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Merge pull request #1215 from TomHarte/PCKeyboard
Attempt to implement the XT keyboard controller.
This commit is contained in:
Thomas Harte
GitHub
commit
593c32f621
@ -35,6 +35,72 @@
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namespace PCCompatible {
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class KeyboardController {
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public:
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KeyboardController(PIC &pic) : pic_(pic) {}
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// KB Status Port 61h high bits:
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//; 01 - normal operation. wait for keypress, when one comes in,
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//; force data line low (forcing keyboard to buffer additional
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//; keypresses) and raise IRQ1 high
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//; 11 - stop forcing data line low. lower IRQ1 and don't raise it again.
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//; drop all incoming keypresses on the floor.
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//; 10 - lower IRQ1 and force clock line low, resetting keyboard
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//; 00 - force clock line low, resetting keyboard, but on a 01->00 transition,
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//; IRQ1 would remain high
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void set_mode(uint8_t mode) {
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mode_ = Mode(mode);
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switch(mode_) {
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case Mode::NormalOperation: break;
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case Mode::NoIRQsIgnoreInput:
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pic_.apply_edge<1>(false);
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break;
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case Mode::ClearIRQReset:
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pic_.apply_edge<1>(false);
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[[fallthrough]];
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case Mode::Reset:
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reset_delay_ = 5; // Arbitrarily.
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break;
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}
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}
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void run_for(Cycles cycles) {
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if(reset_delay_ <= 0) {
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return;
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}
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reset_delay_ -= cycles.as<int>();
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if(reset_delay_ <= 0) {
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post(0xaa);
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}
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}
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uint8_t read() {
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pic_.apply_edge<1>(false);
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const uint8_t key = input_;
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input_ = 0;
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return key;
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}
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private:
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void post(uint8_t value) {
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input_ = value;
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pic_.apply_edge<1>(true);
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}
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enum class Mode {
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NormalOperation = 0b01,
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NoIRQsIgnoreInput = 0b11,
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ClearIRQReset = 0b10,
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Reset = 0b00,
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} mode_;
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uint8_t input_ = 0;
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PIC &pic_;
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int reset_delay_ = 0;
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};
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class MDA {
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public:
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MDA() : crtc_(Motorola::CRTC::Personality::HD6845S, outputter_) {}
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@ -88,10 +154,12 @@ class MDA {
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private:
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struct CRTCOutputter {
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CRTCOutputter() :
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crt(882, 9, 382, 3, Outputs::Display::InputDataType::Luminance1)
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crt(882, 9, 382, 3, Outputs::Display::InputDataType::Red2Green2Blue2)
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// TODO: really this should be a Luminance8 and set an appropriate modal tint colour;
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// consider whether that's worth building into the scan target.
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{
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// crt.set_visible_area(Outputs::Display::Rect(0.1072f, 0.1f, 0.842105263157895f, 0.842105263157895f));
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crt.set_display_type(Outputs::Display::DisplayType::CompositeMonochrome);
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crt.set_display_type(Outputs::Display::DisplayType::RGB);
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}
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void perform_bus_cycle_phase1(const Motorola::CRTC::BusState &state) {
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@ -131,22 +199,42 @@ class MDA {
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}
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}
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// TODO: cursor.
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if(pixels) {
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// TODO: use attributes, as per http://www.seasip.info/VintagePC/mda.html#memmap
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// const uint8_t attributes = ram[((state.refresh_address << 1) + 1) & 0xfff];
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const uint8_t attributes = ram[((state.refresh_address << 1) + 1) & 0xfff];
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const uint8_t glyph = ram[((state.refresh_address << 1) + 0) & 0xfff];
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const uint8_t row = font[(glyph * 14) + state.row_address];
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uint8_t row = font[(glyph * 14) + state.row_address];
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pixel_pointer[0] = row & 0x80;
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pixel_pointer[1] = row & 0x40;
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pixel_pointer[2] = row & 0x20;
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pixel_pointer[3] = row & 0x10;
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pixel_pointer[4] = row & 0x08;
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pixel_pointer[5] = row & 0x04;
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pixel_pointer[6] = row & 0x02;
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pixel_pointer[7] = row & 0x01;
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pixel_pointer[8] = 0; // TODO.
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const uint8_t intensity = (attributes & 0x08) ? 0x0d : 0x09;
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uint8_t blank = 0;
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// Handle irregular attributes.
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// Cf. http://www.seasip.info/VintagePC/mda.html#memmap
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switch(attributes) {
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case 0x00: case 0x08: case 0x80: case 0x88:
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row = 0;
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break;
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case 0x70: case 0x78: case 0xf0: case 0xf8:
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row ^= 0xff;
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blank = intensity;
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break;
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}
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if(((attributes & 7) == 1) && state.row_address == 13) {
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// Draw as underline.
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std::fill(pixel_pointer, pixel_pointer + 9, intensity);
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} else {
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// Draw according to ROM contents, possibly duplicating final column.
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pixel_pointer[0] = (row & 0x80) ? intensity : 0;
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pixel_pointer[1] = (row & 0x40) ? intensity : 0;
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pixel_pointer[2] = (row & 0x20) ? intensity : 0;
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pixel_pointer[3] = (row & 0x10) ? intensity : 0;
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pixel_pointer[4] = (row & 0x08) ? intensity : 0;
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pixel_pointer[5] = (row & 0x04) ? intensity : 0;
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pixel_pointer[6] = (row & 0x02) ? intensity : 0;
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pixel_pointer[7] = (row & 0x01) ? intensity : 0;
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pixel_pointer[8] = (glyph >= 0xc0 && glyph < 0xe0) ? pixel_pointer[7] : blank;
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}
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pixel_pointer += 9;
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}
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}
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@ -254,11 +342,21 @@ using PIT = i8237<false, PITObserver>;
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class i8255PortHandler : public Intel::i8255::PortHandler {
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// Likely to be helpful: https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
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public:
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i8255PortHandler(PCSpeaker &speaker) : speaker_(speaker) {}
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i8255PortHandler(PCSpeaker &speaker, KeyboardController &keyboard) : speaker_(speaker), keyboard_(keyboard) {}
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void set_value(int port, uint8_t value) {
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switch(port) {
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case 1:
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// b7: 0 => enable keyboard read (and IRQ); 1 => don't;
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// b6: 0 => hold keyboard clock low; 1 => don't;
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// b5: 1 => disable IO check; 0 => don't;
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// b4: 1 => disable memory parity check; 0 => don't;
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// b3: [5150] cassette motor control; [5160] high or low switches select;
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// b2: [5150] high or low switches select; [5160] 1 => disable turbo mode;
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// b1, b0: speaker control.
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enable_keyboard_ = !(value & 0x80);
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keyboard_.set_mode(value >> 6);
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high_switches_ = value & 0x08;
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speaker_.set_control(value & 0x01, value & 0x02);
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break;
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@ -268,6 +366,11 @@ class i8255PortHandler : public Intel::i8255::PortHandler {
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uint8_t get_value(int port) {
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switch(port) {
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case 0:
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printf("PPI: from keyboard\n");
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return enable_keyboard_ ? keyboard_.read() : 0b0011'1100;
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// Guesses that switches is high and low combined as below.
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case 2:
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// Common:
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//
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@ -286,18 +389,15 @@ class i8255PortHandler : public Intel::i8255::PortHandler {
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// b0: 1 => floppy drive present; 0 => absent.
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0b0000'1100;
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}
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printf("PPI: from %d\n", port);
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return 0;
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};
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private:
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bool high_switches_ = false;
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PCSpeaker &speaker_;
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KeyboardController &keyboard_;
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// Provisionally, possibly:
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//
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// port 0 = keyboard data output buffer;
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//
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bool enable_keyboard_ = false;
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};
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using PPI = Intel::i8255::i8255<i8255PortHandler>;
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@ -754,8 +854,9 @@ class ConcreteMachine:
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[[maybe_unused]] const Analyser::Static::Target &target,
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const ROMMachine::ROMFetcher &rom_fetcher
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) :
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keyboard_(pic_),
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pit_observer_(pic_, speaker_),
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ppi_handler_(speaker_),
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ppi_handler_(speaker_, keyboard_),
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pit_(pit_observer_),
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ppi_(ppi_handler_),
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context(pit_, dma_, ppi_, pic_, mda_)
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@ -821,6 +922,8 @@ class ConcreteMachine:
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// i.e. CPU instruction rate is 1/3 * ~1.19Mhz ~= 0.4 MIPS.
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//
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keyboard_.run_for(Cycles(1));
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// Query for interrupts and apply if pending.
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if(pic_.pending() && context.flags.flag<InstructionSet::x86::Flag::Interrupt>()) {
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// Regress the IP if a REP is in-progress so as to resume it later.
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@ -899,6 +1002,7 @@ class ConcreteMachine:
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PCSpeaker speaker_;
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MDA mda_;
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KeyboardController keyboard_;
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PITObserver pit_observer_;
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i8255PortHandler ppi_handler_;
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@ -114,13 +114,11 @@ class PIC {
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int acknowledge() {
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awaiting_eoi_ = true;
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// TODO: there's bound to be a better solution than this search?
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// TODO: is this the right priority order?
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in_service_ = 0x80;
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int id = 7;
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while(!(in_service_ & requests_)) {
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in_service_ >>= 1;
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--id;
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in_service_ = 0x01;
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int id = 0;
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while(!(in_service_ & requests_) && in_service_) {
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in_service_ <<= 1;
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++id;
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}
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if(in_service_) {
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