X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=includes%2Fstdarg.h;h=62d0e404e36dbc80d1e0fdfb51e6f7edc04836ff;hb=refs%2Ftags%2FOLD;hp=ab5529aa2b3527d108f8caebf90cc2b86fca93f5;hpb=1e221deb9ee725a14b3656f94e2763f8faeb18dc;p=pdclib

diff --git a/includes/stdarg.h b/includes/stdarg.h
index ab5529a..62d0e40 100644
--- a/includes/stdarg.h
+++ b/includes/stdarg.h
@@ -1,15 +1,80 @@
-// ----------------------------------------------------------------------------
-// $Id$
-// ----------------------------------------------------------------------------
-// Public Domain C Library - http://pdclib.sourceforge.net
-// This code is Public Domain. Use, modify, and redistribute at will.
-// ----------------------------------------------------------------------------
-// TODO
-// ----------------------------------------------------------------------------
+/* ----------------------------------------------------------------------------
+ * $Id$
+ * ----------------------------------------------------------------------------
+ * Public Domain C Library - http://pdclib.sourceforge.net
+ * This code is Public Domain. Use, modify, and redistribute at will.
+ * ----------------------------------------------------------------------------
+ * Variable arguments
+ * ----------------------------------------------------------------------------
+ * This header is part of a freestanding implementation
+ * --------------------------------------------------------------------------*/
 
-#ifndef __STDARG_H
-#define __STDARG_H __STDARG_H
+#ifndef _STDARG_H
+#define _STDARG_H _STDARG_H
 
-// TODO
+/* TODO: This code was contributed by Michael Moody, who added:
+ * "As always with my code it's not guaranteed bug-free (In fact I know for a
+ * fact it won't work properly on certain archs)."
+ * Code assumes that:
+ * - arguments are passed on the stack;
+ * - arguments are alligned to pointer size.
+ */
 
-#endif // __STDARG_H
+/* ----------------------------------------------------------------------------
+ * TYPEDEFS
+ * --------------------------------------------------------------------------*/
+
+typedef char * va_list;
+
+/* ----------------------------------------------------------------------------
+ * MACROS
+ * --------------------------------------------------------------------------*/
+
+/** Returns the size of 'type' rounded up to the nearest multiple of the size
+ * of a pointer. This macro is just here for clarity.
+ */
+#define __va_round(type)                                                      \
+   (                                                                          \
+      (sizeof(type) + sizeof(void *) - 1) & ~(sizeof(void *) - 1)             \
+   )
+
+/** Initialises ap for use by va_arg by setting ap to point at the first
+ * argument in the ellipsis. parmN is the last known parameter in the function
+ * definition (ie the one before the ellipsis).
+ */
+#define va_start(ap, parmN)                                                   \
+   (                                                                          \
+      (ap) = (char *)&parmN + (__va_round(parmN))                               \
+      ,                                                                       \
+      (void)0                                                                 \
+   )
+
+/** Returns the next argument, assumed variable type is 'type', in the
+ * ellipsis.
+ */
+#define va_arg(ap, type)                                                      \
+   (                                                                          \
+      (ap) += (__va_round(type))                                              \
+      ,                                                                       \
+      (*(type*)((ap) - (__va_round(type))))                                   \
+   )
+
+/** Cleans up ap.
+ */
+#define va_end(ap)                                                            \
+   (                                                                          \
+      (ap) = (void *)0                                                        \
+      ,                                                                       \
+      (void)0                                                                 \
+   )
+
+/** Makes the va_list dest be a copy of the va_list src.
+ */
+#define va_copy(dest, src)                                                    \
+   (                                                                          \
+      (dest) = (src)                                                          \
+      ,                                                                       \
+      (void)0                                                                 \
+   )
+
+#endif /* _STDARG_H */