Refactor the Intel hex file loader into it's own class.

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>

src/IntelHexFile.cpp

@@ -0,0 +1,69 @@
+#include "stdafx.h"
+#include "IntelHexFile.h"
+
+#include <sstream>
+
+EightBit::IntelHexFile::IntelHexFile(std::string path)
+:	m_eof(false) {
+	m_file.open(path);
+}
+
+std::map<uint16_t, std::vector<uint8_t>> EightBit::IntelHexFile::parse() {
+
+	std::map<uint16_t, std::vector<uint8_t>> returned;
+
+	while (!m_file.eof() && !m_eof) {
+
+		std::string line;
+		std::getline(m_file, line);
+
+		const auto parsed = parse(line);
+		if (parsed.has_value())
+			returned[parsed.value().first] = parsed.value().second;
+	}
+
+	if (!m_eof)
+		throw std::out_of_range("File is missing an EOF record");
+
+	return returned;
+}
+
+std::optional<std::pair<uint16_t, std::vector<uint8_t>>> EightBit::IntelHexFile::parse(std::string line) {
+
+	const auto colon = line.substr(0, 1);
+	if (colon != ":")
+		throw std::out_of_range("Invalid hex file: line does not begin with a colon");
+
+	const auto countString = line.substr(1, 2);
+	const auto count = fromHex<uint8_t>(countString);
+
+	const auto addressString = line.substr(3, 4);
+	const auto address = fromHex<uint16_t>(addressString);
+
+	const auto recordTypeString = line.substr(7, 2);
+	const auto recordType = fromHex<uint8_t>(recordTypeString);
+
+	switch (recordType) {
+	case 0x00:
+		return std::make_pair(address, parseDataRecord(line, count));
+	case 0x01:
+		m_eof = true;
+		return {};
+	default:
+		throw std::out_of_range("Unhandled hex file record.");
+	}
+}
+
+std::vector<uint8_t> EightBit::IntelHexFile::parseDataRecord(std::string line, uint8_t count) {
+	std::vector<uint8_t> data(count);
+	const auto requiredLength = 9 + 2 + (count * 2);
+	if (line.length() != requiredLength)
+		throw std::out_of_range("Invalid hex file: line is not the required length");
+	for (int i = 0; i < count; ++i) {
+		const auto position = 9 + i * 2;
+		const auto datumString = line.substr(position, 2);
+		const auto datum = fromHex<uint8_t>(datumString);
+		data.at(i) = datum;
+	}
+	return data;
+}