xref: /freebsd/lib/msun/src/s_rintf.c (revision 40a8ac8f62b535d30349faf28cf47106b7041b83)
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 <sys/cdefs.h>
17 __FBSDID("$FreeBSD$");
18 
19 #include <float.h>
20 #include <stdint.h>
21 
22 #include "math.h"
23 #include "math_private.h"
24 
25 static const float
26 TWO23[2]={
27   8.3886080000e+06, /* 0x4b000000 */
28  -8.3886080000e+06, /* 0xcb000000 */
29 };
30 
31 float
32 rintf(float x)
33 {
34 	int32_t i0,j0,sx;
35 	float w,t;
36 	GET_FLOAT_WORD(i0,x);
37 	sx = (i0>>31)&1;
38 	j0 = ((i0>>23)&0xff)-0x7f;
39 	if(j0<23) {
40 	    if(j0<0) {
41 		if((i0&0x7fffffff)==0) return x;
42 		STRICT_ASSIGN(float,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 	    }
48 	    STRICT_ASSIGN(float,w,TWO23[sx]+x);
49 	    return w-TWO23[sx];
50 	}
51 	if(j0==0x80) return x+x;	/* inf or NaN */
52 	else return x;			/* x is integral */
53 }
54