/* Implementation of the EOSHIFT intrinsic
   Copyright 2002 Free Software Foundation, Inc.
   Contributed by Paul Brook <paul@nowt.org>

This file is part of the GNU Fortran 95 runtime library (libgfor).

Libgfor is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

Ligbfor 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with libgfor; see the file COPYING.LIB.  If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "config.h"
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include "libgfortran.h"

static const char zeros[16] =
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

extern void eoshift1_8 (const gfc_array_char *,
				     const gfc_array_char *,
				     const gfc_array_i8 *, const char *,
				     const GFC_INTEGER_8 *);
export_proto(eoshift1_8);

void
eoshift1_8 (const gfc_array_char *ret,
		       const gfc_array_char *array,
		       const gfc_array_i8 *h, const char *pbound,
		       const GFC_INTEGER_8 *pwhich)
{
  /* r.* indicates the return array.  */
  index_type rstride[GFC_MAX_DIMENSIONS - 1];
  index_type rstride0;
  index_type roffset;
  char *rptr;
  char *dest;
  /* s.* indicates the source array.  */
  index_type sstride[GFC_MAX_DIMENSIONS - 1];
  index_type sstride0;
  index_type soffset;
  const char *sptr;
  const char *src;
  /* h.* indicates the shift array.  */
  index_type hstride[GFC_MAX_DIMENSIONS - 1];
  index_type hstride0;
  const GFC_INTEGER_8 *hptr;

  index_type count[GFC_MAX_DIMENSIONS - 1];
  index_type extent[GFC_MAX_DIMENSIONS - 1];
  index_type dim;
  index_type size;
  index_type len;
  index_type n;
  int which;
  GFC_INTEGER_8 sh;
  GFC_INTEGER_8 delta;

  if (pwhich)
    which = *pwhich - 1;
  else
    which = 0;

  if (!pbound)
    pbound = zeros;

  size = GFC_DESCRIPTOR_SIZE (ret);

  extent[0] = 1;
  count[0] = 0;
  size = GFC_DESCRIPTOR_SIZE (array);
  n = 0;
  for (dim = 0; dim < GFC_DESCRIPTOR_RANK (array); dim++)
    {
      if (dim == which)
        {
          roffset = ret->dim[dim].stride * size;
          if (roffset == 0)
            roffset = size;
          soffset = array->dim[dim].stride * size;
          if (soffset == 0)
            soffset = size;
          len = array->dim[dim].ubound + 1 - array->dim[dim].lbound;
        }
      else
        {
          count[n] = 0;
          extent[n] = array->dim[dim].ubound + 1 - array->dim[dim].lbound;
          rstride[n] = ret->dim[dim].stride * size;
          sstride[n] = array->dim[dim].stride * size;

          hstride[n] = h->dim[n].stride;
          n++;
        }
    }
  if (sstride[0] == 0)
    sstride[0] = size;
  if (rstride[0] == 0)
    rstride[0] = size;
  if (hstride[0] == 0)
    hstride[0] = 1;

  dim = GFC_DESCRIPTOR_RANK (array);
  rstride0 = rstride[0];
  sstride0 = sstride[0];
  hstride0 = hstride[0];
  rptr = ret->data;
  sptr = array->data;
  hptr = h->data;

  while (rptr)
    {
      /* Do the shift for this dimension.  */
      sh = *hptr;
      delta = (sh >= 0) ? sh: -sh;
      if (sh > 0)
        {
          src = &sptr[delta * soffset];
          dest = rptr;
        }
      else
        {
          src = sptr;
          dest = &rptr[delta * roffset];
        }
      for (n = 0; n < len - delta; n++)
        {
          memcpy (dest, src, size);
          dest += roffset;
          src += soffset;
        }
      if (sh < 0)
        dest = rptr;
      n = delta;

      while (n--)
        {
          memcpy (dest, pbound, size);
          dest += roffset;
        }

      /* Advance to the next section.  */
      rptr += rstride0;
      sptr += sstride0;
      hptr += hstride0;
      count[0]++;
      n = 0;
      while (count[n] == extent[n])
        {
          /* When we get to the end of a dimension, reset it and increment
             the next dimension.  */
          count[n] = 0;
          /* We could precalculate these products, but this is a less
             frequently used path so proabably not worth it.  */
          rptr -= rstride[n] * extent[n];
          sptr -= sstride[n] * extent[n];
	  hptr -= hstride[n] * extent[n];
          n++;
          if (n >= dim - 1)
            {
              /* Break out of the loop.  */
              rptr = NULL;
              break;
            }
          else
            {
              count[n]++;
              rptr += rstride[n];
              sptr += sstride[n];
	      hptr += hstride[n];
            }
        }
    }
}