1 | /* s_ilogbf.c -- float version of s_ilogb.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 | #if defined(LIBM_SCCS) && !defined(lint) |
17 | static char rcsid[] = "$NetBSD: s_ilogbf.c,v 1.4 1995/05/10 20:47:31 jtc Exp $" ; |
18 | #endif |
19 | |
20 | #include <limits.h> |
21 | #include <math.h> |
22 | #include <math_private.h> |
23 | |
24 | int __ieee754_ilogbf(float x) |
25 | { |
26 | int32_t hx,ix; |
27 | |
28 | GET_FLOAT_WORD(hx,x); |
29 | hx &= 0x7fffffff; |
30 | if(hx<0x00800000) { |
31 | if(hx==0) |
32 | return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */ |
33 | else /* subnormal x */ |
34 | for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1; |
35 | return ix; |
36 | } |
37 | else if (hx<0x7f800000) return (hx>>23)-127; |
38 | else if (FP_ILOGBNAN != INT_MAX) { |
39 | /* ISO C99 requires ilogbf(+-Inf) == INT_MAX. */ |
40 | if (hx==0x7f800000) |
41 | return INT_MAX; |
42 | } |
43 | return FP_ILOGBNAN; |
44 | } |
45 | |