152 lines
6.2 KiB
C
152 lines
6.2 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#include "opus/opus_config.h"
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#include "opus/silk/SigProc_FIX.h"
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#define QA 24
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#define A_LIMIT SILK_FIX_CONST( 0.99975, QA )
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#define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))
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/* Compute inverse of LPC prediction gain, and */
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/* test if LPC coefficients are stable (all poles within unit circle) */
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static opus_int32 LPC_inverse_pred_gain_QA( /* O Returns inverse prediction gain in energy domain, Q30 */
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opus_int32 A_QA[ 2 ][ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */
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const opus_int order /* I Prediction order */
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)
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{
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opus_int k, n, mult2Q;
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opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp_QA;
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opus_int32 *Aold_QA, *Anew_QA;
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Anew_QA = A_QA[ order & 1 ];
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invGain_Q30 = (opus_int32)1 << 30;
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for( k = order - 1; k > 0; k-- ) {
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/* Check for stability */
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if( ( Anew_QA[ k ] > A_LIMIT ) || ( Anew_QA[ k ] < -A_LIMIT ) ) {
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return 0;
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}
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/* Set RC equal to negated AR coef */
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rc_Q31 = -silk_LSHIFT( Anew_QA[ k ], 31 - QA );
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/* rc_mult1_Q30 range: [ 1 : 2^30 ] */
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rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
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silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
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silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
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/* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
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mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
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rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
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/* Update inverse gain */
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/* invGain_Q30 range: [ 0 : 2^30 ] */
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invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
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silk_assert( invGain_Q30 >= 0 );
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silk_assert( invGain_Q30 <= ( 1 << 30 ) );
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/* Swap pointers */
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Aold_QA = Anew_QA;
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Anew_QA = A_QA[ k & 1 ];
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/* Update AR coefficient */
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for( n = 0; n < k; n++ ) {
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tmp_QA = Aold_QA[ n ] - MUL32_FRAC_Q( Aold_QA[ k - n - 1 ], rc_Q31, 31 );
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Anew_QA[ n ] = MUL32_FRAC_Q( tmp_QA, rc_mult2 , mult2Q );
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}
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}
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/* Check for stability */
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if( ( Anew_QA[ 0 ] > A_LIMIT ) || ( Anew_QA[ 0 ] < -A_LIMIT ) ) {
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return 0;
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}
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/* Set RC equal to negated AR coef */
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rc_Q31 = -silk_LSHIFT( Anew_QA[ 0 ], 31 - QA );
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/* Range: [ 1 : 2^30 ] */
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rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
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/* Update inverse gain */
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/* Range: [ 0 : 2^30 ] */
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invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
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silk_assert( invGain_Q30 >= 0 );
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silk_assert( invGain_Q30 <= 1<<30 );
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return invGain_Q30;
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}
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/* For input in Q12 domain */
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opus_int32 silk_LPC_inverse_pred_gain( /* O Returns inverse prediction gain in energy domain, Q30 */
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const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */
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const opus_int order /* I Prediction order */
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)
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{
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opus_int k;
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opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
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opus_int32 *Anew_QA;
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opus_int32 DC_resp = 0;
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Anew_QA = Atmp_QA[ order & 1 ];
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/* Increase Q domain of the AR coefficients */
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for( k = 0; k < order; k++ ) {
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DC_resp += (opus_int32)A_Q12[ k ];
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Anew_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
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}
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/* If the DC is unstable, we don't even need to do the full calculations */
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if( DC_resp >= 4096 ) {
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return 0;
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}
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return LPC_inverse_pred_gain_QA( Atmp_QA, order );
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}
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#ifdef OPUS_FIXED_POINT
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/* For input in Q24 domain */
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opus_int32 silk_LPC_inverse_pred_gain_Q24( /* O Returns inverse prediction gain in energy domain, Q30 */
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const opus_int32 *A_Q24, /* I Prediction coefficients [order] */
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const opus_int order /* I Prediction order */
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)
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{
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opus_int k;
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opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
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opus_int32 *Anew_QA;
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Anew_QA = Atmp_QA[ order & 1 ];
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/* Increase Q domain of the AR coefficients */
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for( k = 0; k < order; k++ ) {
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Anew_QA[ k ] = silk_RSHIFT32( A_Q24[ k ], 24 - QA );
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}
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return LPC_inverse_pred_gain_QA( Atmp_QA, order );
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}
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#endif
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