libgfortran/generated/cshift0_r8.c

   1 /* Helper function for cshift functions.
   2    Copyright (C) 2008-2017 Free Software Foundation, Inc.
   3    Contributed by Thomas Koenig <tkoenig@gcc.gnu.org>
   4
   5 This file is part of the GNU Fortran runtime library (libgfortran).
   6
   7 Libgfortran is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU General Public
   9 License as published by the Free Software Foundation; either
  10 version 3 of the License, or (at your option) any later version.
  11
  12 Libgfortran is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include "libgfortran.h"
  27 #include <string.h>
  28
  29
  30 #if defined (HAVE_GFC_REAL_8)
  31
  32 void
  33 cshift0_r8 (gfc_array_r8 *ret, const gfc_array_r8 *array, ptrdiff_t shift,
  34                      int which)
  35 {
  36   /* r.* indicates the return array.  */
  37   index_type rstride[GFC_MAX_DIMENSIONS];
  38   index_type rstride0;
  39   index_type roffset;
  40   GFC_REAL_8 *rptr;
  41
  42   /* s.* indicates the source array.  */
  43   index_type sstride[GFC_MAX_DIMENSIONS];
  44   index_type sstride0;
  45   index_type soffset;
  46   const GFC_REAL_8 *sptr;
  47
  48   index_type count[GFC_MAX_DIMENSIONS];
  49   index_type extent[GFC_MAX_DIMENSIONS];
  50   index_type dim;
  51   index_type len;
  52   index_type n;
  53
  54   which = which - 1;
  55   sstride[0] = 0;
  56   rstride[0] = 0;
  57
  58   extent[0] = 1;
  59   count[0] = 0;
  60   n = 0;
  61   /* Initialized for avoiding compiler warnings.  */
  62   roffset = 1;
  63   soffset = 1;
  64   len = 0;
  65
  66   for (dim = 0; dim < GFC_DESCRIPTOR_RANK (array); dim++)
  67     {
  68       if (dim == which)
  69         {
  70           roffset = GFC_DESCRIPTOR_STRIDE(ret,dim);
  71           if (roffset == 0)
  72             roffset = 1;
  73           soffset = GFC_DESCRIPTOR_STRIDE(array,dim);
  74           if (soffset == 0)
  75             soffset = 1;
  76           len = GFC_DESCRIPTOR_EXTENT(array,dim);
  77         }
  78       else
  79         {
  80           count[n] = 0;
  81           extent[n] = GFC_DESCRIPTOR_EXTENT(array,dim);
  82           rstride[n] = GFC_DESCRIPTOR_STRIDE(ret,dim);
  83           sstride[n] = GFC_DESCRIPTOR_STRIDE(array,dim);
  84           n++;
  85         }
  86     }
  87   if (sstride[0] == 0)
  88     sstride[0] = 1;
  89   if (rstride[0] == 0)
  90     rstride[0] = 1;
  91
  92   dim = GFC_DESCRIPTOR_RANK (array);
  93   rstride0 = rstride[0];
  94   sstride0 = sstride[0];
  95   rptr = ret->base_addr;
  96   sptr = array->base_addr;
  97
  98   /* Avoid the costly modulo for trivially in-bound shifts.  */
  99   if (shift < 0 || shift >= len)
 100     {
 101       shift = len == 0 ? 0 : shift % (ptrdiff_t)len;
 102       if (shift < 0)
 103         shift += len;
 104     }
 105
 106   while (rptr)
 107     {
 108       /* Do the shift for this dimension.  */
 109
 110       /* If elements are contiguous, perform the operation
 111          in two block moves.  */
 112       if (soffset == 1 && roffset == 1)
 113         {
 114           size_t len1 = shift * sizeof (GFC_REAL_8);
 115           size_t len2 = (len - shift) * sizeof (GFC_REAL_8);
 116           memcpy (rptr, sptr + shift, len2);
 117           memcpy (rptr + (len - shift), sptr, len1);
 118         }
 119       else
 120         {
 121           /* Otherwise, we will have to perform the copy one element at
 122              a time.  */
 123           GFC_REAL_8 *dest = rptr;
 124           const GFC_REAL_8 *src = &sptr[shift * soffset];
 125
 126           for (n = 0; n < len - shift; n++)
 127             {
 128               *dest = *src;
 129               dest += roffset;
 130               src += soffset;
 131             }
 132           for (src = sptr, n = 0; n < shift; n++)
 133             {
 134               *dest = *src;
 135               dest += roffset;
 136               src += soffset;
 137             }
 138         }
 139
 140       /* Advance to the next section.  */
 141       rptr += rstride0;
 142       sptr += sstride0;
 143       count[0]++;
 144       n = 0;
 145       while (count[n] == extent[n])
 146         {
 147           /* When we get to the end of a dimension, reset it and increment
 148              the next dimension.  */
 149           count[n] = 0;
 150           /* We could precalculate these products, but this is a less
 151              frequently used path so probably not worth it.  */
 152           rptr -= rstride[n] * extent[n];
 153           sptr -= sstride[n] * extent[n];
 154           n++;
 155           if (n >= dim - 1)
 156             {
 157               /* Break out of the loop.  */
 158               rptr = NULL;
 159               break;
 160             }
 161           else
 162             {
 163               count[n]++;
 164               rptr += rstride[n];
 165               sptr += sstride[n];
 166             }
 167         }
 168     }
 169
 170   return;
 171 }
 172
 173 #endif