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Ensures good serial line and ACIA behaviour.

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Next stop: having the intelligent keyboard react.
This commit is contained in:
Thomas Harte
2019-10-20 22:10:05 -04:00
parent 313aaa8f95
commit cf07982a9b
6 changed files with 70 additions and 9 deletions
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Components/6850/6850.cpp
+17 -3
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@@ -97,9 +97,13 @@ void ACIA::write(int address, uint8_t value) {
void ACIA::run_for(HalfCycles length) {
// Transmission.
const int transmit_advance = length.as_int();
const auto write_data_time_remaining = transmit.write_data_time_remaining();
if(write_data_time_remaining) {
if(transmit.transmission_data_time_remaining()) {
const auto write_data_time_remaining = transmit.write_data_time_remaining();
// There's at most one further byte available to enqueue, so a single 'if'
// rather than a 'while' is correct here. It's the responsibilit of the caller
// to ensure run_for lengths are appropriate for longer sequences.
if(transmit_advance >= write_data_time_remaining) {
if(next_transmission_ != NoValue) {
transmit.advance_writer(write_data_time_remaining);
@@ -145,6 +149,9 @@ void ACIA::consider_transmission() {
// Output all that.
const int total_bits = 1 + data_bits_ + stop_bits_ + (parity_ != Parity::None);
if(!next_transmission_) {
printf("");
}
transmit.write(divider_ * 2, total_bits, transmission);
printf("Transmitted %02x [%03x]\n", next_transmission_, transmission);
@@ -154,7 +161,14 @@ void ACIA::consider_transmission() {
}
ClockingHint::Preference ACIA::preferred_clocking() {
return (transmit.write_data_time_remaining() > 0) ? ClockingHint::Preference::JustInTime : ClockingHint::Preference::None;
// Real-time clocking is required if a transmission is ongoing; this is a courtesy for whomever
// is on the receiving end.
if(transmit.transmission_data_time_remaining() > 0) return ClockingHint::Preference::RealTime;
// TODO: real-time clocking if a process of receiving is ongoing.
// No clocking required then.
return ClockingHint::Preference::None;
}
bool ACIA::get_interrupt_line() const {