155 lines
6.8 KiB
C
155 lines
6.8 KiB
C
/***********************************************************************
|
|
Copyright (c) 2006-2012, Skype Limited. All rights reserved.
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, (subject to the limitations in the disclaimer below)
|
|
are permitted provided that the following conditions are met:
|
|
- Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
- Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in the
|
|
documentation and/or other materials provided with the distribution.
|
|
- Neither the name of Skype Limited, nor the names of specific
|
|
contributors, may be used to endorse or promote products derived from
|
|
this software without specific prior written permission.
|
|
NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
|
|
BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
|
|
CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
|
|
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
|
|
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
|
|
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
|
|
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
***********************************************************************/
|
|
|
|
/* *
|
|
* SKP_Silk_LPC_inverse_pred_gain.c *
|
|
* *
|
|
* Compute inverse of LPC prediction gain, and *
|
|
* test if LPC coefficients are stable (all poles within unit circle) *
|
|
* *
|
|
* Copyright 2008 (c), Skype Limited *
|
|
* */
|
|
#include "SKP_Silk_SigProc_FIX.h"
|
|
|
|
#undef QA
|
|
#define QA 16
|
|
#define A_LIMIT SKP_FIX_CONST( 0.99975, QA )
|
|
|
|
/* Compute inverse of LPC prediction gain, and */
|
|
/* test if LPC coefficients are stable (all poles within unit circle) */
|
|
static SKP_int LPC_inverse_pred_gain_QA( /* O: Returns 1 if unstable, otherwise 0 */
|
|
SKP_int32 *invGain_Q30, /* O: Inverse prediction gain, Q30 energy domain */
|
|
SKP_int32 A_QA[ 2 ][ SKP_Silk_MAX_ORDER_LPC ],
|
|
/* I: Prediction coefficients */
|
|
const SKP_int order /* I: Prediction order */
|
|
)
|
|
{
|
|
SKP_int k, n, headrm;
|
|
SKP_int32 rc_Q31, rc_mult1_Q30, rc_mult2_Q16, tmp_QA;
|
|
SKP_int32 *Aold_QA, *Anew_QA;
|
|
|
|
Anew_QA = A_QA[ order & 1 ];
|
|
|
|
*invGain_Q30 = ( 1 << 30 );
|
|
for( k = order - 1; k > 0; k-- ) {
|
|
/* Check for stability */
|
|
if( ( Anew_QA[ k ] > A_LIMIT ) || ( Anew_QA[ k ] < -A_LIMIT ) ) {
|
|
return 1;
|
|
}
|
|
|
|
/* Set RC equal to negated AR coef */
|
|
rc_Q31 = -SKP_LSHIFT( Anew_QA[ k ], 31 - QA );
|
|
|
|
/* rc_mult1_Q30 range: [ 1 : 2^30-1 ] */
|
|
rc_mult1_Q30 = ( SKP_int32_MAX >> 1 ) - SKP_SMMUL( rc_Q31, rc_Q31 );
|
|
SKP_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
|
|
SKP_assert( rc_mult1_Q30 < ( 1 << 30 ) );
|
|
|
|
/* rc_mult2_Q16 range: [ 2^16 : SKP_int32_MAX ] */
|
|
rc_mult2_Q16 = SKP_INVERSE32_varQ( rc_mult1_Q30, 46 ); /* 16 = 46 - 30 */
|
|
|
|
/* Update inverse gain */
|
|
/* invGain_Q30 range: [ 0 : 2^30 ] */
|
|
*invGain_Q30 = SKP_LSHIFT( SKP_SMMUL( *invGain_Q30, rc_mult1_Q30 ), 2 );
|
|
SKP_assert( *invGain_Q30 >= 0 );
|
|
SKP_assert( *invGain_Q30 <= ( 1 << 30 ) );
|
|
|
|
/* Swap pointers */
|
|
Aold_QA = Anew_QA;
|
|
Anew_QA = A_QA[ k & 1 ];
|
|
|
|
/* Update AR coefficient */
|
|
headrm = SKP_Silk_CLZ32( rc_mult2_Q16 ) - 1;
|
|
rc_mult2_Q16 = SKP_LSHIFT( rc_mult2_Q16, headrm ); /* Q: 16 + headrm */
|
|
for( n = 0; n < k; n++ ) {
|
|
tmp_QA = Aold_QA[ n ] - SKP_LSHIFT( SKP_SMMUL( Aold_QA[ k - n - 1 ], rc_Q31 ), 1 );
|
|
Anew_QA[ n ] = SKP_LSHIFT( SKP_SMMUL( tmp_QA, rc_mult2_Q16 ), 16 - headrm );
|
|
}
|
|
}
|
|
|
|
/* Check for stability */
|
|
if( ( Anew_QA[ 0 ] > A_LIMIT ) || ( Anew_QA[ 0 ] < -A_LIMIT ) ) {
|
|
return 1;
|
|
}
|
|
|
|
/* Set RC equal to negated AR coef */
|
|
rc_Q31 = -SKP_LSHIFT( Anew_QA[ 0 ], 31 - QA );
|
|
|
|
/* Range: [ 1 : 2^30 ] */
|
|
rc_mult1_Q30 = ( SKP_int32_MAX >> 1 ) - SKP_SMMUL( rc_Q31, rc_Q31 );
|
|
|
|
/* Update inverse gain */
|
|
/* Range: [ 0 : 2^30 ] */
|
|
*invGain_Q30 = SKP_LSHIFT( SKP_SMMUL( *invGain_Q30, rc_mult1_Q30 ), 2 );
|
|
SKP_assert( *invGain_Q30 >= 0 );
|
|
SKP_assert( *invGain_Q30 <= 1<<30 );
|
|
|
|
return 0;
|
|
}
|
|
/* For input in Q12 domain */
|
|
SKP_int SKP_Silk_LPC_inverse_pred_gain( /* O: Returns 1 if unstable, otherwise 0 */
|
|
SKP_int32 *invGain_Q30, /* O: Inverse prediction gain, Q30 energy domain */
|
|
const SKP_int16 *A_Q12, /* I: Prediction coefficients, Q12 [order] */
|
|
const SKP_int order /* I: Prediction order */
|
|
)
|
|
{
|
|
SKP_int k;
|
|
SKP_int32 Atmp_QA[ 2 ][ SKP_Silk_MAX_ORDER_LPC ];
|
|
SKP_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 ] = SKP_LSHIFT( (SKP_int32)A_Q12[ k ], QA - 12 );
|
|
}
|
|
|
|
return LPC_inverse_pred_gain_QA( invGain_Q30, Atmp_QA, order );
|
|
}
|
|
|
|
/* For input in Q24 domain */
|
|
SKP_int SKP_Silk_LPC_inverse_pred_gain_Q24( /* O: Returns 1 if unstable, otherwise 0 */
|
|
SKP_int32 *invGain_Q30, /* O: Inverse prediction gain, Q30 energy domain */
|
|
const SKP_int32 *A_Q24, /* I: Prediction coefficients, Q24 [order] */
|
|
const SKP_int order /* I: Prediction order */
|
|
)
|
|
{
|
|
SKP_int k;
|
|
SKP_int32 Atmp_QA[ 2 ][ SKP_Silk_MAX_ORDER_LPC ];
|
|
SKP_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 ] = SKP_RSHIFT_ROUND( A_Q24[ k ], 24 - QA );
|
|
}
|
|
|
|
return LPC_inverse_pred_gain_QA( invGain_Q30, Atmp_QA, order );
|
|
}
|
|
|