1 /* @(#)s_modf.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 * modfl(long double x, long double *iptr)
15 * return fraction part of x, and return x's integral part in *iptr.
16 * Method:
17 * Bit twiddling.
18 *
19 * Exception:
20 * No exception.
21 */
22
23 #include <math.h>
24
25 #include "math_private.h"
26
27 static const long double one = 1.0;
28
29 long double
modfl(long double x,long double * iptr)30 modfl(long double x, long double *iptr)
31 {
32 int32_t i0,i1,jj0;
33 u_int32_t i,se;
34 GET_LDOUBLE_WORDS(se,i0,i1,x);
35 jj0 = (se&0x7fff)-0x3fff; /* exponent of x */
36 if(jj0<32) { /* integer part in high x */
37 if(jj0<0) { /* |x|<1 */
38 SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0); /* *iptr = +-0 */
39 return x;
40 } else {
41 i = (0x7fffffff)>>jj0;
42 if(((i0&i)|i1)==0) { /* x is integral */
43 *iptr = x;
44 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
45 return x;
46 } else {
47 SET_LDOUBLE_WORDS(*iptr,se,i0&(~i),0);
48 return x - *iptr;
49 }
50 }
51 } else if (jj0>63) { /* no fraction part */
52 *iptr = x*one;
53 /* We must handle NaNs separately. */
54 if (jj0 == 0x4000 && ((i0 & 0x7fffffff) | i1))
55 return x*one;
56 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
57 return x;
58 } else { /* fraction part in low x */
59 i = ((u_int32_t)(0x7fffffff))>>(jj0-32);
60 if((i1&i)==0) { /* x is integral */
61 *iptr = x;
62 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
63 return x;
64 } else {
65 SET_LDOUBLE_WORDS(*iptr,se,i0,i1&(~i));
66 return x - *iptr;
67 }
68 }
69 }
70