From 81fe126068202d9438b79730d3d42a0a62ac6b59 Mon Sep 17 00:00:00 2001
From: Riyyi <riyyi3@gmail.com>
Date: Fri, 26 Aug 2022 07:22:44 +0200
Subject: [PATCH] Emulator: Add cartridge ROM bank loading

---
 src/emu.cpp    | 11 ++++++++++-
 src/emu.h      |  2 ++
 src/loader.cpp | 44 ++++++++++++++++++++++++++++++++++++++++----
 src/loader.h   |  2 ++
 4 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/src/emu.cpp b/src/emu.cpp
index d646bac..db40a8e 100644
--- a/src/emu.cpp
+++ b/src/emu.cpp
@@ -12,6 +12,7 @@
 
 #include "cpu.h"
 #include "emu.h"
+#include "loader.h"
 #include "ruc/format/log.h"
 #include "ruc/format/print.h"
 #include "ruc/meta/assert.h"
@@ -56,11 +57,19 @@ void Emu::addMemorySpace(std::string_view name, uint32_t start_address, uint32_t
 	m_memory_spaces.emplace(name, std::move(memory_space));
 }
 
+void Emu::removeMemorySpace(std::string_view name)
+{
+	m_memory_spaces.erase(name);
+}
+
 void Emu::writeMemory(uint32_t address, uint32_t value)
 {
 	for (auto& memory_space : m_memory_spaces) {
 		auto& memory = memory_space.second;
-		if (address >= memory.start_address && address <= memory.end_address) {
+		if (address == 0xff50) {
+			Loader::the().disableBootrom();
+		}
+		else if (address >= memory.start_address && address <= memory.end_address) {
 			// Note: ECHO RAM hack
 			if (address >= 0xc000 && address <= 0xddff) {
 				writeMemory(address + (0xe000 - 0xc000), value);
diff --git a/src/emu.h b/src/emu.h
index 5a5f5d4..e78530e 100644
--- a/src/emu.h
+++ b/src/emu.h
@@ -36,6 +36,7 @@ public:
 
 	void addProcessingUnit(std::string_view name, ProcessingUnit* processing_unit);
 	void addMemorySpace(std::string_view name, uint32_t start_address, uint32_t end_address, uint32_t amount_of_banks = 1);
+	void removeMemorySpace(std::string_view name);
 
 	void writeMemory(uint32_t address, uint32_t value);
 	uint32_t readMemory(uint32_t address) const;
@@ -43,6 +44,7 @@ public:
 	// -------------------------------------
 
 	ProcessingUnit* processingUnit(std::string_view name) const { return m_processing_units.at(name); }
+	MemorySpace memorySpace(std::string_view name) { return m_memory_spaces[name]; }
 
 private:
 	uint32_t m_frequency { 0 };
diff --git a/src/loader.cpp b/src/loader.cpp
index 6dfd322..5790362 100644
--- a/src/loader.cpp
+++ b/src/loader.cpp
@@ -5,6 +5,7 @@
  */
 
 #include <cstddef> // size_t
+#include <cstdint> // uint32_t
 
 #include "cpu.h"
 #include "emu.h"
@@ -22,6 +23,19 @@ void Loader::loadRom(std::string_view rom_path)
 	init();
 }
 
+void Loader::disableBootrom()
+{
+	Emu::the().removeMemorySpace("BOOTROM1");
+	Emu::the().removeMemorySpace("CARTHEADER");
+	Emu::the().removeMemorySpace("BOOTROM2");
+
+	// Load cartridge bank 0
+	Emu::the().addMemorySpace("CARTROM1", 0x0000, 0x3fff); // 16KiB
+	for (size_t i = 0x0000; i <= 0x3fff; ++i) {
+		Emu::the().writeMemory(i, m_rom_data[i]);
+	}
+}
+
 // -----------------------------------------
 
 void Loader::init()
@@ -40,9 +54,10 @@ void Loader::init()
 	// https://gbdev.io/pandocs/Power_Up_Sequence.html
 	Emu::the().addMemorySpace("BOOTROM1", 0x0000, 0x00ff); // 256B
 	loadCartridgeHeader();
-	Emu::the().addMemorySpace("BOOTROM2", 0x0200, 0x08ff);   // 1792B
+	Emu::the().addMemorySpace("BOOTROM2", 0x0200, 0x08ff); // 1792B
+	loadCartridgeBanks();
 	Emu::the().addMemorySpace("VRAM", 0x8000, 0x9fff, 2);    // 8KiB * 2 banks
-	Emu::the().addMemorySpace("CARDRAM", 0xa000, 0xbfff, 1); // 8KiB * ? banks, if any
+	Emu::the().addMemorySpace("CARTRAM", 0xa000, 0xbfff, 1); // 8KiB * ? banks, if any
 	Emu::the().addMemorySpace("WRAM1", 0xc000, 0xcfff);      // 4 KiB, Work RAM
 	Emu::the().addMemorySpace("WRAM2", 0xd000, 0xdfff, 7);   // 4 KiB * 7 banks, Work RAM
 	Emu::the().addMemorySpace("ECHORAM", 0xe000, 0xfdff);    // 7680B, Mirror of 0xc000~0xddff
@@ -84,9 +99,30 @@ void Loader::loadCartridgeHeader()
 		return;
 	}
 
-	Emu::the().addMemorySpace("CARTHEADER", 0x100, 0x14f);
+	Emu::the().addMemorySpace("CARTHEADER", 0x100, 0x14f); // 80B
 
-	for (size_t i = 0x100; i <= 0x14f; ++i) {
+	for (size_t i = 0x0100; i <= 0x014f; ++i) {
 		Emu::the().writeMemory(i, m_rom_data[i]);
 	}
 }
+
+void Loader::loadCartridgeBanks()
+{
+	if (m_rom_data.empty()) {
+		return;
+	}
+
+	uint32_t rom_size = 32 * 1024 * (1 << m_rom_data[0x0148]);
+	uint32_t rom_banks = rom_size / (16 * 1024) - 1;
+	Emu::the().addMemorySpace("CARTROM2", 0x4000, 0x7fff, rom_banks); // 16KiB * banks
+
+	// Load cartridge bank 1~NN
+	auto rom_memory_spaces = Emu::the().memorySpace("CARTROM2");
+	for (size_t i = 0; i < rom_banks; ++i) {
+		for (size_t i = 0x4000; i <= 0x7fff; ++i) {
+			Emu::the().writeMemory(i, m_rom_data[i]);
+		}
+		rom_memory_spaces.active_bank += 1;
+	}
+	rom_memory_spaces.active_bank = 0;
+}
diff --git a/src/loader.h b/src/loader.h
index 842337b..5200a7d 100644
--- a/src/loader.h
+++ b/src/loader.h
@@ -16,6 +16,7 @@ public:
 	Loader(s) {}
 
 	void loadRom(std::string_view rom_path);
+	void disableBootrom();
 
 	void setBootromPath(std::string_view bootrom_path) { m_bootrom_path = bootrom_path; }
 
@@ -25,6 +26,7 @@ private:
 	void destroy();
 
 	void loadCartridgeHeader();
+	void loadCartridgeBanks();
 
 	std::string_view m_bootrom_path;
 	std::string m_rom_data;