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/******************************************************************************
* *
* N O T I C E *
* *
* Copyright Abandoned, 1987, Fred Fish *
* *
* *
* This previously copyrighted work has been placed into the public *
* domain by the author and may be freely used for any purpose, *
* private or commercial. *
* *
* Because of the number of inquiries I was receiving about the use *
* of this product in commercially developed works I have decided to *
* simply make it public domain to further its unrestricted use. I *
* specifically would be most happy to see this material become a *
* part of the standard Unix distributions by AT&T and the Berkeley *
* Computer Science Research Group, and a standard part of the GNU *
* system from the Free Software Foundation. *
* *
* I would appreciate it, as a courtesy, if this notice is left in *
* all copies and derivative works. Thank you. *
* *
* The author makes no warranty of any kind with respect to this *
* product and explicitly disclaims any implied warranties of mer- *
* chantability or fitness for any particular purpose. *
* *
******************************************************************************
*/
/*
* FILE
*
* vargs.h include file for environments without varargs.h
*
* SCCS
*
* @(#)vargs.h 1.2 5/8/88
*
* SYNOPSIS
*
* #include "vargs.h"
*
* DESCRIPTION
*
* This file implements a varargs macro set for use in those
* environments where there is no system supplied varargs. This
* generally works because systems which don't supply a varargs
* package are precisely those which don't strictly need a varargs
* package. Using this one then allows us to minimize source
* code changes. So in some sense, this is a "portable" varargs
* since it is only used for convenience, when it is not strictly
* needed.
*
*/
/*
* These macros allow us to rebuild an argument list on the stack
* given only a va_list. We can use these to fake a function like
* vfprintf, which gets a fixed number of arguments, the last of
* which is a va_list, by rebuilding a stack and calling the variable
* argument form fprintf. Of course this only works when vfprintf
* is not available in the host environment, and thus is not available
* for fprintf to call (which would give us an infinite loop).
*
* Note that ARGS_TYPE is a long, which lets us get several bytes
* at a time while also preventing lots of "possible pointer alignment
* problem" messages from lint. The messages are valid, because this
* IS nonportable, but then we should only be using it in very
* nonrestrictive environments, and using the real varargs where it
* really counts.
*
*/
#define ARG0 a0
#define ARG1 a1
#define ARG2 a2
#define ARG3 a3
#define ARG4 a4
#define ARG5 a5
#define ARG6 a6
#define ARG7 a7
#define ARG8 a8
#define ARG9 a9
#define ARGS_TYPE long
#define ARGS_LIST ARG0,ARG1,ARG2,ARG3,ARG4,ARG5,ARG6,ARG7,ARG8,ARG9
#define ARGS_DCL auto ARGS_TYPE ARGS_LIST
/*
* A pointer of type "va_list" points to a section of memory
* containing an array of variable sized arguments of unknown
* number. This pointer is initialized by the va_start
* macro to point to the first byte of the first argument.
* We can then use it to walk through the argument list by
* incrementing it by the size of the argument being referenced.
*/
typedef char *va_list;
/*
* The first variable argument overlays va_alist, which is
* nothing more than a "handle" which allows us to get the
* address of the first argument on the stack. Note that
* by definition, the va_dcl macro includes the terminating
* semicolon, which makes use of va_dcl in the source code
* appear to be missing a semicolon.
*/
#define va_dcl ARGS_TYPE va_alist;
/*
* The va_start macro takes a variable of type "va_list" and
* initializes it. In our case, it initializes a local variable
* of type "pointer to char" to point to the first argument on
* the stack.
*/
#define va_start(list) list = (char *) &va_alist
/*
* The va_end macro is a null operation for our use.
*/
#define va_end(list)
/*
* The va_arg macro is the tricky one. This one takes
* a va_list as the first argument, and a type as the second
* argument, and returns a value of the appropriate type
* while advancing the va_list to the following argument.
* For our case, we first increment the va_list arg by the
* size of the type being recovered, cast the result to
* a pointer of the appropriate type, and then dereference
* that pointer as an array to get the previous arg (which
* is the one we wanted.
*/
#define va_arg(list,type) ((type *) (list += sizeof (type)))[-1]
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