gowin: Add GUI.

* Items such as LUT, DFF, MUX, ALU, IOB are displayed;
* Local wires, 1-2-4-8 wires are displayed;
* The clock spines, taps and branches are displayed with some caveats.

For now, you can not create a project in the GUI because of possible
conflict with another PR (about GW1NR-9C support), but you can specify
the board in the command line and load .JSON and .CST in the GUI.

Although ALUs are displayed, but the CIN and COUT wires are not. This is
still an unsolved problem.

Signed-off-by: YRabbit <rabbit@yrabbit.cyou>

1 files changed, 34 insertions, 0 deletions

diff --git a/gowin/cst.h b/gowin/cst.h
new file mode 100644
index 00000000..3fcfd663
--- /dev/null
+++ b/gowin/cst.h
@@ -0,0 +1,34 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Claire Xenia Wolf <claire@yosyshq.com>
+ *  Copyright (C) 2018  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 CST_H
+#define CST_H
+
+#include <iostream>
+#include "nextpnr.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+// Read the constraints file
+bool read_cst(Context *ctx, std::istream &in);
+
+NEXTPNR_NAMESPACE_END
+
+#endif