forked from nwidger/nintengo
/
rom.go
executable file
·349 lines (273 loc) · 6.09 KB
/
rom.go
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package nes
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"archive/zip"
"strings"
"github.com/nwidger/nintengo/rp2ago3"
"github.com/nwidger/nintengo/rp2cgo2"
)
//go:generate stringer -type=Region
type Region uint8
const (
NTSC Region = iota
PAL
)
type ROMFile struct {
gamename string
filename string
prgBanks uint16
chrBanks uint16
mirroring rp2cgo2.Mirroring
battery bool
trainer bool
fourScreen bool
vsCart bool
mapper uint8
ramBanks uint8
region Region
trainerData []uint8
wramBanks [][]uint8
romBanks [][]uint8
vromBanks [][]uint8
irq func(state bool)
setTables func(t0, t1, t2, t3 int)
}
type ROM interface {
rp2ago3.MappableMemory
Region() Region
String() string
GameName() string
LoadBattery()
SaveBattery() (err error)
}
func getBuf(filename string) (buf []byte, suffix string, err error) {
var r *zip.ReadCloser
var rc io.ReadCloser
switch {
case strings.HasSuffix(filename, ".nes"):
suffix = ".nes"
if strings.HasSuffix(filename, suffix) {
buf, err = ioutil.ReadFile(filename)
return
}
case strings.HasSuffix(filename, ".zip"):
suffix = ".zip"
// Open a zip archive for reading.
r, err = zip.OpenReader(filename)
if err != nil {
return
}
defer r.Close()
// Iterate through the files in the archive,
// printing some of their contents.
for _, f := range r.File {
if !strings.HasSuffix(f.Name, ".nes") {
continue
}
rc, err = f.Open()
if err != nil {
return
}
buf, err = ioutil.ReadAll(rc)
if err != nil {
return
}
rc.Close()
break
}
default:
err = errors.New("Unknown filetype, must be .nes or .zip")
}
return
}
func NewROM(filename string, irq func(state bool), setTables func(t0, t1, t2, t3 int)) (rom ROM, err error) {
var buf []byte
var suffix string
buf, suffix, err = getBuf(filename)
if err != nil {
return
}
romf, err := NewROMFile(buf)
if err != nil {
return
}
romf.irq = irq
romf.setTables = setTables
romf.filename = filename
romf.gamename = strings.TrimSuffix(romf.filename, suffix)
romf.setTables(romf.Tables())
switch romf.mapper {
case 0x00, 0x40, 0x41:
rom = NewNROM(romf)
case 0x01:
rom = NewMMC1(romf)
case 0x02, 0x42:
rom = NewUNROM(romf)
case 0x03, 0x43:
rom = NewCNROM(romf)
case 0x04:
rom = NewMMC3(romf)
case 0x07:
rom = NewANROM(romf)
case 0x09:
rom = NewMMC2(romf)
default:
err = errors.New(fmt.Sprintf("Unsupported mapper type %v", romf.mapper))
}
return
}
func NewROMFile(buf []byte) (romf *ROMFile, err error) {
var offset int
if len(buf) < 16 {
err = errors.New("Invalid ROM: Missing 16-byte header")
return
}
if string(buf[0:3]) != "NES" || buf[3] != 0x1a {
err = errors.New("Invalid ROM: Missing 'NES' constant in header")
return
}
romf = &ROMFile{}
i := 4
for ; i < 10; i++ {
byte := buf[i]
switch i {
case 4:
romf.prgBanks = uint16(byte)
case 5:
romf.chrBanks = uint16(byte)
case 6:
for j := 0; j < 4; j++ {
if byte&(0x01<<uint8(j)) != 0 {
switch j {
case 0:
romf.mirroring = rp2cgo2.Vertical
case 1:
romf.battery = true
case 2:
romf.trainer = true
case 3:
romf.fourScreen = true
romf.mirroring = rp2cgo2.FourScreen
}
}
}
romf.mapper = (byte >> 4) & 0x0f
case 7:
if byte&0x01 != 0 {
romf.vsCart = true
}
romf.mapper |= byte & 0xf0
case 8:
romf.ramBanks = byte
if romf.ramBanks == 0 {
romf.ramBanks = 1
}
case 9:
if byte&0x01 != 0 {
romf.region = PAL
}
}
}
i += 6
if romf.trainer {
offset = 512
if len(buf) < (i + offset) {
romf = nil
err = errors.New("Invalid ROM: EOF in trainer data")
return
}
romf.trainerData = buf[i : i+offset]
i += offset
}
offset = 1024 * 16
if len(buf) < (i + (offset * int(romf.prgBanks))) {
romf = nil
err = errors.New("Invalid ROM: EOF in ROM bank data")
return
}
romf.romBanks = make([][]uint8, romf.prgBanks)
for n := 0; n < int(romf.prgBanks); n++ {
romf.romBanks[n] = buf[i : i+offset]
i += offset
}
offset = 1024 * 8
if len(buf) < (i + (offset * int(romf.chrBanks))) {
romf = nil
err = errors.New("Invalid ROM: EOF in VROM bank data")
return
}
romf.vromBanks = make([][]uint8, romf.chrBanks)
for n := 0; n < int(romf.chrBanks); n++ {
romf.vromBanks[n] = buf[i : i+offset]
i += offset
}
offset = 1024 * 8
romf.wramBanks = make([][]uint8, romf.ramBanks)
for n := 0; n < int(romf.ramBanks); n++ {
romf.wramBanks[n] = make([]uint8, offset)
}
return
}
func (romf *ROMFile) Region() Region {
return romf.region
}
func (romf *ROMFile) Tables() (t0, t1, t2, t3 int) {
switch romf.mirroring {
case rp2cgo2.Horizontal:
t0, t1, t2, t3 = 0, 0, 1, 1
case rp2cgo2.Vertical:
t0, t1, t2, t3 = 0, 1, 0, 1
}
return
}
func (romf *ROMFile) String() string {
return fmt.Sprintf("PRG Banks: %v\n", romf.prgBanks) +
fmt.Sprintf("CHR Banks: %v\n", romf.chrBanks) +
fmt.Sprintf("Mirroring: %v\n", romf.mirroring) +
fmt.Sprintf("Battery: %v\n", romf.battery) +
fmt.Sprintf("Trainer: %v\n", romf.trainer) +
fmt.Sprintf("FourScreen: %v\n", romf.fourScreen) +
fmt.Sprintf("VS Cart: %v\n", romf.vsCart) +
fmt.Sprintf("RAM Banks: %v\n", romf.ramBanks) +
fmt.Sprintf("Region: %v\n", romf.region)
}
func (romf *ROMFile) GameName() string {
return romf.gamename
}
func (romf *ROMFile) LoadBattery() {
var ram []byte
if !romf.battery || romf.ramBanks == 0 {
return
}
savename := romf.gamename + ".sav"
ram, err := ioutil.ReadFile(savename)
if err != nil {
return
}
fmt.Println("*** Loading battery from " + savename)
for b := range romf.wramBanks {
for i := uint16(0); i < 0x2000; i++ {
romf.wramBanks[b][i] = ram[i]
}
}
return
}
func (romf *ROMFile) SaveBattery() (err error) {
if !romf.battery || romf.ramBanks == 0 {
return
}
savename := romf.gamename + ".sav"
fmt.Println("*** Saving battery to " + savename)
buf := bytes.Buffer{}
for b := range romf.wramBanks {
for i := uint16(0); i < 0x2000; i++ {
buf.WriteByte(romf.wramBanks[b][i])
}
}
err = ioutil.WriteFile(savename, buf.Bytes(), 0644)
return
}