/* Implementation of the CSHIFT intrinsic
   Copyright 2003 Free Software Foundation, Inc.
   Contributed by Feng Wang <wf_cs@yahoo.com>

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

Libgfortran 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 2 of the License, or (at your option) any later version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

Ligbfortran 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 libgfortran; see the file COPYING.  If not,
write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

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

#if defined (HAVE_GFC_INTEGER_4)

static void
cshift1 (gfc_array_char * ret, const gfc_array_char * array,
	 const gfc_array_i4 * h, const GFC_INTEGER_4 * pwhich, index_type size)
{
  /* r.* indicates the return array.  */
  index_type rstride[GFC_MAX_DIMENSIONS];
  index_type rstride0;
  index_type roffset;
  char *rptr;
  char *dest;
  /* s.* indicates the source array.  */
  index_type sstride[GFC_MAX_DIMENSIONS];
  index_type sstride0;
  index_type soffset;
  const char *sptr;
  const char *src;
  /* h.* indicates the  array.  */
  index_type hstride[GFC_MAX_DIMENSIONS];
  index_type hstride0;
  const GFC_INTEGER_4 *hptr;

  index_type count[GFC_MAX_DIMENSIONS];
  index_type extent[GFC_MAX_DIMENSIONS];
  index_type dim;
  index_type len;
  index_type n;
  int which;
  GFC_INTEGER_4 sh;

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

  if (which < 0 || (which + 1) > GFC_DESCRIPTOR_RANK (array))
    runtime_error ("Argument 'DIM' is out of range in call to 'CSHIFT'");

  if (ret->data == NULL)
    {
      int i;

      ret->data = internal_malloc_size (size * size0 ((array_t *)array));
      ret->offset = 0;
      ret->dtype = array->dtype;
      for (i = 0; i < GFC_DESCRIPTOR_RANK (array); i++)
        {
          ret->dim[i].lbound = 0;
          ret->dim[i].ubound = array->dim[i].ubound - array->dim[i].lbound;

          if (i == 0)
            ret->dim[i].stride = 1;
          else
            ret->dim[i].stride = (ret->dim[i-1].ubound + 1) * ret->dim[i-1].stride;
        }
    }

  extent[0] = 1;
  count[0] = 0;
  n = 0;

  /* Initialized for avoiding compiler warnings.  */
  roffset = size;
  soffset = size;
  len = 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  for this dimension.  */
      sh = *hptr;
      sh = (div (sh, len)).rem;
      if (sh < 0)
        sh += len;

      src = &sptr[sh * soffset];
      dest = rptr;

      for (n = 0; n < len; n++)
        {
          memcpy (dest, src, size);
          dest += roffset;
          if (n == len - sh - 1)
            src = sptr;
          else
            src += soffset;
        }

      /* 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];
            }
        }
    }
}

void cshift1_4 (gfc_array_char *, const gfc_array_char *,
			   const gfc_array_i4 *, const GFC_INTEGER_4 *);
export_proto(cshift1_4);

void
cshift1_4 (gfc_array_char * ret,
		      const gfc_array_char * array,
		      const gfc_array_i4 * h, const GFC_INTEGER_4 * pwhich)
{
  cshift1 (ret, array, h, pwhich, GFC_DESCRIPTOR_SIZE (array));
}

void cshift1_4_char (gfc_array_char * ret, GFC_INTEGER_4,
				  const gfc_array_char * array,
				  const gfc_array_i4 * h, const GFC_INTEGER_4 * pwhich,
				  GFC_INTEGER_4);
export_proto(cshift1_4_char);

void
cshift1_4_char (gfc_array_char * ret,
			     GFC_INTEGER_4 ret_length __attribute__((unused)),
			     const gfc_array_char * array,
			     const gfc_array_i4 * h, const GFC_INTEGER_4 * pwhich,
			     GFC_INTEGER_4 array_length)
{
  cshift1 (ret, array, h, pwhich, array_length);
}

#endif