/* Generic implementation of the CSHIFT intrinsic
   Copyright 2003, 2005, 2006, 2007 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.)

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

static void
cshift0 (gfc_array_char * ret, const gfc_array_char * array,
	 ssize_t shift, int which, index_type size)
{
  /* r.* indicates the return array.  */
  index_type rstride[GFC_MAX_DIMENSIONS];
  index_type rstride0;
  index_type roffset;
  char *rptr;

  /* s.* indicates the source array.  */
  index_type sstride[GFC_MAX_DIMENSIONS];
  index_type sstride0;
  index_type soffset;
  const char *sptr;

  index_type count[GFC_MAX_DIMENSIONS];
  index_type extent[GFC_MAX_DIMENSIONS];
  index_type dim;
  index_type len;
  index_type n;
  index_type arraysize;

  index_type type_size;

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

  arraysize = size0 ((array_t *) array);

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

      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;
        }

      if (arraysize > 0)
	ret->data = internal_malloc_size (size * arraysize);
      else
	{
	  ret->data = internal_malloc_size (1);
	  return;
	}
    }
  
  if (arraysize == 0)
    return;
  type_size = GFC_DTYPE_TYPE_SIZE (array);

  switch(type_size)
    {
    case GFC_DTYPE_LOGICAL_1:
    case GFC_DTYPE_INTEGER_1:
    case GFC_DTYPE_DERIVED_1:
      cshift0_i1 ((gfc_array_i1 *)ret, (gfc_array_i1 *) array, shift, which);
      return;

    case GFC_DTYPE_LOGICAL_2:
    case GFC_DTYPE_INTEGER_2:
      cshift0_i2 ((gfc_array_i2 *)ret, (gfc_array_i2 *) array, shift, which);
      return;

    case GFC_DTYPE_LOGICAL_4:
    case GFC_DTYPE_INTEGER_4:
      cshift0_i4 ((gfc_array_i4 *)ret, (gfc_array_i4 *) array, shift, which);
      return;

    case GFC_DTYPE_LOGICAL_8:
    case GFC_DTYPE_INTEGER_8:
      cshift0_i8 ((gfc_array_i8 *)ret, (gfc_array_i8 *) array, shift, which);
      return;

#ifdef HAVE_GFC_INTEGER_16
    case GFC_DTYPE_LOGICAL_16:
    case GFC_DTYPE_INTEGER_16:
      cshift0_i16 ((gfc_array_i16 *)ret, (gfc_array_i16 *) array, shift,
		   which);
      return;
#endif

    case GFC_DTYPE_REAL_4:
      cshift0_r4 ((gfc_array_r4 *)ret, (gfc_array_r4 *) array, shift, which);
      return;

    case GFC_DTYPE_REAL_8:
      cshift0_r8 ((gfc_array_r8 *)ret, (gfc_array_r8 *) array, shift, which);
      return;

#ifdef HAVE_GFC_REAL_10
    case GFC_DTYPE_REAL_10:
      cshift0_r10 ((gfc_array_r10 *)ret, (gfc_array_r10 *) array, shift,
		   which);
      return;
#endif

#ifdef HAVE_GFC_REAL_16
    case GFC_DTYPE_REAL_16:
      cshift0_r16 ((gfc_array_r16 *)ret, (gfc_array_r16 *) array, shift,
		   which);
      return;
#endif

    case GFC_DTYPE_COMPLEX_4:
      cshift0_c4 ((gfc_array_c4 *)ret, (gfc_array_c4 *) array, shift, which);
      return;

    case GFC_DTYPE_COMPLEX_8:
      cshift0_c8 ((gfc_array_c8 *)ret, (gfc_array_c8 *) array, shift, which);
      return;

#ifdef HAVE_GFC_COMPLEX_10
    case GFC_DTYPE_COMPLEX_10:
      cshift0_c10 ((gfc_array_c10 *)ret, (gfc_array_c10 *) array, shift,
		   which);
      return;
#endif

#ifdef HAVE_GFC_COMPLEX_16
    case GFC_DTYPE_COMPLEX_16:
      cshift0_c16 ((gfc_array_c16 *)ret, (gfc_array_c16 *) array, shift,
		   which);
      return;
#endif

    default:
      break;
    }

  switch (size)
    {
      /* Let's check the actual alignment of the data pointers.  If they
	 are suitably aligned, we can safely call the unpack functions.  */

    case sizeof (GFC_INTEGER_1):
      cshift0_i1 ((gfc_array_i1 *) ret, (gfc_array_i1 *) array, shift,
		  which);
      break;

    case sizeof (GFC_INTEGER_2):
      if (GFC_UNALIGNED_2(ret->data) || GFC_UNALIGNED_2(array->data))
	break;
      else
	{
	  cshift0_i2 ((gfc_array_i2 *) ret, (gfc_array_i2 *) array, shift,
		      which);
	  return;
	}

    case sizeof (GFC_INTEGER_4):
      if (GFC_UNALIGNED_4(ret->data) || GFC_UNALIGNED_4(array->data))
	break;
      else
	{
	  cshift0_i4 ((gfc_array_i4 *)ret, (gfc_array_i4 *) array, shift,
		      which);
	  return;
	}

    case sizeof (GFC_INTEGER_8):
      if (GFC_UNALIGNED_8(ret->data) || GFC_UNALIGNED_8(array->data))
	{
	  /* Let's try to use the complex routines.  First, a sanity
	     check that the sizes match; this should be optimized to
	     a no-op.  */
	  if (sizeof(GFC_INTEGER_8) != sizeof(GFC_COMPLEX_4))
	    break;

	  if (GFC_UNALIGNED_C4(ret->data) || GFC_UNALIGNED_C4(array->data))
	    break;

	  cshift0_c4 ((gfc_array_c4 *) ret, (gfc_array_c4 *) array, shift,
		      which);
	      return;
	}
      else
	{
	  cshift0_i8 ((gfc_array_i8 *)ret, (gfc_array_i8 *) array, shift,
		      which);
	  return;
	}

#ifdef HAVE_GFC_INTEGER_16
    case sizeof (GFC_INTEGER_16):
      if (GFC_UNALIGNED_16(ret->data) || GFC_UNALIGNED_16(array->data))
	{
	  /* Let's try to use the complex routines.  First, a sanity
	     check that the sizes match; this should be optimized to
	     a no-op.  */
	  if (sizeof(GFC_INTEGER_16) != sizeof(GFC_COMPLEX_8))
	    break;

	  if (GFC_UNALIGNED_C8(ret->data) || GFC_UNALIGNED_C8(array->data))
	    break;

	  cshift0_c8 ((gfc_array_c8 *) ret, (gfc_array_c8 *) array, shift,
		      which);
	      return;
	}
      else
	{
	  cshift0_i16 ((gfc_array_i16 *) ret, (gfc_array_i16 *) array,
		       shift, which);
	  return;
	}
#else
    case sizeof (GFC_COMPLEX_8):

      if (GFC_UNALIGNED_C8(ret->data) || GFC_UNALIGNED_C8(array->data))
	break;
      else
	{
	  cshift0_c8 ((gfc_array_c8 *) ret, (gfc_array_c8 *) array, shift,
		      which);
	  return;
	}
#endif

    default:
      break;
    }


  which = which - 1;
  sstride[0] = 0;
  rstride[0] = 0;

  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;
          n++;
        }
    }
  if (sstride[0] == 0)
    sstride[0] = size;
  if (rstride[0] == 0)
    rstride[0] = size;

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

  shift = len == 0 ? 0 : shift % (ssize_t)len;
  if (shift < 0)
    shift += len;

  while (rptr)
    {
      /* Do the shift for this dimension.  */

      /* If elements are contiguous, perform the operation
	 in two block moves.  */
      if (soffset == size && roffset == size)
	{
	  size_t len1 = shift * size;
	  size_t len2 = (len - shift) * size;
	  memcpy (rptr, sptr + len1, len2);
	  memcpy (rptr + len2, sptr, len1);
	}
      else
	{
	  /* Otherwise, we'll have to perform the copy one element at
	     a time.  */
	  char *dest = rptr;
	  const char *src = &sptr[shift * soffset];

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

      /* Advance to the next section.  */
      rptr += rstride0;
      sptr += sstride0;
      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 probably not worth it.  */
          rptr -= rstride[n] * extent[n];
          sptr -= sstride[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];
            }
        }
    }
}

#define DEFINE_CSHIFT(N)						      \
  extern void cshift0_##N (gfc_array_char *, const gfc_array_char *,	      \
			   const GFC_INTEGER_##N *, const GFC_INTEGER_##N *); \
  export_proto(cshift0_##N);						      \
									      \
  void									      \
  cshift0_##N (gfc_array_char *ret, const gfc_array_char *array,	      \
	       const GFC_INTEGER_##N *pshift, const GFC_INTEGER_##N *pdim)    \
  {									      \
    cshift0 (ret, array, *pshift, pdim ? *pdim : 1,			      \
	     GFC_DESCRIPTOR_SIZE (array));				      \
  }									      \
									      \
  extern void cshift0_##N##_char (gfc_array_char *, GFC_INTEGER_4,	      \
				  const gfc_array_char *,		      \
				  const GFC_INTEGER_##N *,		      \
				  const GFC_INTEGER_##N *, GFC_INTEGER_4);    \
  export_proto(cshift0_##N##_char);					      \
									      \
  void									      \
  cshift0_##N##_char (gfc_array_char *ret,				      \
		      GFC_INTEGER_4 ret_length __attribute__((unused)),	      \
		      const gfc_array_char *array,			      \
		      const GFC_INTEGER_##N *pshift,			      \
		      const GFC_INTEGER_##N *pdim,			      \
		      GFC_INTEGER_4 array_length)			      \
  {									      \
    cshift0 (ret, array, *pshift, pdim ? *pdim : 1, array_length);	      \
  }									      \
									      \
  extern void cshift0_##N##_char4 (gfc_array_char *, GFC_INTEGER_4,	      \
				   const gfc_array_char *,		      \
				   const GFC_INTEGER_##N *,		      \
				   const GFC_INTEGER_##N *, GFC_INTEGER_4);   \
  export_proto(cshift0_##N##_char4);					      \
									      \
  void									      \
  cshift0_##N##_char4 (gfc_array_char *ret,				      \
		       GFC_INTEGER_4 ret_length __attribute__((unused)),      \
		       const gfc_array_char *array,			      \
		       const GFC_INTEGER_##N *pshift,			      \
		       const GFC_INTEGER_##N *pdim,			      \
		       GFC_INTEGER_4 array_length)			      \
  {									      \
    cshift0 (ret, array, *pshift, pdim ? *pdim : 1,			      \
	     array_length * sizeof (gfc_char4_t));			      \
  }

DEFINE_CSHIFT (1);
DEFINE_CSHIFT (2);
DEFINE_CSHIFT (4);
DEFINE_CSHIFT (8);
#ifdef HAVE_GFC_INTEGER_16
DEFINE_CSHIFT (16);
#endif