From f9928a1a08c57fe853888119a996c3acc98ee09d Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Fri, 14 Jan 2022 23:51:05 +0100
Subject: Initial version of nodemcuv2 dhcp server

Able to offer IP address + DNS/Gateway ...
Worked with devices at my hand.
---
 lib/dhcp/utils.h | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 lib/dhcp/utils.h

(limited to 'lib/dhcp/utils.h')

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
-- 
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