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Does a better job of shifting output; takes a new guess at the no-receiver case.

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ROM03 at least now reaches "check startup device!"
This commit is contained in:
Thomas Harte 2020-11-11 20:19:35 -05:00
parent 80358cf5bd
commit 72884c3ead
1 changed files with 12 additions and 5 deletions
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17
Components/DiskII/IWM.cpp
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@ -279,7 +279,6 @@ void IWM::run_for(const Cycles cycles) {
--output_bits_remaining_;
if(!output_bits_remaining_) {
if(!(write_handshake_ & 0x80)) {
write_handshake_ |= 0x80;
shift_register_ = next_output_;
output_bits_remaining_ = 8;
// LOG("Next byte: " << PADHEX(2) << int(shift_register_));
@ -287,12 +286,20 @@ void IWM::run_for(const Cycles cycles) {
write_handshake_ &= ~0x40;
if(drives_[active_drive_]) drives_[active_drive_]->end_writing();
LOG("Overrun; done.");
select_shift_mode();
output_bits_remaining_ = 1;
}
// Either way, the IWM is ready for more data.
write_handshake_ |= 0x80;
}
}
cycles_since_shift_ = integer_cycles;
// Either some bits were output, in which case cycles_since_shift_ is no 0 and
// integer_cycles is some number less than bit_length_, or none were and
// cycles_since_shift_ + integer_cycles is less than bit_length, and the new
// part should be accumulated.
cycles_since_shift_ += integer_cycles;
if(drives_[active_drive_] && integer_cycles) {
drives_[active_drive_]->run_for(cycles_since_shift_);
}
@ -329,8 +336,8 @@ void IWM::select_shift_mode() {
}
// If writing mode just began, set the drive into write mode and cue up the first output byte.
if(drives_[active_drive_] && old_shift_mode != ShiftMode::Writing && shift_mode_ == ShiftMode::Writing) {
drives_[active_drive_]->begin_writing(Storage::Time(1, clock_rate_ / bit_length_.as_integral()), false);
if(old_shift_mode != ShiftMode::Writing && shift_mode_ == ShiftMode::Writing) {
if(drives_[active_drive_]) drives_[active_drive_]->begin_writing(Storage::Time(1, clock_rate_ / bit_length_.as_integral()), false);
shift_register_ = next_output_;
write_handshake_ |= 0x80 | 0x40;
output_bits_remaining_ = 8;