1 /* sf_logb.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 "fdlibm.h"
17 
18 #ifdef __STDC__
logbf(float x)19 	float logbf(float x)
20 #else
21 	float logbf(x)
22 	float x;
23 #endif
24 {
25 	__int32_t ix;
26 	GET_FLOAT_WORD(ix,x);
27 	ix &= 0x7fffffff;			/* high |x| */
28 	if(FLT_UWORD_IS_ZERO(ix)) return (float)-1.0/fabsf(x);
29 	if(!FLT_UWORD_IS_FINITE(ix)) return x*x;
30 	if((ix>>=23)==0) 			/* IEEE 754 logb */
31 		return -126.0;
32 	else
33 		return (float) (ix-127);
34 }
35 
36 #ifdef _DOUBLE_IS_32BITS
37 
38 #ifdef __STDC__
logb(double x)39 	double logb(double x)
40 #else
41 	double logb(x)
42 	double x;
43 #endif
44 {
45 	return (double) logbf((float) x);
46 }
47 
48 #endif /* defined(_DOUBLE_IS_32BITS) */
49