From 0665de5951d9b1ea45d36a34c99da6c389e73c4e Mon Sep 17 00:00:00 2001
From: "Adrian.Conlon" <adrian.conlon@gmail.com>
Date: Thu, 7 Sep 2017 00:53:22 +0100
Subject: [PATCH] Make the base BUS architecture a little easier to work with.

Signed-off-by: Adrian.Conlon <adrian.conlon@gmail.com>
---
 inc/Memory.h   | 15 +++++++++++----
 inc/Ram.h      |  2 +-
 inc/Rom.h      |  2 +-
 src/Memory.cpp | 22 ++++++++++++++++------
 4 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/inc/Memory.h b/inc/Memory.h
index dbf0079..c53a609 100644
--- a/inc/Memory.h
+++ b/inc/Memory.h
@@ -6,12 +6,13 @@
 namespace EightBit {
 	class Memory {
 	public:
-		Memory(size_t size)
+		Memory(size_t size = 0)
 		: m_bytes(size) {
 		}
 
-		void load(const std::string& path, uint16_t offset = 0) {
-			loadBinary(path, m_bytes, offset, m_bytes.size() - offset);
+		int load(const std::string& path, int writeOffset = 0, int readOffset = 0, int limit = -1) {
+			const auto maximumSize = (int)m_bytes.size() - writeOffset;
+			return loadBinary(path, m_bytes, writeOffset, readOffset, limit, maximumSize);
 		}
 
 	protected:
@@ -26,6 +27,12 @@ namespace EightBit {
 		}
 
 	private:
-		static int loadBinary(const std::string& path, std::vector<uint8_t>& output, int offset = 0, int maximumSize = -1);
+		static int loadBinary(
+			const std::string& path,
+			std::vector<uint8_t>& output,
+			int writeOffset,
+			int readOffset,
+			int limit,
+			int maximumSize);
 	};
 }
\ No newline at end of file
diff --git a/inc/Ram.h b/inc/Ram.h
index 0a01af0..45526a5 100644
--- a/inc/Ram.h
+++ b/inc/Ram.h
@@ -6,7 +6,7 @@
 namespace EightBit {
 	class Ram : public Memory {
 	public:
-		Ram(size_t size)
+		Ram(size_t size = 0)
 		: Memory(size) {
 		}
 
diff --git a/inc/Rom.h b/inc/Rom.h
index e6235f9..5557de1 100644
--- a/inc/Rom.h
+++ b/inc/Rom.h
@@ -6,7 +6,7 @@
 namespace EightBit {
 	class Rom : public Memory {
 	public:
-		Rom(size_t size)
+		Rom(size_t size = 0)
 		: Memory(size) {
 		}
 
diff --git a/src/Memory.cpp b/src/Memory.cpp
index 3542922..3057297 100644
--- a/src/Memory.cpp
+++ b/src/Memory.cpp
@@ -4,22 +4,32 @@
 #include <iostream>
 #include <fstream>
 
-int EightBit::Memory::loadBinary(const std::string& path, std::vector<uint8_t>& output, int offset, int maximumSize) {
+int EightBit::Memory::loadBinary(
+		const std::string& path,
+		std::vector<uint8_t>& output,
+		int writeOffset,
+		int readOffset,
+		int limit,
+		int maximumSize) {
+
 	std::ifstream file;
 	file.exceptions(std::ios::failbit | std::ios::badbit);
 
 	file.open(path, std::ios::binary | std::ios::ate);
-	auto size = (int)file.tellg();
-	if ((maximumSize > 0) && (size > maximumSize))
+	const auto size = (int)file.tellg();
+	if ((maximumSize > 0) && ((size - readOffset) > maximumSize))
 		throw std::runtime_error("Binary cannot fit");
 
-	size_t extent = size + offset;
+	size_t extent = size + writeOffset;
 	if (output.size() < extent)
 		output.resize(extent);
 
-	file.seekg(0, std::ios::beg);
+	file.seekg(readOffset, std::ios::beg);
 
-	file.read((char*)&output[offset], size);
+	if ((limit < 0) || (limit > size))
+		limit = size;
+
+	file.read((char*)&output[writeOffset], limit);
 	file.close();
 
 	return size;