1 |
|
|
/* @(#)s_floor.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 |
|
|
/* |
14 |
|
|
* trunc(x) |
15 |
|
|
* Return x rounded toward 0 to integral value |
16 |
|
|
* Method: |
17 |
|
|
* Bit twiddling. |
18 |
|
|
* Exception: |
19 |
|
|
* Inexact flag raised if x not equal to trunc(x). |
20 |
|
|
*/ |
21 |
|
|
|
22 |
|
|
#include <float.h> |
23 |
|
|
#include <math.h> |
24 |
|
|
|
25 |
|
|
#include "math_private.h" |
26 |
|
|
|
27 |
|
|
static const double huge = 1.0e300; |
28 |
|
|
|
29 |
|
|
double |
30 |
|
|
trunc(double x) |
31 |
|
|
{ |
32 |
|
|
int32_t i0,i1,jj0; |
33 |
|
|
u_int32_t i; |
34 |
|
|
EXTRACT_WORDS(i0,i1,x); |
35 |
|
|
jj0 = ((i0>>20)&0x7ff)-0x3ff; |
36 |
|
|
if(jj0<20) { |
37 |
|
|
if(jj0<0) { /* raise inexact if x != 0 */ |
38 |
|
|
if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */ |
39 |
|
|
i0 &= 0x80000000U; |
40 |
|
|
i1 = 0; |
41 |
|
|
} |
42 |
|
|
} else { |
43 |
|
|
i = (0x000fffff)>>jj0; |
44 |
|
|
if(((i0&i)|i1)==0) return x; /* x is integral */ |
45 |
|
|
if(huge+x>0.0) { /* raise inexact flag */ |
46 |
|
|
i0 &= (~i); i1=0; |
47 |
|
|
} |
48 |
|
|
} |
49 |
|
|
} else if (jj0>51) { |
50 |
|
|
if(jj0==0x400) return x+x; /* inf or NaN */ |
51 |
|
|
else return x; /* x is integral */ |
52 |
|
|
} else { |
53 |
|
|
i = ((u_int32_t)(0xffffffff))>>(jj0-20); |
54 |
|
|
if((i1&i)==0) return x; /* x is integral */ |
55 |
|
|
if(huge+x>0.0) /* raise inexact flag */ |
56 |
|
|
i1 &= (~i); |
57 |
|
|
} |
58 |
|
|
INSERT_WORDS(x,i0,i1); |
59 |
|
|
return x; |
60 |
|
|
} |
61 |
|
|
DEF_STD(trunc); |
62 |
|
|
LDBL_MAYBE_UNUSED_CLONE(trunc); |