Add BaseClusterInfo for base implementation

Signed-off-by: gatecat <gatecat@ds0.me>

common/base_clusterinfo.h

@@ -0,0 +1,44 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2021  gatecat <gatecat@ds0.me>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#ifndef BASE_CLUSTERINFO_H
+#define BASE_CLUSTERINFO_H
+
+#include "idstring.h"
+#include "nextpnr_namespaces.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+struct CellInfo;
+
+// The 'legacy' cluster data, used for existing arches and to provide a basic implementation for arches without complex
+// clustering requirements
+struct BaseClusterInfo
+{
+    std::vector<CellInfo *> constr_children;
+    const int UNCONSTR = INT_MIN;
+    int constr_x = UNCONSTR;   // this.x - parent.x
+    int constr_y = UNCONSTR;   // this.y - parent.y
+    int constr_z = UNCONSTR;   // this.z - parent.z
+    bool constr_abs_z = false; // parent.z := 0
+};
+
+NEXTPNR_NAMESPACE_END
+
+#endif /* BASE_ARCH_H */