s_rintf.c revision 22993 
158551Skris/* s_rintf.c -- float version of s_rint.c.
258551Skris * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
358551Skris */
458551Skris
558551Skris/*
658551Skris * ====================================================
758551Skris * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
858551Skris *
958551Skris * Developed at SunPro, a Sun Microsystems, Inc. business.
1058551Skris * Permission to use, copy, modify, and distribute this
1158551Skris * software is freely granted, provided that this notice
1258551Skris * is preserved.
1358551Skris * ====================================================
1458551Skris */
1558551Skris
1658551Skris#ifndef lint
1758551Skrisstatic char rcsid[] = "$Id$";
1858551Skris#endif
1958551Skris
2058551Skris#include "math.h"
2158551Skris#include "math_private.h"
2258551Skris
2358551Skris/*
2458551Skris * TWO23 is double instead of float to avoid a bug in gcc.  Without
2558551Skris * this, gcc thinks that TWO23[sx]+x and w-TWO23[sx] already have float
2658551Skris * precision and doesn't clip them to float precision when they are
2758551Skris * assigned and returned.
2858551Skris */
2958551Skris#ifdef __STDC__
3058551Skrisstatic const double
3158551Skris#else
3258551Skrisstatic double
3358551Skris#endif
3458551SkrisTWO23[2]={
3558551Skris  8.3886080000e+06, /* 0x4b000000 */
3658551Skris -8.3886080000e+06, /* 0xcb000000 */
3758551Skris};
3858551Skris
3958551Skris#ifdef __STDC__
4058551Skris	float rintf(float x)
4158551Skris#else
4258551Skris	float rintf(x)
43	float x;
44#endif
45{
46	int32_t i0,j0,sx;
47	u_int32_t i,i1;
48	float w,t;
49	GET_FLOAT_WORD(i0,x);
50	sx = (i0>>31)&1;
51	j0 = ((i0>>23)&0xff)-0x7f;
52	if(j0<23) {
53	    if(j0<0) {
54		if((i0&0x7fffffff)==0) return x;
55		i1 = (i0&0x07fffff);
56		i0 &= 0xfff00000;
57		i0 |= ((i1|-i1)>>9)&0x400000;
58		SET_FLOAT_WORD(x,i0);
59	        w = TWO23[sx]+x;
60	        t =  w-TWO23[sx];
61		GET_FLOAT_WORD(i0,t);
62		SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
63	        return t;
64	    } else {
65		i = (0x007fffff)>>j0;
66		if((i0&i)==0) return x; /* x is integral */
67		i>>=1;
68		if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
69	    }
70	} else {
71	    if(j0==0x80) return x+x;	/* inf or NaN */
72	    else return x;		/* x is integral */
73	}
74	SET_FLOAT_WORD(x,i0);
75	w = TWO23[sx]+x;
76	return w-TWO23[sx];
77}
78