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
24
25 static const long double one = 1.0L;
26
27 long double
modfl(long double x,long double * iptr)28 modfl(long double x, long double *iptr)
29 {
30 int32_t i0,i1,jj0;
31 u_int32_t i,se;
32 GET_LDOUBLE_WORDS(se,i0,i1,x);
33 jj0 = (se&0x7fff)-0x3fff; /* exponent of x */
34 if(jj0<32) { /* integer part in high x */
35 if(jj0<0) { /* |x|<1 */
36 SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0); /* *iptr = +-0 */
37 return x;
38 } else {
39 i = (0x7fffffff)>>jj0;
40 if(((i0&i)|i1)==0) { /* x is integral */
41 *iptr = x;
42 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
43 return x;
44 } else {
45 SET_LDOUBLE_WORDS(*iptr,se,i0&(~i),0);
46 return x - *iptr;
47 }
48 }
49 } else if (jj0>63) { /* no fraction part */
50 *iptr = x*one;
51 /* We must handle NaNs separately. */
52 if (jj0 == 0x4000 && ((i0 & 0x7fffffff) | i1))
53 return x*one;
54 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
55 return x;
56 } else { /* fraction part in low x */
57 i = ((u_int32_t)(0x7fffffff))>>(jj0-32);
58 if((i1&i)==0) { /* x is integral */
59 *iptr = x;
60 SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
61 return x;
62 } else {
63 SET_LDOUBLE_WORDS(*iptr,se,i0,i1&(~i));
64 return x - *iptr;
65 }
66 }
67 }
68
