win32 port: added example for LWIP_PLATFORM_DIAG()

ports/win32/include/arch/cc.h

@@ -83,6 +83,13 @@ typedef int sys_prot_t;
 #define strdup   _strdup
 #endif
 
+/* Define an example for LWIP_PLATFORM_DIAG: since this uses varargs and the old
+ * C standard lwIP targets does not support this in macros, we have extra brackets
+ * around the arguments, which are left out in the following macro definition:
+ */
+void lwip_win32_platform_diag(const char *format, ...);
+#define LWIP_PLATFORM_DIAG(x) lwip_win32_platform_diag x
+
 #ifndef LWIP_NORAND
 extern unsigned int sys_win_rand(void);
 #define LWIP_RAND() (sys_win_rand())

ports/win32/sys_arch.c

@@ -752,3 +752,20 @@ lwip_win32_keypressed(char *key)
   }
   return 0;
 }
+
+#include <stdarg.h>
+
+/* This is an example implementation for LWIP_PLATFORM_DIAG:
+ * format a string and pass it to your output function.
+ */
+void
+lwip_win32_platform_diag(const char *format, ...)
+{
+  va_list ap;
+  /* get the varargs */
+  va_start(ap, format);
+  /* print via varargs; to use another output function, you could use
+     vsnprintf here */
+  vprintf(format, ap);
+  va_end(ap);
+}