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◆ main openmsx / src / fdc / SVIFDC.cc
3.0 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "SVIFDC.hh"
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#include "serialize.hh"
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// Floppy disk controller FD1793
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//
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// 30H         Command to FDC
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// 30H         Status from FDC
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// 31H         Track register
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// 32H         Sector register
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// 33H         Data register
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//
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// 34H         Address of INTRQ and DRQ
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// 10000000B   Interrupt request bit
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// 01000000B   Data request bit
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//
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// 34H         Address of disk select and motor control
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// 00000001B   Select disk 0 bit
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// 00000010B   Select disk 1 bit
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// 00000100B   Disk 0 motor on bit
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// 00001000B   Disk 1 motor on bit
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//
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// 38H         Address of density select flag
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// 00000000B   Density MFM bit
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// 00000001B   Density FM bit
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// 00000010B   Select second side
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namespace openmsx {
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SVIFDC::SVIFDC(DeviceConfig& config)
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	: WD2793BasedFDC(config, "", false) // doesn't require a <rom>
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{
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}
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byte SVIFDC::readIO(uint16_t port, EmuTime time)
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{
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	switch (port & 0x07) {
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	case 0:
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		return controller.getStatusReg(time);
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	case 1:
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		return controller.getTrackReg(time);
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	case 2:
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		return controller.getSectorReg(time);
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	case 3:
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		return controller.getDataReg(time);
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	case 4:
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		return (controller.getIRQ (time) ? 0x80 : 0x00) |
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		       (controller.getDTRQ(time) ? 0x40 : 0x00);
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	}
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	return 255;
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}
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byte SVIFDC::peekIO(uint16_t port, EmuTime time) const
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{
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	switch (port & 0x07) {
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	case 0:
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		return controller.peekStatusReg(time);
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	case 1:
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		return controller.peekTrackReg(time);
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	case 2:
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		return controller.peekSectorReg(time);
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	case 3:
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		return controller.peekDataReg(time);
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	case 4:
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		return (controller.peekIRQ (time) ? 0x80 : 0x00) |
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		       (controller.peekDTRQ(time) ? 0x40 : 0x00);
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	}
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	return 255;
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}
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void SVIFDC::writeIO(uint16_t port, byte value, EmuTime time)
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{
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	switch (port & 0x0F) {
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	case 0:
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		controller.setCommandReg(value, time);
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		break;
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	case 1:
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		controller.setTrackReg(value, time);
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		break;
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	case 2:
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		controller.setSectorReg(value, time);
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		break;
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	case 3:
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		controller.setDataReg(value, time);
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		break;
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	case 4: {
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		// bit 0:  drive select A
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		// bit 1:  drive select B
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		// bit 2:  motor on drive A
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		// bit 3:  motor on drive B
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		auto [drive, motor] = [&] -> std::pair<DriveMultiplexer::Drive, bool> {
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			switch (value & 0x03) {
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			case 1:
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				return {DriveMultiplexer::Drive::A, value & 0x04};
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			case 2:
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				return {DriveMultiplexer::Drive::B, value & 0x08};
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			default:
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				// No drive selected or two drives at same time
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				// In a real machine you must take care to do not select more
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				// than one drive at the same time (you could get data
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				// collision).
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				return {DriveMultiplexer::Drive::NONE, false};
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			}
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		}();
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		multiplexer.selectDrive(drive, time);
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		multiplexer.setMotor(motor, time);
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		break;
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	}
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	case 8:
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		// bit 0:  density flag (1=single, 0=double)
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		// bit 1:  side select
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		// TODO density flag not yet supported
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		multiplexer.setSide((value & 0x02) != 0);
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		break;
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	}
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}
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template<typename Archive>
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void SVIFDC::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<WD2793BasedFDC>(*this);
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}
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INSTANTIATE_SERIALIZE_METHODS(SVIFDC);
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REGISTER_MSXDEVICE(SVIFDC, "SVI-328 FDC");
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} // namespace openmsx