1 files changed, 106 insertions, 0 deletions
diff --git a/wire.c b/wire.c
new file mode 100644
index 0000000..e181d83
--- /dev/null
+++ b/wire.c
@@ -0,0 +1,106 @@
+#include <string.h>
+
+#include "wire.h"
+#include "error.h"
+
+#define WIRE_MAX 1024
+#define NODE_MAX 1024
+
+static size_t wire_count;
+static size_t node_count;
+
+static struct wire wires[WIRE_MAX];
+static struct node nodes[NODE_MAX];
+
+int
+wire_count_guard(void) {
+	if (wire_count >= WIRE_MAX) {
+		emit_error("Internal: too many wires\n");
+	}
+	return 1;
+}
+
+/* check if the nodes in a wire are allowed to be joined together */
+int
+wire_nodes_valid(struct wire *w) {
+	/* FIXME needs to be more explicit if more than NODE_OUTPUT and NODE_INPUT
+	 * out are added to node types */
+	if (w->b->type == w->b->type) {
+		emit_error("Cannot wire %sput to node of same type\n",
+		           w->a->type == NODE_OUTPUT ? "out" : "in" );
+		return 1;
+	}
+	return 0;
+}
+
+int
+wire_add(size_t aoffs, size_t boffs) {
+	struct wire w = {0};
+
+	if (wire_count_guard()) {
+		return 1;
+	}
+
+	if (aoffs >= NODE_MAX || boffs >= NODE_MAX) {
+		emit_error("Internal: cannot wire between node(s) outside allowable range\n");
+		return 1;
+	}
+
+	/* FIXME check that nodes are initialised? */
+
+	w.a = &nodes[aoffs];
+	w.b = &nodes[boffs];
+
+	if (wire_nodes_valid(&w)) {
+		return 1;
+	}
+
+	wires[wire_count++] = w;
+
+	return 0;
+}
+
+int
+node_update(void) {
+	size_t i = 0;
+	struct node *na;
+	struct node *nb;
+
+	if (wire_count_guard()) {
+		return 1;
+	}
+
+	for (i = 0; i < wire_count; i++) {
+		na = wires[i].a;
+		nb = wires[i].b;
+		if (na->type == NODE_OUTPUT && nb->type == NODE_INPUT) {
+			nb->value = na->value;
+		}
+
+		if (na->type == NODE_INPUT && nb->type == NODE_OUTPUT) {
+			na->value = nb->value;
+		}
+	}
+	return 0;
+}
+
+
+int
+tick(void) {
+	nodes[0].value = logic_not(nodes[0].value);
+	node_update();
+	return 0;
+}
+
+void
+wire_init(void) {
+	wire_count = 0;
+	memset(wires, 0, sizeof(wires));
+	memset(nodes, 0, sizeof(nodes));
+
+	/* zeroth node is the clock source */
+	node_count = 1;
+	nodes[0].type = NODE_OUTPUT;
+	nodes[0].value = 0;
+}
+