Modifying the manner in which memory is mapped, allows a fairly clean mechanism for loading Intel "hex" files.

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

src/Bus.cpp

@@ -1,5 +1,12 @@
 #include "stdafx.h"
 #include "Bus.h"
+#include "Ram.h"
+#include "EightBitCompilerDefinitions.h"
+
+#include <fstream>
+#include <cstdlib>
+#include <stdexcept>
+#include <cassert>
 
 uint8_t EightBit::Bus::read() {
 	ReadingByte.fire(EventArgs::empty());
@@ -18,3 +25,75 @@ void EightBit::Bus::write(const uint8_t value) {
 	DATA() = value;
 	write();
 }
+
+void EightBit::Bus::loadHexFile(const std::string path) {
+	const auto chunks = parseHexFile(path);
+	for (const auto& chunk : chunks) {
+		const auto address = chunk.first;
+		const auto content = chunk.second;
+		for (size_t i = 0; i != content.size(); ++i)
+			write(address + i, content[i]);
+		const auto mapped = mapping(address);
+		mapped.memory.load(content, address - mapped.begin);
+	}
+}
+
+std::map<uint16_t, std::vector<uint8_t>> EightBit::Bus::parseHexFile(const std::string path) {
+
+	std::ifstream file;
+	file.open(path);
+
+	std::map<uint16_t, std::vector<uint8_t>> returned;
+
+	bool eof = false;
+	while (!file.eof() && !eof) {
+
+		std::string line;
+		std::getline(file, 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 = (uint8_t)strtoul(countString.c_str(), nullptr, 16); 
+
+		const auto addressString = line.substr(3, 4);
+		const auto address = (uint16_t)strtoul(addressString.c_str(), nullptr, 16); 
+
+		const auto recordTypeString = line.substr(7, 2);
+		const auto recordType = strtoul(recordTypeString.c_str(), nullptr, 16);
+
+		switch (recordType) {
+		case 0x00: {
+				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 = (uint8_t)strtoul(datumString.c_str(), nullptr, 16);
+					data[i] = datum;
+				}
+				returned[address] = data;
+			}
+			break;
+		case 0x01:
+			eof = true;
+			break;
+		default:
+			throw std::out_of_range("Unhandled hex file record.");
+		}
+	}
+	return returned;
+}
+
+uint8_t& EightBit::Bus::reference(uint16_t address) {
+	const auto mapped = mapping(address);
+	const uint16_t offset = address - mapped.begin;
+	if (mapped.access == MemoryMapping::ReadOnly)
+		return DATA() = mapped.memory.peek(offset);
+	Ram& ram = (Ram&)(mapped.memory);
+	return ram.reference(offset);
+}

src/EightBit.vcxproj

@@ -144,6 +144,7 @@
     <ClInclude Include="..\inc\IntelProcessor.h" />
     <ClInclude Include="..\inc\LittleEndianProcessor.h" />
     <ClInclude Include="..\inc\Memory.h" />
+    <ClInclude Include="..\inc\MemoryMapping.h" />
     <ClInclude Include="..\inc\Processor.h" />
     <ClInclude Include="..\inc\Ram.h" />
     <ClInclude Include="..\inc\Register.h" />

src/EightBit.vcxproj.filters

@@ -53,6 +53,9 @@
     <ClInclude Include="..\inc\BigEndianProcessor.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\inc\MemoryMapping.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="stdafx.cpp">