style: rename "tools" -> "tools.h"

include/tools.h

@@ -0,0 +1,31 @@
+#pragma once
+#include "bit.h"
+#include "bit_impl.h"
+#include "wire.h"
+#include "register.h"
+#include "synchronize.h"
+#include "operator.h"
+
+using dark::Bit;
+using dark::sign_extend;
+using dark::zero_extend;
+
+using dark::Wire;
+using dark::Register;
+
+using dark::SyncTags;
+using dark::sync_member;
+using dark::Visitor;
+
+using dark::max_size_t;
+using dark::max_ssize_t;
+
+template <dark::concepts::bit_type _Tp>
+constexpr auto to_unsigned(const _Tp &x) {
+    return static_cast<dark::max_size_t>(x);
+}
+
+template <dark::concepts::bit_type _Tp>
+constexpr auto to_signed(const _Tp &x) {
+    return static_cast<dark::max_ssize_t>(to_unsigned(x));
+}