/src/opus/silk/LPC_inv_pred_gain.c

Source
/***********************************************************************
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, 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 Internet Society, IETF or IETF Trust, nor the
names of specific contributors, may be used to endorse or promote
products derived from this software without specific prior written
permission.
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.
***********************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "SigProc_FIX.h"
#include "define.h"

#define QA                          24
#define A_LIMIT                     SILK_FIX_CONST( 0.99975, QA )

#define MUL32_FRAC_Q(a32, b32, Q)   ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))

/* Compute inverse of LPC prediction gain, and                          */
/* test if LPC coefficients are stable (all poles within unit circle)   */
static opus_int32 LPC_inverse_pred_gain_QA_c(               /* O   Returns inverse prediction gain in energy domain, Q30    */
    opus_int32           A_QA[ SILK_MAX_ORDER_LPC ],        /* I   Prediction coefficients                                  */
    const opus_int       order                              /* I   Prediction order                                         */
)
{
    opus_int   k, n, mult2Q;
    opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp1, tmp2;

    invGain_Q30 = SILK_FIX_CONST( 1, 30 );
    for( k = order - 1; k > 0; k-- ) {
        /* Check for stability */
        if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
            return 0;
        }

        /* Set RC equal to negated AR coef */
        rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA );

        /* rc_mult1_Q30 range: [ 1 : 2^30 ] */
        rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );
        silk_assert( rc_mult1_Q30 > ( 1 << 15 ) );                   /* reduce A_LIMIT if fails */
        silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );

        /* Update inverse gain */
        /* invGain_Q30 range: [ 0 : 2^30 ] */
        invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
        silk_assert( invGain_Q30 >= 0           );
        silk_assert( invGain_Q30 <= ( 1 << 30 ) );
        if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
            return 0;
        }

        /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
        mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
        rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );

        /* Update AR coefficient */
        for( n = 0; n < (k + 1) >> 1; n++ ) {
            opus_int64 tmp64;
            tmp1 = A_QA[ n ];
            tmp2 = A_QA[ k - n - 1 ];
            tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1,
                  MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q);
            if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
               return 0;
            }
            A_QA[ n ] = ( opus_int32 )tmp64;
            tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2,
                  MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q);
            if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
               return 0;
            }
            A_QA[ k - n - 1 ] = ( opus_int32 )tmp64;
        }
    }

    /* Check for stability */
    if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
        return 0;
    }

    /* Set RC equal to negated AR coef */
    rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA );

    /* Range: [ 1 : 2^30 ] */
    rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );

    /* Update inverse gain */
    /* Range: [ 0 : 2^30 ] */
    invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
    silk_assert( invGain_Q30 >= 0           );
    silk_assert( invGain_Q30 <= ( 1 << 30 ) );
    if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
        return 0;
    }

    return invGain_Q30;
}

/* For input in Q12 domain */
opus_int32 silk_LPC_inverse_pred_gain_c(            /* O   Returns inverse prediction gain in energy domain, Q30        */
    const opus_int16            *A_Q12,             /* I   Prediction coefficients, Q12 [order]                         */
    const opus_int              order               /* I   Prediction order                                             */
)
{
    opus_int   k;
    opus_int32 Atmp_QA[ SILK_MAX_ORDER_LPC ];
    opus_int32 DC_resp = 0;

    /* Increase Q domain of the AR coefficients */
    for( k = 0; k < order; k++ ) {
        DC_resp += (opus_int32)A_Q12[ k ];
        Atmp_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
    }
    /* If the DC is unstable, we don't even need to do the full calculations */
    if( DC_resp >= 4096 ) {
        return 0;
    }
    return LPC_inverse_pred_gain_QA_c( Atmp_QA, order );
}

Line	Count	Source
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	12.1M	#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	521k	{
47	521k	opus_int k, n, mult2Q;
48	521k	opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp1, tmp2;
49
50	521k	invGain_Q30 = SILK_FIX_CONST( 1, 30 );
51	6.06M	for( k = order - 1; k > 0; k-- ) {
52		/* Check for stability */
53	5.59M	if( ( A_QA[ k ] > A_LIMIT ) \|\| ( A_QA[ k ] < -A_LIMIT ) ) {
54	45.3k	return 0;
55	45.3k	}
56
57		/* Set RC equal to negated AR coef */
58	5.54M	rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA );
59
60		/* rc_mult1_Q30 range: [ 1 : 2^30 ] */
61	5.54M	rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );
62	5.54M	silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
63	5.54M	silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
64
65		/* Update inverse gain */
66		/* invGain_Q30 range: [ 0 : 2^30 ] */
67	5.54M	invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
68	5.54M	silk_assert( invGain_Q30 >= 0 );
69	5.54M	silk_assert( invGain_Q30 <= ( 1 << 30 ) );
70	5.54M	if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
71	2.33k	return 0;
72	2.33k	}
73
74		/* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
75	5.54M	mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
76	5.54M	rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
77
78		/* Update AR coefficient */
79	24.5M	for( n = 0; n < (k + 1) >> 1; n++ ) {
80	19.0M	opus_int64 tmp64;
81	19.0M	tmp1 = A_QA[ n ];
82	19.0M	tmp2 = A_QA[ k - n - 1 ];
83	19.0M	tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1,
84	19.0M	MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q);
85	19.0M	if( tmp64 > silk_int32_MAX \|\| tmp64 < silk_int32_MIN ) {
86	1.02k	return 0;
87	1.02k	}
88	19.0M	A_QA[ n ] = ( opus_int32 )tmp64;
89	19.0M	tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2,
90	19.0M	MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q);
91	19.0M	if( tmp64 > silk_int32_MAX \|\| tmp64 < silk_int32_MIN ) {
92	0	return 0;
93	0	}
94	19.0M	A_QA[ k - n - 1 ] = ( opus_int32 )tmp64;
95	19.0M	}
96	5.54M	}
97
98		/* Check for stability */
99	473k	if( ( A_QA[ k ] > A_LIMIT ) \|\| ( A_QA[ k ] < -A_LIMIT ) ) {
100	9.46k	return 0;
101	9.46k	}
102
103		/* Set RC equal to negated AR coef */
104	463k	rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA );
105
106		/* Range: [ 1 : 2^30 ] */
107	463k	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	463k	invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
112	463k	silk_assert( invGain_Q30 >= 0 );
113	463k	silk_assert( invGain_Q30 <= ( 1 << 30 ) );
114	463k	if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
115	54.3k	return 0;
116	54.3k	}
117
118	409k	return invGain_Q30;
119	463k	}
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	534k	{
127	534k	opus_int k;
128	534k	opus_int32 Atmp_QA[ SILK_MAX_ORDER_LPC ];
129	534k	opus_int32 DC_resp = 0;
130
131		/* Increase Q domain of the AR coefficients */
132	6.84M	for( k = 0; k < order; k++ ) {
133	6.31M	DC_resp += (opus_int32)A_Q12[ k ];
134	6.31M	Atmp_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
135	6.31M	}
136		/* If the DC is unstable, we don't even need to do the full calculations */
137	534k	if( DC_resp >= 4096 ) {
138	13.2k	return 0;
139	13.2k	}
140	521k	return LPC_inverse_pred_gain_QA_c( Atmp_QA, order );
141	534k	}

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Created: 2025-11-16 07:20