text: 
  /* @(#)s_ceil.c 1.3 95/01/18 */
  /*
   * ====================================================
   * 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.
   * ====================================================
   */
  
  /*
   * ieee_ceil(x)
   * Return x rounded toward -inf to integral value
   * Method:
   *	Bit twiddling.
   * Exception:
   *	Inexact flag raised if x not equal to ieee_ceil(x).
   */
  
  #include "fdlibm.h"
  
  #ifdef __STDC__
  static const double huge = 1.0e300;
  #else
  static double huge = 1.0e300;
  #endif
  
  #ifdef __STDC__
  	double ieee_ceil(double x)
  #else
  	double ieee_ceil(x)
  	double x;
  #endif
  {
  	int i0,i1,j0;
  	unsigned i,j;
  	i0 =  __HI(x);
  	i1 =  __LO(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 = ((unsigned)(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));
  			if(j<i1) i0+=1;	/* got a carry */
  			i1 = j;
  		    }
  		}
  		i1 &= (~i);
  	    }
  	}
  	__HI(x) = i0;
  	__LO(x) = i1;
  	return x;
  }
  