Emulator: Add cli argument to specify bootrom path

When you see a 16-bit register wrapped by parentheses, its referencing
the value at the address the register is pointing to rather than the
address itself.

doc/terminology.org

@@ -36,7 +36,7 @@ We start counting from the right as bit *#0*!
 | register  |    8 | unsigned | r8        |      |  r8 |    r |     | Any of the registers         |                   |
 | register  |   16 | unsigned | r16       |      | r16 |   rr |     | Any of the registers         | little-endian     |
 | address   |    8 | unsigned | a8        |      |     |  (n) |     | Address at value             |                   |
-| address   |   16 | unsigned | a16       |  a16 | n16 | (nn) |  nn | Address at value             | little-endian     |
+| address   |   16 | unsigned | a16 or () |  a16 | n16 | (nn) |  nn | Address at value             | little-endian     |
 | immediate |    8 | signed   | s8        |   r8 |  e8 |    e |  dd | Next byte in memory          |                   |
 | immediate |    8 | unsigned | io8       | (a8) | n16 |  (n) |   n | 0xff00 + next byte in memory | write to I/O-port |
 | condition |      |          | <ZNHC>    |   NZ |  cc |      |   f | Execute if condition met     |                   |

src/cpu.cpp

@@ -72,24 +72,28 @@ void CPU::update()
 		case 0x06: ldi8(); break;
 		case 0x08: ldr16(); break;
 		case 0x0a: ldr8(); break;
+		case 0x0b: decr16(); break;
 		case 0x0d: dec8(); break;
 		case 0x0e: ldi8(); break;
 		case 0x11: ldi16(); break;
 		case 0x12: ldr8(); break;
 		case 0x16: ldi8(); break;
 		case 0x1a: ldr8(); break;
+		case 0x1b: decr16(); break;
 		case 0x1e: ldi8(); break;
 		case 0x20: jr8(); break;
 		case 0x21: ldi16(); break;
 		case 0x22: ldr8(); break;
 		case 0x26: ldi8(); break;
-		case 0x2a: ldr8(); break;
+		case 0x2a: lda8(); break;
+		case 0x2b: decr16(); break;
 		case 0x2e: ldi8(); break;
 		case 0x2f: misc(); break;
 		case 0x31: ldi16(); break;
 		case 0x32: ldr8(); break;
 		case 0x36: ldi8(); break;
 		case 0x3a: ldr8(); break;
+		case 0x3b: decr16(); break;
 		case 0x3e: ldi8(); break;
 		case 0x40: ldr8(); break;
 		case 0x41: ldr8(); break;
@@ -170,6 +174,8 @@ void CPU::update()
 	}
 }
 
+// -------------------------------------
+
 void CPU::add()
 {
 	uint8_t opcode = pcRead();
@@ -279,6 +285,38 @@ void CPU::lda8()
 	}
 }
 
+void CPU::decr16()
+{
+	uint8_t opcode = pcRead();
+	switch (opcode) {
+	case 0x0b: { // DEC BC
+		uint32_t data = (bc() - 1) & 0xffff;
+		m_c = data & 0xff;
+		m_b = data >> 8;
+		break;
+	}
+	case 0x1b: { // DEC DE
+		uint32_t data = (de() - 1) & 0xffff;
+		m_e = data & 0xff;
+		m_d = data >> 8;
+		break;
+	}
+	case 0x2b: { // DEC HL
+		uint32_t data = (hl() - 1) & 0xffff;
+		m_l = data & 0xff;
+		m_h = data >> 8;
+		break;
+	}
+	case 0x3b: /* DEC SP */ m_sp = (m_sp - 1) & 0xffff; break;
+	default:
+		VERIFY_NOT_REACHED();
+	}
+
+	m_wait_cycles += 8;
+}
+
+// -------------------------------------
+
 void CPU::ldi8()
 {
 	uint8_t opcode = pcRead();

src/cpu.h

@@ -33,6 +33,7 @@ public:
 	void xor8();
 
 	// 16-bit
+	void decr16();
 
 	// -------------------------------------
 	// Bit Operations Instructions

src/loader.cpp

@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2022 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <cstddef> // size_t
+
+#include "cpu.h"
+#include "emu.h"
+#include "loader.h"
+#include "ppu.h"
+#include "ruc/file.h"
+#include "ruc/format/print.h"
+
+void Loader::loadRom(std::string_view rom_path)
+{
+	if (!rom_path.empty()) {
+		m_rom_data = ruc::File(rom_path).data();
+	}
+
+	init();
+}
+
+// -----------------------------------------
+
+void Loader::init()
+{
+	destroy();
+
+	Emu::the().init(8000000);
+
+	CPU cpu(8000000);
+	PPU ppu(4000000);
+
+	Emu::the().addProcessingUnit("cpu", &cpu);
+	Emu::the().addProcessingUnit("ppu", &ppu);
+
+	// https://gbdev.io/pandocs/Memory_Map.html
+	// 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("VRAM", 0x8000, 0x9fff, 2);    // 8KiB * 2 banks
+	Emu::the().addMemorySpace("CARDRAM", 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
+	Emu::the().addMemorySpace("OAM", 0xfe00, 0xfe9f);        // 160B, Object Attribute Memory (VRAM Sprite Attribute Table)
+	Emu::the().addMemorySpace("Not Usable", 0xfea0, 0xfeff); // 96B, Nintendo probibits this area
+	Emu::the().addMemorySpace("IO", 0xff00, 0xff7f);         // 128B, I/O Registers
+	Emu::the().addMemorySpace("HRAM", 0xff80, 0xfffe);       // 127B, High RAM (CPU cache)
+	Emu::the().addMemorySpace("IE", 0xffff, 0xffff);         // 1B, Interrupt Enable register
+
+	// Load bootrom
+	auto bootrom = ruc::File(m_bootrom_path).data();
+	for (size_t i = 0; i < bootrom.length(); ++i) {
+		// Skip cartridge header memory range
+		if (i >= 0x0100 && i <= 0x01ff) {
+			continue;
+		}
+
+		Emu::the().writeMemory(i, bootrom[i]);
+	}
+
+	update();
+}
+
+void Loader::update()
+{
+	while (true) {
+		Emu::the().update();
+	}
+}
+
+void Loader::destroy()
+{
+	Emu::destroy();
+}
+
+void Loader::loadCartridgeHeader()
+{
+	if (m_rom_data.empty()) {
+		return;
+	}
+
+	Emu::the().addMemorySpace("CARTHEADER", 0x100, 0x14f);
+
+	for (size_t i = 0x100; i <= 0x14f; ++i) {
+		Emu::the().writeMemory(i, m_rom_data[i]);
+	}
+}

src/loader.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2022 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <string>
+#include <string_view>
+
+#include "ruc/singleton.h"
+
+class Loader final : public ruc::Singleton<Loader> {
+public:
+	Loader(s) {}
+
+	void loadRom(std::string_view rom_path);
+
+	void setBootromPath(std::string_view bootrom_path) { m_bootrom_path = bootrom_path; }
+
+private:
+	void init();
+	void update();
+	void destroy();
+
+	void loadCartridgeHeader();
+
+	std::string_view m_bootrom_path;
+	std::string m_rom_data;
+};

src/main.cpp

@@ -5,63 +5,24 @@
  * SPDX-License-Identifier: MIT
  */
 
-#include "cpu.h"
-#include "emu.h"
-#include "ppu.h"
-#include "ruc/file.h"
+#include "loader.h"
+#include "ruc/argparser.h"
 #include "ruc/format/print.h"
 #include "ruc/timer.h"
+#include <string_view>
 
-int main(int argc, char* argv[])
+int main(int argc, const char* argv[])
 {
-	(void)argc;
-	(void)argv;
+	std::string_view bootrom_path = "gbc_bios.bin";
+	std::string_view rom_path;
 
-	ruc::Timer t;
+	ruc::ArgParser argParser;
+	argParser.addOption(bootrom_path, 'b', "bootrom", nullptr, nullptr, "", ruc::ArgParser::Required::Yes);
+	argParser.addOption(rom_path, 'r', "rom", nullptr, nullptr, "", ruc::ArgParser::Required::Yes);
+	argParser.parse(argc, argv);
 
-	print("{}ms\n", t.elapsedNanoseconds() / 1000000.0);
-
-	Emu::the().init(8000000);
-
-	CPU cpu(8000000);
-	PPU ppu(4000000);
-
-	Emu::the().addProcessingUnit("cpu", &cpu);
-	Emu::the().addProcessingUnit("ppu", &ppu);
-
-	// https://gbdev.io/pandocs/Memory_Map.html
-	// https://gbdev.io/pandocs/Power_Up_Sequence.html
-	Emu::the().addMemorySpace("BOOTROM1", 0x0000, 0x00ff);   // 256B
-	Emu::the().addMemorySpace("BOOTROM2", 0x0200, 0x08ff);   // 1792B
-	Emu::the().addMemorySpace("VRAM", 0x8000, 0x9fff, 2);    // 8KiB * 2 banks
-	Emu::the().addMemorySpace("CARDRAM", 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
-	Emu::the().addMemorySpace("OAM", 0xfe00, 0xfe9f);        // 160B, Object Attribute Memory (VRAM Sprite Attribute Table)
-	Emu::the().addMemorySpace("Not Usable", 0xfea0, 0xfeff); // 96B, Nintendo probibits this area
-	Emu::the().addMemorySpace("IO", 0xff00, 0xff7f);         // 128B, I/O Registers
-	Emu::the().addMemorySpace("HRAM", 0xff80, 0xfffe);       // 127B, High RAM (CPU cache)
-	Emu::the().addMemorySpace("IE", 0xffff, 0xffff);         // 1B, Interrupt Enable register
-
-	// Load bootrom
-	auto bootrom = ruc::File("gbc_bios.bin").data();
-	for (size_t i = 0; i < bootrom.length(); ++i) {
-		// Skip cartridge header memory range
-		if (i >= 0x0100 && i <= 0x01ff) {
-			continue;
-		}
-
-		Emu::the().writeMemory(i, bootrom[i]);
-	}
-
-	// Get shared register
-	print("{}\n", *Emu::the().processingUnit("cpu")->sharedRegister("a"));
-	print("{}\n", *Emu::the().processingUnit("cpu")->sharedRegister("b"));
-
-	while (true) {
-		Emu::the().update();
-	}
+	Loader::the().setBootromPath(bootrom_path);
+	Loader::the().loadRom(rom_path);
 
 	return 0;
 }