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Attempts to implement transmission interrupts and ClockingHint::Source.

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This commit is contained in:
Thomas Harte 2019-10-12 23:46:57 -04:00
parent 8b50a7d6e3
commit 516d78f5a8
2 changed files with 33 additions and 8 deletions
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32
Components/6850/6850.cpp
View File

@ -18,12 +18,14 @@ ACIA::ACIA() {}
uint8_t ACIA::read(int address) {
if(address&1) {
LOG("Read from receive register");
interrupt_request_ = false;
} else {
LOG("Read status");
return
((next_transmission_ == NoTransmission) ? 0x02 : 0x00) |
(data_carrier_detect.read() ? 0x04 : 0x00) |
(clear_to_send.read() ? 0x08 : 0x00)
(clear_to_send.read() ? 0x08 : 0x00) |
(interrupt_request_ ? 0x80 : 0x00)
;
// b0: receive data full.
@ -42,6 +44,8 @@ void ACIA::write(int address, uint8_t value) {
if(address&1) {
next_transmission_ = value;
consider_transmission();
update_clocking_observer();
interrupt_request_ = false;
} else {
if((value&3) == 3) {
transmit.reset_writing();
@ -82,16 +86,22 @@ void ACIA::write(int address, uint8_t value) {
void ACIA::run_for(HalfCycles length) {
// Transmission.
int transmit_advance = length.as_int();
if(next_transmission_ != NoTransmission) {
const auto write_data_time_remaining = transmit.write_data_time_remaining();
if(transmit_advance > write_data_time_remaining) {
const int transmit_advance = length.as_int();
const auto write_data_time_remaining = transmit.write_data_time_remaining();
if(transmit_advance > write_data_time_remaining) {
if(next_transmission_ != NoTransmission) {
transmit.flush_writing();
transmit_advance -= write_data_time_remaining;
consider_transmission();
transmit.advance_writer(transmit_advance - write_data_time_remaining);
} else {
transmit.advance_writer(transmit_advance);
update_clocking_observer();
interrupt_request_ |= transmit_interrupt_enabled_;
}
} else {
transmit.advance_writer(transmit_advance);
}
transmit.advance_writer(transmit_advance);
// Reception.
}
@ -129,3 +139,11 @@ void ACIA::consider_transmission() {
next_transmission_ = NoTransmission;
}
}
ClockingHint::Preference ACIA::preferred_clocking() {
return (transmit.write_data_time_remaining() > 0) ? ClockingHint::Preference::JustInTime : ClockingHint::Preference::None;
}
bool ACIA::get_interrupt_line() {
return interrupt_request_;
}

9
Components/6850/6850.hpp
View File

@ -11,12 +11,13 @@
#include <cstdint>
#include "../../ClockReceiver/ClockReceiver.hpp"
#include "../../ClockReceiver/ClockingHintSource.hpp"
#include "../SerialPort/SerialPort.hpp"
namespace Motorola {
namespace ACIA {
class ACIA {
class ACIA: public ClockingHint::Source {
public:
ACIA();
@ -40,6 +41,8 @@ class ACIA {
void run_for(HalfCycles);
bool get_interrupt_line();
// Input lines.
Serial::Line receive;
Serial::Line clear_to_send;
@ -62,6 +65,10 @@ class ACIA {
bool receive_interrupt_enabled_ = false;
bool transmit_interrupt_enabled_ = false;
bool interrupt_request_ = false;
ClockingHint::Preference preferred_clocking() final;
};
}