Code to support DSK format disk images, not working yet
This commit is contained in:
Ivan Izaguirre
parent
cc45403b43
commit
62608d2e38
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@ -37,7 +37,9 @@ func (a *Apple2) AddDisk2(diskRomFile string, diskImage string) {
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d.cardBase.insert(a, 6)
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if diskImage != "" {
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d.drive[0].loadDisk(diskImage)
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diskette := loadDisquette(diskImage)
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//diskette.saveNib(diskImage + "bak")
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d.drive[0].insertDiskette(diskette)
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}
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}
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@ -15,8 +15,6 @@ NIB: 35 tracks 6656 bytes, 232960 bytes
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*/
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const maxHalfTrack = 68
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const bytesPerTrack = 6656
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const nibImageSize = 35 * bytesPerTrack
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type cardDisk2 struct {
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cardBase
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@ -25,13 +23,12 @@ type cardDisk2 struct {
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}
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type cardDisk2Drive struct {
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isLoaded bool
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diskette *diskette16sector
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currentPhase int
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power bool
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writeMode bool
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halfTrack int
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position int
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data *[]uint8
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}
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// type softSwitchR func(io *ioC0Page) uint8
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@ -102,16 +99,14 @@ func newCardDisk2(filename string) *cardDisk2 {
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c.ssr[0xC] = func(_ *ioC0Page) uint8 {
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//fmt.Printf("DISKII: Reading\n")
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drive := &c.drive[c.selected]
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if drive.isLoaded {
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track := drive.halfTrack / 2
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data := *drive.data
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value := data[track*bytesPerTrack+drive.position]
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//fmt.Printf("DISKII: Reading value 0x%02v from track %v, position %v\n", value, track, drive.position)
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drive.position = (drive.position + 1) % bytesPerTrack
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return value
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} else {
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return 0
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if drive.diskette == nil {
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return 0xff
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}
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track := drive.halfTrack / 2
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value, newPosition := drive.diskette.read(track, drive.position)
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drive.position = newPosition
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//fmt.Printf("DISKII: Reading value 0x%02v from track %v, position %v\n", value, track, drive.position)
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return value
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}
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c.ssw[0xC] = func(_ *ioC0Page, value uint8) {
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@ -176,27 +171,6 @@ func loadCardRom(filename string) []memoryPage {
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return memPages
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}
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func (d *cardDisk2Drive) loadDisk(filename string) {
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f, err := os.Open(filename)
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if err != nil {
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panic(err)
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}
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defer f.Close()
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stats, statsErr := f.Stat()
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if statsErr != nil {
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panic(err)
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}
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size := stats.Size()
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if size != nibImageSize {
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panic("Disk size with nib format has to be 232960 bytes")
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}
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bytes := make([]uint8, size)
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buf := bufio.NewReader(f)
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buf.Read(bytes)
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d.data = &bytes
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d.isLoaded = true
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func (d *cardDisk2Drive) insertDiskette(dt *diskette16sector) {
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d.diskette = dt
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}
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@ -0,0 +1,187 @@
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package apple2
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import (
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"os"
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)
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/* Info from:
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"Beneath Apple DOS" https://fabiensanglard.net/fd_proxy/prince_of_persia/Beneath%20Apple%20DOS.pdf
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https://github.com/TomHarte/CLK/wiki/Apple-GCR-disk-encoding
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*/
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const (
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numberOfTracks = 35
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numberOfSectors = 16
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bytesPerSector = 256
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bytesPerTrack = numberOfSectors * bytesPerSector
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nibBytesPerTrack = 6656
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nibImageSize = numberOfTracks * nibBytesPerTrack
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dskImageSize = numberOfTracks * numberOfSectors * bytesPerSector
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defaultVolumeTag = 254
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)
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type diskette16sector struct {
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track [numberOfTracks][]byte
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}
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func (d *diskette16sector) read(track int, position int) (value uint8, newPosition int) {
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value = d.track[track][position]
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newPosition = (position + 1) % nibBytesPerTrack
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return
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}
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func loadDisquette(filename string) *diskette16sector {
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var d diskette16sector
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f, err := os.Open(filename)
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if err != nil {
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panic(err)
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}
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defer f.Close()
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stats, statsErr := f.Stat()
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if statsErr != nil {
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panic(err)
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}
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size := stats.Size()
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if size == nibImageSize {
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// Load file already in nib format
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for i := 0; i < numberOfTracks; i++ {
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d.track[i] = make([]byte, nibBytesPerTrack)
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n, err := f.Read(d.track[i])
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if err != nil || n != nibBytesPerTrack {
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panic("Error loading file")
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}
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}
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} else if size == dskImageSize {
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// Load file in dsk format
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data := make([]byte, dskImageSize)
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n, err := f.Read(data)
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if err != nil || n != dskImageSize {
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panic("Error loading file")
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}
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// Convert to nib
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for i := 0; i < numberOfTracks; i++ {
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trackData := data[i*bytesPerTrack : (i+1)*bytesPerTrack]
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d.track[i] = nibEncodeTrack(trackData, defaultVolumeTag, byte(i))
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}
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} else {
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panic("Disk size with nib format has to be 232960 bytes")
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}
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return &d
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}
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func (d *diskette16sector) saveNib(filename string) {
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f, err := os.Create(filename)
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if err != nil {
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panic(err)
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}
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defer f.Close()
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for _, v := range d.track {
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_, err := f.Write(v)
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if err != nil {
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panic(err)
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}
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}
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}
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var dos33SectorsLogicOrder = [16]int{
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0x0, 0x7, 0xE, 0x6, 0xD, 0x5, 0xC, 0x4,
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0xB, 0x3, 0xA, 0x2, 0x9, 0x1, 0x8, 0xF,
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}
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var sixAndTwoTranslateTable = [0x40]byte{
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0x96, 0x97, 0x9a, 0x9b, 0x9d, 0x9e, 0x9f, 0xa6,
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0xa7, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb2, 0xb3,
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0xb4, 0xb5, 0xb6, 0xb7, 0xb9, 0xba, 0xbb, 0xbc,
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0xbd, 0xbe, 0xbf, 0xcb, 0xcd, 0xce, 0xcf, 0xd3,
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0xd6, 0xd7, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde,
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0xdf, 0xe5, 0xe6, 0xe7, 0xe9, 0xea, 0xeb, 0xec,
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0xed, 0xee, 0xef, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6,
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0xf7, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
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}
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const (
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gap1Len = 48
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gap2Len = 5
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primaryBufferSize = bytesPerSector
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secondaryBufferSize = bytesPerSector/3 + 1
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)
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func oddEvenEncodeByte(b byte) []byte {
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/*
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A byte is encoded in two bytes to make sure the bytes start with 1 and
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does not have two consecutive zeros.
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Data byte: D7-D6-D5-D4-D3-D2-D1-D0
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resutl[0]: 1-D7- 1-D5- 1-D3-1 -D1
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resutl[1]: 1-D6- 1-D4- 1-D2-1 -D0
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*/
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e := make([]byte, 2)
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e[0] = ((b >> 1) & 0x55) | 0xaa
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e[1] = (b & 0x55) | 0xaa
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return e
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}
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func nibEncodeTrack(data []byte, volume byte, track byte) []byte {
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b := make([]byte, 0, nibBytesPerTrack) // Buffer slice with enough capacity
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// Initialize gaps to be copied for each sector
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gap1 := make([]byte, gap1Len)
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for i := range gap1 {
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gap1[i] = 0xff
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}
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gap2 := make([]byte, gap2Len)
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for i := range gap2 {
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gap2[i] = 0xff
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}
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for physicalSector := byte(0); physicalSector < numberOfSectors; physicalSector++ {
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/* On the DSK file the sectors are in DOS3.3 logical order
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but on the physical encoded track as well as in the nib
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files they are in phisical order.
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*/
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logicalSector := dos33SectorsLogicOrder[physicalSector]
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sectorData := data[logicalSector*bytesPerSector : (logicalSector+1)*bytesPerSector]
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// 6and2 prenibbilizing.
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primaryBuffer := make([]byte, primaryBufferSize)
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secondaryBuffer := make([]byte, secondaryBufferSize)
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for i, v := range sectorData {
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// Primary buffer is easy: the 6 MSB
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primaryBuffer[i] = v >> 2
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// Secondary buffer: the 2 LSB reversed, shifted and in their place
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shift := uint((i / secondaryBufferSize) * 2)
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bit0 := ((v & 0x01) << 1) << shift
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bit1 := ((v & 0x02) >> 1) << shift
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position := i % secondaryBufferSize
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secondaryBuffer[position] |= bit0 | bit1
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}
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// Render sector
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// Address field
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b = append(b, gap1...)
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b = append(b, 0xd5, 0xaa, 0x96) // Address prolog
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b = append(b, oddEvenEncodeByte(volume)...) // 4-4 encoded volume
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b = append(b, oddEvenEncodeByte(track)...) // 4-4 encoded track
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b = append(b, oddEvenEncodeByte(physicalSector)...) // 4-4 encoded sector
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b = append(b, oddEvenEncodeByte(volume^track^physicalSector)...) // Checksum
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b = append(b, 0xde, 0xaa, 0xeb) // Epilog
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// Data field
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b = append(b, gap2...)
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b = append(b, 0xd5, 0xaa, 0xad) // Data prolog
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prevV := byte(0)
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for _, v := range secondaryBuffer {
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b = append(b, sixAndTwoTranslateTable[v|prevV])
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prevV = v
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}
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for _, v := range primaryBuffer {
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b = append(b, sixAndTwoTranslateTable[v|prevV])
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prevV = v
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}
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b = append(b, prevV) // Checksum
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b = append(b, 0xd5, 0xaa, 0xeb) // Data epilog
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}
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return b
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}
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