1/* s_logbl.c -- long double version of s_logb.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16/*
17 * long double logbl(x)
18 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
19 * Use ilogb instead.
20 */
21
22#include "quadmath-imp.h"
23
24__float128
25logbq (__float128 x)
26{
27 int64_t lx, hx, ex;
28
29 GET_FLT128_WORDS64 (hx, lx, x);
30 hx &= 0x7fffffffffffffffLL; /* high |x| */
31 if ((hx | lx) == 0)
32 return -1.0 / fabsq (x);
33 if (hx >= 0x7fff000000000000LL)
34 return x * x;
35 if ((ex = hx >> 48) == 0) /* IEEE 754 logb */
36 {
37 /* POSIX specifies that denormal number is treated as
38 though it were normalized. */
39 int ma;
40 if (hx == 0)
41 ma = __builtin_clzll (lx) + 64;
42 else
43 ma = __builtin_clzll (hx);
44 ex -= ma - 16;
45 }
46 return (__float128) (ex - 16383);
47}
48