1 /* Implementation of the ISO_C_BINDING library helper functions.
2 Copyright (C) 2007 Free Software Foundation, Inc.
3 Contributed by Christopher Rickett.
5 This file is part of the GNU Fortran 95 runtime library (libgfortran).
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.
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
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.
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. */
32 /* Implement the functions and subroutines provided by the intrinsic
33 iso_c_binding module. */
37 #include "libgfortran.h"
38 #include "iso_c_binding.h"
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). */
58 ISO_C_BINDING_PREFIX (c_f_pointer) (void *c_ptr_in,
59 gfc_array_void *f_ptr_out,
61 int type, int elemSize)
65 f_ptr_out->offset = 0;
67 /* Set the necessary dtype field for all pointers. */
70 /* Put in the element size. */
71 f_ptr_out->dtype = f_ptr_out->dtype | (elemSize << GFC_DTYPE_SIZE_SHIFT);
73 /* Set the data type (e.g., GFC_DTYPE_INTEGER). */
74 f_ptr_out->dtype = f_ptr_out->dtype | (type << GFC_DTYPE_TYPE_SHIFT);
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);
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. */
92 ISO_C_BINDING_PREFIX (c_f_pointer_u0) (void *c_ptr_in,
93 gfc_array_void *f_ptr_out,
99 GFC_DESCRIPTOR_DATA (f_ptr_out) = c_ptr_in;
103 f_ptr_out->offset = 0;
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++)
110 /* Lower bound is 1, as specified by the draft. */
111 f_ptr_out->dim[i].lbound = 1;
112 f_ptr_out->dim[i].ubound = ((int *) (shape->data))[i];
115 /* Set the offset and strides.
116 offset is (sum of (dim[i].lbound * dim[i].stride) for all
117 dims) the -1 means we'll back the data pointer up that much
118 perhaps we could just realign the data pointer and not change
120 f_ptr_out->dim[0].stride = 1;
121 f_ptr_out->offset = f_ptr_out->dim[0].lbound * f_ptr_out->dim[0].stride;
122 for (i = 1; i < shapeSize; i++)
124 f_ptr_out->dim[i].stride = (f_ptr_out->dim[i-1].ubound + 1)
125 - f_ptr_out->dim[i-1].lbound;
126 f_ptr_out->offset += f_ptr_out->dim[i].lbound
127 * f_ptr_out->dim[i].stride;
130 f_ptr_out->offset *= -1;
132 /* All we know is the rank, so set it, leaving the rest alone.
133 Make NO assumptions about the state of dtype coming in! If we
134 shift right by TYPE_SHIFT bits we'll throw away the existing
135 rank. Then, shift left by the same number to shift in zeros
136 and or with the new rank. */
137 f_ptr_out->dtype = ((f_ptr_out->dtype >> GFC_DTYPE_TYPE_SHIFT)
138 << GFC_DTYPE_TYPE_SHIFT) | shapeSize;
143 /* Sets the descriptor fields for a Fortran pointer to a derived type,
144 using c_f_pointer_u0 for the majority of the work. */
147 ISO_C_BINDING_PREFIX (c_f_pointer_d0) (void *c_ptr_in,
148 gfc_array_void *f_ptr_out,
149 const array_t *shape)
151 /* Set the common fields. */
152 ISO_C_BINDING_PREFIX (c_f_pointer_u0) (c_ptr_in, f_ptr_out, shape);
154 /* Preserve the size and rank bits, but reset the type. */
157 f_ptr_out->dtype = f_ptr_out->dtype & (~GFC_DTYPE_TYPE_MASK);
158 f_ptr_out->dtype = f_ptr_out->dtype
159 | (GFC_DTYPE_DERIVED << GFC_DTYPE_TYPE_SHIFT);
164 /* This function will change, once there is an actual f90 type for the
165 procedure pointer. */
168 ISO_C_BINDING_PREFIX (c_f_procpointer) (void *c_ptr_in,
169 gfc_array_void *f_ptr_out)
171 GFC_DESCRIPTOR_DATA(f_ptr_out) = c_ptr_in;
175 /* Test if the given c_ptr is associated or not. This function is
176 called if the user only supplied one c_ptr parameter to the
177 c_associated function. The second argument is optional, and the
178 Fortran compiler will resolve the function to this version if only
179 one arg was given. Associated here simply means whether or not the
180 c_ptr is NULL or not. */
183 ISO_C_BINDING_PREFIX (c_associated_1) (void *c_ptr_in_1)
185 if (c_ptr_in_1 != NULL)
192 /* Test if the two c_ptr arguments are associated with one another.
193 This version of the c_associated function is called if the user
194 supplied two c_ptr args in the Fortran source. According to the
195 draft standard (J3/04-007), if c_ptr_in_1 is NULL, the two pointers
196 are NOT associated. If c_ptr_in_1 is non-NULL and it is not equal
197 to c_ptr_in_2, then either c_ptr_in_2 is NULL or is associated with
198 another address; either way, the two pointers are not associated
199 with each other then. */
202 ISO_C_BINDING_PREFIX (c_associated_2) (void *c_ptr_in_1, void *c_ptr_in_2)
204 /* Since we have the second arg, if it doesn't equal the first,
205 return false; true otherwise. However, if the first one is null,
206 then return false; otherwise compare the two ptrs for equality. */
207 if (c_ptr_in_1 == NULL)
209 else if (c_ptr_in_1 != c_ptr_in_2)
216 /* Return the C address of the given Fortran procedure. This
217 routine is expected to return a derived type of type C_FUNPTR,
218 which represents the C address of the given Fortran object. */
221 ISO_C_BINDING_PREFIX (c_funloc) (void *f90_obj)
225 runtime_error ("C_LOC: Attempt to get C address for Fortran object"
226 " that has not been allocated or associated");
230 /* The "C" address should be the address of the object in Fortran. */