xref: /freebsd/lib/msun/src/s_truncf.c (revision 5e3190f700637fcfc1a52daeaa4a031fdd2557c7)
1 /* @(#)s_floor.c 5.1 93/09/24 */
2 /*
3  * ====================================================
4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5  *
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
9  * is preserved.
10  * ====================================================
11  */
12 
13 #include <sys/cdefs.h>
14 /*
15  * truncf(x)
16  * Return x rounded toward 0 to integral value
17  * Method:
18  *	Bit twiddling.
19  * Exception:
20  *	Inexact flag raised if x not equal to truncf(x).
21  */
22 
23 #include "math.h"
24 #include "math_private.h"
25 
26 static const float huge = 1.0e30F;
27 
28 float
29 truncf(float x)
30 {
31 	int32_t i0,j0;
32 	u_int32_t i;
33 	GET_FLOAT_WORD(i0,x);
34 	j0 = ((i0>>23)&0xff)-0x7f;
35 	if(j0<23) {
36 	    if(j0<0) { 	/* raise inexact if x != 0 */
37 		if(huge+x>0.0F)		/* |x|<1, so return 0*sign(x) */
38 		    i0 &= 0x80000000;
39 	    } else {
40 		i = (0x007fffff)>>j0;
41 		if((i0&i)==0) return x; /* x is integral */
42 		if(huge+x>0.0F)		/* raise inexact flag */
43 		    i0 &= (~i);
44 	    }
45 	} else {
46 	    if(j0==0x80) return x+x;	/* inf or NaN */
47 	    else return x;		/* x is integral */
48 	}
49 	SET_FLOAT_WORD(x,i0);
50 	return x;
51 }
52