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◆ main openmsx / src / MSXDeviceSwitch.hh
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#ifndef MSXDEVICESWITCH_HH
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#define MSXDEVICESWITCH_HH
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#include "MSXDevice.hh"
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#include <array>
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namespace openmsx {
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/**
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 * The MSX2 Hardware Specification says ports 0x41-0x4F are Switched I/O ports.
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 * Output of a ID value to port 0x40 selects a specific I/O device and connects
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 * it to the CPU.
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 *
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 * It is possible to give numbers between 0 and 255 as a device number.
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 * However, when reading the device number, the complement is given, so 0 and
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 * 255 are not used. ID numbers between 1 and 127 are manufacturers ID number
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 * as in expanded BIOS call. 128 to 254 are device numbers. As a basic rule,
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 * those device which are designed specifically for one machine should contain
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 * the manufacturers company ID while peripheral device which can be used for
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 * all MSX should have device ID number. Also, Z80 CPU has 16 bit address in
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 * I/O space so it is recommended to access in 16 bit by decoding the upper 8
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 * bit for those ID which might be expanded in the future. Especially for
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 * device which are connected with make ID can expand the address space by 256
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 * times so it is future proofed.
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 *
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 * Maker ID
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 *    1 ASCII/Microsoft
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 *    2 Canon
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 *    3 Casio
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 *    4 Fujitsu
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 *    5 General
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 *    6 Hitachi
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 *    7 Kyocera
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 *    8 Matsushita
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 *    9 Mitsubishi
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 *   10 NEC
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 *   11 Nippon Gakki
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 *   12 JVC
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 *   13 Philips
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 *   14 Pioneer
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 *   15 Sanyo
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 *   16 Sharp
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 *   17 SONY
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 *   18 Spectravideo
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 *   19 Toshiba
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 *   20 Mitsumi
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 *
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 * Device ID
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 *  128 Image Scanner (Matsushita)
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 *  247 Kanji 12x12
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 *  254 MPS2 (ASCII)
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 */
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class MSXSwitchedDevice;
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class MSXDeviceSwitch final : public MSXDevice
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{
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public:
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	explicit MSXDeviceSwitch(const DeviceConfig& config);
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	~MSXDeviceSwitch() override;
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	// (un)register methods for devices
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	void registerDevice(byte id, MSXSwitchedDevice* device);
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	void unregisterDevice(byte id);
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	[[nodiscard]] bool hasRegisteredDevices() const { return count != 0; }
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	void reset(EmuTime time) override;
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	[[nodiscard]] byte readIO(uint16_t port, EmuTime time) override;
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	[[nodiscard]] byte peekIO(uint16_t port, EmuTime time) const override;
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	void writeIO(uint16_t port, byte value, EmuTime time) override;
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	template<typename Archive>
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	void serialize(Archive& ar, unsigned version);
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private:
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	std::array<MSXSwitchedDevice*, 256> devices;
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	unsigned count = 0;
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	byte selected = 0;
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};
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} // namespace openmsx
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#endif