1/*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
10 */
11
12/*
13 * trunc(x)
14 * Return x rounded toward 0 to integral value
15 * Method:
16 *	Bit twiddling.
17 * Exception:
18 *	Inexact flag raised if x not equal to trunc(x).
19 */
20
21#include <float.h>
22
23#include "math.h"
24#include "math_private.h"
25
26static const double huge = 1.0e300;
27
28double
29trunc(double x)
30{
31	int32_t i0,i1,j0;
32	u_int32_t i;
33	EXTRACT_WORDS(i0,i1,x);
34	j0 = ((i0>>20)&0x7ff)-0x3ff;
35	if(j0<20) {
36	    if(j0<0) { 	/* raise inexact if x != 0 */
37		if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */
38		    i0 &= 0x80000000U;
39		    i1 = 0;
40		}
41	    } else {
42		i = (0x000fffff)>>j0;
43		if(((i0&i)|i1)==0) return x; /* x is integral */
44		if(huge+x>0.0) {	/* raise inexact flag */
45		    i0 &= (~i); i1=0;
46		}
47	    }
48	} else if (j0>51) {
49	    if(j0==0x400) return x+x;	/* inf or NaN */
50	    else return x;		/* x is integral */
51	} else {
52	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
53	    if((i1&i)==0) return x;	/* x is integral */
54	    if(huge+x>0.0)		/* raise inexact flag */
55		i1 &= (~i);
56	}
57	INSERT_WORDS(x,i0,i1);
58	return x;
59}
60
61#if LDBL_MANT_DIG == 53
62__weak_reference(trunc, truncl);
63#endif
64