1/* @(#)s_logb.c 5.1 93/09/24 */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13#ifndef lint
| 1/* @(#)s_logb.c 5.1 93/09/24 */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13#ifndef lint
|
14static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_logb.c 117912 2003-07-23 04:53:47Z peter $";
| 14static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_logb.c 153049 2005-12-03 11:57:19Z bde $";
|
15#endif
16
17/*
18 * double logb(x)
19 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
20 * Use ilogb instead.
21 */
22
23#include "math.h"
24#include "math_private.h"
25
| 15#endif
16
17/*
18 * double logb(x)
19 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
20 * Use ilogb instead.
21 */
22
23#include "math.h"
24#include "math_private.h"
25
|
| 26static const double
27two54 = 1.80143985094819840000e+16; /* 43500000 00000000 */
28
|
26double
27logb(double x)
28{
29 int32_t lx,ix;
30 EXTRACT_WORDS(ix,lx,x);
31 ix &= 0x7fffffff; /* high |x| */
32 if((ix|lx)==0) return -1.0/fabs(x);
33 if(ix>=0x7ff00000) return x*x;
| 29double
30logb(double x)
31{
32 int32_t lx,ix;
33 EXTRACT_WORDS(ix,lx,x);
34 ix &= 0x7fffffff; /* high |x| */
35 if((ix|lx)==0) return -1.0/fabs(x);
36 if(ix>=0x7ff00000) return x*x;
|
34 if((ix>>=20)==0) /* IEEE 754 logb */
35 return -1022.0;
36 else
37 return (double) (ix-1023);
| 37 if(ix<0x00100000) {
38 x *= two54; /* convert subnormal x to normal */
39 GET_FLOAT_WORD(ix,x);
40 ix &= 0x7fffffff;
41 return (float) ((ix>>20)-1023-54);
42 } else
43 return (double) ((ix>>20)-1023);
|
38}
| 44}
|