[all] move min/max and upcast macros into common/util.h

common/include/common/util.h

@@ -0,0 +1,32 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * 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 2 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, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _H_LG_COMMON_UTIL_
+#define _H_LG_COMMON_UTIL_
+
+#define min(a,b) ({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); \
+    _a < _b ? _a : _b; })
+#define max(a,b) ({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); \
+    _a > _b ? _a : _b; })
+
+#define UPCAST(type, x) \
+  (type *)((uintptr_t)(x) - offsetof(type, base))
+
+#endif

common/src/rects.c

@@ -19,12 +19,10 @@
  */
 
 #include "common/rects.h"
+#include "common/util.h"
 
 #include <stdlib.h>
 
-#define min(a,b) ({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); _a < _b ? _a : _b; })
-#define max(a,b) ({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); _a > _b ? _a : _b; })
-
 struct Corner
 {
   int x;