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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/ieee754/ldbl-96/e_ilogbl.c
1 /* s_ilogbl.c -- long double version of s_ilogb.c.
2 * Conversion to long double by Ulrich Drepper,
3 * Cygnus Support, drepper@cygnus.com.
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
14 * ====================================================
17 #if defined(LIBM_SCCS) && !defined(lint)
18 static char rcsid
[] = "$NetBSD: $";
21 /* ilogbl(long double x)
22 * return the binary exponent of non-zero x
23 * ilogbl(0) = FP_ILOGB0
24 * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
25 * ilogbl(+-Inf) = INT_MAX (no signal is raised)
30 #include <math_private.h>
32 int __ieee754_ilogbl (long double x
)
36 GET_LDOUBLE_EXP(es
,x
);
39 GET_LDOUBLE_WORDS(es
,hx
,lx
,x
);
41 return FP_ILOGB0
; /* ilogbl(0) = FP_ILOGB0 */
42 else /* subnormal x */
44 for (ix
= -16415; lx
>0; lx
<<=1) ix
-=1;
46 for (ix
= -16383; hx
>0; hx
<<=1) ix
-=1;
50 else if (es
<0x7fff) return es
-0x3fff;
51 else if (FP_ILOGBNAN
!= INT_MAX
)
53 GET_LDOUBLE_WORDS(es
,hx
,lx
,x
);
54 if (((hx
& 0x7fffffff)|lx
) == 0)
55 /* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */