Imported GNU Classpath 0.90
[official-gcc.git] / libjava / classpath / native / fdlibm / s_rint.c
blobfcd3916e824cfb46459c0fe40b477be370f69ce7
2 /* @(#)s_rint.c 1.3 95/01/18 */
3 /*
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 * Developed at SunSoft, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
10 * is preserved.
11 * ====================================================
15 * rint(x)
16 * Return x rounded to integral value according to the prevailing
17 * rounding mode.
18 * Method:
19 * Using floating addition.
20 * Exception:
21 * Inexact flag raised if x not equal to rint(x).
24 #include "fdlibm.h"
26 #ifndef _DOUBLE_IS_32BITS
28 #ifdef __STDC__
29 static const double
30 #else
31 static double
32 #endif
33 TWO52[2]={
34 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
35 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
38 #ifdef __STDC__
39 double rint(double x)
40 #else
41 double rint(x)
42 double x;
43 #endif
45 int32_t i0,j0,sx;
46 uint32_t i,i1;
47 double t;
48 volatile double w;
49 EXTRACT_WORDS(i0,i1,x);
50 sx = (i0>>31)&1;
51 j0 = ((i0>>20)&0x7ff)-0x3ff;
52 if(j0<20) {
53 if(j0<0) {
54 if(((i0&0x7fffffff)|i1)==0) return x;
55 i1 |= (i0&0x0fffff);
56 i0 &= 0xfffe0000;
57 i0 |= ((i1|-i1)>>12)&0x80000;
58 SET_HIGH_WORD(x,i0);
59 w = TWO52[sx]+x;
60 t = w-TWO52[sx];
61 GET_HIGH_WORD(i0,t);
62 SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
63 return t;
64 } else {
65 i = (0x000fffff)>>j0;
66 if(((i0&i)|i1)==0) return x; /* x is integral */
67 i>>=1;
68 if(((i0&i)|i1)!=0) {
69 if(j0==19) i1 = 0x40000000; else
70 i0 = (i0&(~i))|((0x20000)>>j0);
73 } else if (j0>51) {
74 if(j0==0x400) return x+x; /* inf or NaN */
75 else return x; /* x is integral */
76 } else {
77 i = ((uint32_t)(0xffffffff))>>(j0-20);
78 if((i1&i)==0) return x; /* x is integral */
79 i>>=1;
80 if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20));
82 INSERT_WORDS(x,i0,i1);
83 w = TWO52[sx]+x;
84 return w-TWO52[sx];
86 #endif /* _DOUBLE_IS_32BITS */