--- mstools/h/varargs.h	2018/08/09 18:20:33	1.1.1.2
+++ mstools/h/varargs.h	2018/08/09 18:25:27	1.1.1.4
@@ -21,13 +21,23 @@ extern "C" {
 #endif
 
 #ifndef _VA_LIST_DEFINED
+
+#ifdef _ALPHA_
+typedef struct {
+    char *a0;           /* pointer to first homed integer argument */
+    int offset;         /* byte offset of next parameter */
+} va_list;
+
+#else
 typedef char *va_list;
+#endif
+
 #define _VA_LIST_DEFINED
 #endif
 
 
 
-#ifdef i386
+#ifdef _X86_
 /*
  * define a macro to compute the size of a type, variable or expression,
  * rounded up to the nearest multiple of sizeof(int). This number is its
@@ -43,15 +53,8 @@ typedef char *va_list;
 #define va_end(ap) ap = (va_list)0
 #endif
 
-#ifdef M_MRX000
 
-#define va_dcl int va_alist;
-#define va_start(ap) ap = (va_list)&va_alist
-#define va_arg(ap,t) *((t*)(_va_arg(&(ap),sizeof(t),(t*)0,(t*)0)))
-#define va_end(ap)
-
-#else
-#ifdef MIPS
+#if defined(_M_MRX000)
 #define va_dcl int va_alist;
 #define va_start(list) list = (char *) &va_alist
 #define va_end(list)
@@ -65,7 +68,37 @@ typedef char *va_list;
     use a pointer for array types
     +++++++++++++++++++++++++++++++++++++++++++ */
 #endif
+
+
+#ifdef _ALPHA_
+
+/*
+ * The Alpha compiler supports two builtin functions that are used to
+ * implement stdarg/varargs.  The __builtin_va_start function is used
+ * by va_start to initialize the data structure that locates the next
+ * argument.  The __builtin_isfloat function is used by va_arg to pick
+ * which part of the home area a given register argument is stored in.
+ * The home area is where up to six integer and/or six floating point
+ * register arguments are stored down (so they can also be referenced
+ * by a pointer like any arguments passed on the stack).
+ */
+
+#ifdef __cplusplus
+extern __builtin_va_start(va_list, ...);
 #endif
+#define va_dcl long va_alist;
+#define va_start(list) __builtin_va_start(list, va_alist, 0)
+#define va_end(list)
+#define va_arg(list, mode) \
+    ( *(        ((list).offset += ((int)sizeof(mode) + 7) & -8) , \
+        (mode *)((list).a0 + (list).offset - \
+                    ((__builtin_isfloat(mode) && (list).offset <= (6 * 8)) ? \
+                        (6 * 8) + 8 : ((int)sizeof(mode) + 7) & -8) \
+                ) \
+       ) \
+    )
+
+#endif /* _ALPHA_ */
 
 
 #ifdef __cplusplus