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| permission. |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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| ***********************************************************************/ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include "SigProc_FIX.h" |
| |
| #define QA 24 |
| #define A_LIMIT SILK_FIX_CONST( 0.99975, QA ) |
| |
| #define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q))) |
| |
| /* Compute inverse of LPC prediction gain, and */ |
| /* test if LPC coefficients are stable (all poles within unit circle) */ |
| static opus_int32 LPC_inverse_pred_gain_QA( /* O Returns inverse prediction gain in energy domain, Q30 */ |
| opus_int32 A_QA[ 2 ][ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */ |
| const opus_int order /* I Prediction order */ |
| ) |
| { |
| opus_int k, n, mult2Q; |
| opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp_QA; |
| opus_int32 *Aold_QA, *Anew_QA; |
| |
| Anew_QA = A_QA[ order & 1 ]; |
| |
| invGain_Q30 = (opus_int32)1 << 30; |
| for( k = order - 1; k > 0; k-- ) { |
| /* Check for stability */ |
| if( ( Anew_QA[ k ] > A_LIMIT ) || ( Anew_QA[ k ] < -A_LIMIT ) ) { |
| return 0; |
| } |
| |
| /* Set RC equal to negated AR coef */ |
| rc_Q31 = -silk_LSHIFT( Anew_QA[ k ], 31 - QA ); |
| |
| /* rc_mult1_Q30 range: [ 1 : 2^30 ] */ |
| rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 ); |
| silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */ |
| silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) ); |
| |
| /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */ |
| mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) ); |
| rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 ); |
| |
| /* Update inverse gain */ |
| /* invGain_Q30 range: [ 0 : 2^30 ] */ |
| invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 ); |
| silk_assert( invGain_Q30 >= 0 ); |
| silk_assert( invGain_Q30 <= ( 1 << 30 ) ); |
| |
| /* Swap pointers */ |
| Aold_QA = Anew_QA; |
| Anew_QA = A_QA[ k & 1 ]; |
| |
| /* Update AR coefficient */ |
| for( n = 0; n < k; n++ ) { |
| tmp_QA = Aold_QA[ n ] - MUL32_FRAC_Q( Aold_QA[ k - n - 1 ], rc_Q31, 31 ); |
| Anew_QA[ n ] = MUL32_FRAC_Q( tmp_QA, rc_mult2 , mult2Q ); |
| } |
| } |
| |
| /* Check for stability */ |
| if( ( Anew_QA[ 0 ] > A_LIMIT ) || ( Anew_QA[ 0 ] < -A_LIMIT ) ) { |
| return 0; |
| } |
| |
| /* Set RC equal to negated AR coef */ |
| rc_Q31 = -silk_LSHIFT( Anew_QA[ 0 ], 31 - QA ); |
| |
| /* Range: [ 1 : 2^30 ] */ |
| rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 ); |
| |
| /* Update inverse gain */ |
| /* Range: [ 0 : 2^30 ] */ |
| invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 ); |
| silk_assert( invGain_Q30 >= 0 ); |
| silk_assert( invGain_Q30 <= 1<<30 ); |
| |
| return invGain_Q30; |
| } |
| |
| /* For input in Q12 domain */ |
| opus_int32 silk_LPC_inverse_pred_gain( /* O Returns inverse prediction gain in energy domain, Q30 */ |
| const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */ |
| const opus_int order /* I Prediction order */ |
| ) |
| { |
| opus_int k; |
| opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ]; |
| opus_int32 *Anew_QA; |
| opus_int32 DC_resp = 0; |
| |
| Anew_QA = Atmp_QA[ order & 1 ]; |
| |
| /* Increase Q domain of the AR coefficients */ |
| for( k = 0; k < order; k++ ) { |
| DC_resp += (opus_int32)A_Q12[ k ]; |
| Anew_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 ); |
| } |
| /* If the DC is unstable, we don't even need to do the full calculations */ |
| if( DC_resp >= 4096 ) { |
| return 0; |
| } |
| return LPC_inverse_pred_gain_QA( Atmp_QA, order ); |
| } |
| |
| #ifdef FIXED_POINT |
| |
| /* For input in Q24 domain */ |
| opus_int32 silk_LPC_inverse_pred_gain_Q24( /* O Returns inverse prediction gain in energy domain, Q30 */ |
| const opus_int32 *A_Q24, /* I Prediction coefficients [order] */ |
| const opus_int order /* I Prediction order */ |
| ) |
| { |
| opus_int k; |
| opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ]; |
| opus_int32 *Anew_QA; |
| |
| Anew_QA = Atmp_QA[ order & 1 ]; |
| |
| /* Increase Q domain of the AR coefficients */ |
| for( k = 0; k < order; k++ ) { |
| Anew_QA[ k ] = silk_RSHIFT32( A_Q24[ k ], 24 - QA ); |
| } |
| |
| return LPC_inverse_pred_gain_QA( Atmp_QA, order ); |
| } |
| #endif |
