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The ACIA actually has two clocks, though on an ST they're both 500,000 Hz.

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This commit is contained in:
Thomas Harte 2019-10-13 21:32:34 -04:00
parent f86dc082bb
commit 8d87e9eb1c
3 changed files with 28 additions and 11 deletions
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12
Components/6850/6850.cpp
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@ -13,9 +13,13 @@
using namespace Motorola::ACIA; using namespace Motorola::ACIA;
ACIA::ACIA(int clock_rate) { const HalfCycles ACIA::SameAsTransmit;
transmit.set_writer_clock_rate(clock_rate);
request_to_send.set_writer_clock_rate(clock_rate); ACIA::ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate) :
transmit_clock_rate_(transmit_clock_rate),
receive_clock_rate_((receive_clock_rate != SameAsTransmit) ? receive_clock_rate : transmit_clock_rate) {
transmit.set_writer_clock_rate(transmit_clock_rate.as_int());
request_to_send.set_writer_clock_rate(transmit_clock_rate.as_int());
} }
uint8_t ACIA::read(int address) { uint8_t ACIA::read(int address) {
@ -149,6 +153,6 @@ ClockingHint::Preference ACIA::preferred_clocking() {
return (transmit.write_data_time_remaining() > 0) ? ClockingHint::Preference::JustInTime : ClockingHint::Preference::None; return (transmit.write_data_time_remaining() > 0) ? ClockingHint::Preference::JustInTime : ClockingHint::Preference::None;
} }
bool ACIA::get_interrupt_line() { bool ACIA::get_interrupt_line() const {
return interrupt_request_; return interrupt_request_;
} }

19
Components/6850/6850.hpp
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@ -19,7 +19,13 @@ namespace ACIA {
class ACIA: public ClockingHint::Source { class ACIA: public ClockingHint::Source {
public: public:
ACIA(int clock_rate); static constexpr const HalfCycles SameAsTransmit = HalfCycles(0);
/*!
Constructs a new instance of ACIA which will receive a transmission clock at a rate of
@c transmit_clock_rate, and a receive clock at a rate of @c receive_clock_rate.
*/
ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate = SameAsTransmit);
/*! /*!
Reads from the ACIA. Reads from the ACIA.
@ -39,9 +45,13 @@ class ACIA: public ClockingHint::Source {
*/ */
void write(int address, uint8_t value); void write(int address, uint8_t value);
void run_for(HalfCycles); /*!
Advances @c transmission_cycles in time, which should be
counted relative to the @c transmit_clock_rate.
*/
void run_for(HalfCycles transmission_cycles);
bool get_interrupt_line(); bool get_interrupt_line() const;
// Input lines. // Input lines.
Serial::Line receive; Serial::Line receive;
@ -69,6 +79,9 @@ class ACIA: public ClockingHint::Source {
bool interrupt_request_ = false; bool interrupt_request_ = false;
ClockingHint::Preference preferred_clocking() final; ClockingHint::Preference preferred_clocking() final;
HalfCycles transmit_clock_rate_;
HalfCycles receive_clock_rate_;
}; };
} }

8
Machines/AtariST/AtariST.cpp
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@ -39,8 +39,8 @@ class ConcreteMachine:
public: public:
ConcreteMachine(const Target &target, const ROMMachine::ROMFetcher &rom_fetcher) : ConcreteMachine(const Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
mc68000_(*this), mc68000_(*this),
keyboard_acia_(CLOCK_RATE / 10), keyboard_acia_(Cycles(500000)),
midi_acia_(CLOCK_RATE / 10), midi_acia_(Cycles(500000)),
ay_(audio_queue_), ay_(audio_queue_),
speaker_(ay_) { speaker_(ay_) {
set_clock_rate(CLOCK_RATE); set_clock_rate(CLOCK_RATE);
@ -372,8 +372,8 @@ class ConcreteMachine:
HalfCycles cycles_until_video_event_; HalfCycles cycles_until_video_event_;
JustInTimeActor<Motorola::MFP68901::MFP68901> mfp_; JustInTimeActor<Motorola::MFP68901::MFP68901> mfp_;
JustInTimeActor<Motorola::ACIA::ACIA, 10> keyboard_acia_; JustInTimeActor<Motorola::ACIA::ACIA, 16> keyboard_acia_;
JustInTimeActor<Motorola::ACIA::ACIA, 10> midi_acia_; JustInTimeActor<Motorola::ACIA::ACIA, 16> midi_acia_;
Concurrency::DeferringAsyncTaskQueue audio_queue_; Concurrency::DeferringAsyncTaskQueue audio_queue_;
GI::AY38910::AY38910 ay_; GI::AY38910::AY38910 ay_;