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 /*
14  * truncf(x)
15  * Return x rounded toward 0 to integral value
16  * Method:
17  *	Bit twiddling.
18  * Exception:
19  *	Inexact flag raised if x not equal to truncf(x).
20  */
21 
22 #include "math.h"
23 #include "math_private.h"
24 
25 static const float huge = 1.0e30F;
26 
27 float
28 truncf(float x)
29 {
30 	int32_t i0,jj0;
31 	u_int32_t i;
32 	GET_FLOAT_WORD(i0,x);
33 	jj0 = ((i0>>23)&0xff)-0x7f;
34 	if(jj0<23) {
35 	    if(jj0<0) { 	/* raise inexact if x != 0 */
36 		if(huge+x>0.0F)		/* |x|<1, so return 0*sign(x) */
37 		    i0 &= 0x80000000;
38 	    } else {
39 		i = (0x007fffff)>>jj0;
40 		if((i0&i)==0) return x; /* x is integral */
41 		if(huge+x>0.0F)		/* raise inexact flag */
42 		    i0 &= (~i);
43 	    }
44 	} else {
45 	    if(jj0==0x80) return x+x;	/* inf or NaN */
46 	    else return x;		/* x is integral */
47 	}
48 	SET_FLOAT_WORD(x,i0);
49 	return x;
50 }
51