DataArchive system which saves in native endian (for better performance working with local files), but is also able to load in any endian depending on archive's header information

1 files changed, 65 insertions, 0 deletions

diff --git a/core/src/Utils/IO/Archive.cpp b/core/src/Utils/IO/Archive.cpp
new file mode 100644
index 0000000..559c476
--- /dev/null
+++ b/core/src/Utils/IO/Archive.cpp
@@ -0,0 +1,65 @@
+#include "Archive.hpp"
+
+constexpr uint8_t kMagicNumbers[] = { 0x98, 0xd8, 0xa4, 0x65, 0x18, 0xa2, 0xd6, 0xa0 };
+constexpr size_t kMagicNumberCount = std::size(kMagicNumbers);
+
+constexpr uint8_t kByteOrderMark = []() {
+	switch (std::endian::native) {
+		case std::endian::little: return 0;
+		case std::endian::big: return 1;
+	}
+}();
+
+std::optional<DataArchive> DataArchive::SaveFile(const std::filesystem::path& path)
+{
+	auto archive = DataArchive(DataStream(std::fstream(path)));
+	auto& stream = archive.mStream;
+
+	stream.WriteBytes(kMagicNumberCount, kMagicNumbers);
+	stream.Write(kByteOrderMark);
+
+	stream.SetEndianness(std::endian::native);
+
+	return archive;
+}
+
+std::optional<DataArchive> DataArchive::LoadFile(const std::filesystem::path& path)
+{
+	auto archive = DataArchive(DataStream(std::fstream(path)));
+	auto& stream = archive.mStream;
+
+	uint8_t magicNumbers[kMagicNumberCount];
+	stream.ReadBytes(kMagicNumberCount, magicNumbers);
+
+	for (size_t i = 0; i < kMagicNumberCount; ++i) {
+		if (magicNumbers[i] != kMagicNumbers[i]) {
+			return {};
+		}
+	}
+
+	uint8_t byteOrderMark;
+	stream.Read(byteOrderMark);
+
+	switch (byteOrderMark) {
+		case 0: stream.SetEndianness(std::endian::little); break;
+		case 1: stream.SetEndianness(std::endian::big); break;
+		default: std::abort();
+	}
+
+	return archive;
+}
+
+const DataStream& DataArchive::GetStream() const
+{
+	return mStream;
+}
+
+DataStream& DataArchive::GetStream()
+{
+	return mStream;
+}
+
+DataArchive::DataArchive(DataStream stream)
+	: mStream(std::move(stream))
+{
+}