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◆ main openmsx / src / cpu / IRQHelper.hh
2.5 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#ifndef IRQHELPER_HH
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#define IRQHELPER_HH
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#include "MSXMotherBoard.hh"
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#include "Probe.hh"
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#include "serialize.hh"
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#include <cstdint>
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#include <string>
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namespace openmsx {
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class MSXCPU;
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class DeviceConfig;
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/** Helper class for doing interrupt request (IRQ) administration.
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  * IRQ is either enabled or disabled; when enabled it contributes
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  * one to the CPU IRQ count, when disabled zero.
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  * Calling set() in enabled state does nothing;
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  * neither does calling reset() in disabled state.
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  */
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// policy class for IRQ source
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class IRQSource
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{
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protected:
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	explicit IRQSource(MSXCPU& cpu);
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	void raise();
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	void lower();
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private:
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	MSXCPU& cpu;
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};
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// supports <irq_connected> tag in hardware config
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class OptionalIRQ
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{
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protected:
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	OptionalIRQ(MSXCPU& cpu, const DeviceConfig& config);
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	void raise();
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	void lower();
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private:
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	MSXCPU& cpu;
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	enum Type : uint8_t { NotConnected, Maskable, NonMaskable };
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	const Type type;
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};
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// generic implementation
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template<typename SOURCE> class IntHelper : public SOURCE
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{
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public:
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	IntHelper(const IntHelper&) = delete;
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	IntHelper(IntHelper&&) = delete;
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	IntHelper& operator=(const IntHelper&) = delete;
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	IntHelper& operator=(IntHelper&&) = delete;
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	/** Create a new IntHelper.
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	  * Initially there is no interrupt request on the bus.
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	  */
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	template<typename ...Args>
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	IntHelper(MSXMotherBoard& motherboard, const std::string& name,
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	          Args&& ...args)
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		: SOURCE(motherboard.getCPU(), std::forward<Args>(args)...)
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		, request(motherboard.getDebugger(), name,
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		          "Outgoing IRQ signal.", false)
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	{
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	}
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	/** Destroy this IntHelper.
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	  * Resets interrupt request if it is active.
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	  */
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	~IntHelper() {
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		reset();
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	}
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	/** Set the interrupt request on the bus.
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	  */
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	void set() {
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		if (!request) {
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			request = true;
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			SOURCE::raise();
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		}
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	}
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	/** Reset the interrupt request on the bus.
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	  */
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	void reset() {
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		if (request) {
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			request = false;
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			SOURCE::lower();
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		}
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	}
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	/** Convenience function: calls set() or reset().
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	  */
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	void set(bool s) {
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		if (s) {
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			set();
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		} else {
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			reset();
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		}
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	}
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	/** Get the interrupt state.
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	  * @return true iff interrupt request is active.
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	  */
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	[[nodiscard]] bool getState() const {
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		return request;
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	}
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	template<typename Archive>
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	void serialize(Archive& ar, unsigned /*version*/)
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	{
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		bool pending = request;
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		ar.serialize("pending", pending);
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		if constexpr (Archive::IS_LOADER) {
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			set(pending);
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		}
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	}
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private:
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	Probe<bool> request;
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};
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// convenience types
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using IRQHelper         = IntHelper<IRQSource>;
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using OptionalIRQHelper = IntHelper<OptionalIRQ>;
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} // namespace openmsx
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#endif