Improved explanation of __pure and __dead and put the defines back in.

Put undefines of ANSI qualifiers back in -- never meant to remove these
in the first place -- woops.

HAVE NOT put back the gcc -ansi re-definitions of ANSI qualifiers back.

diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h
index e2ecb7b..c976935 100644 (file)
--- a/sys/sys/cdefs.h
+++ b/sys/sys/cdefs.h
@@ -61,5 +61,33 @@
 #define        __CONCAT(x,y)   x/**/y
 #define        __STRING(x)     "x"
 
 #define        __CONCAT(x,y)   x/**/y
 #define        __STRING(x)     "x"
 

+/* delete ANSI C keywords */
+#define const                           
+#define inline
+#define signed
+#define volatile

 #endif /* !(__STDC__ || __cplusplus) */
 #endif /* !(__STDC__ || __cplusplus) */

+
+/*
+ * GCC has extensions for declaring functions as const (`pure' - always returns
+ * the same value given the same inputs, i.e., has no external state and
+ * no side effects) and volatile (nonreturning or `dead').
+ * These mainly affect optimization and warnings.  
+ *
+ * To facilitate portability of a non-standard extension we define __pure
+ * and __dead and use these for qualifying functions. Non-gcc compilers
+ * which have similar extensions can then define these appropriately.
+ *
+ * Unfortunately, GCC complains if these are used under strict ANSI mode 
+ * (`gcc -ansi -pedantic'), hence we need to define them only if compiling 
+ * without this.
+ */
+#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+#define __dead __volatile
+#define __pure __const
+#else
+#define __dead
+#define __pure
+#endif
+

 #endif /* !_CDEFS_H_ */
 #endif /* !_CDEFS_H_ */