--- mstools/h/stdarg.h	2018/08/09 18:20:30	1.1.1.2
+++ mstools/h/stdarg.h	2018/08/09 18:23:03	1.1.1.3
@@ -1,7 +1,7 @@
 /***
 *stdarg.h - defines ANSI-style macros for variable argument functions
 *
-*	Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
+*	Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved.
 *
 *Purpose:
 *	This file defines ANSI-style macros for accessing arguments
@@ -19,11 +19,19 @@ extern "C" {
 
 
 #ifndef _VA_LIST_DEFINED
+#if	defined(_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 _M_IX86
 
 #define _INTSIZEOF(n)	( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 
 
@@ -33,13 +41,7 @@ typedef char *	va_list;
 
 #endif
 
-#ifdef M_MRX000
-#define va_start(ap,v) _va_start(&(ap),0)
-#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) || defined(_MIPS_)
 
 #define va_start(ap,v) ap  = (va_list)&v + sizeof(v)
 #define va_end(list)
@@ -56,8 +58,37 @@ typedef char *	va_list;
 
 
 #endif
+
+#if     defined (_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 _CFRONT
+extern __builtin_va_start(va_list, ...);
+#define __builtin_isfloat(a) __builtin_alignof(a)
 #endif
 
+#define va_start(list, v) __builtin_va_start(list, v, 1)
+#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