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fixup for using both drives; repair spindown delay (which was a factor of 1000 too aggressive, which is why disk access was slow)

This commit is contained in:
Jorj Bauer 2020-06-27 22:10:24 -04:00
parent 29542704bd
commit f66049ce8e
2 changed files with 72 additions and 104 deletions
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166
apple/diskii.cpp
View File

@ -19,8 +19,8 @@
#define DISKIIMAGIC 0xAA
// how many CPU cycles do we wait to spin down the disk drive?
#define SPINDOWNDELAY (1023)
// how many CPU cycles do we wait to spin down the disk drive? 1023000 == 1 second
#define SPINDOWNDELAY (1023000)
DiskII::DiskII(AppleMMU *mmu)
{
@ -35,15 +35,12 @@ DiskII::DiskII(AppleMMU *mmu)
readWriteLatch = 0x00;
sequencer = 0;
dataRegister = 0;
lastDiskRead[0] = lastDiskRead[1] = 0;
driveSpinupCycles[0] = driveSpinupCycles[1] = 0;
deliveredDiskBits[0] = deliveredDiskBits[1] = 0;
disk[0] = disk[1] = NULL;
diskIsSpinningUntil[0] = diskIsSpinningUntil[1] = 0;
selectedDisk = 0;
driveSpinupCycles = 0;
deliveredDiskBits = 0;
// debugDeliveredDiskBits = 0;
}
DiskII::~DiskII()
@ -184,17 +181,14 @@ void DiskII::driveOn()
// 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 = g_cpu->cycles;
//printf("driveOn @ cycle %d\n", driveSpinupCycles);
deliveredDiskBits = 0;
// debugDeliveredDiskBits = 0;
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?
// Start the given disk drive spinning
lastDiskRead[selectedDisk] = g_cpu->cycles;
}
uint8_t DiskII::readSwitches(uint8_t s)
@ -403,7 +397,6 @@ void DiskII::setPhase(uint8_t phase)
// We're changing track - flush the old track back to disk
// FIXME flush
curWozTrack[selectedDisk] = disk[selectedDisk]->dataTrackNumberForQuarterTrack(curHalfTrack[selectedDisk]*2);
printf("track change => %d\n", curWozTrack[selectedDisk]);
}
}
@ -469,12 +462,21 @@ void DiskII::select(int8_t which)
return;
if (which != selectedDisk) {
#if 0
*** fixme check if the drive is still "on"
indicatorIsOn[selectedDisk] = 100; // spindown time (fixme)
g_ui->drawOnOffUIElement(UIeDisk1_activity + selectedDisk, false); // FIXME: queue for later drawing?
#endif
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".
}
// Flush the cache of the disk that's no longer selected
if (disk[selectedDisk])
disk[selectedDisk]->flush();
// set the selected disk drive
selectedDisk = which;
}
@ -494,106 +496,79 @@ uint8_t DiskII::readOrWriteByte()
}
uint32_t curCycles = g_cpu->cycles;
bool updateCycles = false;
// 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);
updateCycles = true; // need to update when we last read, b/c disk is still spinning
goto done;
}
if (diskIsSpinningUntil[selectedDisk] >= curCycles) {
if (lastDiskRead[selectedDisk] == 0) {
// assume it's a first-read-after-spinup; return the first valid data
printf("FIRST SPIN\n");
sequencer = disk[selectedDisk]->nextDiskBit(curWozTrack[selectedDisk]);
updateCycles = true;
goto done;
}
// Otherwise we figure out how many cycles we missed since the last
// disk read, and pop the right number of bits off the woz track
// uint32_t missedCycles;
// missedCycles = curCycles - lastDiskRead[selectedDisk];
// The stock 4ms disk bit timing is just missedCycles >> 2. But we
// want to support others, too. We can't simply base it on cycle
// count any more at that point, because of fractional cycles
// being important.
// So instead of just "missedCycles >>= 2" here, we need to calculate
// how many *bits* should have been transited at time (x); and we need
// a floating counter of how long the drive has been spinning (b/c
// that's not a constant since startup!); and we need the counter of
// how many bits we actually did pull from the drive. Then we can
// calculate exactly how many bits we should pull this time, update the
// number that did transit, and be more or less where we're supposed
// to be for this clock cycle.
// 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 > g_cpu->cycles) {
if (driveSpinupCycles[selectedDisk] > g_cpu->cycles) {
printf("Cycle rollover\n");
driveSpinupCycles = g_cpu->cycles-1;
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;
// printf("cy: %d cp: %d ", g_cpu->cycles, cyclesPassed);
// bits = cycles * (us per cycle) * (bits/us)
//#define BITSPEED 4.0
// uint64_t expectedDiskBits = (float)cyclesPassed * (float)(1.0/(1.023*BITSPEED)); // clock speed*2 b/c the disk clock runs at twice the speed?
// uint64_t expectedDiskBits = (float)cyclesPassed / 8.0;
uint64_t expectedDiskBits = (float) cyclesPassed / 3.52;
int64_t bitsToDeliver = expectedDiskBits - deliveredDiskBits;
// printf("btd: %llu\n",bitsToDeliver);
// printf("mc>>2: %d; btd: %llu\n", missedCycles >> 2, bitsToDeliver);
//int64_t bitsToDeliver = missedCycles>>2;
// debugDeliveredDiskBits += (missedCycles >> 2);
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) {
#if 1
/* TESTING - try delivering a byte, if there's a simple request, and let it drift forward in time very slightly */
// 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) {
// if (bitsToDeliver >= 8) { sequencer = 0; }
while (bitsToDeliver > -16 && ((sequencer & 0x80) == 0)) {
sequencer <<= 1;
sequencer |= disk[selectedDisk]->nextDiskBit(curWozTrack[selectedDisk]);
bitsToDeliver--;
deliveredDiskBits++;
deliveredDiskBits[selectedDisk]++;
}
updateCycles = true;
goto done;
}
/* END TESTING */
// printf("WARNING: missed data [%lld]\n", bitsToDeliver);
#endif
updateCycles = true;
// Something is wrong here. I don't know why
// debugDeliveredDiskBits doesn't match bitsToDeliver. In
// theory, debugDDB is just missedCycles/4. deliveredDiskBits
// should be pretty much the same (1.023/4.0, so off by
// 2.3%). But in reality the drift is much greater.
//
// Is it related to the disk on/off timers? How does
// missedCycles differ? I could use missedCycles, except that it
// loses precision when we're talking about using a 3.5us bit
// timing, so that's a problem -- which is why I'm trying to
// base it on "real time" from when the disk drive starts
// spinning...
deliveredDiskBits += bitsToDeliver;
// 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]);
@ -604,12 +579,6 @@ uint8_t DiskII::readOrWriteByte()
done:
if (updateCycles) {
// We only update the lastDiskRead counter if the number of passed
// cycles indicates that we did some sort of work...
lastDiskRead[selectedDisk] = curCycles;
}
return sequencer;
}
@ -645,7 +614,7 @@ void DiskII::flushTrack(int8_t track, int8_t sel)
return;
}
// ***
// FIXME: *** needs implementing
}
void DiskII::maintenance(uint32_t cycle)
@ -656,10 +625,11 @@ void DiskII::maintenance(uint32_t cycle)
if (diskIsSpinningUntil[i] &&
g_cpu->cycles > diskIsSpinningUntil[i]) {
// Stop the given disk drive spinning
lastDiskRead[i] = 0; // FIXME: magic value. We need a tristate for this. ***
diskIsSpinningUntil[i] = 0;
// FIXME: consume any disk bits that need to be consumed, and spin it down
if (disk[i]) {
// ensure any changes are written to our disk image
disk[i]->flush();
}

10
apple/diskii.h
View File

@ -60,12 +60,10 @@ class DiskII : public Slot {
volatile int8_t curHalfTrack[2];
volatile uint8_t curWozTrack[2];
volatile int8_t curPhase[2];
uint8_t readWriteLatch;
uint8_t sequencer, dataRegister; // diskII logic state sequencer vars
uint32_t lastDiskRead[2];
uint64_t driveSpinupCycles;
uint64_t deliveredDiskBits;
uint64_t debugDeliveredDiskBits;
volatile uint8_t readWriteLatch;
volatile uint8_t sequencer, dataRegister; // diskII logic state sequencer vars
volatile uint64_t driveSpinupCycles[2];
volatile uint64_t deliveredDiskBits[2];
bool writeMode;
bool writeProt;