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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 0 : 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 0 : invGain_Q30 = SILK_FIX_CONST( 1, 30 );
51 0 : for( k = order - 1; k > 0; k-- ) {
52 : /* Check for stability */
53 0 : if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
54 0 : return 0;
55 : }
56 :
57 : /* Set RC equal to negated AR coef */
58 0 : rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA );
59 :
60 : /* rc_mult1_Q30 range: [ 1 : 2^30 ] */
61 0 : rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );
62 0 : silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
63 0 : silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
64 :
65 : /* Update inverse gain */
66 : /* invGain_Q30 range: [ 0 : 2^30 ] */
67 0 : invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
68 0 : silk_assert( invGain_Q30 >= 0 );
69 0 : silk_assert( invGain_Q30 <= ( 1 << 30 ) );
70 0 : if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
71 0 : return 0;
72 : }
73 :
74 : /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
75 0 : mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
76 0 : rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
77 :
78 : /* Update AR coefficient */
79 0 : for( n = 0; n < (k + 1) >> 1; n++ ) {
80 : opus_int64 tmp64;
81 0 : tmp1 = A_QA[ n ];
82 0 : tmp2 = A_QA[ k - n - 1 ];
83 0 : tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1,
84 : MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q);
85 0 : if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
86 0 : return 0;
87 : }
88 0 : A_QA[ n ] = ( opus_int32 )tmp64;
89 0 : tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2,
90 : MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q);
91 0 : if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
92 0 : return 0;
93 : }
94 0 : A_QA[ k - n - 1 ] = ( opus_int32 )tmp64;
95 : }
96 : }
97 :
98 : /* Check for stability */
99 0 : if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
100 0 : return 0;
101 : }
102 :
103 : /* Set RC equal to negated AR coef */
104 0 : rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA );
105 :
106 : /* Range: [ 1 : 2^30 ] */
107 0 : 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 0 : invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
112 0 : silk_assert( invGain_Q30 >= 0 );
113 0 : silk_assert( invGain_Q30 <= ( 1 << 30 ) );
114 0 : if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
115 0 : return 0;
116 : }
117 :
118 0 : return invGain_Q30;
119 : }
120 :
121 : /* For input in Q12 domain */
122 0 : 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 0 : opus_int32 DC_resp = 0;
130 :
131 : /* Increase Q domain of the AR coefficients */
132 0 : for( k = 0; k < order; k++ ) {
133 0 : DC_resp += (opus_int32)A_Q12[ k ];
134 0 : 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 0 : if( DC_resp >= 4096 ) {
138 0 : return 0;
139 : }
140 0 : return LPC_inverse_pred_gain_QA_c( Atmp_QA, order );
141 : }
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