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/* Implementation of the MATMUL intrinsic

   Copyright 2002, 2005 Free Software Foundation, Inc.

   Contributed by Paul Brook <paul@nowt.org>

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 "config.h"

#include <stdlib.h>

#include <string.h>

#include <assert.h>

#include "libgfortran.h"

#if defined (HAVE_GFC_COMPLEX_8)

/* This is a C version of the following fortran pseudo-code. The key

   point is the loop order -- we access all arrays column-first, which

   improves the performance enough to boost galgel spec score by 50%.

   DIMENSION A(M,COUNT), B(COUNT,N), C(M,N)

   C = 0

   DO J=1,N

     DO K=1,COUNT

       DO I=1,M

         C(I,J) = C(I,J)+A(I,K)*B(K,J)

*/

extern void matmul_c8 (gfc_array_c8 * const restrict retarray,

        gfc_array_c8 * const restrict a, gfc_array_c8 * const restrict b);

export_proto(matmul_c8);

void

matmul_c8 (gfc_array_c8 * const restrict retarray,

        gfc_array_c8 * const restrict a, gfc_array_c8 * const restrict b)

{

  const GFC_COMPLEX_8 * restrict abase;

  const GFC_COMPLEX_8 * restrict bbase;

  GFC_COMPLEX_8 * restrict dest;

  index_type rxstride, rystride, axstride, aystride, bxstride, bystride;

  index_type x, y, n, count, xcount, ycount;

  assert (GFC_DESCRIPTOR_RANK (a) == 2

          || GFC_DESCRIPTOR_RANK (b) == 2);

/* C[xcount,ycount] = A[xcount, count] * B[count,ycount]

   Either A or B (but not both) can be rank 1:

   o One-dimensional argument A is implicitly treated as a row matrix

     dimensioned [1,count], so xcount=1.

   o One-dimensional argument B is implicitly treated as a column matrix

     dimensioned [count, 1], so ycount=1.

  */

  if (retarray->data == NULL)

    {

      if (GFC_DESCRIPTOR_RANK (a) == 1)

        {

          retarray->dim[0].lbound = 0;

          retarray->dim[0].ubound = b->dim[1].ubound - b->dim[1].lbound;

          retarray->dim[0].stride = 1;

        }

      else if (GFC_DESCRIPTOR_RANK (b) == 1)

        {

          retarray->dim[0].lbound = 0;

          retarray->dim[0].ubound = a->dim[0].ubound - a->dim[0].lbound;

          retarray->dim[0].stride = 1;

        }

      else

        {

          retarray->dim[0].lbound = 0;

          retarray->dim[0].ubound = a->dim[0].ubound - a->dim[0].lbound;

          retarray->dim[0].stride = 1;

          retarray->dim[1].lbound = 0;

          retarray->dim[1].ubound = b->dim[1].ubound - b->dim[1].lbound;

          retarray->dim[1].stride = retarray->dim[0].ubound+1;

        }

      retarray->data

        = internal_malloc_size (sizeof (GFC_COMPLEX_8) * size0 ((array_t *) retarray));

      retarray->offset = 0;

    }

  if (retarray->dim[0].stride == 0)

    retarray->dim[0].stride = 1;

  /* This prevents constifying the input arguments.  */

  if (a->dim[0].stride == 0)

    a->dim[0].stride = 1;

  if (b->dim[0].stride == 0)

    b->dim[0].stride = 1;

  if (GFC_DESCRIPTOR_RANK (retarray) == 1)

    {

      /* One-dimensional result may be addressed in the code below

         either as a row or a column matrix. We want both cases to

         work. */

      rxstride = rystride = retarray->dim[0].stride;

    }

  else

    {

      rxstride = retarray->dim[0].stride;

      rystride = retarray->dim[1].stride;

    }

  if (GFC_DESCRIPTOR_RANK (a) == 1)

    {

      /* Treat it as a a row matrix A[1,count]. */

      axstride = a->dim[0].stride;

      aystride = 1;

      xcount = 1;

      count = a->dim[0].ubound + 1 - a->dim[0].lbound;

    }

  else

    {

      axstride = a->dim[0].stride;

      aystride = a->dim[1].stride;

      count = a->dim[1].ubound + 1 - a->dim[1].lbound;

      xcount = a->dim[0].ubound + 1 - a->dim[0].lbound;

    }

  assert(count == b->dim[0].ubound + 1 - b->dim[0].lbound);

  if (GFC_DESCRIPTOR_RANK (b) == 1)

    {

      /* Treat it as a column matrix B[count,1] */

      bxstride = b->dim[0].stride;

      /* bystride should never be used for 1-dimensional b.

         in case it is we want it to cause a segfault, rather than

         an incorrect result. */

      bystride = 0xDEADBEEF;

      ycount = 1;

    }

  else

    {

      bxstride = b->dim[0].stride;

      bystride = b->dim[1].stride;

      ycount = b->dim[1].ubound + 1 - b->dim[1].lbound;

    }

  abase = a->data;

  bbase = b->data;

  dest = retarray->data;

  if (rxstride == 1 && axstride == 1 && bxstride == 1)

    {

      const GFC_COMPLEX_8 * restrict bbase_y;

      GFC_COMPLEX_8 * restrict dest_y;

      const GFC_COMPLEX_8 * restrict abase_n;

      GFC_COMPLEX_8 bbase_yn;

      if (rystride == xcount)

        memset (dest, 0, (sizeof (GFC_COMPLEX_8) * xcount * ycount));

      else

        {

          for (y = 0; y < ycount; y++)

            for (x = 0; x < xcount; x++)

              dest[x + y*rystride] = (GFC_COMPLEX_8)0;

        }

      for (y = 0; y < ycount; y++)

        {

          bbase_y = bbase + y*bystride;

          dest_y = dest + y*rystride;

          for (n = 0; n < count; n++)

            {

              abase_n = abase + n*aystride;

              bbase_yn = bbase_y[n];

              for (x = 0; x < xcount; x++)

                {

                  dest_y[x] += abase_n[x] * bbase_yn;

                }

            }

        }

    }

  else

    {

      for (y = 0; y < ycount; y++)

        for (x = 0; x < xcount; x++)

          dest[x*rxstride + y*rystride] = (GFC_COMPLEX_8)0;

      for (y = 0; y < ycount; y++)

        for (n = 0; n < count; n++)

          for (x = 0; x < xcount; x++)

            /* dest[x,y] += a[x,n] * b[n,y] */

            dest[x*rxstride + y*rystride] += abase[x*axstride + n*aystride] * bbase[n*bxstride + y*bystride];

    }

}

#endif