PhilipsFDC.cc

Go to the documentation of this file.

#include "PhilipsFDC.hh"
#include "CacheLine.hh"
#include "DriveMultiplexer.hh"
#include "WD2793.hh"
#include "serialize.hh"

namespace openmsx {

PhilipsFDC::PhilipsFDC(const DeviceConfig& config)
        : WD2793BasedFDC(config)
{
        reset(getCurrentTime());
}

void PhilipsFDC::reset(EmuTime::param time)
{
        WD2793BasedFDC::reset(time);
        writeMem(0x3FFC, 0x00, time);
        writeMem(0x3FFD, 0x00, time);
}

byte PhilipsFDC::readMem(word address, EmuTime::param time)
{
        byte value;
        switch (address & 0x3FFF) {
        case 0x3FF8:
                value = controller.getStatusReg(time);
                break;
        case 0x3FF9:
                value = controller.getTrackReg(time);
                break;
        case 0x3FFA:
                value = controller.getSectorReg(time);
                break;
        case 0x3FFB:
                value = controller.getDataReg(time);
                break;
        case 0x3FFF:
                value = 0xC0;
                if (controller.getIRQ(time)) value &= ~0x40;
                if (controller.getDTRQ(time)) value &= ~0x80;
                break;
        default:
                value = PhilipsFDC::peekMem(address, time);
                break;
        }
        return value;
}

byte PhilipsFDC::peekMem(word address, EmuTime::param time) const
{
        byte value;
        // FDC registers are mirrored in
        //   0x3FF8-0x3FFF
        //   0x7FF8-0x7FFF
        //   0xBFF8-0xBFFF
        //   0xFFF8-0xFFFF
        switch (address & 0x3FFF) {
        case 0x3FF8:
                value = controller.peekStatusReg(time);
                break;
        case 0x3FF9:
                value = controller.peekTrackReg(time);
                break;
        case 0x3FFA:
                value = controller.peekSectorReg(time);
                break;
        case 0x3FFB:
                value = controller.peekDataReg(time);
                break;
        case 0x3FFC:
                // bit 0 = side select
                // TODO check other bits !!
                value = sideReg; // value = multiplexer.getSideSelect();
                break;
        case 0x3FFD:
                // bit 1,0 -> drive number
                // (00 or 10: drive A, 01: drive B, 11: nothing)
                // bit 7 -> motor on
                // TODO check other bits !!
                value = driveReg; // multiplexer.getSelectedDrive();
                break;
        case 0x3FFE:
                // not used
                value = 255;
                break;
        case 0x3FFF:
                // Drive control IRQ and DRQ lines are not connected to Z80
                // interrupt request
                // bit 6: !intrq
                // bit 7: !dtrq
                // TODO check other bits !!
                value = 0xC0;
                if (controller.peekIRQ(time)) value &= ~0x40;
                if (controller.peekDTRQ(time)) value &= ~0x80;
                break;

        default:
                if ((0x4000 <= address) && (address < 0x8000)) {
                        // ROM only visible in 0x4000-0x7FFF
                        value = MSXFDC::peekMem(address, time);
                } else {
                        value = 255;
                }
                break;
        }
        return value;
}

const byte* PhilipsFDC::getReadCacheLine(word start) const
{
        // if address overlap 0x7ff8-0x7ffb then return nullptr,
        // else normal ROM behaviour
        if ((start & 0x3FF8 & CacheLine::HIGH) == (0x3FF8 & CacheLine::HIGH)) {
                return nullptr;
        } else if ((0x4000 <= start) && (start < 0x8000)) {
                // ROM visible in 0x4000-0x7FFF
                return MSXFDC::getReadCacheLine(start);
        } else {
                return unmappedRead;
        }
}

void PhilipsFDC::writeMem(word address, byte value, EmuTime::param time)
{
        switch (address & 0x3FFF) {
        case 0x3FF8:
                controller.setCommandReg(value, time);
                break;
        case 0x3FF9:
                controller.setTrackReg(value, time);
                break;
        case 0x3FFA:
                controller.setSectorReg(value, time);
                break;
        case 0x3FFB:
                controller.setDataReg(value, time);
                break;
        case 0x3FFC:
                // bit 0 = side select
                // TODO check other bits !!
                sideReg = value;
                multiplexer.setSide(value & 1);
                break;
        case 0x3FFD:
                // bit 1,0 -> drive number
                // (00 or 10: drive A, 01: drive B, 11: nothing)
                // TODO bit 6 -> drive LED (0 -> off, 1 -> on)
                // bit 7 -> motor on
                // TODO check other bits !!
                driveReg = value;
                DriveMultiplexer::DriveNum drive;
                switch (value & 3) {
                        case 0:
                        case 2:
                                drive = DriveMultiplexer::DRIVE_A;
                                break;
                        case 1:
                                drive = DriveMultiplexer::DRIVE_B;
                                break;
                        case 3:
                        default:
                                drive = DriveMultiplexer::NO_DRIVE;
                }
                multiplexer.selectDrive(drive, time);
                multiplexer.setMotor((value & 128) != 0, time);
                break;
        }
}

byte* PhilipsFDC::getWriteCacheLine(word address) const
{
        if ((address & 0x3FF8) == (0x3FF8 & CacheLine::HIGH)) {
                return nullptr;
        } else {
                return unmappedWrite;
        }
}


template<typename Archive>
void PhilipsFDC::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<WD2793BasedFDC>(*this);
        ar.serialize("sideReg", sideReg);
        ar.serialize("driveReg", driveReg);
}
INSTANTIATE_SERIALIZE_METHODS(PhilipsFDC);
REGISTER_MSXDEVICE(PhilipsFDC, "PhilipsFDC");

} // namespace openmsx