1  /* SPDX-License-Identifier: GPL-2.0-only */
 2  
 3  #ifndef __SRC_INCLUDE_BASE3_H__
 4  #define __SRC_INCLUDE_BASE3_H__
 5  
 6  /* We translate a floating pin (Z) as the ternary digit 2. */
 7  #define Z 2
 8  
 9  /*
10   * This provides a variadic macro BASE3() that can be used to translate a set of
11   * pin states into its base-3 integer representation, even in the context of a
12   * static initializer. You can call it with any number of up to 6 arguments,
13   * e.g. BASE3(1, Z) -> 5 or BASE3(0, Z, 1, 0) -> 21. Just don't look too closely
14   * at how the sausage is made. (Pay extra attention to typos when expanding it!)
15   */
16  #define _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5) arg0
17  #define _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5) \
18  	(arg1 + (3 * _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5)))
19  #define _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5) \
20  	(arg2 + (3 * _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5)))
21  #define _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5) \
22  	(arg3 + (3 * _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5)))
23  #define _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5) \
24  	(arg4 + (3 * _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5)))
25  #define _BASE3_IMPL_6(arg0, arg1, arg2, arg3, arg4, arg5) \
26  	(arg5 + (3 * _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5)))
27  #define _BASE3_IMPL(arg0, arg1, arg2, arg3, arg4, arg5, NARGS, ...) \
28  	_BASE3_IMPL##NARGS(arg0, arg1, arg2, arg3, arg4, arg5)
29  #define BASE3(...) _BASE3_IMPL(__VA_ARGS__, _6, _5, _4, _3, _2, _1)
30  
31  #endif /* __SRC_INCLUDE_BASE3_H__ */