45 lines
2.0 KiB
C
45 lines
2.0 KiB
C
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/*
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* This file is part of the coreboot project.
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*
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* Copyright 2014 Google Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __SRC_INCLUDE_BASE3_H__
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#define __SRC_INCLUDE_BASE3_H__
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/* We translate a floating pin (Z) as the ternary digit 2. */
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#define Z 2
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/*
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* This provides a variadic macro BASE3() that can be used to translate a set of
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* pin states into its base-3 integer representation, even in the context of a
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* static initializer. You can call it with any number of up to 6 arguments,
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* e.g. BASE3(1, Z) -> 5 or BASE3(0, Z, 1, 0) -> 21. Just don't look too closely
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* at how the sausage is made. (Pay extra attention to typos when expanding it!)
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*/
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#define _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5) arg0
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#define _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5) \
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(arg1 + (3 * _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5)))
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#define _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5) \
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(arg2 + (3 * _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5)))
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#define _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5) \
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(arg3 + (3 * _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5)))
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#define _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5) \
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(arg4 + (3 * _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5)))
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#define _BASE3_IMPL_6(arg0, arg1, arg2, arg3, arg4, arg5) \
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(arg5 + (3 * _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5)))
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#define _BASE3_IMPL(arg0, arg1, arg2, arg3, arg4, arg5, NARGS, ...) \
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_BASE3_IMPL##NARGS(arg0, arg1, arg2, arg3, arg4, arg5)
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#define BASE3(...) _BASE3_IMPL(__VA_ARGS__, _6, _5, _4, _3, _2, _1)
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#endif /* __SRC_INCLUDE_BASE3_H__ */
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