[PATCH v2 1/2] drm/xe: Add helpers for manipulating macro arguments

[Lucas De Marchi]

On Thu, May 02, 2024 at 09:56:18PM GMT, Michal Wajdeczko wrote:
>Define generic helpers that will replace private definitions used
>by the RTP code and will allow reuse by the new code.
>
>Put them in new xe_args.h file (instead of infamous xe_macros.h)
>as once we find more potential users outside of the Xe driver we
>may want to move all of these macros as-is to linux/args.h.
>
>Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>Cc: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>---
>v2: don't pollute linux/args.h yet (Andy)
>---
> drivers/gpu/drm/xe/xe_args.h | 114 +++++++++++++++++++++++++++++++++++
> 1 file changed, 114 insertions(+)
> create mode 100644 drivers/gpu/drm/xe/xe_args.h
>
>diff --git a/drivers/gpu/drm/xe/xe_args.h b/drivers/gpu/drm/xe/xe_args.h
>new file mode 100644
>index 000000000000..6899fcc9405d
>--- /dev/null
>+++ b/drivers/gpu/drm/xe/xe_args.h
>@@ -0,0 +1,114 @@
>+/* SPDX-License-Identifier: MIT */
>+/*
>+ * Copyright © 2023 Intel Corporation
>+ */
>+
>+#ifndef _XE_ARGS_H_
>+#define _XE_ARGS_H_
>+

as Andy mentioned, we could add a comment here stating this can
eventually be moved to linux/args.h once more users show up.

or... once we start conflicting with other macros since we are not using
an XE_ prefix anymore.

>+#include <linux/args.h>
>+
>+/**
>+ * CALL_ARGS - Invoke a macro, but allow parameters to be expanded beforehand.
>+ * @f: name of the macro to invoke
>+ * @args: arguments for the macro
>+ *
>+ * This macro allows calling macros which names might generated or we want to
>+ * make sure it's arguments will be correctly expanded.
>+ *
>+ * Example:
>+ *
>+ *	#define foo	X,Y,Z,Q
>+ *	#define bar	COUNT_ARGS(foo)
>+ *	#define buz	CALL_ARGS(COUNT_ARGS, foo)
>+ *
>+ *	With above definitions bar expands to 1 while buz expands to 4.
>+ */
>+#define CALL_ARGS(f, args...)		__CALL_ARGS(f, args)
>+#define __CALL_ARGS(f, args...)		f(args)
>+
>+/**
>+ * DROP_FIRST - Returns all arguments except the first one.
>+ * @args: arguments
>+ *
>+ * This helper macro allows manipulation the argument list before passing it
>+ * to the next level macro.
>+ *
>+ * Example:
>+ *
>+ *	#define foo	X,Y,Z,Q
>+ *	#define bar	CALL_ARGS(COUNT_ARGS, DROP_FIRST(foo))
>+ *
>+ *	With above definitions bar expands to 3.
>+ */
>+#define DROP_FIRST(args...)		__DROP_FIRST(args)
>+#define __DROP_FIRST(a, b...)		b
>+
>+/**
>+ * PICK_FIRST - Returns the first argument.
>+ * @args: arguments
>+ *
>+ * This helper macro allows manipulation the argument list before passing it
>+ * to the next level macro.
>+ *
>+ * Example:
>+ *
>+ *	#define foo	X,Y,Z,Q
>+ *	#define bar	PICK_FIRST(foo)
>+ *
>+ *	With above definitions bar expands to X.
>+ */
>+#define PICK_FIRST(args...)		__PICK_FIRST(args)
>+#define __PICK_FIRST(a, b...)		a
>+
>+/**
>+ * PICK_LAST - Returns the last argument.
>+ * @args: arguments
>+ *
>+ * This helper macro allows manipulation the argument list before passing it
>+ * to the next level macro.
>+ *
>+ * Like COUNT_ARGS() this macro works up to 12 arguments.
>+ *
>+ * Example:
>+ *
>+ *	#define foo	X,Y,Z,Q
>+ *	#define bar	PICK_LAST(foo)
>+ *
>+ *	With above definitions bar expands to Q.
>+ */
>+#define PICK_LAST(args...)		__PICK_ARG(COUNT_ARGS(args), args)
>+#define __PICK_ARG(n, args...)		CALL_ARGS(CONCATENATE(PICK_ARG, n), args)
>+#define PICK_ARG1(args...)		PICK_FIRST(args)
>+#define PICK_ARG2(args...)		PICK_ARG1(DROP_FIRST(args))
>+#define PICK_ARG3(args...)		PICK_ARG2(DROP_FIRST(args))
>+#define PICK_ARG4(args...)		PICK_ARG3(DROP_FIRST(args))
>+#define PICK_ARG5(args...)		PICK_ARG4(DROP_FIRST(args))
>+#define PICK_ARG6(args...)		PICK_ARG5(DROP_FIRST(args))
>+#define PICK_ARG7(args...)		PICK_ARG6(DROP_FIRST(args))
>+#define PICK_ARG8(args...)		PICK_ARG7(DROP_FIRST(args))
>+#define PICK_ARG9(args...)		PICK_ARG8(DROP_FIRST(args))
>+#define PICK_ARG10(args...)		PICK_ARG9(DROP_FIRST(args))
>+#define PICK_ARG11(args...)		PICK_ARG10(DROP_FIRST(args))
>+#define PICK_ARG12(args...)		PICK_ARG11(DROP_FIRST(args))
>+
>+/**
>+ * ARGS_SEP_COMMA - Definition of a comma character.
>+ *
>+ * This definition can be used in cases where any intermediate macro expects
>+ * fixed number of arguments, but we want to pass more arguments which can
>+ * be properly evaluated only by the next level macro.
>+ *
>+ * Example:
>+ *
>+ *	#define foo(f)	f(X) f(Y) f(Z) f(Q)
>+ *	#define bar	DROP_FIRST(foo(ARGS_SEP_COMMA __stringify))
>+ *	#define buz	CALL_ARGS(COUNT_ARGS, DROP_FIRST(foo(ARGS_SEP_COMMA)))
>+ *
>+ *	With above definitions bar expands to
>+ *		"X", "Y", "Z", "Q"
>+ *	and buz expands to 4.
>+ */
>+#define ARGS_SEP_COMMA			,
>+
>+#endif	/* _LINUX_ARGS_H */

		^ wrong one, and anyway can be removed as we don't use
these comments in xe


Eventually we may also add a kunit to make sure we don't have surprises.
As long as the .o match on next patch, not required for now.

with those fixed:


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>


thanks
Lucas De Marchi

>-- 
>2.43.0
>