1147191Sjkoshy/* @(#)s_ceil.c 5.1 93/09/24 */
2147191Sjkoshy/*
3147191Sjkoshy * ====================================================
4147191Sjkoshy * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5147191Sjkoshy *
6147191Sjkoshy * Developed at SunPro, a Sun Microsystems, Inc. business.
7147191Sjkoshy * Permission to use, copy, modify, and distribute this
8147191Sjkoshy * software is freely granted, provided that this notice
9147191Sjkoshy * is preserved.
10147191Sjkoshy * ====================================================
11147191Sjkoshy */
12147191Sjkoshy
13147191Sjkoshy#include <sys/cdefs.h>
14147191Sjkoshy__FBSDID("$FreeBSD$");
15147191Sjkoshy
16147191Sjkoshy/*
17147191Sjkoshy * ceil(x)
18147191Sjkoshy * Return x rounded toward -inf to integral value
19147191Sjkoshy * Method:
20147191Sjkoshy *	Bit twiddling.
21147191Sjkoshy * Exception:
22147191Sjkoshy *	Inexact flag raised if x not equal to ceil(x).
23147191Sjkoshy */
24147191Sjkoshy
25147191Sjkoshy#include <float.h>
26147191Sjkoshy
27147191Sjkoshy#include "math.h"
28147191Sjkoshy#include "math_private.h"
29147191Sjkoshy
30147191Sjkoshystatic const double huge = 1.0e300;
31147191Sjkoshy
32147191Sjkoshydouble
33147191Sjkoshyceil(double x)
34147191Sjkoshy{
35147191Sjkoshy	int32_t i0,i1,j0;
36147191Sjkoshy	u_int32_t i,j;
37147191Sjkoshy	EXTRACT_WORDS(i0,i1,x);
38147191Sjkoshy	j0 = ((i0>>20)&0x7ff)-0x3ff;
39147191Sjkoshy	if(j0<20) {
40147191Sjkoshy	    if(j0<0) { 	/* raise inexact if x != 0 */
41147191Sjkoshy		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
42147191Sjkoshy		    if(i0<0) {i0=0x80000000;i1=0;}
43147191Sjkoshy		    else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;}
44147191Sjkoshy		}
45147191Sjkoshy	    } else {
46147191Sjkoshy		i = (0x000fffff)>>j0;
47184802Sjkoshy		if(((i0&i)|i1)==0) return x; /* x is integral */
48147191Sjkoshy		if(huge+x>0.0) {	/* raise inexact flag */
49147191Sjkoshy		    if(i0>0) i0 += (0x00100000)>>j0;
50147191Sjkoshy		    i0 &= (~i); i1=0;
51147191Sjkoshy		}
52147191Sjkoshy	    }
53147191Sjkoshy	} else if (j0>51) {
54147191Sjkoshy	    if(j0==0x400) return x+x;	/* inf or NaN */
55147191Sjkoshy	    else return x;		/* x is integral */
56147191Sjkoshy	} else {
57147191Sjkoshy	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
58147191Sjkoshy	    if((i1&i)==0) return x;	/* x is integral */
59147191Sjkoshy	    if(huge+x>0.0) { 		/* raise inexact flag */
60147191Sjkoshy		if(i0>0) {
61147191Sjkoshy		    if(j0==20) i0+=1;
62147191Sjkoshy		    else {
63147191Sjkoshy			j = i1 + (1<<(52-j0));
64147191Sjkoshy			if(j<i1) i0+=1;	/* got a carry */
65147191Sjkoshy			i1 = j;
66147191Sjkoshy		    }
67147191Sjkoshy		}
68147191Sjkoshy		i1 &= (~i);
69147191Sjkoshy	    }
70147191Sjkoshy	}
71147191Sjkoshy	INSERT_WORDS(x,i0,i1);
72147191Sjkoshy	return x;
73147191Sjkoshy}
74147191Sjkoshy
75147191Sjkoshy#if LDBL_MANT_DIG == 53
76147191Sjkoshy__weak_reference(ceil, ceill);
77147191Sjkoshy#endif
78147191Sjkoshy