Add a bytecode interpreter.

I wrote it in C because I actually like programming in C. Turns out
setting up a Makefile is really easy too.

1 files changed, 93 insertions, 0 deletions

diff --git a/bytecode/oper.c b/bytecode/oper.c
new file mode 100644
index 0000000..ed4a681
--- /dev/null
+++ b/bytecode/oper.c
@@ -0,0 +1,93 @@
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "encoding.h"
+#include "panic.h"
+#include "slice.h"
+#include "value.h"
+
+#include "oper.h"
+
+struct st {
+	size_t i;
+	value locals[8];
+};
+
+static value read_arg(struct st *s, struct arg arg)
+{
+	if (arg.constant) {
+		return arg.constant;
+	}
+	return s->locals[arg.local];
+}
+
+static void alloc(struct st *s, struct op oper)
+{
+	s->locals[oper.alloc.out] = from_pointer(calloc(to_int(read_arg(s, oper.alloc.size)), sizeof(value)));
+}
+
+static void call(struct st *s)
+{
+	s->i = to_int(s->locals[0]);
+}
+
+static void poke(struct st *s, struct op oper)
+{
+	value *p = to_pointer(s->locals[oper.poke.pointer]);
+	p[oper.poke.offset] = read_arg(s, oper.poke.value);
+}
+
+static void peek(struct st *s, struct op oper)
+{
+	value *p = to_pointer(read_arg(s, oper.peek.value));
+	s->locals[oper.peek.out] = p[oper.peek.offset];
+}
+
+static void shuf(struct st *s, struct op oper)
+{
+	s->locals[oper.shuf.out] = read_arg(s, oper.shuf.value);
+}
+
+static void oexit(struct st *s, struct op oper)
+{
+	exit(to_int(read_arg(s, oper.exit.value)));
+}
+
+static void op(struct st *s, struct op oper)
+{
+	switch (oper.code) {
+	case OALLOC:
+		alloc(s, oper);
+		break;
+	case OCALL:
+		call(s);
+		break;
+	case OPOKE:
+		poke(s, oper);
+		break;
+	case OPEEK:
+		peek(s, oper);
+		break;
+	case OSHUF:
+		shuf(s, oper);
+		break;
+	case OEXIT:
+		oexit(s, oper);
+		break;
+	default:
+		panicf("Invalid op: %x\n", oper.code);
+	}
+}
+
+void run(struct slice prog)
+{
+	struct st s = {
+		.i = 0,
+		.locals = { 0 },
+	};
+	while (true) {
+		struct result oper = parse(slice1(prog, s.i));
+		s.i += oper.n;
+		op(&s, oper.op);
+	}
+}