mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-16 04:05:16 +00:00
237 lines
6.8 KiB
C++
237 lines
6.8 KiB
C++
//
|
|
// MDA.hpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 05/12/2023.
|
|
// Copyright © 2023 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#pragma once
|
|
|
|
#include "../../Components/6845/CRTC6845.hpp"
|
|
#include "../../Outputs/CRT/CRT.hpp"
|
|
#include "../../Machines/Utility/ROMCatalogue.hpp"
|
|
|
|
namespace PCCompatible {
|
|
|
|
class MDA {
|
|
public:
|
|
MDA() : crtc_(outputter_) {}
|
|
|
|
static constexpr uint32_t BaseAddress = 0xb'0000;
|
|
static constexpr auto FontROM = ROM::Name::PCCompatibleMDAFont;
|
|
|
|
void set_source(const uint8_t *ram, std::vector<uint8_t> font) {
|
|
outputter_.ram = ram;
|
|
outputter_.font = font;
|
|
}
|
|
|
|
void run_for(Cycles cycles) {
|
|
// Input rate is the PIT rate of 1,193,182 Hz.
|
|
// MDA is actually clocked at 16.257 MHz; which is treated internally as 1,806,333.333333333333333... Hz
|
|
//
|
|
// The GCD of those two numbers is... 2. Oh well.
|
|
full_clock_ += 8'128'500 * cycles.as<int>();
|
|
crtc_.run_for(Cycles(full_clock_ / (596'591 * 9)));
|
|
full_clock_ %= (596'591 * 9);
|
|
}
|
|
|
|
template <int address>
|
|
void write(uint8_t value) {
|
|
switch(address) {
|
|
case 0: case 2: case 4: case 6:
|
|
crtc_.select_register(value);
|
|
break;
|
|
case 1: case 3: case 5: case 7:
|
|
crtc_.set_register(value);
|
|
break;
|
|
|
|
case 0x8:
|
|
outputter_.set_control(value);
|
|
break;
|
|
|
|
default: break;
|
|
}
|
|
}
|
|
|
|
template <int address>
|
|
uint8_t read() {
|
|
switch(address) {
|
|
case 1: case 3: case 5: case 7:
|
|
return crtc_.get_register();
|
|
|
|
case 0x8: return outputter_.control();
|
|
|
|
default: return 0xff;
|
|
}
|
|
}
|
|
|
|
// MARK: - Call-ins for ScanProducer.
|
|
|
|
void set_scan_target(Outputs::Display::ScanTarget *scan_target) {
|
|
outputter_.crt.set_scan_target(scan_target);
|
|
}
|
|
Outputs::Display::ScanStatus get_scaled_scan_status() const {
|
|
return outputter_.crt.get_scaled_scan_status() * 596591.0f / 8128500.0f;
|
|
}
|
|
|
|
// MARK: - Display type configuration.
|
|
|
|
void set_display_type(Outputs::Display::DisplayType) {}
|
|
Outputs::Display::DisplayType get_display_type() const {
|
|
return outputter_.crt.get_display_type();
|
|
}
|
|
|
|
private:
|
|
struct CRTCOutputter {
|
|
CRTCOutputter() :
|
|
crt(882, 9, 370, 3, Outputs::Display::InputDataType::Red2Green2Blue2)
|
|
// TODO: really this should be a Luminance8 and set an appropriate modal tint colour;
|
|
// consider whether that's worth building into the scan target.
|
|
{
|
|
crt.set_visible_area(Outputs::Display::Rect(0.028f, 0.025f, 0.98f, 0.98f));
|
|
crt.set_display_type(Outputs::Display::DisplayType::RGB);
|
|
}
|
|
|
|
void set_control(uint8_t control) {
|
|
// b0: 'high resolution' (probably breaks if not 1)
|
|
// b3: video enable
|
|
// b5: enable blink
|
|
control_ = control;
|
|
}
|
|
|
|
uint8_t control() {
|
|
return control_;
|
|
}
|
|
|
|
void perform_bus_cycle_phase1(const Motorola::CRTC::BusState &state) {
|
|
// Determine new output state.
|
|
const OutputState new_state =
|
|
(state.hsync | state.vsync) ? OutputState::Sync :
|
|
((state.display_enable && control_&0x08) ? OutputState::Pixels : OutputState::Border);
|
|
|
|
// Upon either a state change or just having accumulated too much local time...
|
|
if(new_state != output_state || count > 882) {
|
|
// (1) flush preexisting state.
|
|
if(count) {
|
|
switch(output_state) {
|
|
case OutputState::Sync: crt.output_sync(count); break;
|
|
case OutputState::Border: crt.output_blank(count); break;
|
|
case OutputState::Pixels:
|
|
crt.output_data(count);
|
|
pixels = pixel_pointer = nullptr;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// (2) adopt new state.
|
|
output_state = new_state;
|
|
count = 0;
|
|
}
|
|
|
|
// Collect pixels if applicable.
|
|
if(output_state == OutputState::Pixels) {
|
|
if(!pixels) {
|
|
pixel_pointer = pixels = crt.begin_data(DefaultAllocationSize);
|
|
|
|
// Flush any period where pixels weren't recorded due to back pressure.
|
|
if(pixels && count) {
|
|
crt.output_blank(count);
|
|
count = 0;
|
|
}
|
|
}
|
|
|
|
if(pixels) {
|
|
static constexpr uint8_t high_intensity = 0x0d;
|
|
static constexpr uint8_t low_intensity = 0x09;
|
|
static constexpr uint8_t off = 0x00;
|
|
|
|
if(state.cursor) {
|
|
pixel_pointer[0] = pixel_pointer[1] = pixel_pointer[2] = pixel_pointer[3] =
|
|
pixel_pointer[4] = pixel_pointer[5] = pixel_pointer[6] = pixel_pointer[7] =
|
|
pixel_pointer[8] = low_intensity;
|
|
} else {
|
|
const uint8_t attributes = ram[((state.refresh_address << 1) + 1) & 0xfff];
|
|
const uint8_t glyph = ram[((state.refresh_address << 1) + 0) & 0xfff];
|
|
uint8_t row = font[(glyph * 14) + state.row_address];
|
|
|
|
const uint8_t intensity = (attributes & 0x08) ? high_intensity : low_intensity;
|
|
uint8_t blank = off;
|
|
|
|
// Handle irregular attributes.
|
|
// Cf. http://www.seasip.info/VintagePC/mda.html#memmap
|
|
switch(attributes) {
|
|
case 0x00: case 0x08: case 0x80: case 0x88:
|
|
row = 0;
|
|
break;
|
|
case 0x70: case 0x78: case 0xf0: case 0xf8:
|
|
row ^= 0xff;
|
|
blank = intensity;
|
|
break;
|
|
}
|
|
|
|
// Apply blink if enabled.
|
|
if((control_ & 0x20) && (attributes & 0x80) && (state.field_count & 16)) {
|
|
row ^= 0xff;
|
|
blank = (blank == off) ? intensity : off;
|
|
}
|
|
|
|
if(((attributes & 7) == 1) && state.row_address == 13) {
|
|
// Draw as underline.
|
|
std::fill(pixel_pointer, pixel_pointer + 9, intensity);
|
|
} else {
|
|
// Draw according to ROM contents, possibly duplicating final column.
|
|
pixel_pointer[0] = (row & 0x80) ? intensity : off;
|
|
pixel_pointer[1] = (row & 0x40) ? intensity : off;
|
|
pixel_pointer[2] = (row & 0x20) ? intensity : off;
|
|
pixel_pointer[3] = (row & 0x10) ? intensity : off;
|
|
pixel_pointer[4] = (row & 0x08) ? intensity : off;
|
|
pixel_pointer[5] = (row & 0x04) ? intensity : off;
|
|
pixel_pointer[6] = (row & 0x02) ? intensity : off;
|
|
pixel_pointer[7] = (row & 0x01) ? intensity : off;
|
|
pixel_pointer[8] = (glyph >= 0xc0 && glyph < 0xe0) ? pixel_pointer[7] : blank;
|
|
}
|
|
}
|
|
pixel_pointer += 9;
|
|
}
|
|
}
|
|
|
|
// Advance.
|
|
count += 9;
|
|
|
|
// Output pixel row prematurely if storage is exhausted.
|
|
if(output_state == OutputState::Pixels && pixel_pointer == pixels + DefaultAllocationSize) {
|
|
crt.output_data(count);
|
|
count = 0;
|
|
|
|
pixels = pixel_pointer = nullptr;
|
|
}
|
|
}
|
|
void perform_bus_cycle_phase2(const Motorola::CRTC::BusState &) {}
|
|
|
|
Outputs::CRT::CRT crt;
|
|
|
|
enum class OutputState {
|
|
Sync, Pixels, Border
|
|
} output_state = OutputState::Sync;
|
|
int count = 0;
|
|
|
|
uint8_t *pixels = nullptr;
|
|
uint8_t *pixel_pointer = nullptr;
|
|
static constexpr size_t DefaultAllocationSize = 720;
|
|
|
|
const uint8_t *ram = nullptr;
|
|
std::vector<uint8_t> font;
|
|
|
|
uint8_t control_ = 0;
|
|
} outputter_;
|
|
Motorola::CRTC::CRTC6845<
|
|
CRTCOutputter,
|
|
Motorola::CRTC::Personality::HD6845S,
|
|
Motorola::CRTC::CursorType::MDA> crtc_;
|
|
|
|
int full_clock_ = 0;
|
|
};
|
|
|
|
}
|