xref: /freebsd/lib/msun/src/s_floorf.c (revision 55141f2c8991b2a6adbf30bb0fe3e6cbc303f06d)
1 /* s_floorf.c -- float version of s_floor.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 /*
18  * floorf(x)
19  * Return x rounded toward -inf to integral value
20  * Method:
21  *	Bit twiddling.
22  * Exception:
23  *	Inexact flag raised if x not equal to floorf(x).
24  */
25 
26 #include "math.h"
27 #include "math_private.h"
28 
29 static const float huge = 1.0e30;
30 
31 float
32 floorf(float x)
33 {
34 	int32_t i0,j0;
35 	u_int32_t i;
36 	GET_FLOAT_WORD(i0,x);
37 	j0 = ((i0>>23)&0xff)-0x7f;
38 	if(j0<23) {
39 	    if(j0<0) { 	/* raise inexact if x != 0 */
40 		if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
41 		    if(i0>=0) {i0=0;}
42 		    else if((i0&0x7fffffff)!=0)
43 			{ i0=0xbf800000;}
44 		}
45 	    } else {
46 		i = (0x007fffff)>>j0;
47 		if((i0&i)==0) return x; /* x is integral */
48 		if(huge+x>(float)0.0) {	/* raise inexact flag */
49 		    if(i0<0) i0 += (0x00800000)>>j0;
50 		    i0 &= (~i);
51 		}
52 	    }
53 	} else {
54 	    if(j0==0x80) return x+x;	/* inf or NaN */
55 	    else return x;		/* x is integral */
56 	}
57 	SET_FLOAT_WORD(x,i0);
58 	return x;
59 }
60