mirror of
https://github.com/sigmasternchen/fibonacci
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67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
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/*
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* This file uses C macros to generate the fibonacci sequence.
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*
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* Run with:
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* gcc -E -P macros.c | sed 's/\\n /\n/g'
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*/
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#define FIRST(a, ...) a
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#define SECOND(a, b, ...) b
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#define IS_PROBE(...) SECOND(__VA_ARGS__, 0)
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#define PROBE() ~, 1
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#define CAT(a, b) a ## b
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#define NOT(x) IS_PROBE(CAT(_NOT_, x))
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#define _NOT_0 PROBE()
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#define BOOL(x) NOT(NOT(x))
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#define IF_ELSE(condition) _IF_ELSE(BOOL(condition))
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#define _IF_ELSE(condition) CAT(_IF_, condition)
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#define _IF_1(...) __VA_ARGS__ _IF_1_ELSE
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#define _IF_0(...) _IF_0_ELSE
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#define _IF_1_ELSE(...)
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#define _IF_0_ELSE(...) __VA_ARGS__
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#define EMPTY()
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#define DEFER1(m) m EMPTY()
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#define DEFER2(m) m EMPTY EMPTY()()
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#define EVAL(...) EVAL1024(__VA_ARGS__)
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#define EVAL1024(...) EVAL512(EVAL512(__VA_ARGS__))
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#define EVAL512(...) EVAL256(EVAL256(__VA_ARGS__))
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#define EVAL256(...) EVAL128(EVAL128(__VA_ARGS__))
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#define EVAL128(...) EVAL64(EVAL64(__VA_ARGS__))
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#define EVAL64(...) EVAL32(EVAL32(__VA_ARGS__))
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#define EVAL32(...) EVAL16(EVAL16(__VA_ARGS__))
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#define EVAL16(...) EVAL8(EVAL8(__VA_ARGS__))
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#define EVAL8(...) EVAL4(EVAL4(__VA_ARGS__))
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#define EVAL4(...) EVAL2(EVAL2(__VA_ARGS__))
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#define EVAL2(...) EVAL1(EVAL1(__VA_ARGS__))
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#define EVAL1(...) __VA_ARGS__
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#define HAS_ARGS(...) BOOL(FIRST(_END_OF_ARGUMENTS_ __VA_ARGS__)())
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#define _END_OF_ARGUMENTS_() 0
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#define INC(a) CAT(a, I)
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#define ADD(a, b) a ## b
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#define ZERO
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#define ONE INC(ZERO)
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#define FIB(a, b, i, ...) a + b = ADD(a, b)\
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IF_ELSE(HAS_ARGS(__VA_ARGS__))(\
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\n \
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DEFER2(_FIB)()(b, ADD(a, b), __VA_ARGS__)\
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)(\
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/* ignore */\
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)
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#define _FIB() FIB
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EVAL(FIB(ONE, ONE, 1,2,3,4,5))
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