Switch to preferred Acorn-world extension: DAT.

Storage/MassStorage/Formats/DAT.cpp

@@ -0,0 +1,41 @@
+//
+//  DAT.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 31/01/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "DAT.hpp"
+
+using namespace Storage::MassStorage;
+
+DAT::DAT(const std::string &file_name) : file_(file_name) {
+	// Is the file a multiple of 256 bytes in size?
+	const auto file_size = file_.stats().st_size;
+	if(file_size & 255) throw std::exception();
+
+	// Does it contain the 'Hugo' signature?
+	file_.seek(0x201, SEEK_SET);
+	if(!file_.check_signature("Hugo")) {
+		throw std::exception();
+	}
+}
+
+size_t DAT::get_block_size() {
+	return 256;
+}
+
+size_t DAT::get_number_of_blocks() {
+	return size_t(file_.stats().st_size) / 256;
+}
+
+std::vector<uint8_t> DAT::get_block(size_t address) {
+	file_.seek(long(address * 256), SEEK_SET);
+	return file_.read(256);
+}
+
+void DAT::set_block(size_t address, const std::vector<uint8_t> &contents) {
+	file_.seek(long(address * 256), SEEK_SET);
+	file_.write(contents);
+}