mg2d: factor out the boundary condition-related API

1 files changed, 97 insertions, 0 deletions

diff --git a/mg2d_boundary.h b/mg2d_boundary.h
new file mode 100644
index 0000000..4a7dcee
--- /dev/null
+++ b/mg2d_boundary.h
@@ -0,0 +1,97 @@
+/*
+ * Boundary condition declaration.
+ * Copyright 2018 Anton Khirnov <anton@khirnov.net>
+ *
+ * This program 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MG2D_BOUNDARY_H
+#define MG2D_BOUNDARY_H
+
+#include <stddef.h>
+
+typedef struct MG2DBoundaryInternal MG2DBoundaryInternal;
+
+/**
+ * Type of the boundary condition on a given boundary.
+ */
+enum MG2DBCType {
+    /**
+     * The value of the unknown function is fixed on the boundary.
+     */
+    MG2D_BC_TYPE_FIXVAL,
+    /**
+     * The normal derivative of the unkown function is fixed on the boundary.
+     *
+     * TODO: the only supported value of the derivative is currently zero, i.e.
+     * periodic boundary conditions.
+     */
+    MG2D_BC_TYPE_FIXDIFF,
+};
+
+/**
+ * Location of the boundary.
+ */
+enum MG2DBoundaryLoc {
+    /**
+     * coord0 lower
+     */
+    MG2D_BOUNDARY_0L,
+    /**
+     * coord0 upper
+     */
+    MG2D_BOUNDARY_0U,
+    /**
+     * coord1 lower
+     */
+    MG2D_BOUNDARY_1L,
+    /**
+     * coord1 upper
+     */
+    MG2D_BOUNDARY_1U,
+};
+
+/**
+ * Boundary condition definition.
+ */
+typedef struct MG2DBoundary {
+    /**
+     * Type of the boundary condition.
+     */
+    enum MG2DBCType type;
+    /**
+     * For type = MG2D_BC_TYPE_FIXVAL:
+     *     Values of the unknown function on the boundary.
+     *     The number of boundary layers is equal to fd_stencil.
+     *     The first boundary layer has the number of points equal to the
+     *     corresponding domain_size. Each subsequent boundary layer has one
+     *     more boundary point at each end of the domain.
+     *
+     * Ignored otherwise.
+     */
+    double *val;
+    /**
+     * Number of elements between rows in val. I.e. if val[0] is the first
+     * boundary point, then val[val_stride - 1] is the first boundary point in
+     * the second row and so on.
+     */
+    size_t  val_stride;
+
+    /**
+     * Private data, not to be touched by callers.
+     */
+    MG2DBoundaryInternal *priv;
+} MG2DBoundary;
+
+#endif // MG2D_BOUNDARY_H