1/* s_logbf.c -- float version of s_logb.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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#include <math.h>
17#include <math_private.h>
18#include <libm-alias-float.h>
19#include <fix-int-fp-convert-zero.h>
20
21float
22__logbf (float x)
23{
24 int32_t ix, rix;
25
26 GET_FLOAT_WORD (ix, x);
27 ix &= 0x7fffffff; /* high |x| */
28 if (ix == 0)
29 return (float) -1.0 / fabsf (x);
30 if (ix >= 0x7f800000)
31 return x * x;
32 if (__glibc_unlikely ((rix = ix >> 23) == 0))
33 {
34 /* POSIX specifies that denormal number is treated as
35 though it were normalized. */
36 rix -= __builtin_clz (ix) - 9;
37 }
38 if (FIX_INT_FP_CONVERT_ZERO && rix == 127)
39 return 0.0f;
40 return (float) (rix - 127);
41}
42libm_alias_float (__logb, logb)
43