examples

commit 7f468e9155e4ea68b86dc56e85be7f29e832633c
parent 2ab69cd62797c8ed33a89ff22c276d609eb94ca2
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Thu, 25 Nov 2021 21:25:28 +0000

Add token threaded FORTH

Diffstat:
A
src/token-threaded-forth.cpp
 | 
92
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 92 insertions(+), 0 deletions(-)
diff --git a/src/token-threaded-forth.cpp b/src/token-threaded-forth.cpp
@@ -0,0 +1,92 @@
+#include <cstdint>
+#include <iostream>
+
+#define LITERAL(x) DOLIT, x
+
+enum : unsigned char
+{
+	EXIT,
+	DOLIT,
+	DUP,
+	PRINT,
+	CR,
+	ADD,
+	NEGATE,
+	INCREMENT,
+};
+
+int main()
+{
+	void const* const tokens[] =
+	{
+		&&exit,
+		&&dolit,
+		&&dup,
+		&&print,
+		&&cr,
+		&&add,
+		&&negate,
+		&&increment,
+	};
+	char const code[] =
+	{
+		LITERAL(6),
+		DUP,
+		PRINT,
+		CR,
+
+		LITERAL(101),
+		DUP,
+		PRINT,
+		CR,
+
+		ADD,
+		PRINT,
+		CR,
+
+		EXIT,
+	};
+	std::intptr_t stack[1024];
+	char const* return_stack[1024];
+	char const** ret = return_stack;
+
+	std::intptr_t* top = stack;
+	char const* instruction = code;
+
+next:
+	goto *tokens[*instruction++];
+
+dolit:
+	*top++ = *instruction++;
+	goto next;
+
+dup:
+	top[0] = top[-1];
+	++top;
+	goto next;
+
+print:
+	std::cout << *--top;
+	goto next;
+
+cr:
+	std::cout << std::endl;
+	goto next;
+
+increment:
+	top[-1]++;
+	goto next;
+
+add:
+	--top;
+	top[-1] = top[-1] + top[0];
+	goto next;
+
+negate:
+	top[-1] = -top[-1];
+	goto next;
+
+exit:
+	std::cout << "Done!" << std::endl;
+	return 0;
+}