1  #if !defined(__ppc__)
 2  /* @(#)s_ceil.c 5.1 93/09/24 */
 3  /*
 4   * ====================================================
 5   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 6   *
 7   * Developed at SunPro, a Sun Microsystems, Inc. business.
 8   * Permission to use, copy, modify, and distribute this
 9   * software is freely granted, provided that this notice 
10   * is preserved.
11   * ====================================================
12   */
13  
14  #if defined(LIBM_SCCS) && !defined(lint)
15  static char rcsid[] = "$NetBSD: s_ceil.c,v 1.8 1995/05/10 20:46:53 jtc Exp $";
16  #endif
17  
18  /*
19   * ceil(x)
20   * Return x rounded toward -inf to integral value
21   * Method:
22   *	Bit twiddling.
23   * Exception:
24   *	Inexact flag raised if x not equal to ceil(x).
25   */
26  
27  #include "math.h"
28  #include "mathP.h"
29  
30  #ifdef __STDC__
31  static const double huge = 1.0e300;
32  #else
33  static double huge = 1.0e300;
34  #endif
35  
36  #ifdef __STDC__
37  	double ceil(double x)
38  #else
39  	double ceil(x)
40  	double x;
41  #endif
42  {
43  	int32_t i0,i1,j0;
44  	u_int32_t i,j;
45  	EXTRACT_WORDS(i0,i1,x);
46  	j0 = ((i0>>20)&0x7ff)-0x3ff;
47  	if(j0<20) {
48  	    if(j0<0) { 	/* raise inexact if x != 0 */
49  		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
50  		    if(i0<0) {i0=0x80000000;i1=0;} 
51  		    else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;}
52  		}
53  	    } else {
54  		i = (0x000fffff)>>j0;
55  		if(((i0&i)|i1)==0) return x; /* x is integral */
56  		if(huge+x>0.0) {	/* raise inexact flag */
57  		    if(i0>0) i0 += (0x00100000)>>j0;
58  		    i0 &= (~i); i1=0;
59  		}
60  	    }
61  	} else if (j0>51) {
62  	    if(j0==0x400) return x+x;	/* inf or NaN */
63  	    else return x;		/* x is integral */
64  	} else {
65  	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
66  	    if((i1&i)==0) return x;	/* x is integral */
67  	    if(huge+x>0.0) { 		/* raise inexact flag */
68  		if(i0>0) {
69  		    if(j0==20) i0+=1; 
70  		    else {
71  			j = i1 + (1<<(52-j0));
72  			if(j<i1) i0+=1;	/* got a carry */
73  			i1 = j;
74  		    }
75  		}
76  		i1 &= (~i);
77  	    }
78  	}
79  	INSERT_WORDS(x,i0,i1);
80  	return x;
81  }
82  #endif /* !__ppc__ */