1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/LPC_inv_pred_gain.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,154 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +#include "SigProc_FIX.h"
1.36 +
1.37 +#define QA 24
1.38 +#define A_LIMIT SILK_FIX_CONST( 0.99975, QA )
1.39 +
1.40 +#define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))
1.41 +
1.42 +/* Compute inverse of LPC prediction gain, and */
1.43 +/* test if LPC coefficients are stable (all poles within unit circle) */
1.44 +static opus_int32 LPC_inverse_pred_gain_QA( /* O Returns inverse prediction gain in energy domain, Q30 */
1.45 + opus_int32 A_QA[ 2 ][ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */
1.46 + const opus_int order /* I Prediction order */
1.47 +)
1.48 +{
1.49 + opus_int k, n, mult2Q;
1.50 + opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp_QA;
1.51 + opus_int32 *Aold_QA, *Anew_QA;
1.52 +
1.53 + Anew_QA = A_QA[ order & 1 ];
1.54 +
1.55 + invGain_Q30 = (opus_int32)1 << 30;
1.56 + for( k = order - 1; k > 0; k-- ) {
1.57 + /* Check for stability */
1.58 + if( ( Anew_QA[ k ] > A_LIMIT ) || ( Anew_QA[ k ] < -A_LIMIT ) ) {
1.59 + return 0;
1.60 + }
1.61 +
1.62 + /* Set RC equal to negated AR coef */
1.63 + rc_Q31 = -silk_LSHIFT( Anew_QA[ k ], 31 - QA );
1.64 +
1.65 + /* rc_mult1_Q30 range: [ 1 : 2^30 ] */
1.66 + rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
1.67 + silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
1.68 + silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
1.69 +
1.70 + /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
1.71 + mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
1.72 + rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
1.73 +
1.74 + /* Update inverse gain */
1.75 + /* invGain_Q30 range: [ 0 : 2^30 ] */
1.76 + invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
1.77 + silk_assert( invGain_Q30 >= 0 );
1.78 + silk_assert( invGain_Q30 <= ( 1 << 30 ) );
1.79 +
1.80 + /* Swap pointers */
1.81 + Aold_QA = Anew_QA;
1.82 + Anew_QA = A_QA[ k & 1 ];
1.83 +
1.84 + /* Update AR coefficient */
1.85 + for( n = 0; n < k; n++ ) {
1.86 + tmp_QA = Aold_QA[ n ] - MUL32_FRAC_Q( Aold_QA[ k - n - 1 ], rc_Q31, 31 );
1.87 + Anew_QA[ n ] = MUL32_FRAC_Q( tmp_QA, rc_mult2 , mult2Q );
1.88 + }
1.89 + }
1.90 +
1.91 + /* Check for stability */
1.92 + if( ( Anew_QA[ 0 ] > A_LIMIT ) || ( Anew_QA[ 0 ] < -A_LIMIT ) ) {
1.93 + return 0;
1.94 + }
1.95 +
1.96 + /* Set RC equal to negated AR coef */
1.97 + rc_Q31 = -silk_LSHIFT( Anew_QA[ 0 ], 31 - QA );
1.98 +
1.99 + /* Range: [ 1 : 2^30 ] */
1.100 + rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
1.101 +
1.102 + /* Update inverse gain */
1.103 + /* Range: [ 0 : 2^30 ] */
1.104 + invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
1.105 + silk_assert( invGain_Q30 >= 0 );
1.106 + silk_assert( invGain_Q30 <= 1<<30 );
1.107 +
1.108 + return invGain_Q30;
1.109 +}
1.110 +
1.111 +/* For input in Q12 domain */
1.112 +opus_int32 silk_LPC_inverse_pred_gain( /* O Returns inverse prediction gain in energy domain, Q30 */
1.113 + const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */
1.114 + const opus_int order /* I Prediction order */
1.115 +)
1.116 +{
1.117 + opus_int k;
1.118 + opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
1.119 + opus_int32 *Anew_QA;
1.120 + opus_int32 DC_resp = 0;
1.121 +
1.122 + Anew_QA = Atmp_QA[ order & 1 ];
1.123 +
1.124 + /* Increase Q domain of the AR coefficients */
1.125 + for( k = 0; k < order; k++ ) {
1.126 + DC_resp += (opus_int32)A_Q12[ k ];
1.127 + Anew_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
1.128 + }
1.129 + /* If the DC is unstable, we don't even need to do the full calculations */
1.130 + if( DC_resp >= 4096 ) {
1.131 + return 0;
1.132 + }
1.133 + return LPC_inverse_pred_gain_QA( Atmp_QA, order );
1.134 +}
1.135 +
1.136 +#ifdef FIXED_POINT
1.137 +
1.138 +/* For input in Q24 domain */
1.139 +opus_int32 silk_LPC_inverse_pred_gain_Q24( /* O Returns inverse prediction gain in energy domain, Q30 */
1.140 + const opus_int32 *A_Q24, /* I Prediction coefficients [order] */
1.141 + const opus_int order /* I Prediction order */
1.142 +)
1.143 +{
1.144 + opus_int k;
1.145 + opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
1.146 + opus_int32 *Anew_QA;
1.147 +
1.148 + Anew_QA = Atmp_QA[ order & 1 ];
1.149 +
1.150 + /* Increase Q domain of the AR coefficients */
1.151 + for( k = 0; k < order; k++ ) {
1.152 + Anew_QA[ k ] = silk_RSHIFT32( A_Q24[ k ], 24 - QA );
1.153 + }
1.154 +
1.155 + return LPC_inverse_pred_gain_QA( Atmp_QA, order );
1.156 +}
1.157 +#endif
