ported rewrite2 to c3

src/fifo.c3

@@ -0,0 +1,49 @@
+module fifo(<Type>);
+
+import std::core::mem;
+
+fault FifoErr {
+	FULL,
+	EMPTY,
+}
+
+// TODO: specify the allocator
+
+struct Fifo {
+	Type[] arr;
+	usz out;
+	usz count;
+}
+
+fn void! Fifo.init(&fifo, usz size)
+{
+	fifo.arr = mem::new_array(Type, size);
+	fifo.out = 0;
+	fifo.count = 0;
+}
+
+fn void Fifo.free(&fifo)
+{
+	(void)mem::free(fifo.arr);
+}
+
+fn void! Fifo.enqueue(&fifo, Type *elem)
+{
+	if (fifo.count >= fifo.arr.len) {
+		return FifoErr.FULL?;
+	}
+	usz in = (fifo.out + fifo.count) % fifo.arr.len;
+	fifo.arr[in] = *elem;
+	fifo.count++;
+}
+
+fn Type*! Fifo.dequeue(&fifo)
+{
+	if (fifo.count == 0) {
+		return FifoErr.EMPTY?;
+	}
+	Type *ret = &fifo.arr[fifo.out];
+	fifo.count--;
+	fifo.out = (fifo.out + 1) % fifo.arr.len;
+	return ret;
+}