Add guid type

src/modules/kutil/guid.h

@@ -0,0 +1,38 @@
+#pragma once
+/// \file guid.h
+/// Definition of the guid type and related functions
+#include <stdint.h>
+#include "kutil/misc.h"
+
+namespace kutil {
+
+
+/// A GUID
+struct guid
+{
+	uint64_t a, b;
+};
+
+/// Make a GUID by writing it naturally-ordered in code:
+///  AAAAAAAA-BBBB-CCCC-DDDD-EEEEEEEEEEEE becomes:
+///  make_guid(0xAAAAAAAA, 0xBBBB, 0xCCCC, 0xDDDD, 0xEEEEEEEEEEEE);
+/// \returns  The guid object
+inline constexpr guid make_guid(uint32_t a, uint16_t b, uint16_t c, uint16_t d, uint64_t e)
+{
+	const uint64_t h =
+		static_cast<uint64_t>(c) << 48 |
+		static_cast<uint64_t>(b) << 32 |
+		a;
+
+	const uint64_t l =
+		static_cast<uint64_t>(byteswap(e & 0xffffffff)) << 32 |
+		(byteswap(e >> 32) & 0xffff0000) |
+		((d << 8) & 0xff00) | ((d >> 8) & 0xff);
+
+	return {h, l};
+}
+
+} // namespace kutil
+
+
+inline bool operator==(const kutil::guid &a, const kutil::guid &b) { return a.a == b.a && a.b == b.b; }