[U-Boot] [PATCH 3/9] include: Add a variadic macro to call a callback for all arguments

[Marek Behún]

Add a header variadic-macro.h which defines the CALL_MACRO_FOR_EACH marco.

This macro can be used as follows:
  #define TEST(x)
  CALL_MACRO_FOR_EACH(TEST, a, b, c, d)

This will expand to
  TEST(a) TEST(b) TEST(c) TEST(d)

The nice thing is that CALL_MACRO_FOR_EACH is a variadic macro, thus the
number of arguments can vary (although it has an upper limit - in this
implementation 32 arguments).

Signed-off-by: Marek Behun <marek.behun at nic.cz>

 create mode 100644 include/u-boot/variadic-macro.h

diff --git a/include/u-boot/variadic-macro.h b/include/u-boot/variadic-macro.h
new file mode 100644
index 0000000000..922beafcea
--- /dev/null
+++ b/include/u-boot/variadic-macro.h
@@ -0,0 +1,59 @@
+/*
+ * Helper for work with variadic macros
+ *
+ * 2017 Marek Behun, CZ.NIC, marek.behun at nic.cz
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __VARIADIC_MACRO_H__
+#define __VARIADIC_MACRO_H__
+
+#define _VM_GET_NTH_ARG(_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, N, ...) N
+
+#define _VM_HELP_0(_call, ...)
+#define _VM_HELP_1(_call, x, ...) _call(x)
+#define _VM_HELP_2(_call, x, ...) _call(x) _VM_HELP_1(_call, __VA_ARGS__)
+#define _VM_HELP_3(_call, x, ...) _call(x) _VM_HELP_2(_call, __VA_ARGS__)
+#define _VM_HELP_4(_call, x, ...) _call(x) _VM_HELP_3(_call, __VA_ARGS__)
+#define _VM_HELP_5(_call, x, ...) _call(x) _VM_HELP_4(_call, __VA_ARGS__)
+#define _VM_HELP_6(_call, x, ...) _call(x) _VM_HELP_5(_call, __VA_ARGS__)
+#define _VM_HELP_7(_call, x, ...) _call(x) _VM_HELP_6(_call, __VA_ARGS__)
+#define _VM_HELP_8(_call, x, ...) _call(x) _VM_HELP_7(_call, __VA_ARGS__)
+#define _VM_HELP_9(_call, x, ...) _call(x) _VM_HELP_8(_call, __VA_ARGS__)
+#define _VM_HELP_10(_call, x, ...) _call(x) _VM_HELP_9(_call, __VA_ARGS__)
+#define _VM_HELP_11(_call, x, ...) _call(x) _VM_HELP_10(_call, __VA_ARGS__)
+#define _VM_HELP_12(_call, x, ...) _call(x) _VM_HELP_11(_call, __VA_ARGS__)
+#define _VM_HELP_13(_call, x, ...) _call(x) _VM_HELP_12(_call, __VA_ARGS__)
+#define _VM_HELP_14(_call, x, ...) _call(x) _VM_HELP_13(_call, __VA_ARGS__)
+#define _VM_HELP_15(_call, x, ...) _call(x) _VM_HELP_14(_call, __VA_ARGS__)
+#define _VM_HELP_16(_call, x, ...) _call(x) _VM_HELP_15(_call, __VA_ARGS__)
+#define _VM_HELP_17(_call, x, ...) _call(x) _VM_HELP_16(_call, __VA_ARGS__)
+#define _VM_HELP_18(_call, x, ...) _call(x) _VM_HELP_17(_call, __VA_ARGS__)
+#define _VM_HELP_19(_call, x, ...) _call(x) _VM_HELP_18(_call, __VA_ARGS__)
+#define _VM_HELP_20(_call, x, ...) _call(x) _VM_HELP_19(_call, __VA_ARGS__)
+#define _VM_HELP_21(_call, x, ...) _call(x) _VM_HELP_20(_call, __VA_ARGS__)
+#define _VM_HELP_22(_call, x, ...) _call(x) _VM_HELP_21(_call, __VA_ARGS__)
+#define _VM_HELP_23(_call, x, ...) _call(x) _VM_HELP_22(_call, __VA_ARGS__)
+#define _VM_HELP_24(_call, x, ...) _call(x) _VM_HELP_23(_call, __VA_ARGS__)
+#define _VM_HELP_25(_call, x, ...) _call(x) _VM_HELP_24(_call, __VA_ARGS__)
+#define _VM_HELP_26(_call, x, ...) _call(x) _VM_HELP_25(_call, __VA_ARGS__)
+#define _VM_HELP_27(_call, x, ...) _call(x) _VM_HELP_26(_call, __VA_ARGS__)
+#define _VM_HELP_28(_call, x, ...) _call(x) _VM_HELP_27(_call, __VA_ARGS__)
+#define _VM_HELP_29(_call, x, ...) _call(x) _VM_HELP_28(_call, __VA_ARGS__)
+#define _VM_HELP_30(_call, x, ...) _call(x) _VM_HELP_29(_call, __VA_ARGS__)
+#define _VM_HELP_31(_call, x, ...) _call(x) _VM_HELP_30(_call, __VA_ARGS__)
+
+#define CALL_MACRO_FOR_EACH(x, ...)					 \
+	_VM_GET_NTH_ARG("", ##__VA_ARGS__, _VM_HELP_31, _VM_HELP_30,	 \
+	_VM_HELP_29, _VM_HELP_28, _VM_HELP_27, _VM_HELP_26, _VM_HELP_25, \
+	_VM_HELP_24, _VM_HELP_23, _VM_HELP_22, _VM_HELP_21, _VM_HELP_20, \
+	_VM_HELP_19, _VM_HELP_18, _VM_HELP_17, _VM_HELP_16, _VM_HELP_15, \
+	_VM_HELP_14, _VM_HELP_13, _VM_HELP_12, _VM_HELP_11, _VM_HELP_10, \
+	_VM_HELP_9, _VM_HELP_8, _VM_HELP_7, _VM_HELP_6, _VM_HELP_5,	 \
+	_VM_HELP_4, _VM_HELP_3, _VM_HELP_2, _VM_HELP_1,			 \
+	_VM_HELP_0)(x, __VA_ARGS__)
+
+#endif /* __VARIADIC_MACRO_H__ */
-- 
2.13.5