1#include "SDL_internal.h"
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 * modf(double x, 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_libm.h"
24#include "math_private.h"
25
26static const double one = 1.0;
27
28double modf(double x, double *iptr)
29{
30 int32_t i0,i1,_j0;
31 u_int32_t i;
32 EXTRACT_WORDS(i0,i1,x);
33 _j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */
34 if(_j0<20) { /* integer part in high x */
35 if(_j0<0) { /* |x|<1 */
36 INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */
37 return x;
38 } else {
39 i = (0x000fffff)>>_j0;
40 if(((i0&i)|i1)==0) { /* x is integral */
41 *iptr = x;
42 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
43 return x;
44 } else {
45 INSERT_WORDS(*iptr,i0&(~i),0);
46 return x - *iptr;
47 }
48 }
49 } else if (_j0>51) { /* no fraction part */
50 *iptr = x*one;
51 /* We must handle NaNs separately. */
52 if (_j0 == 0x400 && ((i0 & 0xfffff) | i1))
53 return x*one;
54 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
55 return x;
56 } else { /* fraction part in low x */
57 i = ((u_int32_t)(0xffffffff))>>(_j0-20);
58 if((i1&i)==0) { /* x is integral */
59 *iptr = x;
60 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
61 return x;
62 } else {
63 INSERT_WORDS(*iptr,i0,i1&(~i));
64 return x - *iptr;
65 }
66 }
67}
68libm_hidden_def(modf)
69