aiie/apple/diskii.cpp
2017-12-30 20:22:22 -05:00

687 lines
18 KiB
C++

#include "diskii.h"
#ifdef TEENSYDUINO
#include <Arduino.h>
#else
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#endif
#include "applemmu.h" // for FLOATING
#include "globals.h"
#include "diskii-rom.h"
#define DISKIIMAGIC 0xAA
DiskII::DiskII(AppleMMU *mmu)
{
this->trackBuffer = new LRingBuffer(NIBTRACKSIZE);
this->rawTrackBuffer = (uint8_t *)malloc(4096);
this->mmu = mmu;
curPhase[0] = curPhase[1] = 0;
curHalfTrack[0] = curHalfTrack[1] = 0;
trackDirty = false;
trackToRead = -1;
trackToFlush = -1;
writeMode = false;
writeProt = false; // FIXME: expose an interface to this
readWriteLatch = 0x00;
disk[0] = disk[1] = -1;
indicatorIsOn[0] = indicatorIsOn[1] = 0;
selectedDisk = 0;
diskType[0] = diskType[1] = dosDisk;
}
DiskII::~DiskII()
{
delete this->trackBuffer; this->trackBuffer = NULL;
free(this->rawTrackBuffer); this->rawTrackBuffer = NULL;
}
bool DiskII::Serialize(int8_t fd)
{
/* Make sure to flush anything to disk first */
checkFlush(curHalfTrack[selectedDisk]>>1);
if (trackToFlush != -1) {
flushTrack(trackToFlush, diskToFlush);
}
trackToFlush = -1;
g_filemanager->writeByte(fd, DISKIIMAGIC);
g_filemanager->writeByte(fd, curHalfTrack[0]);
g_filemanager->writeByte(fd, curHalfTrack[1]);
g_filemanager->writeByte(fd, curPhase[0]);
g_filemanager->writeByte(fd, curPhase[1]);
g_filemanager->writeByte(fd, readWriteLatch);
g_filemanager->writeByte(fd, writeMode);
g_filemanager->writeByte(fd, writeProt);
// Don't save disk[0,1]; save their file names & cursors
g_filemanager->SerializeFile(fd, disk[0]);
g_filemanager->SerializeFile(fd, disk[1]);
g_filemanager->writeByte(fd, indicatorIsOn[0]);
g_filemanager->writeByte(fd, indicatorIsOn[1]);
g_filemanager->writeByte(fd, diskType[0]);
g_filemanager->writeByte(fd, diskType[1]);
g_filemanager->writeByte(fd, selectedDisk);
trackBuffer->Serialize(fd);
// FIXME: don't know if we need these
// trackDirty - should always be unset, since we just flushed
// rawTrackBuffer - only used when reading an image
// trackToRead - should be able to leave this unset & reread
// trackToFlush - just flushed
// diskToFlush - just flushed
g_filemanager->writeByte(fd, DISKIIMAGIC);
return true;
}
bool DiskII::Deserialize(int8_t fd)
{
/* Make sure to flush anything to disk first */
checkFlush(curHalfTrack[selectedDisk]>>1);
if (trackToFlush != -1) {
flushTrack(trackToFlush, diskToFlush);
}
trackToFlush = -1;
if (g_filemanager->readByte(fd) != DISKIIMAGIC) {
return false;
}
curHalfTrack[0] = g_filemanager->readByte(fd);
curHalfTrack[1] = g_filemanager->readByte(fd);
curPhase[0] = g_filemanager->readByte(fd);
curPhase[1] = g_filemanager->readByte(fd);
readWriteLatch = g_filemanager->readByte(fd);
writeMode = g_filemanager->readByte(fd);
writeProt = g_filemanager->readByte(fd);
disk[0] = g_filemanager->DeserializeFile(fd);
disk[1] = g_filemanager->DeserializeFile(fd);
indicatorIsOn[0] = g_filemanager->readByte(fd);
indicatorIsOn[1] = g_filemanager->readByte(fd);
diskType[0] = g_filemanager->readByte(fd);
diskType[1] = g_filemanager->readByte(fd);
selectedDisk = g_filemanager->readByte(fd);
trackBuffer->Deserialize(fd);
// Reset the dirty caches and whatnot
trackDirty = -1;
trackToRead = -1;
trackToFlush = -1;
diskToFlush = -1;
if (g_filemanager->readByte(fd) != DISKIIMAGIC) {
return false;
}
return true;
}
void DiskII::Reset()
{
curPhase[0] = curPhase[1] = 0;
curHalfTrack[0] = curHalfTrack[1] = 0;
trackDirty = false;
trackToRead = -1;
trackToFlush = -1;
writeMode = false;
writeProt = false; // FIXME: expose an interface to this
readWriteLatch = 0x00;
ejectDisk(0);
ejectDisk(1);
}
void DiskII::checkFlush(int8_t track)
{
if (trackDirty && trackToFlush == -1) {
diskToFlush = selectedDisk;
trackToFlush = track;
trackDirty = false; // just so we don't overwrite disk/track to flush before continuing...
}
}
uint8_t DiskII::readSwitches(uint8_t s)
{
switch (s) {
case 0x00: // change stepper motor phase
break;
case 0x01:
setPhase(0);
break;
case 0x02:
break;
case 0x03:
setPhase(1);
break;
case 0x04:
break;
case 0x05:
setPhase(2);
break;
case 0x06: // 3 off
break;
case 0x07: // 3 on
setPhase(3);
break;
case 0x08: // drive off
indicatorIsOn[selectedDisk] = 99;
g_display->setDriveIndicator(selectedDisk, false); // FIXME: after a spell...
checkFlush(curHalfTrack[selectedDisk]>>1);
break;
case 0x09: // drive on
indicatorIsOn[selectedDisk] = 100;
g_display->setDriveIndicator(selectedDisk, true);
break;
case 0x0A: // select drive 1
select(0);
break;
case 0x0B: // select drive 2
select(1);
break;
case 0x0C: // shift one read or write byte
readWriteLatch = readOrWriteByte();
break;
case 0x0D: // load data register (latch)
// This is complex and incomplete. cf. Logic State Sequencer,
// UTA2E, p. 9-14
if (!writeMode) {
if (isWriteProtected())
readWriteLatch |= 0x80;
else
readWriteLatch &= 0x7F;
}
break;
case 0x0E: // set read mode
setWriteMode(false);
break;
case 0x0F: // set write mode
setWriteMode(true);
break;
}
// FIXME: improve the spin-down here. We need a CPU cycle callback
// for some period of time instead of this silly decrement counter.
if (!indicatorIsOn[selectedDisk]) {
// printf("Unexpected read while disk isn't on?\n");
indicatorIsOn[selectedDisk] = 100;
g_display->setDriveIndicator(selectedDisk, true);
}
if (indicatorIsOn[selectedDisk] > 0 && indicatorIsOn[selectedDisk] < 100) {
// slowly spin it down...
if (--indicatorIsOn[selectedDisk] == 0) {
g_display->setDriveIndicator(selectedDisk, false);
}
}
// Any even address read returns the readWriteLatch (UTA2E Table 9.1,
// p. 9-12, note 2)
// if ((s & 1) == 0 && curHalfTrack[selectedDisk] <= 3) {
// printf("Read: %X\n", readWriteLatch);
// fflush(stdout);
// }
return (s & 1) ? FLOATING : readWriteLatch;
}
void DiskII::writeSwitches(uint8_t s, uint8_t v)
{
switch (s) {
case 0x00: // change stepper motor phase
break;
case 0x01:
setPhase(0);
break;
case 0x02:
break;
case 0x03:
setPhase(1);
break;
case 0x04:
break;
case 0x05:
setPhase(2);
break;
case 0x06: // 3 off
break;
case 0x07: // 3 on
setPhase(3);
break;
case 0x08: // drive off
break;
case 0x09: // drive on
break;
case 0x0A: // select drive 1
select(0);
break;
case 0x0B: // select drive 2
select(1);
break;
case 0x0C: // shift one read or write byte
readOrWriteByte();
break;
case 0x0D: // drive write
break;
case 0x0E: // set read mode
setWriteMode(false);
break;
case 0x0F: // set write mode
setWriteMode(true);
break;
}
// All writes update the latch
if (writeMode) {
readWriteLatch = v;
}
}
/* The Disk ][ has a stepper motor that moves the head across the tracks.
* Switches 0-7 turn off and on the four different magnet phases; pulsing
* from (e.g.) phase 0 to phase 1 makes the motor move up a track, and
* (e.g.) phase 1 to phase 0 makes the motor move down a track.
*
* Except that's not quite true: the stepper actually moves the head a
* _half_ track.
*
* This is a very simplified version of the stepper motor code. In theory,
* we should keep track of all 4 phase magnets; and then only move up or down
* a half track when two adjacent motors are on (not three adjacent motors;
* and not two opposite motors). But that physical characteristic isn't
* important for most diskettes, and our image formats aren't likely to
* be able to provide appropriate half-track data to the programs that played
* tricks with these half-tracks (for copy protection or whatever).
*
* This setPhase is only called when turning *on* a phase. It's assumed that
* something is turning *off* the phases correctly; and that the combination
* of the previous phase that was on and the current phase that's being turned
* on are reliable enough to determine direction.
*
* The _phase_delta array is four sets of offsets - one for each
* current phase, detailing what the step will be given the next
* phase. This kind of emulates the messiness of going from phase 0
* to 2 -- it's going to move forward two half-steps -- but then doing
* the same thing again is just going to move you back two half-steps...
*
*/
void DiskII::setPhase(uint8_t phase)
{
const int8_t _phase_delta[16] = { 0, 1, 2, -1, // prev phase 0 -> 0/1/2/3
-1, 0, 1, 2, // prev phase 1 -> 0/1/2/3
-2, -1, 0, 1, // prev phase 2 -> 0/1/2/3
1, -2, -1, 0 // prev phase 3 -> 0/1/2/3
};
int8_t prevPhase = curPhase[selectedDisk];
int8_t prevHalfTrack = curHalfTrack[selectedDisk];
curHalfTrack[selectedDisk] += _phase_delta[(prevPhase * 4) + phase];
curPhase[selectedDisk] = phase;
// Cap at 35 tracks (a normal disk size). Some drives let you go farther,
// and we could support that by increasing this limit - but the images
// would be different too, so there would be more work to abstract out...
if (curHalfTrack[selectedDisk] > 35 * 2 - 1) {
curHalfTrack[selectedDisk] = 35 * 2 - 1;
}
// Don't go past the innermost track, of course.
if (curHalfTrack[selectedDisk] < 0) {
curHalfTrack[selectedDisk] = 0;
// recalibrate! This is where the fun noise goes DaDaDaDaDaDaDaDaDa
}
/*
printf("phase %d => %d; curHalfTrack %d => %d\n",
prevPhase, curPhase[selectedDisk],
prevHalfTrack, curHalfTrack[selectedDisk]);
*/
if (curHalfTrack[selectedDisk]>>1 != prevHalfTrack>>1) {
// We're changing track - flush the old track back to disk
checkFlush(prevHalfTrack>>1);
// mark the new track to be read
trackToRead = curHalfTrack[selectedDisk]>>1;
}
}
bool DiskII::isWriteProtected()
{
return (writeProt ? 0xFF : 0x00);
}
void DiskII::setWriteMode(bool enable)
{
writeMode = enable;
}
static uint8_t _lc(char c)
{
if (c >= 'A' && c <= 'Z') {
c = c - 'A' + 'a';
}
return c;
}
static bool _endsWithI(const char *s1, const char *s2)
{
if (strlen(s2) > strlen(s1)) {
return false;
}
const char *p = &s1[strlen(s1)-1];
int16_t l = strlen(s2)-1;
while (l >= 0) {
if (_lc(*p--) != _lc(s2[l]))
return false;
l--;
}
return true;
}
void DiskII::insertDisk(int8_t driveNum, const char *filename, bool drawIt)
{
ejectDisk(driveNum);
disk[driveNum] = g_filemanager->openFile(filename);
if (drawIt)
g_display->drawDriveDoor(driveNum, false);
if (_endsWithI(filename, ".nib")) {
diskType[driveNum] = nibDisk;
} else if (_endsWithI(filename, ".po")) {
diskType[driveNum] = prodosDisk;
} else {
diskType[driveNum] = dosDisk;
#ifndef TEENSYDUINO
// debugging: make a nib copy of the image to play with
// convertDskToNib("/tmp/debug.nib");
#endif
}
}
void DiskII::ejectDisk(int8_t driveNum)
{
if (disk[driveNum] != -1) {
g_filemanager->closeFile(disk[driveNum]);
disk[driveNum] = -1;
g_display->drawDriveDoor(driveNum, true);
}
}
void DiskII::select(int8_t which)
{
if (which != 0 && which != 1)
return;
if (which != selectedDisk) {
indicatorIsOn[selectedDisk] = 0;
g_display->setDriveIndicator(selectedDisk, false);
checkFlush(curHalfTrack[selectedDisk]>>1);
// set the selected disk drive
selectedDisk = which;
// trackToRead = curHalfTrack[selectedDisk]>>1;
trackToRead = -1; // Assume we don't have to read anything on the
// newly selected drive. When we get the first
// read, we'll notice the track buffer is empty...
trackBuffer->clear();
}
}
uint8_t DiskII::readOrWriteByte()
{
if (disk[selectedDisk] == -1) {
return GAP;
}
if (writeMode && !writeProt) {
if (!trackBuffer->hasData()) {
// Error: writing to empty track buffer? That's a raw write w/o
// knowing where we are on the disk.
return GAP;
}
trackDirty = true;
// It's possible that a badly behaving OS could try to write more
// data than we have buffer to handle. Don't let it. We should
// only need something like 500 bytes, at worst. In the typical
// case, we're talking about something like
//
// ~5 bytes of GAP
// 3 bytes of sector prolog
// 2 bytes of volume
// 2 bytes of track
// 2 bytes of sector
// 2 bytes of checksum
// 2 bytes of epilog
// ~5 bytes of GAP
// 3 bytes of data prolog
// 342 bytes of GRP-encoded (6:2) data
// 1 byte of checksum
// 3 bytes of epilog
// 1 byte of GAP
// == 373 bytes
//
// ... so if we get up to the full 1024 we've allocated, there's
// something suspicious happening.
if (readWriteLatch < 0x96) {
// Can't write a de-nibblized byte...
g_display->debugMsg("DII: bad write");
return 0;
}
trackBuffer->replaceByte(readWriteLatch);
return 0;
}
// trackToRead is -1 when we have a filled buffer, or we have no data at all.
// trackToRead is != -1 when we're flushing our buffer and re-filling it.
//
// Don't fill it right here, b/c we don't want to bog down the CPU
// thread/ISR.
if (trackToRead == curHalfTrack[selectedDisk]>>1) {// waiting for a read to complete for the current track
return GAP;
}
// return 0x00 every other byte. Helps the logic sequencer stay in sync.
// Otherwise we wind up waiting long periods of time for it to sync up,
// presumably because we're overrunning it (returning data faster than
// the actual drive would be able to)?
static bool whitespace = false;
if (whitespace) {
whitespace = false;
return 0x00;
}
whitespace = !whitespace;
if ((trackToRead != -1) || !trackBuffer->hasData()) {
checkFlush(curHalfTrack[selectedDisk]>>1);
// Need to read in a track of data and nibblize it. We'll return 0xFF
// until that completes.
// This might update trackToRead with a different track than the
// one we're reading. When we finish the read, we'll need to check
// to be sure that we're still trying to read the same track that
// we started with.
trackToRead = curHalfTrack[selectedDisk]>>1;
// While we're waiting for the sector to come around, we'll return
// GAP bytes.
return GAP;
}
return trackBuffer->peekNext();
}
void DiskII::fillDiskBuffer()
{
if (trackToFlush != -1) {
flushTrack(trackToFlush, diskToFlush); // in case it's dirty: flush before changing drives
trackBuffer->clear();
trackToFlush = -1;
}
// No work to do if trackToRead is -1
if (trackToRead == -1)
return;
trackDirty = false;
int8_t trackWeAreReading = trackToRead;
int8_t diskWeAreUsing = selectedDisk;
trackBuffer->clear();
trackBuffer->setPeekCursor(0);
if (diskType[diskWeAreUsing] == nibDisk) {
// Read one nibblized sector at a time and jam it in trackBuf
// directly. We don't read the whole track at once only because
// of RAM constraints on the Teensy. There's no reason we
// couldn't, though, if RAM weren't at a premium.
for (int i=0; i<16; i++) {
g_filemanager->seekBlock(disk[diskWeAreUsing], trackWeAreReading * 16 + i, true);
if (!g_filemanager->readBlock(disk[diskWeAreUsing], rawTrackBuffer, true)) {
// FIXME: error handling?
trackToRead = -1;
return;
}
trackBuffer->addBytes(rawTrackBuffer, 416);
}
} else {
// It's a .dsk / .po disk image. Read the whole track in to
// rawTrackBuffer and nibblize it.
g_filemanager->seekBlock(disk[diskWeAreUsing], trackWeAreReading * 16, false);
if (!g_filemanager->readTrack(disk[diskWeAreUsing], rawTrackBuffer, false)) {
// FIXME: error handling?
trackToRead = -1;
return;
}
nibblizeTrack(trackBuffer, rawTrackBuffer, diskType[diskWeAreUsing], curHalfTrack[selectedDisk]>>1);
}
// Make sure we're still intending to read the track we just read
if (trackWeAreReading != trackToRead ||
diskWeAreUsing != selectedDisk) {
// Abort and let it start over next time
return;
}
// Buffer is full, we're done - reset trackToRead and that will let the reads reach the CPU!
trackToRead = -1;
}
const char *DiskII::DiskName(int8_t num)
{
if (disk[num] != -1)
return g_filemanager->fileName(disk[num]);
return "";
}
void DiskII::loadROM(uint8_t *toWhere)
{
#ifdef TEENSYDUINO
Serial.println("loading DiskII rom");
for (uint16_t i=0; i<=0xFF; i++) {
toWhere[i] = pgm_read_byte(&romData[i]);
}
#else
printf("loading DiskII rom\n");
memcpy(toWhere, romData, 256);
#endif
}
void DiskII::flushTrack(int8_t track, int8_t sel)
{
// safety check: if we're write-protected, then how did we get here?
if (writeProt) {
g_display->debugMsg("Write Protected");
return;
}
if (!trackBuffer->hasData()) {
// Dunno what happened - we're writing but haven't initialized the sector buffer?
return;
}
if (diskType[sel] == nibDisk) {
// Write the whole track out exactly as we've got it. Hopefully
// someone has re-calcuated appropriate checksums on it...
g_display->debugMsg("Not writing Nib image");
return;
}
nibErr e = denibblizeTrack(trackBuffer, rawTrackBuffer, diskType[sel], curHalfTrack[selectedDisk]>>1);
switch (e) {
case errorShortTrack:
g_display->debugMsg("DII: short track");
trackBuffer->clear();
return;
case errorMissingSectors:
g_display->debugMsg("DII: missing sectors");
trackBuffer->clear();
break;
case errorNone:
break;
}
// ok, write the track!
g_filemanager->seekBlock(disk[sel], track * 16);
g_filemanager->writeTrack(disk[sel], rawTrackBuffer);
}