1 /* @(#)s_rint.c 5.1 93/09/24 */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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
10 * ====================================================
12 * $FreeBSD: src/lib/msun/src/s_rint.c,v 1.7 1999/08/28 00:06:54 peter Exp $
13 * $DragonFly: src/lib/msun/src/Attic/s_rint.c,v 1.2 2003/06/17 04:26:53 dillon Exp $
18 * Return x rounded to integral value according to the prevailing
21 * Using floating addition.
23 * Inexact flag raised if x not equal to rint(x).
27 #include "math_private.h"
30 * TWO23 is long double instead of double to avoid a bug in gcc. Without
31 * this, gcc thinks that TWO23[sx]+x and w-TWO23[sx] already have double
32 * precision and doesn't clip them to double precision when they are
33 * assigned and returned. Use long double even in the !__STDC__ case in
34 * case this is compiled with gcc -traditional.
37 static const long double
42 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
43 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
47 double __generic_rint(double x)
49 double __generic_rint(x)
56 EXTRACT_WORDS(i0,i1,x);
58 j0 = ((i0>>20)&0x7ff)-0x3ff;
61 if(((i0&0x7fffffff)|i1)==0) return x;
64 i0 |= ((i1|-i1)>>12)&0x80000;
69 SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
73 if(((i0&i)|i1)==0) return x; /* x is integral */
76 if(j0==19) i1 = 0x40000000; else
77 i0 = (i0&(~i))|((0x20000)>>j0);
81 if(j0==0x400) return x+x; /* inf or NaN */
82 else return x; /* x is integral */
84 i = ((u_int32_t)(0xffffffff))>>(j0-20);
85 if((i1&i)==0) return x; /* x is integral */
87 if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20));
89 INSERT_WORDS(x,i0,i1);