add support to MBC3 cartridges

README.md

@@ -6,7 +6,7 @@ Gameboy emulator in go
 * Joypad
 * Video
 * Timers
-* Support MBC1 & MBC2 roms
+* Support MBC1, MBC2 & MBC3 roms
 * Load saved games
 * Cpu test roms passed
 ### Tested Games
@@ -19,14 +19,16 @@ Gameboy emulator in go
 * The Legend of Zelda - Link's Awakening
 * The Final Fantasy Legend
 * Seiken Densetsu
+* Pokemon - Red Version
+* Pokemon - Gold Version
 
 ![out3](https://cloud.githubusercontent.com/assets/5223817/25020097/09d047b4-2085-11e7-87af-c88fafc6a51a.gif)
 ![out2](https://cloud.githubusercontent.com/assets/5223817/24856667/7309c2f0-1ddd-11e7-82f3-ff527d51b0d8.gif)
 ![out](https://cloud.githubusercontent.com/assets/5223817/23906938/74379006-08c7-11e7-9f99-e7e6121e1a64.gif)
 
 ## TODO:
 * STOP and HALT instructions
-* Support MBC3 & MBC5
+* Support MBC5
 * Sound
 
 ## Compile and run

gameboygo/MBC1_cart.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"io/ioutil"
 	"fmt"
 )
@@ -89,6 +90,9 @@ func (r *MBC1)ramWrite(addr uint16, b uint8) {
 func (r *MBC1)loadRam() {
 	newCartRam, err := ioutil.ReadFile(r.rom_file + "_save")
 	if err != nil {
+		if os.IsNotExist(err){
+			return	
+		}
 		fmt.Printf("ERROR reading cart Ram")
 		return
 	}

gameboygo/MBC2_cart.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"io/ioutil"
 	"fmt"
 )
@@ -68,6 +69,9 @@ func (r *MBC2)ramWrite(addr uint16, b uint8) {
 func (r *MBC2)loadRam() {
 	newCartRam, err := ioutil.ReadFile(r.rom_file + "_save")
 	if err != nil {
+		if os.IsNotExist(err){
+			return	
+		}
 		fmt.Printf("ERROR reading cart Ram")
 		return
 	}

gameboygo/MBC3_cart.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"os"
+	"io/ioutil"
+	"fmt"
+)
+
+type MBC3 struct {
+	rom_file  string
+	head      rom_header
+	RomData []uint8
+	cartRam []uint8
+	RTCregs []uint8
+	romBank   uint8
+	ramBank   uint8
+	mapRTC	  bool
+	ramRTCEnabled bool
+}
+func (r *MBC3)init(data []uint8, filename string) bool{
+	r.head.init(data)
+	r.rom_file = filename
+	r.romBank = 1
+	r.RTCregs = make([]uint8, 5)
+	r.cartRam = make([]uint8, 0x1FFF*4)
+	r.loadRam()
+	r.RomData = make([]uint8, len(data))
+	if num := copy(r.RomData, data); num != len(data){
+		return false
+	}
+	return true
+}
+func (r *MBC3)romRead(addr uint16) uint8 {
+	if addr >= 0x4000 {
+		return r.RomData[(0x4000 * uint32(r.romBank)) + (uint32(addr)-0x4000)]
+	}
+	return r.RomData[addr]
+}
+func (r *MBC3)romWrite(addr uint16, b uint8) {
+	if addr >= 0x2000 && addr <= 0x3FFF{
+		switch b & 0x7F{
+		case 0x00:
+			r.romBank = 0x01
+		default:
+			r.romBank = (b & 0x7F)
+		}
+	} else if addr >= 0x4000 && addr <= 0x5FFF{
+		if b >= 0x08 && b <= 0x0C{
+			r.mapRTC = true
+			r.ramBank = b
+			return
+		}
+		if b <= 0x03 {
+			r.mapRTC = false
+			r.ramBank = b
+		}
+	} else if addr >= 0x0000 && addr <= 0x1FFF{
+		//enable or disable ram
+		if b & 0x0F == 0x0A{
+			r.ramRTCEnabled = true
+		} else{
+			r.ramRTCEnabled = false
+		}
+	} else if addr >= 0x6000 && addr <= 0x7FFF{
+		if b == 0x01 {
+			//latch rtc
+		}
+	}
+}
+func (r *MBC3)ramRead(addr uint16) uint8 {
+	if !r.ramRTCEnabled {
+		return 0xFF
+	}
+	if r.mapRTC {
+		return r.RTCregs[r.ramBank - 0x08]
+	}
+	return r.cartRam[(0x1FFF * uint32(r.ramBank)) + (uint32(addr)-0xA000)]
+}
+func (r *MBC3)ramWrite(addr uint16, b uint8) {
+	if !r.ramRTCEnabled {
+		return
+	}
+	if r.mapRTC {
+		r.RTCregs[r.ramBank - 0x08] = b
+		return 
+	}
+	r.cartRam[(0x1FFF * uint32(r.ramBank)) + (uint32(addr)-0xA000)] = b
+}
+
+func (r *MBC3)loadRam() {
+	newCartRam, err := ioutil.ReadFile(r.rom_file + "_save")
+	if err != nil {
+		if os.IsNotExist(err){
+			return	
+		}
+		fmt.Printf("ERROR reading cart Ram")
+		return
+	}
+	if len(newCartRam) != len(r.cartRam) {
+		fmt.Printf("ERROR reading cart Ram")
+		return
+	}
+	r.cartRam = newCartRam
+}
+
+func (r *MBC3)saveCartRam() {
+	if err := ioutil.WriteFile(r.rom_file + "_save", r.cartRam, 0666); err != nil{
+		panic(err)
+	}
+}

gameboygo/rom.go

@@ -12,7 +12,6 @@ type rom_header struct{
 	ram_size 		uint8
 	header_checksum	uint8
 	version			uint8
-	rom_file		string
 }
 
 type Cart interface{
@@ -71,13 +70,12 @@ func Load_rom(filename string) bool{
 	}
 	switch RomData[0x147]{
 	case ROM_MBC1, ROM_MBC1_RAM, ROM_MBC1_RAM_BATT:
-		fmt.Printf("MBC1\n")
 		cart = new(MBC1)
 	case ROM_MBC2, ROM_MBC2_BATT:
-		fmt.Printf("MBC2\n")
 		cart = new(MBC2)
+	case ROM_MBC3_TIMER_BATT, ROM_MBC3_TIMER_RAM_BATT, ROM_MBC3, ROM_MBC3_RAM, ROM_MBC3_RAM_BATT:
+		cart = new(MBC3)
 	default:
-		fmt.Printf("Gen\n")
 		cart = new(genericCart)
 	}
 	if !cart.init(RomData, filename){