flonum-copy.c

早期freebsd实现

/* flonum_copy.c - copy a flonum
   Copyright (C) 1987 Free Software Foundation, Inc.

This file is part of GAS, the GNU Assembler.

GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "flonum.h"
#ifdef USG
#define bzero(s,n) memset(s,0,n)
#define bcopy(from,to,n) memcpy(to,from,n)
#endif

void
flonum_copy (in, out)
     FLONUM_TYPE *	in;
     FLONUM_TYPE *	out;
{
  int			in_length;	/* 0 origin */
  int			out_length;	/* 0 origin */

  out -> sign = in -> sign;
  in_length = in  -> leader - in -> low;
  if (in_length < 0)
    {
      out -> leader = out -> low - 1; /* 0.0 case */
    }
  else
    {
      out_length = out -> high - out -> low;
      /*
       * Assume no GAPS in packing of littlenums.
       * I.e. sizeof(array) == sizeof(element) * number_of_elements.
       */
      if (in_length <= out_length)
	{
	  {
	    /*
	     * For defensive programming, zero any high-order littlenums we don't need.
	     * This is destroying evidence and wasting time, so why bother???
	     */
	    if (in_length < out_length)
	      {
		bzero ((char *)(out->low + in_length + 1), out_length - in_length);
	      }
	  }
	  bcopy ((char *)(in->low), (char *)(out->low), (int)((in_length + 1) * sizeof(LITTLENUM_TYPE)));
	  out -> exponent = in -> exponent;
	  out -> leader   = in -> leader - in -> low + out -> low;
	}
      else
	{
	  int	shorten;		/* 1-origin. Number of littlenums we drop. */

	  shorten = in_length - out_length;
	  /* Assume out_length >= 0 ! */
	  bcopy ((char *)(in->low + shorten),(char *)( out->low), (int)((out_length + 1) * sizeof(LITTLENUM_TYPE)));
	  out -> leader = out -> high;
	  out -> exponent = in -> exponent + shorten;
	}
    }				/* if any significant bits */
}

/* end: flonum_copy.c */