1 files changed, 31 insertions, 0 deletions
diff --git a/lib/dhcp/utils.h b/lib/dhcp/utils.h
new file mode 100644
index 0000000..9016007
--- /dev/null
+++ b/lib/dhcp/utils.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2022 Johannes Stoelp
+
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <type_traits>
+
+// Convert from an underlying enum type into an enum variant.
+template<typename E>
+constexpr E from_raw(std::underlying_type_t<E> u) {
+    static_assert(std::is_enum_v<E>);
+    return static_cast<E>(u);
+}
+
+// Convert from an enum variant into an underlying enum type.
+template<typename E>
+constexpr std::underlying_type_t<E> into_raw(E e) {
+    static_assert(std::is_enum_v<E>);
+    return static_cast<std::underlying_type_t<E>>(e);
+}
+
+// Simple cyclic rotation hash function.
+constexpr u32 hash(const u8* data, usize len) {
+    u32 hash = 0xa5a55a5a /* seed */;
+    for (usize i = 0; i < len; ++i) {
+        hash += ((hash << 25) | (hash >> 7) /* rrot(7) */) ^ data[i];
+    }
+    return hash;
+}
+
+#endif