libgfortran/intrinsics/iso_c_binding.c

   1 /* Implementation of the ISO_C_BINDING library helper functions.
   2    Copyright (C) 2007 Free Software Foundation, Inc.
   3    Contributed by Christopher Rickett.
   4
   5 This file is part of the GNU Fortran 95 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 2 of the License, or (at your option) any later version.
  11
  12 In addition to the permissions in the GNU General Public License, the
  13 Free Software Foundation gives you unlimited permission to link the
  14 compiled version of this file into combinations with other programs,
  15 and to distribute those combinations without any restriction coming
  16 from the use of this file.  (The General Public License restrictions
  17 do apply in other respects; for example, they cover modification of
  18 the file, and distribution when not linked into a combine
  19 executable.)
  20
  21 Libgfortran is distributed in the hope that it will be useful,
  22 but WITHOUT ANY WARRANTY; without even the implied warranty of
  23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24 GNU General Public License for more details.
  25
  26 You should have received a copy of the GNU General Public
  27 License along with libgfortran; see the file COPYING.  If not,
  28 write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  29 Boston, MA 02110-1301, USA.  */
  30
  31
  32 /* Implement the functions and subroutines provided by the intrinsic
  33    iso_c_binding module.  */
  34
  35 #include <stdlib.h>
  36
  37 #include "libgfortran.h"
  38 #include "iso_c_binding.h"
  39
  40
  41 /* Set the fields of a Fortran pointer descriptor to point to the
  42    given C address.  It uses c_f_pointer_u0 for the common
  43    fields, and will set up the information necessary if this C address
  44    is to an array (i.e., offset, type, element size).  The parameter
  45    c_ptr_in represents the C address to have Fortran point to.  The
  46    parameter f_ptr_out is the Fortran pointer to associate with the C
  47    address.  The parameter shape is a one-dimensional array of integers
  48    specifying the upper bound(s) of the array pointed to by the given C
  49    address, if applicable.  The shape parameter is optional in Fortran,
  50    which will cause it to come in here as NULL.  The parameter type is
  51    the type of the data being pointed to (i.e.,libgfortran.h). The
  52    elem_size parameter is the size, in bytes, of the data element being
  53    pointed to.  If the address is for an array, then the size needs to
  54    be the size of a single element (i.e., for an array of doubles, it
  55    needs to be the number of bytes for the size of one double).  */
  56
  57 void
  58 ISO_C_BINDING_PREFIX (c_f_pointer) (void *c_ptr_in,
  59                                     gfc_array_void *f_ptr_out,
  60                                     const array_t *shape,
  61                                     int type, int elemSize)
  62 {
  63   if (shape != NULL)
  64     {
  65       f_ptr_out->offset = 0;
  66
  67       /* Set the necessary dtype field for all pointers.  */
  68       f_ptr_out->dtype = 0;
  69
  70       /* Put in the element size.  */
  71       f_ptr_out->dtype = f_ptr_out->dtype | (elemSize << GFC_DTYPE_SIZE_SHIFT);
  72
  73       /* Set the data type (e.g., GFC_DTYPE_INTEGER).  */
  74       f_ptr_out->dtype = f_ptr_out->dtype | (type << GFC_DTYPE_TYPE_SHIFT);
  75     }
  76
  77   /* Use the generic version of c_f_pointer to set common fields.  */
  78   ISO_C_BINDING_PREFIX (c_f_pointer_u0) (c_ptr_in, f_ptr_out, shape);
  79 }
  80
  81
  82 /* A generic function to set the common fields of all descriptors, no
  83    matter whether it's to a scalar or an array.  Fields set are: data,
  84    and if appropriate, rank, offset, dim[*].lbound, dim[*].ubound, and
  85    dim[*].stride.  Parameter shape is a rank 1 array of integers
  86    containing the upper bound of each dimension of what f_ptr_out
  87    points to.  The length of this array must be EXACTLY the rank of
  88    what f_ptr_out points to, as required by the draft (J3/04-007).  If
  89    f_ptr_out points to a scalar, then this parameter will be NULL.  */
  90
  91 void
  92 ISO_C_BINDING_PREFIX (c_f_pointer_u0) (void *c_ptr_in,
  93                                        gfc_array_void *f_ptr_out,
  94                                        const array_t *shape)
  95 {
  96   int i = 0;
  97   int shapeSize = 0;
  98
  99   GFC_DESCRIPTOR_DATA (f_ptr_out) = c_ptr_in;
 100
 101   if (shape != NULL)
 102     {
 103       f_ptr_out->offset = 0;
 104       shapeSize = 0;
 105
 106       /* shape's length (rank of the output array) */
 107       shapeSize = shape->dim[0].ubound + 1 - shape->dim[0].lbound;
 108       for (i = 0; i < shapeSize; i++)
 109         {
 110           /* Lower bound is 1, as specified by the draft.  */
 111           f_ptr_out->dim[i].lbound = 1;
 112           /* Have to allow for the SHAPE array to be any valid kind for
 113              an INTEGER type.  */
 114 #ifdef HAVE_GFC_INTEGER_1
 115           if (GFC_DESCRIPTOR_SIZE (shape) == 1)
 116             f_ptr_out->dim[i].ubound = ((GFC_INTEGER_1 *) (shape->data))[i];
 117 #endif
 118 #ifdef HAVE_GFC_INTEGER_2
 119           if (GFC_DESCRIPTOR_SIZE (shape) == 2)
 120             f_ptr_out->dim[i].ubound = ((GFC_INTEGER_2 *) (shape->data))[i];
 121 #endif
 122 #ifdef HAVE_GFC_INTEGER_4
 123           if (GFC_DESCRIPTOR_SIZE (shape) == 4)
 124             f_ptr_out->dim[i].ubound = ((GFC_INTEGER_4 *) (shape->data))[i];
 125 #endif
 126 #ifdef HAVE_GFC_INTEGER_8
 127           if (GFC_DESCRIPTOR_SIZE (shape) == 8)
 128             f_ptr_out->dim[i].ubound = ((GFC_INTEGER_8 *) (shape->data))[i];
 129 #endif
 130 #ifdef HAVE_GFC_INTEGER_16
 131           if (GFC_DESCRIPTOR_SIZE (shape) == 16)
 132             f_ptr_out->dim[i].ubound = ((GFC_INTEGER_16 *) (shape->data))[i];
 133 #endif
 134         }
 135
 136       /* Set the offset and strides.
 137          offset is (sum of (dim[i].lbound * dim[i].stride) for all
 138          dims) the -1 means we'll back the data pointer up that much
 139          perhaps we could just realign the data pointer and not change
 140          the offset?  */
 141       f_ptr_out->dim[0].stride = 1;
 142       f_ptr_out->offset = f_ptr_out->dim[0].lbound * f_ptr_out->dim[0].stride;
 143       for (i = 1; i < shapeSize; i++)
 144         {
 145           f_ptr_out->dim[i].stride = (f_ptr_out->dim[i-1].ubound + 1)
 146             - f_ptr_out->dim[i-1].lbound;
 147           f_ptr_out->offset += f_ptr_out->dim[i].lbound
 148             * f_ptr_out->dim[i].stride;
 149         }
 150
 151       f_ptr_out->offset *= -1;
 152
 153       /* All we know is the rank, so set it, leaving the rest alone.
 154          Make NO assumptions about the state of dtype coming in!  If we
 155          shift right by TYPE_SHIFT bits we'll throw away the existing
 156          rank.  Then, shift left by the same number to shift in zeros
 157          and or with the new rank.  */
 158       f_ptr_out->dtype = ((f_ptr_out->dtype >> GFC_DTYPE_TYPE_SHIFT)
 159                            << GFC_DTYPE_TYPE_SHIFT) | shapeSize;
 160     }
 161 }
 162
 163
 164 /* Sets the descriptor fields for a Fortran pointer to a derived type,
 165    using c_f_pointer_u0 for the majority of the work.  */
 166
 167 void
 168 ISO_C_BINDING_PREFIX (c_f_pointer_d0) (void *c_ptr_in,
 169                                        gfc_array_void *f_ptr_out,
 170                                        const array_t *shape)
 171 {
 172   /* Set the common fields.  */
 173   ISO_C_BINDING_PREFIX (c_f_pointer_u0) (c_ptr_in, f_ptr_out, shape);
 174
 175   /* Preserve the size and rank bits, but reset the type.  */
 176   if (shape != NULL)
 177     {
 178       f_ptr_out->dtype = f_ptr_out->dtype & (~GFC_DTYPE_TYPE_MASK);
 179       f_ptr_out->dtype = f_ptr_out->dtype
 180                          | (GFC_DTYPE_DERIVED << GFC_DTYPE_TYPE_SHIFT);
 181     }
 182 }
 183
 184
 185 /* This function will change, once there is an actual f90 type for the
 186    procedure pointer.  */
 187
 188 void
 189 ISO_C_BINDING_PREFIX (c_f_procpointer) (void *c_ptr_in,
 190                                         gfc_array_void *f_ptr_out)
 191 {
 192   GFC_DESCRIPTOR_DATA(f_ptr_out) = c_ptr_in;
 193 }
 194
 195
 196 /* Test if the given c_ptr is associated or not.  This function is
 197    called if the user only supplied one c_ptr parameter to the
 198    c_associated function.  The second argument is optional, and the
 199    Fortran compiler will resolve the function to this version if only
 200    one arg was given.  Associated here simply means whether or not the
 201    c_ptr is NULL or not.  */
 202
 203 GFC_LOGICAL_4
 204 ISO_C_BINDING_PREFIX (c_associated_1) (void *c_ptr_in_1)
 205 {
 206   if (c_ptr_in_1 != NULL)
 207     return 1;
 208   else
 209     return 0;
 210 }
 211
 212
 213 /* Test if the two c_ptr arguments are associated with one another.
 214    This version of the c_associated function is called if the user
 215    supplied two c_ptr args in the Fortran source.  According to the
 216    draft standard (J3/04-007), if c_ptr_in_1 is NULL, the two pointers
 217    are NOT associated.  If c_ptr_in_1 is non-NULL and it is not equal
 218    to c_ptr_in_2, then either c_ptr_in_2 is NULL or is associated with
 219    another address; either way, the two pointers are not associated
 220    with each other then.  */
 221
 222 GFC_LOGICAL_4
 223 ISO_C_BINDING_PREFIX (c_associated_2) (void *c_ptr_in_1, void *c_ptr_in_2)
 224 {
 225   /* Since we have the second arg, if it doesn't equal the first,
 226      return false; true otherwise.  However, if the first one is null,
 227      then return false; otherwise compare the two ptrs for equality.  */
 228   if (c_ptr_in_1 == NULL)
 229     return 0;
 230   else if (c_ptr_in_1 != c_ptr_in_2)
 231     return 0;
 232   else
 233     return 1;
 234 }