xref: /freebsd/lib/msun/src/s_modff.c (revision 2008043f386721d58158e37e0d7e50df8095942d)
1 /* s_modff.c -- float version of s_modf.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 #include "math.h"
18 #include "math_private.h"
19 
20 static const float one = 1.0;
21 
22 float
23 modff(float x, float *iptr)
24 {
25 	int32_t i0,j0;
26 	u_int32_t i;
27 	GET_FLOAT_WORD(i0,x);
28 	j0 = ((i0>>23)&0xff)-0x7f;	/* exponent of x */
29 	if(j0<23) {			/* integer part in x */
30 	    if(j0<0) {			/* |x|<1 */
31 	        SET_FLOAT_WORD(*iptr,i0&0x80000000);	/* *iptr = +-0 */
32 		return x;
33 	    } else {
34 		i = (0x007fffff)>>j0;
35 		if((i0&i)==0) {			/* x is integral */
36 		    u_int32_t ix;
37 		    *iptr = x;
38 		    GET_FLOAT_WORD(ix,x);
39 		    SET_FLOAT_WORD(x,ix&0x80000000);	/* return +-0 */
40 		    return x;
41 		} else {
42 		    SET_FLOAT_WORD(*iptr,i0&(~i));
43 		    return x - *iptr;
44 		}
45 	    }
46 	} else {			/* no fraction part */
47 	    u_int32_t ix;
48 	    *iptr = x*one;
49 	    if (x != x)			/* NaN */
50 		return x;
51 	    GET_FLOAT_WORD(ix,x);
52 	    SET_FLOAT_WORD(x,ix&0x80000000);	/* return +-0 */
53 	    return x;
54 	}
55 }
56