From c22f18f06001f7e87a861413d0f9e3d750b6c351 Mon Sep 17 00:00:00 2001
From: overflowerror <mail@overfloweror.com>
Date: Sat, 8 Aug 2020 22:02:27 +0200
Subject: [PATCH] added c-macro version

---
 c/macros.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 c/macros.c

diff --git a/c/macros.c b/c/macros.c
new file mode 100644
index 0000000..26a4e8e
--- /dev/null
+++ b/c/macros.c
@@ -0,0 +1,66 @@
+/*
+ * This file uses C macros to generate the fibonacci sequence.
+ *
+ * Run with:
+ * gcc -E -P macros.c | sed 's/\\n /\n/g'
+ */
+
+#define FIRST(a, ...) a
+#define SECOND(a, b, ...) b
+
+#define IS_PROBE(...) SECOND(__VA_ARGS__, 0)
+#define PROBE() ~, 1
+
+#define CAT(a, b) a ## b
+
+#define NOT(x) IS_PROBE(CAT(_NOT_, x))
+#define _NOT_0 PROBE()
+
+#define BOOL(x) NOT(NOT(x))
+
+#define IF_ELSE(condition) _IF_ELSE(BOOL(condition))
+#define _IF_ELSE(condition) CAT(_IF_, condition)
+
+#define _IF_1(...) __VA_ARGS__ _IF_1_ELSE
+#define _IF_0(...)             _IF_0_ELSE
+#define _IF_1_ELSE(...)
+#define _IF_0_ELSE(...) __VA_ARGS__
+
+#define EMPTY()
+
+#define DEFER1(m) m EMPTY()
+#define DEFER2(m) m EMPTY EMPTY()()
+
+#define EVAL(...) EVAL1024(__VA_ARGS__)
+#define EVAL1024(...) EVAL512(EVAL512(__VA_ARGS__))
+#define EVAL512(...) EVAL256(EVAL256(__VA_ARGS__))
+#define EVAL256(...) EVAL128(EVAL128(__VA_ARGS__))
+#define EVAL128(...) EVAL64(EVAL64(__VA_ARGS__))
+#define EVAL64(...) EVAL32(EVAL32(__VA_ARGS__))
+#define EVAL32(...) EVAL16(EVAL16(__VA_ARGS__))
+#define EVAL16(...) EVAL8(EVAL8(__VA_ARGS__))
+#define EVAL8(...) EVAL4(EVAL4(__VA_ARGS__))
+#define EVAL4(...) EVAL2(EVAL2(__VA_ARGS__))
+#define EVAL2(...) EVAL1(EVAL1(__VA_ARGS__))
+#define EVAL1(...) __VA_ARGS__
+
+#define HAS_ARGS(...) BOOL(FIRST(_END_OF_ARGUMENTS_ __VA_ARGS__)())
+#define _END_OF_ARGUMENTS_() 0
+
+#define INC(a) CAT(a, I)
+
+#define ADD(a, b) a ## b
+
+#define ZERO
+#define ONE INC(ZERO)
+
+#define FIB(a, b, i, ...) a + b = ADD(a, b)\
+IF_ELSE(HAS_ARGS(__VA_ARGS__))(\
+\n \
+DEFER2(_FIB)()(b, ADD(a, b), __VA_ARGS__)\
+)(\
+	/* ignore */\
+)
+#define _FIB() FIB
+
+EVAL(FIB(ONE, ONE, 1,2,3,4,5))