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NIB to DSK
This commit is contained in:
Ivan Izaguirre
parent
06704ed1e3
commit
9935510445
@ -44,7 +44,6 @@ func (c *cardBase) assign(a *Apple2, slot int) {
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if slot != 0 {
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if c.romCsxx != nil {
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// Relocate to the assigned slot
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//c.romCsxx.base = uint16(0xc000 + slot*0x100)
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c.romCsxx.setBase(uint16(0xc000 + slot*0x100))
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a.mmu.setCardROM(slot, c.romCsxx)
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}
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@ -11,12 +11,6 @@ type diskette16sector struct {
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position int
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}
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func newDisquette16Sector(f *fileNib) *diskette16sector {
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var d diskette16sector
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d.nib = f
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return &d
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}
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func (d *diskette16sector) powerOn(cycle uint64) {
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// Not used
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}
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@ -5,12 +5,6 @@ type diskette16sectorTimed struct {
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cycleOn uint64 // Cycle when the disk was last turned on
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}
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func newDisquette16SectorTimed(f *fileNib) *diskette16sectorTimed {
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var d diskette16sectorTimed
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d.nib = f
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return &d
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}
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func (d *diskette16sectorTimed) powerOn(cycle uint64) {
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d.cycleOn = cycle
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}
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118
fileNib.go
118
fileNib.go
@ -1,6 +1,8 @@
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package apple2
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import (
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"errors"
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"fmt"
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"os"
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)
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@ -100,6 +102,25 @@ var sixAndTwoTranslateTable = [0x40]byte{
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0xf7, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
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}
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var sixAndTwoUntranslateTable = [256]int16{
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, 0, 1, -1, -1, 2, 3, -1, 4, 5, 6,
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-1, -1, -1, -1, -1, -1, 7, 8, -1, -1, -1, 9, 10, 11, 12, 13,
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-1, -1, 14, 15, 16, 17, 18, 19, -1, 20, 21, 22, 23, 24, 25, 26,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 27, -1, 28, 29, 30,
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-1, -1, -1, 31, -1, -1, 32, 33, -1, 34, 35, 36, 37, 38, 39, 40,
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-1, -1, -1, -1, -1, 41, 42, 43, -1, 44, 45, 46, 47, 48, 49, 50,
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-1, -1, 51, 52, 53, 54, 55, 56, -1, 57, 58, 59, 60, 61, 62, 63,
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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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@ -112,8 +133,8 @@ func oddEvenEncodeByte(b byte) []byte {
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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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result[0]: 1-D7- 1-D5- 1-D3- 1-D1
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result[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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@ -121,6 +142,24 @@ func oddEvenEncodeByte(b byte) []byte {
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return e
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}
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func oddEvenDecodeByte(b0, b1 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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b0: 1-D7- 1-D5- 1-D3- 1-D1
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b1: 1-D6- 1-D4- 1-D2- 1-D0
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result: D7-D6-D5-D4-D3-D2-D1-D0
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*/
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return ((b0 & 0x55) << 1) | (b1 & 0x55)
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}
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const (
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diskPrologByte1 = uint8(0xd5)
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diskPrologByte2 = uint8(0xaa)
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diskPrologByte3Address = uint8(0x96)
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diskPrologByte3Data = uint8(0xad)
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)
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func nibEncodeTrack(data []byte, volume byte, track byte, logicalOrder *[16]int) []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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@ -135,7 +174,7 @@ func nibEncodeTrack(data []byte, volume byte, track byte, logicalOrder *[16]int)
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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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files they are in physical order.
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*/
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logicalSector := logicalOrder[physicalSector]
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sectorData := data[logicalSector*bytesPerSector : (logicalSector+1)*bytesPerSector]
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@ -181,3 +220,76 @@ func nibEncodeTrack(data []byte, volume byte, track byte, logicalOrder *[16]int)
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return b
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}
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func findProlog(diskPrologByte3 uint8, data []byte, position int) int {
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l := len(data)
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for i := position; i < l; i++ {
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if (data[i] == diskPrologByte1) &&
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(data[(i+1)%l] == diskPrologByte2) &&
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(data[(i+2)%l] == diskPrologByte3) {
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return (i + 3) % l
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}
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}
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return -1
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}
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func nibDecodeTrack(data []byte, track byte, logicalOrder *[16]int) ([]byte, error) {
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b := make([]byte, bytesPerTrack) // Buffer slice with enough capacity
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i := int(0)
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l := len(data)
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for {
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// Find address field prolog
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i = findProlog(diskPrologByte3Address, data, i)
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if i == -1 {
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break
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}
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// We just want the sector from the address field, we ignore the rest, no error detection
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sector := oddEvenDecodeByte(data[(i+4)%l], data[(i+5)%l])
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logicalSector := logicalOrder[sector]
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dst := int(logicalSector) * bytesPerSector
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fmt.Printf("Processing sector %v (%v), destination: %v\n", sector, logicalSector, dst)
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i = (i + 8 + 3) % l // We skip the four two byte fields and the epilog
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// Find data prolog
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i = findProlog(diskPrologByte3Data, data, i)
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// Read secondary buffer
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prevV := byte(0)
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for j := 0; j < secondaryBufferSize; j++ {
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w := sixAndTwoUntranslateTable[data[i%l]]
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if w == -1 {
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return nil, errors.New("Invalid byte from nib data")
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}
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v := byte(w) ^ prevV
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prevV = v
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for k := 0; k < 3; k++ {
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// The elements of the secondary buffer add two bits to three bytes
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offset := j + k*secondaryBufferSize
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if offset < bytesPerSector {
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b[dst+offset] |= ((v & 0x02) >> 1) | ((v & 0x01) << 1)
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}
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v >>= 2
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}
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i++
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}
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// Read primary buffer
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for j := 0; j < primaryBufferSize; j++ {
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w := sixAndTwoUntranslateTable[data[i%l]]
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if w == -1 {
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return nil, errors.New("Invalid byte from nib data")
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}
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v := byte(w) ^ prevV
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b[dst+j] |= v << 2 // The elements of the secondary buffer are the 6 MSB bits
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prevV = v
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i++
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}
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}
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return b, nil
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}
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25
fileNib_test.go
Normal file
25
fileNib_test.go
Normal file
@ -0,0 +1,25 @@
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package apple2
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import (
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"testing"
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)
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func TestNibBackAndForth(t *testing.T) {
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// Init data
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data := make([]byte, bytesPerTrack)
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for i := 0; i < bytesPerTrack; i++ {
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data[i] = byte(i % 100)
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}
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nib := nibEncodeTrack(data, 255, 0, &dos33SectorsLogicalOrder)
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data2, err := nibDecodeTrack(nib, 0, &dos33SectorsLogicalOrder)
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if err != nil {
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t.Error(err)
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}
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for i := 0; i < bytesPerTrack; i++ {
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if data[i] != data2[i] {
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t.Errorf("Mismatch in %v: %02x -> %02x", i, data[i], data2[i])
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}
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}
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}
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