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