adtools/clib2

/*
 * $Id: math_lround.c,v 1.4 2006-01-08 12:04:23 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * PowerPC math library based in part on work by Sun Microsystems
 * 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.
 */

#ifndef _MATH_HEADERS_H
#include "math_headers.h"
#endif /* _MATH_HEADERS_H */

/****************************************************************************/

#if defined(FLOATING_POINT_SUPPORT)

/****************************************************************************/

long int
lround(double x)
{
  LONG sign, exponent_less_1023;
  /* Most significant word, least significant word. */
  ULONG msw, lsw;
  long int result;
  
  EXTRACT_WORDS(msw, lsw, x);

  /* Extract sign. */
  sign = ((msw & 0x80000000) ? -1 : 1);
  /* Extract exponent field. */
  exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
  msw &= 0x000fffff;
  msw |= 0x00100000;

  if (exponent_less_1023 < 20)
    {
      if (exponent_less_1023 < 0)
        {
          if (exponent_less_1023 < -1)
            return 0;
          else
            return sign;
        }
      else
        {
          msw += 0x80000 >> exponent_less_1023;
          result = msw >> (20 - exponent_less_1023);
        }
    }
  else if (exponent_less_1023 < (LONG)(8 * sizeof (long int)) - 1)
    {
      if (exponent_less_1023 >= 52)
        result = ((long int) msw << (exponent_less_1023 - 20)) | (lsw << (exponent_less_1023 - 52));
      else
        {
          unsigned int tmp = lsw + (0x80000000 >> (exponent_less_1023 - 20));
          if (tmp < lsw)
            ++msw;
          result = ((long int) msw << (exponent_less_1023 - 20)) | (tmp >> (52 - exponent_less_1023));
        }
    }
  else
    /* Result is too large to be represented by a long int. */
    return (long int)x;

  return sign * result;
}

/****************************************************************************/

#endif /* FLOATING_POINT_SUPPORT */