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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libquadmath/] [printf/] [rshift.c] - Blame information for rev 740

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1 740 jeremybenn
/* mpn_rshift -- Shift right a low-level natural-number integer.
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Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include <config.h>
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#include "gmp-impl.h"
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/* Shift U (pointed to by UP and USIZE limbs long) CNT bits to the right
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   and store the USIZE least significant limbs of the result at WP.
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   The bits shifted out to the right are returned.
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   Argument constraints:
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   1. 0 < CNT < BITS_PER_MP_LIMB
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   2. If the result is to be written over the input, WP must be <= UP.
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*/
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mp_limb_t
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#if __STDC__
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mpn_rshift (register mp_ptr wp,
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            register mp_srcptr up, mp_size_t usize,
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            register unsigned int cnt)
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#else
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mpn_rshift (wp, up, usize, cnt)
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     register mp_ptr wp;
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     register mp_srcptr up;
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     mp_size_t usize;
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     register unsigned int cnt;
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#endif
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{
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  register mp_limb_t high_limb, low_limb;
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  register unsigned sh_1, sh_2;
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  register mp_size_t i;
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  mp_limb_t retval;
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#ifdef DEBUG
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  if (usize == 0 || cnt == 0)
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    abort ();
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#endif
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  sh_1 = cnt;
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#if 0
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  if (sh_1 == 0)
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    {
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      if (wp != up)
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        {
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          /* Copy from low end to high end, to allow specified input/output
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             overlapping.  */
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          for (i = 0; i < usize; i++)
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            wp[i] = up[i];
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        }
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      return usize;
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    }
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#endif
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  wp -= 1;
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  sh_2 = BITS_PER_MP_LIMB - sh_1;
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  high_limb = up[0];
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  retval = high_limb << sh_2;
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  low_limb = high_limb;
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  for (i = 1; i < usize; i++)
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    {
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      high_limb = up[i];
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      wp[i] = (low_limb >> sh_1) | (high_limb << sh_2);
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      low_limb = high_limb;
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    }
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  wp[i] = low_limb >> sh_1;
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  return retval;
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}

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