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 #include <LibConfig.h>
13 #include <sys/EfiCdefs.h>
14 #if defined(LIBM_SCCS) && !defined(lint)
15 __RCSID("$NetBSD: s_modf.c,v 1.11 2002/05/26 22:01:57 wiz Exp $");
16 #endif
17
18 /*
19 * modf(double x, double *iptr)
20 * return fraction part of x, and return x's integral part in *iptr.
21 * Method:
22 * Bit twiddling.
23 *
24 * Exception:
25 * No exception.
26 */
27
28 #include "math.h"
29 #include "math_private.h"
30
31 static const double one = 1.0;
32
33 double
modf(double x,double * iptr)34 modf(double x, double *iptr)
35 {
36 int32_t i0,i1,j0;
37 u_int32_t i;
38 EXTRACT_WORDS(i0,i1,x);
39 j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */
40 if(j0<20) { /* integer part in high x */
41 if(j0<0) { /* |x|<1 */
42 INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */
43 return x;
44 } else {
45 i = (0x000fffff)>>j0;
46 if(((i0&i)|i1)==0) { /* x is integral */
47 u_int32_t high;
48 *iptr = x;
49 GET_HIGH_WORD(high,x);
50 INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
51 return x;
52 } else {
53 INSERT_WORDS(*iptr,i0&(~i),0);
54 return x - *iptr;
55 }
56 }
57 } else if (j0>51) { /* no fraction part */
58 u_int32_t high;
59 *iptr = x*one;
60 GET_HIGH_WORD(high,x);
61 INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
62 return x;
63 } else { /* fraction part in low x */
64 i = ((u_int32_t)(0xffffffff))>>(j0-20);
65 if((i1&i)==0) { /* x is integral */
66 u_int32_t high;
67 *iptr = x;
68 GET_HIGH_WORD(high,x);
69 INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
70 return x;
71 } else {
72 INSERT_WORDS(*iptr,i0,i1&(~i));
73 return x - *iptr;
74 }
75 }
76 }
77