1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
/******************************************************************************
* *
* 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]
|