1/* s_logbf.c -- float 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#include <math.h>
16#include <math_private.h>
17#include <libm-alias-float.h>
18#include <fix-int-fp-convert-zero.h>
19
20float
21__logbf (float x)
22{
23 int32_t ix, rix;
24
25 GET_FLOAT_WORD (ix, x);
26 ix &= 0x7fffffff; /* high |x| */
27 if (ix == 0)
28 return (float) -1.0 / fabsf (x);
29 if (ix >= 0x7f800000)
30 return x * x;
31 if (__glibc_unlikely ((rix = ix >> 23) == 0))
32 {
33 /* POSIX specifies that denormal number is treated as
34 though it were normalized. */
35 rix -= __builtin_clz (ix) - 9;
36 }
37 if (FIX_INT_FP_CONVERT_ZERO && rix == 127)
38 return 0.0f;
39 return (float) (rix - 127);
40}
41libm_alias_float (__logb, logb)
42