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◆ main openmsx / src / sound / AY8910Periphery.hh
1.4 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#ifndef AY8910PERIPHERY_HH
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#define AY8910PERIPHERY_HH
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#include "EmuTime.hh"
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#include <cstdint>
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namespace openmsx {
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/** Models the general purpose I/O ports of the AY8910.
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  * The default implementation handles an empty periphery:
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  * nothing is connected to the I/O ports.
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  * This class can be overridden to connect peripherals.
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  */
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class AY8910Periphery
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{
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public:
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	/** Reads the state of the peripheral on port A.
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	  * Since the AY8910 doesn't have control lines for the I/O ports,
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	  * a peripheral is not aware that it is read, which means that
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	  * "peek" and "read" are equivalent.
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	  * @param time The moment in time the peripheral's state is read.
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	  *   On subsequent calls, the time will always be increasing.
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	  * @return the value read; unconnected bits should be 1
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	  */
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	[[nodiscard]] virtual uint8_t readA(EmuTime time);
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	/** Similar to readA, but reads port B. */
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	[[nodiscard]] virtual uint8_t readB(EmuTime time);
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	/** Writes to the peripheral on port A.
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	  * @param value The value to write.
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	  * @param time The moment in time the value is written.
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	  *   On subsequent calls, the time will always be increasing.
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	  */
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	virtual void writeA(uint8_t value, EmuTime time);
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	/** Similar to writeA, but writes port B. */
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	virtual void writeB(uint8_t value, EmuTime time);
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protected:
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	AY8910Periphery() = default;
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	~AY8910Periphery() = default;
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};
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} // namespace openmsx
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#endif // AY8910PERIPHERY_HH