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aiie/apple/diskii.cpp
Jorj Bauer b6e475841e add lazy flushing
2020-06-28 08:28:49 -04:00

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#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 "appleui.h"
#include "diskii-rom.h"
#define DISKIIMAGIC 0xAA
// how many CPU cycles do we wait to spin down the disk drive? 1023000 == 1 second
#define SPINDOWNDELAY (1023000)
// 10 second delay before flushing
#define FLUSHDELAY (1023000 * 10)
DiskII::DiskII(AppleMMU *mmu)
{
this->mmu = mmu;
curPhase[0] = curPhase[1] = 0;
curHalfTrack[0] = curHalfTrack[1] = 0;
curWozTrack[0] = curWozTrack[1] = 0xFF;
writeMode = false;
writeProt = false; // FIXME: expose an interface to this
readWriteLatch = 0x00;
sequencer = 0;
dataRegister = 0;
driveSpinupCycles[0] = driveSpinupCycles[1] = 0;
deliveredDiskBits[0] = deliveredDiskBits[1] = 0;
disk[0] = disk[1] = NULL;
diskIsSpinningUntil[0] = diskIsSpinningUntil[1] = 0;
flushAt[0] = flushAt[1] = 0;
selectedDisk = 0;
}
DiskII::~DiskII()
{
}
bool DiskII::Serialize(int8_t fd)
{
g_filemanager->writeByte(fd, DISKIIMAGIC);
g_filemanager->writeByte(fd, readWriteLatch);
g_filemanager->writeByte(fd, sequencer);
g_filemanager->writeByte(fd, dataRegister);
g_filemanager->writeByte(fd, writeMode);
g_filemanager->writeByte(fd, writeProt);
g_filemanager->writeByte(fd, selectedDisk);
for (int i=0; i<2; i++) {
g_filemanager->writeByte(fd, curHalfTrack[i]);
g_filemanager->writeByte(fd, curWozTrack[i]);
g_filemanager->writeByte(fd, curPhase[i]);
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 56) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 48) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 40) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 32) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 24) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 16) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] >> 8) & 0xFF));
g_filemanager->writeByte(fd,
((driveSpinupCycles[i] ) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 56) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 48) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 40) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 32) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 24) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 16) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] >> 8) & 0xFF));
g_filemanager->writeByte(fd,
((deliveredDiskBits[i] ) & 0xFF));
g_filemanager->writeByte(fd,
(diskIsSpinningUntil[i] >> 24) & 0xFF);
g_filemanager->writeByte(fd,
(diskIsSpinningUntil[i] >> 16) & 0xFF);
g_filemanager->writeByte(fd,
(diskIsSpinningUntil[i] >> 8) & 0xFF);
g_filemanager->writeByte(fd,
(diskIsSpinningUntil[i] ) & 0xFF);
if (disk[i]) {
// Make sure we have flushed the disk images
disk[i]->flush();
flushAt[i] = 0; // and there's no need to re-flush them now
g_filemanager->writeByte(fd, 1);
// FIXME: this ONLY works for builds using the filemanager to read
// the disk image, so it's broken until we port Woz to do that!
const char *fn = disk[i]->diskName();
for (int j=0; j<strlen(fn); j++) {
g_filemanager->writeByte(fd, fn[j]);
}
g_filemanager->writeByte(fd, 0);
if (!disk[i]->Serialize(fd))
return false;
} else {
g_filemanager->writeByte(fd, 0);
}
}
g_filemanager->writeByte(fd, DISKIIMAGIC);
return true;
}
bool DiskII::Deserialize(int8_t fd)
{
if (g_filemanager->readByte(fd) != DISKIIMAGIC) {
return false;
}
readWriteLatch = g_filemanager->readByte(fd);
sequencer = g_filemanager->readByte(fd);
dataRegister = g_filemanager->readByte(fd);
writeMode = g_filemanager->readByte(fd);
writeProt = g_filemanager->readByte(fd);
selectedDisk = g_filemanager->readByte(fd);
for (int i=0; i<2; i++) {
curHalfTrack[i] = g_filemanager->readByte(fd);
curWozTrack[i] = g_filemanager->readByte(fd);
curPhase[i] = g_filemanager->readByte(fd);
driveSpinupCycles[i] = g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
driveSpinupCycles[i] <<= 8; driveSpinupCycles[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] = g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
deliveredDiskBits[i] <<= 8; deliveredDiskBits[i] |= g_filemanager->readByte(fd);
diskIsSpinningUntil[i] = g_filemanager->readByte(fd);
diskIsSpinningUntil[i] <<= 8; diskIsSpinningUntil[i] |= g_filemanager->readByte(fd);
diskIsSpinningUntil[i] <<= 8; diskIsSpinningUntil[i] |= g_filemanager->readByte(fd);
diskIsSpinningUntil[i] <<= 8; diskIsSpinningUntil[i] |= g_filemanager->readByte(fd);
if (disk[i])
delete disk[i];
if (g_filemanager->readByte(fd) == 1) {
disk[i] = new WozSerializer();
char buf[MAXPATH];
char c;
int ptr = 0;
while ( (c = g_filemanager->readByte(fd) != 0) ) {
buf[ptr++] = c;
}
buf[ptr] = 0;
if (buf[0]) {
// Important we don't read all the tracks, so we can also flush
// writes back to the fd...
disk[i]->readFile(buf, false, T_AUTO); // FIXME error checking
} else {
// ERROR: there's a disk but we don't have the path to its image?
return false;
}
if (!disk[i]->Deserialize(fd))
return false;
} else {
disk[i] = NULL;
}
}
if (g_filemanager->readByte(fd) != DISKIIMAGIC) {
return false;
}
return true;
}
void DiskII::Reset()
{
curPhase[0] = curPhase[1] = 0;
curHalfTrack[0] = curHalfTrack[1] = 0;
writeMode = false;
writeProt = false; // FIXME: expose an interface to this
readWriteLatch = 0x00;
ejectDisk(0);
ejectDisk(1);
}
void DiskII::driveOff()
{
diskIsSpinningUntil[selectedDisk] = g_cpu->cycles + SPINDOWNDELAY; // 1 second lag
if (diskIsSpinningUntil[selectedDisk] == -1 ||
diskIsSpinningUntil[selectedDisk] == 0)
diskIsSpinningUntil[selectedDisk] = 2; // fudge magic numbers; 0 is "off" and -1 is "forever".
// The drive-is-on-indicator is turned off later, when the disk
// actually spins down.
if (disk[selectedDisk]) {
flushAt[selectedDisk] = g_cpu->cycles + FLUSHDELAY;
if (flushAt[selectedDisk] == 0)
flushAt[selectedDisk] = 1; // fudge magic number; 0 is "don't flush"
}
}
void DiskII::driveOn()
{
if (diskIsSpinningUntil[selectedDisk] != -1) {
// If the drive isn't already spinning, then start keeping track of how
// many bits we've delivered (so we can honor the disk bit-delivery time
// that might be in the Woz disk image).
driveSpinupCycles[selectedDisk] = g_cpu->cycles;
deliveredDiskBits[selectedDisk] = 0;
diskIsSpinningUntil[selectedDisk] = -1; // magic "forever"
}
// FIXME: does the sequencer get reset? Maybe if it's the selected disk? Or no?
// sequencer = 0;
g_ui->drawOnOffUIElement(UIeDisk1_activity + selectedDisk, true); // FIXME: do we really want to update the UI from inside this thread?
}
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
driveOff();
break;
case 0x09: // drive on
driveOn();
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();
if (readWriteLatch & 0x80) {
// static uint32_t lastC = 0;
// printf("%u: read data\n", g_cpu->cycles - lastC);
// lastC = g_cpu->cycles;
if (!(sequencer & 0x80)) {
// printf("SEQ RESET EARLY [1]\n");
}
sequencer = 0;
}
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;
}
if (!(sequencer & 0x80)) {
// printf("SEQ RESET EARLY [2]\n");
}
sequencer = 0;
break;
case 0x0E: // set read mode
setWriteMode(false);
break;
case 0x0F: // set write mode
setWriteMode(true);
break;
}
// Any even address read returns the readWriteLatch (UTA2E Table 9.1,
// p. 9-12, note 2)
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
driveOff();
break;
case 0x09: // drive on
driveOn();
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
if (readOrWriteByte() & 0x80) {
if (!(sequencer & 0x80)) {
// printf("SEQ RESET EARLY [3]\n");
}
sequencer = 0;
}
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
}
if (curHalfTrack[selectedDisk] != prevHalfTrack) {
curWozTrack[selectedDisk] = disk[selectedDisk]->dataTrackNumberForQuarterTrack(curHalfTrack[selectedDisk]*2);
}
}
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] = new WozSerializer();
// intentionally 'false' (see above call to readFile)
disk[driveNum]->readFile(filename, false, T_AUTO); // FIXME error checking
curWozTrack[driveNum] = disk[driveNum]->dataTrackNumberForQuarterTrack(curHalfTrack[driveNum]*2);
if (drawIt)
g_ui->drawOnOffUIElement(UIeDisk1_state + driveNum, false);
}
void DiskII::ejectDisk(int8_t driveNum)
{
if (disk[driveNum]) {
disk[driveNum]->flush();
flushAt[driveNum] = 0;
delete disk[driveNum];
disk[driveNum] = NULL;
g_ui->drawOnOffUIElement(UIeDisk1_state + driveNum, true);
}
}
void DiskII::select(int8_t which)
{
if (which != 0 && which != 1)
return;
if (which != selectedDisk) {
if (diskIsSpinningUntil[selectedDisk] == -1) {
// FIXME: I'm not sure what the right behavior is here (read
// UTA2E and see if the state diagrams show the right
// behavior). For now, I'm setting the spindown of the
// now-deselected disk.
diskIsSpinningUntil[selectedDisk] = g_cpu->cycles + SPINDOWNDELAY;
if (diskIsSpinningUntil[selectedDisk] == -1 ||
diskIsSpinningUntil[selectedDisk] == 0)
diskIsSpinningUntil[selectedDisk] = 2; // fudge magic numbers; 0 is "off" and -1 is "forever".
}
// Queue flushing the cache of the disk that's no longer selected
if (disk[selectedDisk]) {
flushAt[selectedDisk] = g_cpu->cycles + FLUSHDELAY;
if (flushAt[selectedDisk] == 0)
flushAt[selectedDisk] = 1; // fudge magic number; 0 is "don't flush"
}
// set the selected disk drive
selectedDisk = which;
}
// Update the current woz track for the given disk drive
if (disk[selectedDisk]) {
curWozTrack[selectedDisk] =
disk[selectedDisk]->dataTrackNumberForQuarterTrack(curHalfTrack[selectedDisk]*2);
}
}
uint8_t DiskII::readOrWriteByte()
{
if (!disk[selectedDisk]) {
//printf("reading from uninserted disk\n");
return 0xFF;
}
uint32_t curCycles = g_cpu->cycles;
// FIXME: for writes, we need to check s/t like ... if (diskIsSpinningUntil[selectedDisk] >= curCycles) { return } ...
if (writeMode && !writeProt) {
// It's a write request. Inject 'readWriteLatch'.
disk[selectedDisk]->writeNextWozByte(curWozTrack[selectedDisk], readWriteLatch);
goto done;
}
if (diskIsSpinningUntil[selectedDisk] >= curCycles) {
// Figure out how many cycles we missed since the last disk read,
// and pop the right number of bits off the woz track.
// Handle rollover, which is a mess.
if (driveSpinupCycles[selectedDisk] > g_cpu->cycles) {
// printf("Cycle rollover\n");
driveSpinupCycles[selectedDisk] = g_cpu->cycles-1; // FIXME: is the -1 correct? What if we were @ 0?
#ifndef TEENSYDUINO
exit(2); // for debugging, FIXME ***
#endif
}
uint32_t cyclesPassed = g_cpu->cycles - driveSpinupCycles[selectedDisk];
// FIXME: this is a bit of a magic constant, which makes the drive
// test in Copy2+ at 179.4ms per revolution (334.4rpm). I'd like to
// understand that better and get to to the proper 200ms (300rpm).
uint64_t expectedDiskBits = (float) cyclesPassed / 3.51;
int64_t bitsToDeliver = expectedDiskBits - deliveredDiskBits[selectedDisk];
if (bitsToDeliver > 0) {
// We're expected to deliver some bits to the Disk II sequencer.
// Instead of piecemeal delivering a small number of bits (which we
// could do, but it's kinda busywork) - instead, we'll do one of two
// possible things.
//
// The first: if we're expecting a small number of bits to be delivered,
// then we'll grab the next byte from the nibble stream and return it.
// This itself has three possible cases -
// (a) we should be delivering less than a full byte, but we're
// actually going to deliver a full byte. bitsToDeliver will
// become negative, because we're delivering these too early.
// The next call will probably see that it has nothing to deliver
// and, as long as the disk image we're using doesn't have a
// really fine tolerance on the delivery rate of the bits,
// it will all come out in the wash.
// (b) we should be delivering exactly a byte, and we're doing the
// absolute right thing.
// (c) we are more than 1 byte, but less than 2 bytes, behind. If
// this is the case, we're probably making up for a timing
// problem in this code - where the bits would now have been
// lost. By returning the first byte that we found, we're hoping
// that the next call will be closer to on time, and we will
// eventually catch back up to the stream. Hopefully this makes
// the stream a little more resilient - and the error isn't
// so far off that the reader notices something is weird on the
// timing. (Standard RWTS doesn't, but some copy protection
// might.)
if (bitsToDeliver < 16) {
while (bitsToDeliver > -16 && ((sequencer & 0x80) == 0)) {
sequencer <<= 1;
sequencer |= disk[selectedDisk]->nextDiskBit(curWozTrack[selectedDisk]);
bitsToDeliver--;
deliveredDiskBits[selectedDisk]++;
}
goto done;
}
// If we reach here, we're throwing away a bunch of missed data.
// This might be normal (where the machine wasn't listening for the data),
// or it might be exceptional (something wrong with the tuning of data
// delivery, based on the magic constant in expectedDiskBits above)...
deliveredDiskBits[selectedDisk] += bitsToDeliver;
while (bitsToDeliver) {
sequencer <<= 1;
sequencer |= disk[selectedDisk]->nextDiskBit(curWozTrack[selectedDisk]);
bitsToDeliver--;
}
}
}
done:
return sequencer;
}
const char *DiskII::DiskName(int8_t num)
{
if (disk[num]) {
return disk[num]->diskName();
}
// Nothing inserted in that drive
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::maintenance(uint32_t cycle)
{
// Handle spin-down for the drive. Drives stay on for a second after
// the stop was noticed.
for (int i=0; i<2; i++) {
if (diskIsSpinningUntil[i] &&
g_cpu->cycles > diskIsSpinningUntil[i]) {
// Stop the given disk drive spinning
diskIsSpinningUntil[i] = 0;
// FIXME: consume any disk bits that need to be consumed, and spin it down
g_ui->drawOnOffUIElement(UIeDisk1_activity + i, false); // FIXME: queue for later drawing?
}
if (flushAt[i] &&
g_cpu->cycles > flushAt[i]) {
if (disk[i]) {
disk[i]->flush();
}
flushAt[i] = 0;
}
}
}
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