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- #include "I8255.hh"
- #include "I8255Interface.hh"
- #include "serialize.hh"
- #include "unreachable.hh"
- namespace openmsx {
- const int MODE_A = 0x60;
- const int MODEA_0 = 0x00;
- const int MODEA_1 = 0x20;
- const int MODEA_2 = 0x40;
- const int MODEA_2_ = 0x60;
- const int MODE_B = 0x04;
- const int MODEB_0 = 0x00;
- const int MODEB_1 = 0x04;
- const int DIRECTION_A = 0x10;
- const int DIRECTION_B = 0x02;
- const int DIRECTION_C0 = 0x01;
- const int DIRECTION_C1 = 0x08;
- const int SET_MODE = 0x80;
- const int BIT_NR = 0x0E;
- const int SET_RESET = 0x01;
- I8255::I8255(I8255Interface& interf, EmuTime::param time,
- StringSetting& invalidPpiModeSetting)
- : interface(interf)
- , ppiModeCallback(invalidPpiModeSetting)
- {
- reset(time);
- }
- void I8255::reset(EmuTime::param time)
- {
- latchPortA = 0;
- latchPortB = 0;
- latchPortC = 0;
- writeControlPort(SET_MODE | DIRECTION_A | DIRECTION_B |
- DIRECTION_C0 | DIRECTION_C1, time); // all input
- }
- byte I8255::read(byte port, EmuTime::param time)
- {
- switch (port) {
- case 0:
- return readPortA(time);
- case 1:
- return readPortB(time);
- case 2:
- return readPortC(time);
- case 3:
- return readControlPort(time);
- default:
- UNREACHABLE;
- return 0; // avoid warning
- }
- }
- byte I8255::peek(byte port, EmuTime::param time) const
- {
- switch (port) {
- case 0:
- return peekPortA(time);
- case 1:
- return peekPortB(time);
- case 2:
- return peekPortC(time);
- case 3:
- return readControlPort(time);
- default:
- UNREACHABLE;
- return 0; // avoid warning
- }
- }
- void I8255::write(byte port, byte value, EmuTime::param time)
- {
- switch (port) {
- case 0:
- writePortA(value, time);
- break;
- case 1:
- writePortB(value, time);
- break;
- case 2:
- writePortC(value, time);
- break;
- case 3:
- writeControlPort(value, time);
- break;
- default:
- UNREACHABLE;
- }
- }
- byte I8255::readPortA(EmuTime::param time)
- {
- switch (control & MODE_A) {
- case MODEA_0:
- if (control & DIRECTION_A) {
- // input
- return interface.readA(time); // input not latched
- } else {
- // output
- return latchPortA; // output is latched
- }
- case MODEA_1: // TODO but not relevant for MSX
- case MODEA_2: case MODEA_2_:
- default:
- return 255; // avoid warning
- }
- }
- byte I8255::peekPortA(EmuTime::param time) const
- {
- switch (control & MODE_A) {
- case MODEA_0:
- if (control & DIRECTION_A) {
- return interface.peekA(time); // input not latched
- } else {
- return latchPortA; // output is latched
- }
- case MODEA_1: // TODO but not relevant for MSX
- case MODEA_2: case MODEA_2_:
- default:
- return 255;
- }
- }
- byte I8255::readPortB(EmuTime::param time)
- {
- switch (control & MODE_B) {
- case MODEB_0:
- if (control & DIRECTION_B) {
- // input
- return interface.readB(time); // input not latched
- } else {
- // output
- return latchPortB; // output is latched
- }
- case MODEB_1: // TODO but not relevant for MSX
- default:
- return 255; // avoid warning
- }
- }
- byte I8255::peekPortB(EmuTime::param time) const
- {
- switch (control & MODE_B) {
- case MODEB_0:
- if (control & DIRECTION_B) {
- return interface.peekB(time); // input not latched
- } else {
- return latchPortB; // output is latched
- }
- case MODEB_1: // TODO but not relevant for MSX
- default:
- return 255;
- }
- }
- byte I8255::readPortC(EmuTime::param time)
- {
- byte tmp = readC1(time) | readC0(time);
- switch (control & MODE_A) {
- case MODEA_0:
- // do nothing
- break;
- case MODEA_1:
- case MODEA_2: case MODEA_2_:
- // TODO but not relevant for MSX
- break;
- }
- switch (control & MODE_B) {
- case MODEB_0:
- // do nothing
- break;
- case MODEB_1:
- // TODO but not relevant for MSX
- break;
- }
- return tmp;
- }
- byte I8255::peekPortC(EmuTime::param time) const
- {
- return peekC1(time) | peekC0(time);
- }
- byte I8255::readC1(EmuTime::param time)
- {
- if (control & DIRECTION_C1) {
- // input
- return interface.readC1(time) << 4; // input not latched
- } else {
- // output
- return latchPortC & 0xf0; // output is latched
- }
- }
- byte I8255::peekC1(EmuTime::param time) const
- {
- if (control & DIRECTION_C1) {
- return interface.peekC1(time) << 4; // input not latched
- } else {
- return latchPortC & 0xf0; // output is latched
- }
- }
- byte I8255::readC0(EmuTime::param time)
- {
- if (control & DIRECTION_C0) {
- // input
- return interface.readC0(time); // input not latched
- } else {
- // output
- return latchPortC & 0x0f; // output is latched
- }
- }
- byte I8255::peekC0(EmuTime::param time) const
- {
- if (control & DIRECTION_C0) {
- return interface.peekC0(time); // input not latched
- } else {
- return latchPortC & 0x0f; // output is latched
- }
- }
- byte I8255::readControlPort(EmuTime::param /*time*/) const
- {
- return control;
- }
- void I8255::writePortA(byte value, EmuTime::param time)
- {
- switch (control & MODE_A) {
- case MODEA_0:
- // do nothing
- break;
- case MODEA_1:
- case MODEA_2: case MODEA_2_:
- // TODO but not relevant for MSX
- break;
- }
- outputPortA(value, time);
- }
- void I8255::writePortB(byte value, EmuTime::param time)
- {
- switch (control & MODE_B) {
- case MODEB_0:
- // do nothing
- break;
- case MODEB_1:
- // TODO but not relevant for MSX
- break;
- }
- outputPortB(value, time);
- }
- void I8255::writePortC(byte value, EmuTime::param time)
- {
- switch (control & MODE_A) {
- case MODEA_0:
- // do nothing
- break;
- case MODEA_1:
- case MODEA_2: case MODEA_2_:
- // TODO but not relevant for MSX
- break;
- }
- switch (control & MODE_B) {
- case MODEB_0:
- // do nothing
- break;
- case MODEB_1:
- // TODO but not relevant for MSX
- break;
- }
- outputPortC(value, time);
- }
- void I8255::outputPortA(byte value, EmuTime::param time)
- {
- latchPortA = value;
- if (!(control & DIRECTION_A)) {
- // output
- interface.writeA(value, time);
- }
- }
- void I8255::outputPortB(byte value, EmuTime::param time)
- {
- latchPortB = value;
- if (!(control & DIRECTION_B)) {
- // output
- interface.writeB(value, time);
- }
- }
- void I8255::outputPortC(byte value, EmuTime::param time)
- {
- latchPortC = value;
- if (!(control & DIRECTION_C1)) {
- // output
- interface.writeC1(latchPortC >> 4, time);
- }
- if (!(control & DIRECTION_C0)) {
- // output
- interface.writeC0(latchPortC & 15, time);
- }
- }
- void I8255::writeControlPort(byte value, EmuTime::param time)
- {
- if (value & SET_MODE) {
- // set new control mode
- control = value;
- if ((control & (MODE_A | MODE_B))) {
- ppiModeCallback.execute();
- }
- outputPortA(latchPortA, time);
- outputPortB(latchPortB, time);
- outputPortC(latchPortC, time);
- } else {
- // (re)set bit of port C
- byte bitmask = 1 << ((value & BIT_NR) >> 1);
- if (value & SET_RESET) {
- // set
- latchPortC |= bitmask;
- } else {
- // reset
- latchPortC &= ~bitmask;
- }
- outputPortC(latchPortC, time);
- // check for special (re)set commands
- // not releant for mode 0
- switch (control & MODE_A) {
- case MODEA_0:
- // do nothing
- break;
- case MODEA_1:
- case MODEA_2: case MODEA_2_:
- // TODO but not relevant for MSX
- break;
- }
- switch (control & MODE_B) {
- case MODEB_0:
- // do nothing
- break;
- case MODEB_1:
- // TODO but not relevant for MSX
- break;
- }
- }
- }
- template<typename Archive>
- void I8255::serialize(Archive& ar, unsigned /*version*/)
- {
- ar.serialize("latchPortA", latchPortA,
- "latchPortB", latchPortB,
- "latchPortC", latchPortC,
- "control", control);
- // note: don't write to any output ports (is handled elsewhere)
- // don't serialize 'warningPrinted'
- }
- INSTANTIATE_SERIALIZE_METHODS(I8255);
- } // namespace openmsx
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