1/* @(#)s_floor.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
13#include <sys/cdefs.h>
14__FBSDID("$FreeBSD: head/lib/msun/src/s_trunc.c 176305 2008-02-15 07:01:40Z bde $");
15
16/*
17 * trunc(x)
18 * Return x rounded toward 0 to integral value
19 * Method:
20 * Bit twiddling.
21 * Exception:
22 * Inexact flag raised if x not equal to trunc(x).
23 */
24
25#include <float.h>
26
27#include "math.h"
28#include "math_private.h"
29
30static const double huge = 1.0e300;
31
32double
33trunc(double x)
34{
35 int32_t i0,i1,j0;
36 u_int32_t i,j;
37 EXTRACT_WORDS(i0,i1,x);
38 j0 = ((i0>>20)&0x7ff)-0x3ff;
39 if(j0<20) {
40 if(j0<0) { /* raise inexact if x != 0 */
41 if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */
42 i0 &= 0x80000000U;
43 i1 = 0;
44 }
45 } else {
46 i = (0x000fffff)>>j0;
47 if(((i0&i)|i1)==0) return x; /* x is integral */
48 if(huge+x>0.0) { /* raise inexact flag */
49 i0 &= (~i); i1=0;
50 }
51 }
52 } else if (j0>51) {
53 if(j0==0x400) return x+x; /* inf or NaN */
54 else return x; /* x is integral */
55 } else {
56 i = ((u_int32_t)(0xffffffff))>>(j0-20);
57 if((i1&i)==0) return x; /* x is integral */
58 if(huge+x>0.0) /* raise inexact flag */
59 i1 &= (~i);
60 }
61 INSERT_WORDS(x,i0,i1);
62 return x;
63}
64
65#if LDBL_MANT_DIG == 53
66__weak_reference(trunc, truncl);
67#endif