s_rintf.c revision 2117 
1/* s_rintf.c -- float version of s_rint.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef lint
17static char rcsid[] = "$Id: s_rintf.c,v 1.2 1994/08/18 23:07:17 jtc Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24static const float
25#else
26static float
27#endif
28TWO23[2]={
29  8.3886080000e+06, /* 0x4b000000 */
30 -8.3886080000e+06, /* 0xcb000000 */
31};
32
33#ifdef __STDC__
34	float rintf(float x)
35#else
36	float rintf(x)
37	float x;
38#endif
39{
40	int32_t i0,j0,sx;
41	u_int32_t i,i1;
42	float w,t;
43	GET_FLOAT_WORD(i0,x);
44	sx = (i0>>31)&1;
45	j0 = ((i0>>23)&0xff)-0x7f;
46	if(j0<23) {
47	    if(j0<0) {
48		if((i0&0x7fffffff)==0) return x;
49		i1 = (i0&0x07fffff);
50		i0 &= 0xfff00000;
51		i0 |= ((i1|-i1)>>9)&0x400000;
52		SET_FLOAT_WORD(x,i0);
53	        w = TWO23[sx]+x;
54	        t =  w-TWO23[sx];
55		GET_FLOAT_WORD(i0,t);
56		SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
57	        return t;
58	    } else {
59		i = (0x007fffff)>>j0;
60		if((i0&i)==0) return x; /* x is integral */
61		i>>=1;
62		if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
63	    }
64	} else {
65	    if(j0==0x80) return x+x;	/* inf or NaN */
66	    else return x;		/* x is integral */
67	}
68	SET_FLOAT_WORD(x,i0);
69	w = TWO23[sx]+x;
70	return w-TWO23[sx];
71}
72