1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
/* sf_ilogb.c -- float version of s_ilogb.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include <limits.h>
#include "fdlibm.h"
int ilogbf(float x)
{
__int32_t hx,ix;
GET_FLOAT_WORD(hx,x);
hx &= 0x7fffffff;
if(FLT_UWORD_IS_ZERO(hx)) {
(void) __math_invalidf(0.0);
return FP_ILOGB0; /* ilogb(0) = special case error */
}
if(FLT_UWORD_IS_SUBNORMAL(hx)) {
for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
return ix;
}
#if FP_ILOGBNAN != INT_MAX
else if (FLT_UWORD_IS_NAN(hx)) {
(void) __math_invalidf(0.0);
return FP_ILOGBNAN; /* NAN */
}
#endif
else if (!FLT_UWORD_IS_FINITE(hx)) {
(void) __math_invalidf(0.0);
return INT_MAX;
}
else return (hx>>23)-127;
}
_MATH_ALIAS_i_f(ilogb)
|
