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 #include "math.h"
17 #include "math_private.h"
18 
19 static const float
20 TWO23[2]={
21   8.3886080000e+06, /* 0x4b000000 */
22  -8.3886080000e+06, /* 0xcb000000 */
23 };
24 
25 float
26 rintf(float x)
27 {
28 	int32_t i0,jj0,sx;
29 	u_int32_t i,i1;
30 	float t;
31 	volatile float w;	/* clip extra precision */
32 	GET_FLOAT_WORD(i0,x);
33 	sx = (i0>>31)&1;
34 	jj0 = ((i0>>23)&0xff)-0x7f;
35 	if(jj0<23) {
36 	    if(jj0<0) {
37 		if((i0&0x7fffffff)==0) return x;
38 		i1 = (i0&0x07fffff);
39 		i0 &= 0xfff00000;
40 		i0 |= ((i1|-i1)>>9)&0x400000;
41 		SET_FLOAT_WORD(x,i0);
42 	        w = TWO23[sx]+x;
43 	        t =  w-TWO23[sx];
44 		GET_FLOAT_WORD(i0,t);
45 		SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
46 	        return t;
47 	    } else {
48 		i = (0x007fffff)>>jj0;
49 		if((i0&i)==0) return x; /* x is integral */
50 		i>>=1;
51 		if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>jj0);
52 	    }
53 	} else {
54 	    if(jj0==0x80) return x+x;	/* inf or NaN */
55 	    else return x;		/* x is integral */
56 	}
57 	SET_FLOAT_WORD(x,i0);
58 	w = TWO23[sx]+x;
59 	return w-TWO23[sx];
60 }
61