ceil.c File Reference

#include "prim.h"

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Functions
double	ceil (double x)
	Mathematical ceiling function. More...

Variables
static const double	huge = 1.0e300

Function Documentation

double ceil

(

double

x

)

Mathematical ceiling function.

Version

1.3

Date

95/01/18

Return x rounded toward -inf to integral value
Method:
 Bit twiddling.
Exception:
 Inexact flag raised if x not equal to ceil(x).

Copyright

Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. Developed at SunSoft, a Sun Microsystems, Inc. business. Permission to use, copy, modify, and distribute this software is freely granted, provided that this notice is preserved.

Definition at line 65 of file ceil.c.

References huge.

{
    sword i0,i1,j0;
    uword i,j;
    EXTRACT_WORDS(i0,i1,x);
    j0 = ((i0>>20)&0x7ff)-0x3ff;
    if(j0<20) {
        if(j0<0) {          /* raise inexact if x != 0 */
            if(huge+x>0.0) {        /* return 0*sign(x) if |x|<1 */
                if(i0<0) {
                    i0=0x80000000;
                    i1=0;
                }
                else if((i0|i1)!=0) {
                    i0=0x3ff00000;
                    i1=0;
                }
            }
        } else {
            i = (0x000fffff)>>j0;
            if(((i0&i)|i1)==0) return x; /* x is integral */
            if(huge+x>0.0) {        /* raise inexact flag */
                if(i0>0) i0 += (0x00100000)>>j0;
                i0 &= (~i);
                i1=0;
            }
        }
    } else if (j0>51) {
        if(j0==0x400) return x+x;   /* inf or NaN */
        else return x;          /* x is integral */
    } else {
        i = ((uword)(0xffffffff))>>(j0-20);
        if((i1&i)==0) return x;     /* x is integral */
        if(huge+x>0.0) {        /* raise inexact flag */
            if(i0>0) {
                if(j0==20) i0+=1;
                else {
                    j = i1 + (1<<(52-j0));
                    // NOTICE: Is this a correct cast?
                    if((sword)j<(sword)i1) i0+=1;   /* got a carry */
                    i1 = j;
                }
            }
            i1 &= (~i);
        }
    }
    INSERT_WORDS(x,i0,i1);
    return x;
}

Variable Documentation

const double huge = 1.0e300

static

Definition at line 46 of file ceil.c.

Referenced by ceil().