1 /* s_modfl.c -- long double version of s_modf.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
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 #if defined(LIBM_SCCS) && !defined(lint)
17 static char rcsid[] = "$NetBSD: $";
18 #endif
19
20 /*
21 * modfq(long double x, long double *iptr)
22 * return fraction part of x, and return x's integral part in *iptr.
23 * Method:
24 * Bit twiddling.
25 *
26 * Exception:
27 * No exception.
28 */
29
30 #include "quadmath-imp.h"
31
32 static const __float128 one = 1.0;
33
modfq(__float128 x,__float128 * iptr)34 __float128 modfq(__float128 x, __float128 *iptr)
35 {
36 int64_t i0,i1,j0;
37 uint64_t i;
38 GET_FLT128_WORDS64(i0,i1,x);
39 j0 = ((i0>>48)&0x7fff)-0x3fff; /* exponent of x */
40 if(j0<48) { /* integer part in high x */
41 if(j0<0) { /* |x|<1 */
42 /* *iptr = +-0 */
43 SET_FLT128_WORDS64(*iptr,i0&0x8000000000000000ULL,0);
44 return x;
45 } else {
46 i = (0x0000ffffffffffffLL)>>j0;
47 if(((i0&i)|i1)==0) { /* x is integral */
48 *iptr = x;
49 /* return +-0 */
50 SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
51 return x;
52 } else {
53 SET_FLT128_WORDS64(*iptr,i0&(~i),0);
54 return x - *iptr;
55 }
56 }
57 } else if (j0>111) { /* no fraction part */
58 *iptr = x*one;
59 /* We must handle NaNs separately. */
60 if (j0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1))
61 return x*one;
62 /* return +-0 */
63 SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
64 return x;
65 } else { /* fraction part in low x */
66 i = -1ULL>>(j0-48);
67 if((i1&i)==0) { /* x is integral */
68 *iptr = x;
69 /* return +-0 */
70 SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
71 return x;
72 } else {
73 SET_FLT128_WORDS64(*iptr,i0,i1&(~i));
74 return x - *iptr;
75 }
76 }
77 }
78