 24 ); for( i = 0; i < order; i++ ) { coefs_syn_Q24[ i ] = silk_SMULWW( gain_syn_Q16, coefs_syn_Q24[ i ] ); coefs_ana_Q24[ i ] = silk_SMULWW( gain_ana_Q16, coefs_ana_Q24[ i ] ); } } silk_assert( 0 ); }