1*49393c00Smartynas /* @(#)s_modf.c 5.1 93/09/24 */
2*49393c00Smartynas /*
3*49393c00Smartynas * ====================================================
4*49393c00Smartynas * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5*49393c00Smartynas *
6*49393c00Smartynas * Developed at SunPro, a Sun Microsystems, Inc. business.
7*49393c00Smartynas * Permission to use, copy, modify, and distribute this
8*49393c00Smartynas * software is freely granted, provided that this notice
9*49393c00Smartynas * is preserved.
10*49393c00Smartynas * ====================================================
11*49393c00Smartynas */
12*49393c00Smartynas
13*49393c00Smartynas /*
14*49393c00Smartynas * modfl(long double x, long double *iptr)
15*49393c00Smartynas * return fraction part of x, and return x's integral part in *iptr.
16*49393c00Smartynas * Method:
17*49393c00Smartynas * Bit twiddling.
18*49393c00Smartynas *
19*49393c00Smartynas * Exception:
20*49393c00Smartynas * No exception.
21*49393c00Smartynas */
22*49393c00Smartynas
23*49393c00Smartynas #include <math.h>
24*49393c00Smartynas
25*49393c00Smartynas #include "math_private.h"
26*49393c00Smartynas
27*49393c00Smartynas static const long double one = 1.0;
28*49393c00Smartynas
29*49393c00Smartynas long double
modfl(long double x,long double * iptr)30*49393c00Smartynas modfl(long double x, long double *iptr)
31*49393c00Smartynas {
32*49393c00Smartynas int64_t i0,i1,jj0;
33*49393c00Smartynas u_int64_t i;
34*49393c00Smartynas GET_LDOUBLE_WORDS64(i0,i1,x);
35*49393c00Smartynas jj0 = ((i0>>48)&0x7fff)-0x3fff; /* exponent of x */
36*49393c00Smartynas if(jj0<48) { /* integer part in high x */
37*49393c00Smartynas if(jj0<0) { /* |x|<1 */
38*49393c00Smartynas /* *iptr = +-0 */
39*49393c00Smartynas SET_LDOUBLE_WORDS64(*iptr,i0&0x8000000000000000ULL,0);
40*49393c00Smartynas return x;
41*49393c00Smartynas } else {
42*49393c00Smartynas i = (0x0000ffffffffffffLL)>>jj0;
43*49393c00Smartynas if(((i0&i)|i1)==0) { /* x is integral */
44*49393c00Smartynas *iptr = x;
45*49393c00Smartynas /* return +-0 */
46*49393c00Smartynas SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
47*49393c00Smartynas return x;
48*49393c00Smartynas } else {
49*49393c00Smartynas SET_LDOUBLE_WORDS64(*iptr,i0&(~i),0);
50*49393c00Smartynas return x - *iptr;
51*49393c00Smartynas }
52*49393c00Smartynas }
53*49393c00Smartynas } else if (jj0>111) { /* no fraction part */
54*49393c00Smartynas *iptr = x*one;
55*49393c00Smartynas /* We must handle NaNs separately. */
56*49393c00Smartynas if (jj0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1))
57*49393c00Smartynas return x*one;
58*49393c00Smartynas /* return +-0 */
59*49393c00Smartynas SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
60*49393c00Smartynas return x;
61*49393c00Smartynas } else { /* fraction part in low x */
62*49393c00Smartynas i = -1ULL>>(jj0-48);
63*49393c00Smartynas if((i1&i)==0) { /* x is integral */
64*49393c00Smartynas *iptr = x;
65*49393c00Smartynas /* return +-0 */
66*49393c00Smartynas SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
67*49393c00Smartynas return x;
68*49393c00Smartynas } else {
69*49393c00Smartynas SET_LDOUBLE_WORDS64(*iptr,i0,i1&(~i));
70*49393c00Smartynas return x - *iptr;
71*49393c00Smartynas }
72*49393c00Smartynas }
73*49393c00Smartynas }
74