1 /* s_logbl.c -- long double version of s_logb.c.
2 */
3
4 /*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 */
14
15 /*
16 * long double logbl(x)
17 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
18 * Use ilogb instead.
19 */
20
21 #include <math.h>
22 #include <math_private.h>
23
24 long double
__logbl(long double x)25 __logbl (long double x)
26 {
27 int32_t es, lx, ix;
28
29 GET_LDOUBLE_WORDS (es, ix, lx, x);
30 es &= 0x7fff; /* exponent */
31 if ((es | ix | lx) == 0)
32 return -1.0 / fabsl (x);
33 if (es == 0x7fff)
34 return x * x;
35 if (es == 0) /* IEEE 754 logb */
36 {
37 /* POSIX specifies that denormal number is treated as
38 though it were normalized. */
39 if (ix == 0)
40 es = -(__builtin_clz (lx) + 32);
41 else
42 es = -__builtin_clz (ix);
43 }
44 return (long double) (es - 16383);
45 }
46
47 weak_alias (__logbl, logbl)
48