/src/opus/silk/LPC_inv_pred_gain.c
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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 |
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22 | | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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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 | 0 | #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 | 0 | { |
47 | 0 | opus_int k, n, mult2Q; |
48 | 0 | 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 | 0 | } |
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 | 0 | } |
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 | 0 | 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 | 0 | 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 | 0 | } |
88 | 0 | A_QA[ n ] = ( opus_int32 )tmp64; |
89 | 0 | tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2, |
90 | 0 | 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 | 0 | } |
94 | 0 | A_QA[ k - n - 1 ] = ( opus_int32 )tmp64; |
95 | 0 | } |
96 | 0 | } |
97 | | |
98 | | /* Check for stability */ |
99 | 0 | if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) { |
100 | 0 | return 0; |
101 | 0 | } |
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 | 0 | } |
117 | | |
118 | 0 | return invGain_Q30; |
119 | 0 | } |
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 | 0 | { |
127 | 0 | opus_int k; |
128 | 0 | 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 | 0 | } |
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 | 0 | } |
140 | 0 | return LPC_inverse_pred_gain_QA_c( Atmp_QA, order ); |
141 | 0 | } |