xref: /freebsd/lib/msun/src/s_modff.c (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
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 "math.h"
17 #include "math_private.h"
18 
19 static const float one = 1.0;
20 
21 float
22 modff(float x, float *iptr)
23 {
24 	int32_t i0,j0;
25 	u_int32_t i;
26 	GET_FLOAT_WORD(i0,x);
27 	j0 = ((i0>>23)&0xff)-0x7f;	/* exponent of x */
28 	if(j0<23) {			/* integer part in x */
29 	    if(j0<0) {			/* |x|<1 */
30 	        SET_FLOAT_WORD(*iptr,i0&0x80000000);	/* *iptr = +-0 */
31 		return x;
32 	    } else {
33 		i = (0x007fffff)>>j0;
34 		if((i0&i)==0) {			/* x is integral */
35 		    u_int32_t ix;
36 		    *iptr = x;
37 		    GET_FLOAT_WORD(ix,x);
38 		    SET_FLOAT_WORD(x,ix&0x80000000);	/* return +-0 */
39 		    return x;
40 		} else {
41 		    SET_FLOAT_WORD(*iptr,i0&(~i));
42 		    return x - *iptr;
43 		}
44 	    }
45 	} else {			/* no fraction part */
46 	    u_int32_t ix;
47 	    *iptr = x*one;
48 	    if (x != x)			/* NaN */
49 		return x;
50 	    GET_FLOAT_WORD(ix,x);
51 	    SET_FLOAT_WORD(x,ix&0x80000000);	/* return +-0 */
52 	    return x;
53 	}
54 }
55