1/* SPDX-License-Identifier: MIT */
2/*
3 * Copyright © 2024 Intel Corporation
4 */
5
6#ifndef _XE_ARGS_H_
7#define _XE_ARGS_H_
8
9#include <linux/args.h>
10
11/*
12 * Why don't the following macros have the XE prefix?
13 *
14 * Once we find more potential users outside of the Xe driver, we plan to move
15 * all of the following macros unchanged to linux/args.h.
16 */
17
18/**
19 * CALL_ARGS - Invoke a macro, but allow parameters to be expanded beforehand.
20 * @f: name of the macro to invoke
21 * @args: arguments for the macro
22 *
23 * This macro allows calling macros which names might generated or we want to
24 * make sure it's arguments will be correctly expanded.
25 *
26 * Example:
27 *
28 * #define foo X,Y,Z,Q
29 * #define bar COUNT_ARGS(foo)
30 * #define buz CALL_ARGS(COUNT_ARGS, foo)
31 *
32 * With above definitions bar expands to 1 while buz expands to 4.
33 */
34#define CALL_ARGS(f, args...) __CALL_ARGS(f, args)
35#define __CALL_ARGS(f, args...) f(args)
36
37/**
38 * DROP_FIRST_ARG - Returns all arguments except the first one.
39 * @args: arguments
40 *
41 * This helper macro allows manipulation the argument list before passing it
42 * to the next level macro.
43 *
44 * Example:
45 *
46 * #define foo X,Y,Z,Q
47 * #define bar CALL_ARGS(COUNT_ARGS, DROP_FIRST_ARG(foo))
48 *
49 * With above definitions bar expands to 3.
50 */
51#define DROP_FIRST_ARG(args...) __DROP_FIRST_ARG(args)
52#define __DROP_FIRST_ARG(a, b...) b
53
54/**
55 * FIRST_ARG - Returns the first argument.
56 * @args: arguments
57 *
58 * This helper macro allows manipulation the argument list before passing it
59 * to the next level macro.
60 *
61 * Example:
62 *
63 * #define foo X,Y,Z,Q
64 * #define bar FIRST_ARG(foo)
65 *
66 * With above definitions bar expands to X.
67 */
68#define FIRST_ARG(args...) __FIRST_ARG(args)
69#define __FIRST_ARG(a, b...) a
70
71/**
72 * LAST_ARG - Returns the last argument.
73 * @args: arguments
74 *
75 * This helper macro allows manipulation the argument list before passing it
76 * to the next level macro.
77 *
78 * Like COUNT_ARGS() this macro works up to 12 arguments.
79 *
80 * Example:
81 *
82 * #define foo X,Y,Z,Q
83 * #define bar LAST_ARG(foo)
84 *
85 * With above definitions bar expands to Q.
86 */
87#define LAST_ARG(args...) __LAST_ARG(args)
88#define __LAST_ARG(args...) PICK_ARG(COUNT_ARGS(args), args)
89
90/**
91 * PICK_ARG - Returns the n-th argument.
92 * @n: argument number to be returned
93 * @args: arguments
94 *
95 * This helper macro allows manipulation the argument list before passing it
96 * to the next level macro.
97 *
98 * Like COUNT_ARGS() this macro supports n up to 12.
99 * Specialized macros PICK_ARG1() to PICK_ARG12() are also available.
100 *
101 * Example:
102 *
103 * #define foo X,Y,Z,Q
104 * #define bar PICK_ARG(2, foo)
105 * #define buz PICK_ARG3(foo)
106 *
107 * With above definitions bar expands to Y and buz expands to Z.
108 */
109#define PICK_ARG(n, args...) __PICK_ARG(n, args)
110#define __PICK_ARG(n, args...) CALL_ARGS(CONCATENATE(PICK_ARG, n), args)
111#define PICK_ARG1(args...) FIRST_ARG(args)
112#define PICK_ARG2(args...) PICK_ARG1(DROP_FIRST_ARG(args))
113#define PICK_ARG3(args...) PICK_ARG2(DROP_FIRST_ARG(args))
114#define PICK_ARG4(args...) PICK_ARG3(DROP_FIRST_ARG(args))
115#define PICK_ARG5(args...) PICK_ARG4(DROP_FIRST_ARG(args))
116#define PICK_ARG6(args...) PICK_ARG5(DROP_FIRST_ARG(args))
117#define PICK_ARG7(args...) PICK_ARG6(DROP_FIRST_ARG(args))
118#define PICK_ARG8(args...) PICK_ARG7(DROP_FIRST_ARG(args))
119#define PICK_ARG9(args...) PICK_ARG8(DROP_FIRST_ARG(args))
120#define PICK_ARG10(args...) PICK_ARG9(DROP_FIRST_ARG(args))
121#define PICK_ARG11(args...) PICK_ARG10(DROP_FIRST_ARG(args))
122#define PICK_ARG12(args...) PICK_ARG11(DROP_FIRST_ARG(args))
123
124/**
125 * ARGS_SEP_COMMA - Definition of a comma character.
126 *
127 * This definition can be used in cases where any intermediate macro expects
128 * fixed number of arguments, but we want to pass more arguments which can
129 * be properly evaluated only by the next level macro.
130 *
131 * Example:
132 *
133 * #define foo(f) f(X) f(Y) f(Z) f(Q)
134 * #define bar DROP_FIRST_ARG(foo(ARGS_SEP_COMMA __stringify))
135 * #define buz CALL_ARGS(COUNT_ARGS, DROP_FIRST_ARG(foo(ARGS_SEP_COMMA)))
136 *
137 * With above definitions bar expands to
138 * "X", "Y", "Z", "Q"
139 * and buz expands to 4.
140 */
141#define ARGS_SEP_COMMA ,
142
143#endif
144

source code of linux/drivers/gpu/drm/xe/xe_args.h