1 files changed, 15 insertions, 0 deletions
diff --git a/src/doomdef.h b/src/doomdef.h
index 37c6810c..bcd27e27 100644
--- a/src/doomdef.h
+++ b/src/doomdef.h
@@ -32,6 +32,21 @@
 #include <string.h>
 
 //
+// The packed attribute forces structures to be packed into the minimum 
+// space necessary.  If this is not done, the compiler may align structure
+// fields differently to optimise memory access, inflating the overall
+// structure size.  It is important to use the packed attribute on certain
+// structures where alignment is important, particularly data read/written
+// to disk.
+//
+
+#ifdef __GNUC__
+#define PACKEDATTR __attribute__((packed))
+#else
+#define PACKEDATTR
+#endif
+
+//
 // Global parameters/defines.
 //
 // DOOM version