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 /*
17  * floorf(x)
18  * Return x rounded toward -inf to integral value
19  * Method:
20  *	Bit twiddling.
21  * Exception:
22  *	Inexact flag raised if x not equal to floorf(x).
23  */
24 
25 #include "math.h"
26 #include "math_private.h"
27 
28 static const float huge = 1.0e30;
29 
30 float
31 floorf(float x)
32 {
33 	int32_t i0,jj0;
34 	u_int32_t i;
35 	GET_FLOAT_WORD(i0,x);
36 	jj0 = ((i0>>23)&0xff)-0x7f;
37 	if(jj0<23) {
38 	    if(jj0<0) { 	/* raise inexact if x != 0 */
39 		if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
40 		    if(i0>=0) {i0=0;}
41 		    else if((i0&0x7fffffff)!=0)
42 			{ i0=0xbf800000;}
43 		}
44 	    } else {
45 		i = (0x007fffff)>>jj0;
46 		if((i0&i)==0) return x; /* x is integral */
47 		if(huge+x>(float)0.0) {	/* raise inexact flag */
48 		    if(i0<0) i0 += (0x00800000)>>jj0;
49 		    i0 &= (~i);
50 		}
51 	    }
52 	} else {
53 	    if(jj0==0x80) return x+x;	/* inf or NaN */
54 	    else return x;		/* x is integral */
55 	}
56 	SET_FLOAT_WORD(x,i0);
57 	return x;
58 }
59