/* @(#)s_ceil.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

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

#include "..\Math.h"


static const tDouble huge = 1.0e300;


tDouble math_ceil(tDouble x)
{
  tLong i0, i1, j0, j;
  tULong i;
  
  EXTRACT_WORDS (i0, i1, x);
  
  j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
  if (j0 < 20)
  {
    if (j0 < 0)       /* raise inexact if x != 0 */
    {
      //math_force_eval (huge + x);
      /* 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 */
      //math_force_eval (huge + x);           /* 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 = ((tULong) (0xffffffff)) >> (j0 - 20);
    if ((i1 & i) == 0)
      return x;                       /* x is integral */
    //math_force_eval (huge + x);               /* 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);
  }
  
  INSERT_WORDS (x, i0, i1);
  
  return x;
}

