1 /*********************************************************************** 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. 3 Redistribution and use in source and binary forms, with or without 4 modification, are permitted provided that the following conditions 5 are met: 6 - Redistributions of source code must retain the above copyright notice, 7 this list of conditions and the following disclaimer. 8 - Redistributions in binary form must reproduce the above copyright 9 notice, this list of conditions and the following disclaimer in the 10 documentation and/or other materials provided with the distribution. 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the 12 names of specific contributors, may be used to endorse or promote 13 products derived from this software without specific prior written 14 permission. 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25 POSSIBILITY OF SUCH DAMAGE. 26 ***********************************************************************/ 27 28 #ifdef HAVE_CONFIG_H 29 #include "config.h" 30 #endif 31 32 #include "SigProc_FIX.h" 33 #include "define.h" 34 35 #define QA 24 36 #define A_LIMIT SILK_FIX_CONST( 0.99975, QA ) 37 38 #define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q))) 39 40 /* Compute inverse of LPC prediction gain, and */ 41 /* test if LPC coefficients are stable (all poles within unit circle) */ 42 static opus_int32 LPC_inverse_pred_gain_QA_c( /* O Returns inverse prediction gain in energy domain, Q30 */ 43 opus_int32 A_QA[ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */ 44 const opus_int order /* I Prediction order */ 45 ) 46 { 47 opus_int k, n, mult2Q; 48 opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp1, tmp2; 49 50 invGain_Q30 = SILK_FIX_CONST( 1, 30 ); 51 for( k = order - 1; k > 0; k-- ) { 52 /* Check for stability */ 53 if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) { 54 return 0; 55 } 56 57 /* Set RC equal to negated AR coef */ 58 rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA ); 59 60 /* rc_mult1_Q30 range: [ 1 : 2^30 ] */ 61 rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) ); 62 silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */ 63 silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) ); 64 65 /* Update inverse gain */ 66 /* invGain_Q30 range: [ 0 : 2^30 ] */ 67 invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 ); 68 silk_assert( invGain_Q30 >= 0 ); 69 silk_assert( invGain_Q30 <= ( 1 << 30 ) ); 70 if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) { 71 return 0; 72 } 73 74 /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */ 75 mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) ); 76 rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 ); 77 78 /* Update AR coefficient */ 79 for( n = 0; n < (k + 1) >> 1; n++ ) { 80 opus_int64 tmp64; 81 tmp1 = A_QA[ n ]; 82 tmp2 = A_QA[ k - n - 1 ]; 83 tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1, 84 MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q); 85 if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) { 86 return 0; 87 } 88 A_QA[ n ] = ( opus_int32 )tmp64; 89 tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2, 90 MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q); 91 if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) { 92 return 0; 93 } 94 A_QA[ k - n - 1 ] = ( opus_int32 )tmp64; 95 } 96 } 97 98 /* Check for stability */ 99 if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) { 100 return 0; 101 } 102 103 /* Set RC equal to negated AR coef */ 104 rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA ); 105 106 /* Range: [ 1 : 2^30 ] */ 107 rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) ); 108 109 /* Update inverse gain */ 110 /* Range: [ 0 : 2^30 ] */ 111 invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 ); 112 silk_assert( invGain_Q30 >= 0 ); 113 silk_assert( invGain_Q30 <= ( 1 << 30 ) ); 114 if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) { 115 return 0; 116 } 117 118 return invGain_Q30; 119 } 120 121 /* For input in Q12 domain */ 122 opus_int32 silk_LPC_inverse_pred_gain_c( /* O Returns inverse prediction gain in energy domain, Q30 */ 123 const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */ 124 const opus_int order /* I Prediction order */ 125 ) 126 { 127 opus_int k; 128 opus_int32 Atmp_QA[ SILK_MAX_ORDER_LPC ]; 129 opus_int32 DC_resp = 0; 130 131 /* Increase Q domain of the AR coefficients */ 132 for( k = 0; k < order; k++ ) { 133 DC_resp += (opus_int32)A_Q12[ k ]; 134 Atmp_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 ); 135 } 136 /* If the DC is unstable, we don't even need to do the full calculations */ 137 if( DC_resp >= 4096 ) { 138 return 0; 139 } 140 return LPC_inverse_pred_gain_QA_c( Atmp_QA, order ); 141 } 142
