I8254.hh

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// This class implements the Intel 8254 chip (and 8253)
//
// * Only the 8254 is emulated, no surrounding hardware.
//   Use the class I8254Interface to do that.
 
#ifndef I8254_HH
#define I8254_HH
 
#include "ClockPin.hh"
#include "EmuTime.hh"
#include <array>
#include <cstdint>
 
namespace openmsx {
 
class Scheduler;
class ClockPinListener;
 
class Counter {
public:
        Counter(Scheduler& scheduler, ClockPinListener* listener,
                EmuTime::param time);
        void reset(EmuTime::param time);
        [[nodiscard]] uint8_t readIO(EmuTime::param time);
        [[nodiscard]] uint8_t peekIO(EmuTime::param time) const;
        void writeIO(uint8_t value, EmuTime::param time);
        void setGateStatus(bool status, EmuTime::param time);
        void writeControlWord(uint8_t value, EmuTime::param time);
        void latchStatus(EmuTime::param time);
        void latchCounter(EmuTime::param time);
 
        template<typename Archive>
        void serialize(Archive& ar, unsigned version);
 
//private:
        enum class ByteOrder {LOW, HIGH};
 
private:
        static constexpr uint8_t WRT_FRMT = 0x30;
        static constexpr uint8_t WF_LATCH = 0x00;
        static constexpr uint8_t WF_LOW   = 0x10;
        static constexpr uint8_t WF_HIGH  = 0x20;
        static constexpr uint8_t WF_BOTH  = 0x30;
        static constexpr uint8_t CNTR_MODE = 0x0E;
        static constexpr uint8_t CNTR_M0   = 0x00;
        static constexpr uint8_t CNTR_M1   = 0x02;
        static constexpr uint8_t CNTR_M2   = 0x04;
        static constexpr uint8_t CNTR_M3   = 0x06;
        static constexpr uint8_t CNTR_M4   = 0x08;
        static constexpr uint8_t CNTR_M5   = 0x0A;
        static constexpr uint8_t CNTR_M2_  = 0x0C;
        static constexpr uint8_t CNTR_M3_  = 0x0E;
 
        void writeLoad(uint16_t value, EmuTime::param time);
        void advance(EmuTime::param time);
 
private:
        ClockPin clock;
        ClockPin output;
        EmuTime currentTime;
        int counter = 0;
        uint16_t latchedCounter;
        uint16_t counterLoad = 0;
        uint8_t control, latchedControl;
        bool ltchCtrl, ltchCntr;
        ByteOrder readOrder, writeOrder;
        uint8_t writeLatch;
        bool gate = true;
        bool active, triggered, counting;
 
        friend class I8254;
};
 
class I8254
{
public:
        I8254(Scheduler& scheduler, ClockPinListener* output0,
              ClockPinListener* output1, ClockPinListener* output2,
              EmuTime::param time);
 
        void reset(EmuTime::param time);
        [[nodiscard]] uint8_t readIO(uint16_t port, EmuTime::param time);
        [[nodiscard]] uint8_t peekIO(uint16_t port, EmuTime::param time) const;
        void writeIO(uint16_t port, uint8_t value, EmuTime::param time);
 
        void setGate(unsigned cntr, bool status, EmuTime::param time);
        [[nodiscard]] ClockPin& getClockPin(unsigned cntr);
        [[nodiscard]] ClockPin& getOutputPin(unsigned cntr);
 
        template<typename Archive>
        void serialize(Archive& ar, unsigned version);
 
private:
        void readBackHelper(uint8_t value, unsigned cntr, EmuTime::param time);
 
private:
        std::array<Counter, 3> counter;
};
 
} // namespace openmsx
 
#endif