/src/opus/silk/A2NLSF.c

Source (jump to first uncovered line)
/***********************************************************************
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.
***********************************************************************/

/* Conversion between prediction filter coefficients and NLSFs  */
/* Requires the order to be an even number                      */
/* A piecewise linear approximation maps LSF <-> cos(LSF)       */
/* Therefore the result is not accurate NLSFs, but the two      */
/* functions are accurate inverses of each other                */

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

#include "SigProc_FIX.h"
#include "tables.h"

/* Number of binary divisions, when not in low complexity mode */
#define BIN_DIV_STEPS_A2NLSF_FIX      3 /* must be no higher than 16 - log2( LSF_COS_TAB_SZ_FIX ) */
#define MAX_ITERATIONS_A2NLSF_FIX    16

/* Helper function for A2NLSF(..)                    */
/* Transforms polynomials from cos(n*f) to cos(f)^n  */
static OPUS_INLINE void silk_A2NLSF_trans_poly(
    opus_int32          *p,                     /* I/O    Polynomial                                */
    const opus_int      dd                      /* I      Polynomial order (= filter order / 2 )    */
)
{
    opus_int k, n;

    for( k = 2; k <= dd; k++ ) {
        for( n = dd; n > k; n-- ) {
            p[ n - 2 ] -= p[ n ];
        }
        p[ k - 2 ] -= silk_LSHIFT( p[ k ], 1 );
    }
}
/* Helper function for A2NLSF(..) */
/* Polynomial evaluation          */
static OPUS_INLINE opus_int32 silk_A2NLSF_eval_poly( /* return the polynomial evaluation, in Q16     */
    opus_int32          *p,                     /* I    Polynomial, Q16                         */
    const opus_int32    x,                      /* I    Evaluation point, Q12                   */
    const opus_int      dd                      /* I    Order                                   */
)
{
    opus_int   n;
    opus_int32 x_Q16, y32;

    y32 = p[ dd ];                                  /* Q16 */
    x_Q16 = silk_LSHIFT( x, 4 );

    if ( opus_likely( 8 == dd ) )
    {
        y32 = silk_SMLAWW( p[ 7 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 6 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 5 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 4 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 3 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 2 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 1 ], y32, x_Q16 );
        y32 = silk_SMLAWW( p[ 0 ], y32, x_Q16 );
    }
    else
    {
        for( n = dd - 1; n >= 0; n-- ) {
            y32 = silk_SMLAWW( p[ n ], y32, x_Q16 );    /* Q16 */
        }
    }
    return y32;
}

static OPUS_INLINE void silk_A2NLSF_init(
     const opus_int32    *a_Q16,
     opus_int32          *P,
     opus_int32          *Q,
     const opus_int      dd
)
{
    opus_int k;

    /* Convert filter coefs to even and odd polynomials */
    P[dd] = silk_LSHIFT( 1, 16 );
    Q[dd] = silk_LSHIFT( 1, 16 );
    for( k = 0; k < dd; k++ ) {
        P[ k ] = -a_Q16[ dd - k - 1 ] - a_Q16[ dd + k ];    /* Q16 */
        Q[ k ] = -a_Q16[ dd - k - 1 ] + a_Q16[ dd + k ];    /* Q16 */
    }

    /* Divide out zeros as we have that for even filter orders, */
    /* z =  1 is always a root in Q, and                        */
    /* z = -1 is always a root in P                             */
    for( k = dd; k > 0; k-- ) {
        P[ k - 1 ] -= P[ k ];
        Q[ k - 1 ] += Q[ k ];
    }

    /* Transform polynomials from cos(n*f) to cos(f)^n */
    silk_A2NLSF_trans_poly( P, dd );
    silk_A2NLSF_trans_poly( Q, dd );
}

/* Compute Normalized Line Spectral Frequencies (NLSFs) from whitening filter coefficients      */
/* If not all roots are found, the a_Q16 coefficients are bandwidth expanded until convergence. */
void silk_A2NLSF(
    opus_int16                  *NLSF,              /* O    Normalized Line Spectral Frequencies in Q15 (0..2^15-1) [d] */
    opus_int32                  *a_Q16,             /* I/O  Monic whitening filter coefficients in Q16 [d]              */
    const opus_int              d                   /* I    Filter order (must be even)                                 */
)
{
    opus_int   i, k, m, dd, root_ix, ffrac;
    opus_int32 xlo, xhi, xmid;
    opus_int32 ylo, yhi, ymid, thr;
    opus_int32 nom, den;
    opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ];
    opus_int32 Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
    opus_int32 *PQ[ 2 ];
    opus_int32 *p;

    /* Store pointers to array */
    PQ[ 0 ] = P;
    PQ[ 1 ] = Q;

    dd = silk_RSHIFT( d, 1 );

    silk_A2NLSF_init( a_Q16, P, Q, dd );

    /* Find roots, alternating between P and Q */
    p = P;                          /* Pointer to polynomial */

    xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
    ylo = silk_A2NLSF_eval_poly( p, xlo, dd );

    if( ylo < 0 ) {
        /* Set the first NLSF to zero and move on to the next */
        NLSF[ 0 ] = 0;
        p = Q;                      /* Pointer to polynomial */
        ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
        root_ix = 1;                /* Index of current root */
    } else {
        root_ix = 0;                /* Index of current root */
    }
    k = 1;                          /* Loop counter */
    i = 0;                          /* Counter for bandwidth expansions applied */
    thr = 0;
    while( 1 ) {
        /* Evaluate polynomial */
        xhi = silk_LSFCosTab_FIX_Q12[ k ]; /* Q12 */
        yhi = silk_A2NLSF_eval_poly( p, xhi, dd );

        /* Detect zero crossing */
        if( ( ylo <= 0 && yhi >= thr ) || ( ylo >= 0 && yhi <= -thr ) ) {
            if( yhi == 0 ) {
                /* If the root lies exactly at the end of the current       */
                /* interval, look for the next root in the next interval    */
                thr = 1;
            } else {
                thr = 0;
            }
            /* Binary division */
            ffrac = -256;
            for( m = 0; m < BIN_DIV_STEPS_A2NLSF_FIX; m++ ) {
                /* Evaluate polynomial */
                xmid = silk_RSHIFT_ROUND( xlo + xhi, 1 );
                ymid = silk_A2NLSF_eval_poly( p, xmid, dd );

                /* Detect zero crossing */
                if( ( ylo <= 0 && ymid >= 0 ) || ( ylo >= 0 && ymid <= 0 ) ) {
                    /* Reduce frequency */
                    xhi = xmid;
                    yhi = ymid;
                } else {
                    /* Increase frequency */
                    xlo = xmid;
                    ylo = ymid;
                    ffrac = silk_ADD_RSHIFT( ffrac, 128, m );
                }
            }

            /* Interpolate */
            if( silk_abs( ylo ) < 65536 ) {
                /* Avoid dividing by zero */
                den = ylo - yhi;
                nom = silk_LSHIFT( ylo, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) + silk_RSHIFT( den, 1 );
                if( den != 0 ) {
                    ffrac += silk_DIV32( nom, den );
                }
            } else {
                /* No risk of dividing by zero because abs(ylo - yhi) >= abs(ylo) >= 65536 */
                ffrac += silk_DIV32( ylo, silk_RSHIFT( ylo - yhi, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) );
            }
            NLSF[ root_ix ] = (opus_int16)silk_min_32( silk_LSHIFT( (opus_int32)k, 8 ) + ffrac, silk_int16_MAX );

            silk_assert( NLSF[ root_ix ] >= 0 );

            root_ix++;        /* Next root */
            if( root_ix >= d ) {
                /* Found all roots */
                break;
            }
            /* Alternate pointer to polynomial */
            p = PQ[ root_ix & 1 ];

            /* Evaluate polynomial */
            xlo = silk_LSFCosTab_FIX_Q12[ k - 1 ]; /* Q12*/
            ylo = silk_LSHIFT( 1 - ( root_ix & 2 ), 12 );
        } else {
            /* Increment loop counter */
            k++;
            xlo = xhi;
            ylo = yhi;
            thr = 0;

            if( k > LSF_COS_TAB_SZ_FIX ) {
                i++;
                if( i > MAX_ITERATIONS_A2NLSF_FIX ) {
                    /* Set NLSFs to white spectrum and exit */
                    NLSF[ 0 ] = (opus_int16)silk_DIV32_16( 1 << 15, d + 1 );
                    for( k = 1; k < d; k++ ) {
                        NLSF[ k ] = (opus_int16)silk_ADD16( NLSF[ k-1 ], NLSF[ 0 ] );
                    }
                    return;
                }

                /* Error: Apply progressively more bandwidth expansion and run again */
                silk_bwexpander_32( a_Q16, d, 65536 - silk_LSHIFT( 1, i ) );

                silk_A2NLSF_init( a_Q16, P, Q, dd );
                p = P;                            /* Pointer to polynomial */
                xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
                ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
                if( ylo < 0 ) {
                    /* Set the first NLSF to zero and move on to the next */
                    NLSF[ 0 ] = 0;
                    p = Q;                        /* Pointer to polynomial */
                    ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
                    root_ix = 1;                  /* Index of current root */
                } else {
                    root_ix = 0;                  /* Index of current root */
                }
                k = 1;                            /* Reset loop counter */
            }
        }
    }
}

Coverage Report

Created: 2024-09-06 07:53

Line	Count	Source (jump to first uncovered line)
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		/* Conversion between prediction filter coefficients and NLSFs */
29		/* Requires the order to be an even number */
30		/* A piecewise linear approximation maps LSF <-> cos(LSF) */
31		/* Therefore the result is not accurate NLSFs, but the two */
32		/* functions are accurate inverses of each other */
33
34		#ifdef HAVE_CONFIG_H
35		#include "config.h"
36		#endif
37
38		#include "SigProc_FIX.h"
39		#include "tables.h"
40
41		/* Number of binary divisions, when not in low complexity mode */
42	0	#define BIN_DIV_STEPS_A2NLSF_FIX 3 /* must be no higher than 16 - log2( LSF_COS_TAB_SZ_FIX ) */
43	0	#define MAX_ITERATIONS_A2NLSF_FIX 16
44
45		/* Helper function for A2NLSF(..) */
46		/* Transforms polynomials from cos(nf) to cos(f)^n /
47		static OPUS_INLINE void silk_A2NLSF_trans_poly(
48		opus_int32 p, / I/O Polynomial */
49		const opus_int dd /* I Polynomial order (= filter order / 2 ) */
50		)
51	0	{
52	0	opus_int k, n;
53
54	0	for( k = 2; k <= dd; k++ ) {
55	0	for( n = dd; n > k; n-- ) {
56	0	p[ n - 2 ] -= p[ n ];
57	0	}
58	0	p[ k - 2 ] -= silk_LSHIFT( p[ k ], 1 );
59	0	}
60	0	}
61		/* Helper function for A2NLSF(..) */
62		/* Polynomial evaluation */
63		static OPUS_INLINE opus_int32 silk_A2NLSF_eval_poly( /* return the polynomial evaluation, in Q16 */
64		opus_int32 p, / I Polynomial, Q16 */
65		const opus_int32 x, /* I Evaluation point, Q12 */
66		const opus_int dd /* I Order */
67		)
68	0	{
69	0	opus_int n;
70	0	opus_int32 x_Q16, y32;
71
72	0	y32 = p[ dd ]; /* Q16 */
73	0	x_Q16 = silk_LSHIFT( x, 4 );
74
75	0	if ( opus_likely( 8 == dd ) )
76	0	{
77	0	y32 = silk_SMLAWW( p[ 7 ], y32, x_Q16 );
78	0	y32 = silk_SMLAWW( p[ 6 ], y32, x_Q16 );
79	0	y32 = silk_SMLAWW( p[ 5 ], y32, x_Q16 );
80	0	y32 = silk_SMLAWW( p[ 4 ], y32, x_Q16 );
81	0	y32 = silk_SMLAWW( p[ 3 ], y32, x_Q16 );
82	0	y32 = silk_SMLAWW( p[ 2 ], y32, x_Q16 );
83	0	y32 = silk_SMLAWW( p[ 1 ], y32, x_Q16 );
84	0	y32 = silk_SMLAWW( p[ 0 ], y32, x_Q16 );
85	0	}
86	0	else
87	0	{
88	0	for( n = dd - 1; n >= 0; n-- ) {
89	0	y32 = silk_SMLAWW( p[ n ], y32, x_Q16 ); /* Q16 */
90	0	}
91	0	}
92	0	return y32;
93	0	}
94
95		static OPUS_INLINE void silk_A2NLSF_init(
96		const opus_int32 *a_Q16,
97		opus_int32 *P,
98		opus_int32 *Q,
99		const opus_int dd
100		)
101	0	{
102	0	opus_int k;
103
104		/* Convert filter coefs to even and odd polynomials */
105	0	P[dd] = silk_LSHIFT( 1, 16 );
106	0	Q[dd] = silk_LSHIFT( 1, 16 );
107	0	for( k = 0; k < dd; k++ ) {
108	0	P[ k ] = -a_Q16[ dd - k - 1 ] - a_Q16[ dd + k ]; /* Q16 */
109	0	Q[ k ] = -a_Q16[ dd - k - 1 ] + a_Q16[ dd + k ]; /* Q16 */
110	0	}
111
112		/* Divide out zeros as we have that for even filter orders, */
113		/* z = 1 is always a root in Q, and */
114		/* z = -1 is always a root in P */
115	0	for( k = dd; k > 0; k-- ) {
116	0	P[ k - 1 ] -= P[ k ];
117	0	Q[ k - 1 ] += Q[ k ];
118	0	}
119
120		/* Transform polynomials from cos(nf) to cos(f)^n /
121	0	silk_A2NLSF_trans_poly( P, dd );
122	0	silk_A2NLSF_trans_poly( Q, dd );
123	0	}
124
125		/* Compute Normalized Line Spectral Frequencies (NLSFs) from whitening filter coefficients */
126		/* If not all roots are found, the a_Q16 coefficients are bandwidth expanded until convergence. */
127		void silk_A2NLSF(
128		opus_int16 NLSF, / O Normalized Line Spectral Frequencies in Q15 (0..2^15-1) [d] */
129		opus_int32 a_Q16, / I/O Monic whitening filter coefficients in Q16 [d] */
130		const opus_int d /* I Filter order (must be even) */
131		)
132	0	{
133	0	opus_int i, k, m, dd, root_ix, ffrac;
134	0	opus_int32 xlo, xhi, xmid;
135	0	opus_int32 ylo, yhi, ymid, thr;
136	0	opus_int32 nom, den;
137	0	opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ];
138	0	opus_int32 Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
139	0	opus_int32 *PQ[ 2 ];
140	0	opus_int32 *p;
141
142		/* Store pointers to array */
143	0	PQ[ 0 ] = P;
144	0	PQ[ 1 ] = Q;
145
146	0	dd = silk_RSHIFT( d, 1 );
147
148	0	silk_A2NLSF_init( a_Q16, P, Q, dd );
149
150		/* Find roots, alternating between P and Q */
151	0	p = P; /* Pointer to polynomial */
152
153	0	xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
154	0	ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
155
156	0	if( ylo < 0 ) {
157		/* Set the first NLSF to zero and move on to the next */
158	0	NLSF[ 0 ] = 0;
159	0	p = Q; /* Pointer to polynomial */
160	0	ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
161	0	root_ix = 1; /* Index of current root */
162	0	} else {
163	0	root_ix = 0; /* Index of current root */
164	0	}
165	0	k = 1; /* Loop counter */
166	0	i = 0; /* Counter for bandwidth expansions applied */
167	0	thr = 0;
168	0	while( 1 ) {
169		/* Evaluate polynomial */
170	0	xhi = silk_LSFCosTab_FIX_Q12[ k ]; /* Q12 */
171	0	yhi = silk_A2NLSF_eval_poly( p, xhi, dd );
172
173		/* Detect zero crossing */
174	0	if( ( ylo <= 0 && yhi >= thr ) \|\| ( ylo >= 0 && yhi <= -thr ) ) {
175	0	if( yhi == 0 ) {
176		/* If the root lies exactly at the end of the current */
177		/* interval, look for the next root in the next interval */
178	0	thr = 1;
179	0	} else {
180	0	thr = 0;
181	0	}
182		/* Binary division */
183	0	ffrac = -256;
184	0	for( m = 0; m < BIN_DIV_STEPS_A2NLSF_FIX; m++ ) {
185		/* Evaluate polynomial */
186	0	xmid = silk_RSHIFT_ROUND( xlo + xhi, 1 );
187	0	ymid = silk_A2NLSF_eval_poly( p, xmid, dd );
188
189		/* Detect zero crossing */
190	0	if( ( ylo <= 0 && ymid >= 0 ) \|\| ( ylo >= 0 && ymid <= 0 ) ) {
191		/* Reduce frequency */
192	0	xhi = xmid;
193	0	yhi = ymid;
194	0	} else {
195		/* Increase frequency */
196	0	xlo = xmid;
197	0	ylo = ymid;
198	0	ffrac = silk_ADD_RSHIFT( ffrac, 128, m );
199	0	}
200	0	}
201
202		/* Interpolate */
203	0	if( silk_abs( ylo ) < 65536 ) {
204		/* Avoid dividing by zero */
205	0	den = ylo - yhi;
206	0	nom = silk_LSHIFT( ylo, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) + silk_RSHIFT( den, 1 );
207	0	if( den != 0 ) {
208	0	ffrac += silk_DIV32( nom, den );
209	0	}
210	0	} else {
211		/* No risk of dividing by zero because abs(ylo - yhi) >= abs(ylo) >= 65536 */
212	0	ffrac += silk_DIV32( ylo, silk_RSHIFT( ylo - yhi, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) );
213	0	}
214	0	NLSF[ root_ix ] = (opus_int16)silk_min_32( silk_LSHIFT( (opus_int32)k, 8 ) + ffrac, silk_int16_MAX );
215
216	0	silk_assert( NLSF[ root_ix ] >= 0 );
217
218	0	root_ix++; /* Next root */
219	0	if( root_ix >= d ) {
220		/* Found all roots */
221	0	break;
222	0	}
223		/* Alternate pointer to polynomial */
224	0	p = PQ[ root_ix & 1 ];
225
226		/* Evaluate polynomial */
227	0	xlo = silk_LSFCosTab_FIX_Q12[ k - 1 ]; /* Q12*/
228	0	ylo = silk_LSHIFT( 1 - ( root_ix & 2 ), 12 );
229	0	} else {
230		/* Increment loop counter */
231	0	k++;
232	0	xlo = xhi;
233	0	ylo = yhi;
234	0	thr = 0;
235
236	0	if( k > LSF_COS_TAB_SZ_FIX ) {
237	0	i++;
238	0	if( i > MAX_ITERATIONS_A2NLSF_FIX ) {
239		/* Set NLSFs to white spectrum and exit */
240	0	NLSF[ 0 ] = (opus_int16)silk_DIV32_16( 1 << 15, d + 1 );
241	0	for( k = 1; k < d; k++ ) {
242	0	NLSF[ k ] = (opus_int16)silk_ADD16( NLSF[ k-1 ], NLSF[ 0 ] );
243	0	}
244	0	return;
245	0	}
246
247		/* Error: Apply progressively more bandwidth expansion and run again */
248	0	silk_bwexpander_32( a_Q16, d, 65536 - silk_LSHIFT( 1, i ) );
249
250	0	silk_A2NLSF_init( a_Q16, P, Q, dd );
251	0	p = P; /* Pointer to polynomial */
252	0	xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
253	0	ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
254	0	if( ylo < 0 ) {
255		/* Set the first NLSF to zero and move on to the next */
256	0	NLSF[ 0 ] = 0;
257	0	p = Q; /* Pointer to polynomial */
258	0	ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
259	0	root_ix = 1; /* Index of current root */
260	0	} else {
261	0	root_ix = 0; /* Index of current root */
262	0	}
263	0	k = 1; /* Reset loop counter */
264	0	}
265	0	}
266	0	}
267	0	}