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https://github.com/TomHarte/CLK.git
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743 lines
20 KiB
C++
743 lines
20 KiB
C++
//
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// Archimedes.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 04/03/2024.
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// Copyright © 2024 Thomas Harte. All rights reserved.
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//
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#include "Archimedes.hpp"
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#include "../../AudioProducer.hpp"
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#include "../../KeyboardMachine.hpp"
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#include "../../MediaTarget.hpp"
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#include "../../ScanProducer.hpp"
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#include "../../TimedMachine.hpp"
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#include "../../../InstructionSets/ARM/Executor.hpp"
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#include "../../../Outputs/Log.hpp"
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#include <algorithm>
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#include <array>
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#include <vector>
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namespace {
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Log::Logger<Log::Source::Archimedes> logger;
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enum class Zone {
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LogicallyMappedRAM,
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PhysicallyMappedRAM,
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IOControllers,
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LowROM,
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HighROM,
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VideoController,
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DMAAndMEMC,
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AddressTranslator,
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};
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constexpr std::array<Zone, 0x20> zones(bool is_read) {
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std::array<Zone, 0x20> zones{};
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for(size_t c = 0; c < zones.size(); c++) {
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const auto address = c << 21;
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if(address < 0x200'0000) {
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zones[c] = Zone::LogicallyMappedRAM;
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} else if(address < 0x300'0000) {
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zones[c] = Zone::PhysicallyMappedRAM;
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} else if(address < 0x340'0000) {
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zones[c] = Zone::IOControllers;
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} else if(address < 0x360'0000) {
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zones[c] = is_read ? Zone::LowROM : Zone::VideoController;
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} else if(address < 0x380'0000) {
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zones[c] = is_read ? Zone::LowROM : Zone::DMAAndMEMC;
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} else {
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zones[c] = is_read ? Zone::HighROM : Zone::AddressTranslator;
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}
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}
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return zones;
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}
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}
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namespace Archimedes {
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struct Video {
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void write(uint32_t value) {
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const auto target = (value >> 24) & 0xfc;
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switch(target) {
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case 0x00: case 0x04: case 0x08: case 0x0c:
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case 0x10: case 0x14: case 0x18: case 0x1c:
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case 0x20: case 0x24: case 0x28: case 0x2c:
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case 0x30: case 0x34: case 0x38: case 0x3c:
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logger.error().append("TODO: Video palette logical colour %d to %03x", (target >> 2), value & 0x1fff);
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break;
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case 0x40:
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logger.error().append("TODO: Video border colour to %03x", value & 0x1fff);
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break;
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case 0x44: case 0x48: case 0x4c:
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logger.error().append("TODO: Cursor colour %d to %03x", (target - 0x44) >> 2, value & 0x1fff);
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break;
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case 0x60: case 0x64: case 0x68: case 0x6c:
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case 0x70: case 0x74: case 0x78: case 0x7c:
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logger.error().append("TODO: Stereo image register %d to %03x", (target - 0x60) >> 2, value & 0x7);
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break;
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case 0x80:
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logger.error().append("TODO: Video horizontal period: %d", (value >> 14) & 0x3ff);
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break;
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case 0x84:
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logger.error().append("TODO: Video horizontal sync width: %d", (value >> 14) & 0x3ff);
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break;
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case 0x88:
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logger.error().append("TODO: Video horizontal border start: %d", (value >> 14) & 0x3ff);
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break;
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case 0x8c:
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logger.error().append("TODO: Video horizontal display start: %d", (value >> 14) & 0x3ff);
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break;
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case 0x90:
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logger.error().append("TODO: Video horizontal display end: %d", (value >> 14) & 0x3ff);
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break;
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case 0x94:
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logger.error().append("TODO: Video horizontal border end: %d", (value >> 14) & 0x3ff);
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break;
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case 0x98:
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logger.error().append("TODO: Video horizontal cursor end: %d", (value >> 14) & 0x3ff);
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break;
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case 0x9c:
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logger.error().append("TODO: Video horizontal interlace: %d", (value >> 14) & 0x3ff);
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break;
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case 0xa0:
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logger.error().append("TODO: Video vertical period: %d", (value >> 14) & 0x3ff);
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break;
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case 0xa4:
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logger.error().append("TODO: Video vertical sync width: %d", (value >> 14) & 0x3ff);
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break;
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case 0xa8:
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logger.error().append("TODO: Video vertical border start: %d", (value >> 14) & 0x3ff);
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break;
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case 0xac:
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logger.error().append("TODO: Video vertical display start: %d", (value >> 14) & 0x3ff);
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break;
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case 0xb0:
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logger.error().append("TODO: Video vertical display end: %d", (value >> 14) & 0x3ff);
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break;
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case 0xb4:
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logger.error().append("TODO: Video vertical border end: %d", (value >> 14) & 0x3ff);
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break;
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case 0xb8:
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logger.error().append("TODO: Video vertical cursor start: %d", (value >> 14) & 0x3ff);
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break;
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case 0xbc:
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logger.error().append("TODO: Video vertical cursor end: %d", (value >> 14) & 0x3ff);
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break;
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case 0xc0:
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logger.error().append("TODO: Sound frequency: %d", value & 0x7f);
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break;
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case 0xe0:
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logger.error().append("TODO: video control: %08x", value);
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break;
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default:
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logger.error().append("TODO: unrecognised VIDC write of %08x", value);
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break;
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}
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}
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};
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struct Interrupts {
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// TODO: timers, which decrement at 2Mhz.
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void tick_timers() {
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for(int c = 0; c < 4; c++) {
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// Events happen only on a decrement to 0; a reload value of 0 effectively means 'don't count'.
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if(!counters_[c].value && !counters_[c].reload) {
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continue;
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}
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--counters_[c].value;
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if(!counters_[c].value) {
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counters_[c].value = counters_[c].reload;
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// TODO: event triggered here.
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}
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}
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}
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bool read(uint32_t address, uint8_t &value) {
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const auto target = address & 0x7f;
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switch(target) {
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default: break;
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case 0x00:
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logger.error().append("TODO: IOC control read");
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value = 0;
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return true;
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// IRQ A.
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case 0x10: value = irq_a_.status; return true;
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case 0x14: value = irq_a_.request(); return true;
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case 0x18: value = irq_a_.mask; return true;
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// IRQ B.
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case 0x20: value = irq_b_.status; return true;
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case 0x24: value = irq_b_.request(); return true;
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case 0x28: value = irq_b_.mask; return true;
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// FIQ.
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case 0x30: value = fiq_.status; return true;
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case 0x34: value = fiq_.request(); return true;
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case 0x38: value = fiq_.mask; return true;
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// Counters.
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case 0x40: case 0x50: case 0x60: case 0x70:
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value = counters_[(target >> 4) - 0x4].output & 0xff;
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return true;
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case 0x44: case 0x54: case 0x64: case 0x74:
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value = counters_[(target >> 4) - 0x4].output >> 8;
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return true;
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}
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logger.error().append("TODO: IO controller read from %08x", address);
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return false;
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}
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bool write(uint32_t address, uint8_t value) {
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const auto target = address & 0x7f;
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switch(target) {
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default: break;
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case 0x00:
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logger.error().append("TODO: IOC control write %02x", value);
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return true;
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case 0x14:
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logger.error().append("TODO: IRQ clear write %02x", value);
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// b2: clear IF.
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// b3: clear IR.
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// b4: clear POR.
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// b5: clear TM[0].
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// b6: clear TM[1].
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return true;
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// Interrupts.
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case 0x18: irq_a_.mask = value; return true;
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case 0x28: irq_b_.mask = value; return true;
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case 0x38: fiq_.mask = value; return true;
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// Counters.
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case 0x40: case 0x50: case 0x60: case 0x70:
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counters_[(target >> 4) - 0x4].reload = uint16_t(
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(counters_[(target >> 4) - 0x4].reload & 0xff00) | value
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);
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return true;
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case 0x44: case 0x54: case 0x64: case 0x74:
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counters_[(target >> 4) - 0x4].reload = uint16_t(
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(counters_[(target >> 4) - 0x4].reload & 0x00ff) | (value << 8)
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);
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return true;
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case 0x48: case 0x58: case 0x68: case 0x78:
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counters_[(target >> 4) - 0x4].value = counters_[(target >> 4) - 0x4].reload;
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return true;
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case 0x4c: case 0x5c: case 0x6c: case 0x7c:
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counters_[(target >> 4) - 0x4].output = counters_[(target >> 4) - 0x4].value;
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return true;
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}
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logger.error().append("TODO: IO controller write of %02x at %08x", value, address);
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return false;
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}
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Interrupts() {
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irq_a_.status = 0x80 | 0x10; // i.e. 'set always' + 'power-on'.
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irq_b_.status = 0x00;
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fiq_.status = 0x80; // 'set always'.
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}
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private:
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struct Interrupt {
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uint8_t status, mask;
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uint8_t request() const {
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return status & mask;
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}
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};
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Interrupt irq_a_, irq_b_, fiq_;
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struct Counter {
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uint16_t value;
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uint16_t reload;
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uint16_t output;
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};
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Counter counters_[4];
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};
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/// Primarily models the MEMC.
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struct Memory {
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void set_rom(const std::vector<uint8_t> &rom) {
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std::copy(
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rom.begin(),
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rom.begin() + static_cast<ptrdiff_t>(std::min(rom.size(), rom_.size())),
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rom_.begin());
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}
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template <typename IntT>
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bool write(uint32_t address, IntT source, InstructionSet::ARM::Mode mode, bool trans) {
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(void)trans;
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switch (write_zones_[(address >> 21) & 31]) {
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case Zone::DMAAndMEMC:
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// if(mode != InstructionSet::ARM::Mode::Supervisor) return false;
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if((address & 0b1110'0000'0000'0000'0000) == 0b1110'0000'0000'0000'0000) {
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// "The parameters are encoded into the processor address lines".
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os_mode_ = address & (1 << 12);
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sound_dma_enable_ = address & (1 << 11);
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video_dma_enable_ = address & (1 << 10);
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switch((address >> 8) & 3) {
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default:
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dynamic_ram_refresh_ = DynamicRAMRefresh::None;
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break;
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case 0b01:
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case 0b11:
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dynamic_ram_refresh_ = DynamicRAMRefresh((address >> 8) & 3);
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break;
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}
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high_rom_access_time_ = ROMAccessTime((address >> 6) & 3);
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low_rom_access_time_ = ROMAccessTime((address >> 4) & 3);
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page_size_ = PageSize((address >> 2) & 3);
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logger.info().append("MEMC Control: %08x -> OS:%d sound:%d video:%d high:%d low:%d size:%d", address, os_mode_, sound_dma_enable_, video_dma_enable_, high_rom_access_time_, low_rom_access_time_, page_size_);
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update_mapping();
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return true;
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} else {
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logger.error().append("TODO: DMA/MEMC %08x to %08x", source, address);
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}
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break;
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case Zone::LogicallyMappedRAM: {
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const auto item = logical_ram<IntT, false>(address, mode);
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if(!item) {
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return false;
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}
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*item = source;
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return true;
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} break;
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case Zone::IOControllers:
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ioc_.write(address, source);
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return true;
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case Zone::VideoController:
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// TODO: handle byte writes correctly.
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vidc_.write(source);
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break;
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case Zone::PhysicallyMappedRAM:
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// if(mode != InstructionSet::ARM::Mode::Supervisor) return false;
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physical_ram<IntT>(address) = source;
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return true;
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case Zone::AddressTranslator:
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pages_[address & 0x7f] = address;
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update_mapping();
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break;
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default:
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printf("TODO: write of %08x to %08x [%lu]\n", source, address, sizeof(IntT));
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break;
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}
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return true;
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}
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template <typename IntT>
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bool read(uint32_t address, IntT &source, InstructionSet::ARM::Mode mode, bool trans) {
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(void)trans;
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// logger.info().append("R %08x", address);
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switch (read_zones_[(address >> 21) & 31]) {
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case Zone::PhysicallyMappedRAM:
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// if(mode != InstructionSet::ARM::Mode::Supervisor) return false;
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source = physical_ram<IntT>(address);
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return true;
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case Zone::LogicallyMappedRAM: {
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if(!has_moved_rom_) { // TODO: maintain this state in the zones table.
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source = high_rom<IntT>(address);
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return true;
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}
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const auto item = logical_ram<IntT, true>(address, mode);
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if(!item) {
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return false;
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}
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source = *item;
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return true;
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} break;
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case Zone::LowROM:
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logger.error().append("TODO: Low ROM read from %08x", address);
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break;
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case Zone::HighROM:
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// Real test is: require A24=A25=0, then A25=1.
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// TODO: as above, move this test into the zones tables.
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has_moved_rom_ = true;
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source = high_rom<IntT>(address);
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return true;
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case Zone::IOControllers: {
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if constexpr (std::is_same_v<IntT, uint8_t>) {
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ioc_.read(address, source);
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return true;
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} else {
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// TODO: generalise this adaptation of an 8-bit device to the 32-bit bus, which probably isn't right anyway.
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uint8_t value;
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ioc_.read(address, value);
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// if(!ioc_.read(address, value)) {
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// return false;
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// }
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source = value;
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return true;
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}
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}
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default:
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logger.error().append("TODO: read from %08x", address);
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break;
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}
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source = 0;
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return true;
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}
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Memory() {
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// Install initial logical memory map.
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update_mapping();
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}
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void tick_timers() {
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ioc_.tick_timers();
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}
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private:
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bool has_moved_rom_ = false;
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std::array<uint8_t, 4*1024*1024> ram_{};
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std::array<uint8_t, 2*1024*1024> rom_;
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Interrupts ioc_;
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Video vidc_;
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template <typename IntT>
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IntT &physical_ram(uint32_t address) {
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return *reinterpret_cast<IntT *>(&ram_[address & (ram_.size() - 1)]);
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}
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template <typename IntT>
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IntT &high_rom(uint32_t address) {
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return *reinterpret_cast<IntT *>(&rom_[address & (rom_.size() - 1)]);
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}
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static constexpr std::array<Zone, 0x20> read_zones_ = zones(true);
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static constexpr std::array<Zone, 0x20> write_zones_ = zones(false);
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// Control register values.
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bool os_mode_ = false;
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bool sound_dma_enable_ = false;
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bool video_dma_enable_ = false; // "Unaffected" by reset, so here picked arbitrarily.
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enum class DynamicRAMRefresh {
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None = 0b00,
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DuringFlyback = 0b01,
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Continuous = 0b11,
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} dynamic_ram_refresh_ = DynamicRAMRefresh::None; // State at reset is undefined; constrain to a valid enum value.
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enum class ROMAccessTime {
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ns450 = 0b00,
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ns325 = 0b01,
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ns200 = 0b10,
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ns200with60nsNibble = 0b11,
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} high_rom_access_time_ = ROMAccessTime::ns450, low_rom_access_time_ = ROMAccessTime::ns450;
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enum class PageSize {
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kb4 = 0b00,
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kb8 = 0b01,
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kb16 = 0b10,
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kb32 = 0b11,
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} page_size_ = PageSize::kb4;
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// Address translator.
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//
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// MEMC contains one entry per a physical page number, indicating where it goes logically.
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// Any logical access is tested against all 128 mappings. So that's backwards compared to
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// the ideal for an emulator, which would map from logical to physical, even if a lot more
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// compact — there are always 128 physical pages; there are up to 8192 logical pages.
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//
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// So captured here are both the physical -> logical map as representative of the real
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// hardware, and the reverse logical -> physical map, which is built (and rebuilt, and rebuilt)
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// from the other.
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// Physical to logical mapping.
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std::array<uint32_t, 128> pages_{};
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// Logical to physical mapping.
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struct MappedPage {
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uint8_t *target = nullptr;
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uint8_t protection_level = 0;
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};
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std::array<MappedPage, 8192> mapping_;
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template <typename IntT, bool is_read>
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IntT *logical_ram(uint32_t address, InstructionSet::ARM::Mode mode) {
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address &= 0x1ff'ffff;
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size_t page;
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// TODO: eliminate switch here.
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switch(page_size_) {
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default:
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case PageSize::kb4:
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page = address >> 12;
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address &= 0x0fff;
|
|
break;
|
|
case PageSize::kb8:
|
|
page = address >> 13;
|
|
address &= 0x1fff;
|
|
break;
|
|
case PageSize::kb16:
|
|
page = address >> 14;
|
|
address &= 0x3fff;
|
|
break;
|
|
case PageSize::kb32:
|
|
page = address >> 15;
|
|
address &= 0x7fff;
|
|
break;
|
|
}
|
|
|
|
if(!mapping_[page].target) {
|
|
return nullptr;
|
|
}
|
|
|
|
// TODO: eliminate switch here.
|
|
// Top of my head idea: is_read, is_user and is_os_mode make three bits, so
|
|
// keep a one-byte bitmap of permitted accesses rather than the raw protection
|
|
// level?
|
|
switch(mapping_[page].protection_level) {
|
|
case 0b00: break;
|
|
case 0b01:
|
|
if(!is_read && mode == InstructionSet::ARM::Mode::User) {
|
|
return nullptr;
|
|
}
|
|
break;
|
|
default:
|
|
if(mode == InstructionSet::ARM::Mode::User) {
|
|
return nullptr;
|
|
}
|
|
if(!is_read && !os_mode_) {
|
|
return nullptr;
|
|
}
|
|
break;
|
|
}
|
|
|
|
return reinterpret_cast<IntT *>(mapping_[page].target + address);
|
|
}
|
|
|
|
void update_mapping() {
|
|
logger.info().append("Updated logical RAM mapping");
|
|
|
|
// For each physical page, project it into logical space.
|
|
switch(page_size_) {
|
|
default:
|
|
case PageSize::kb4: update_mapping<PageSize::kb4>(); break;
|
|
case PageSize::kb8: update_mapping<PageSize::kb8>(); break;
|
|
case PageSize::kb16: update_mapping<PageSize::kb16>(); break;
|
|
case PageSize::kb32: update_mapping<PageSize::kb32>(); break;
|
|
}
|
|
}
|
|
|
|
template <PageSize size>
|
|
void update_mapping() {
|
|
// Clear all logical mappings.
|
|
std::fill(mapping_.begin(), mapping_.end(), MappedPage{});
|
|
|
|
const auto bits = [](int start, int end) -> uint32_t {
|
|
return ((1 << start) - 1) - ((1 << end) - 1);
|
|
};
|
|
|
|
// For each physical page, project it into logical space
|
|
// and store it.
|
|
for(const auto page: pages_) {
|
|
uint32_t physical, logical;
|
|
|
|
switch(size) {
|
|
case PageSize::kb4:
|
|
// 4kb:
|
|
// A[6:0] -> PPN[6:0]
|
|
// A[11:10] -> LPN[12:11]; A[22:12] -> LPN[10:0] i.e. 8192 logical pages
|
|
physical = page & bits(6, 0);
|
|
|
|
physical <<= 12;
|
|
|
|
logical = (page & bits(11, 10)) << 1;
|
|
logical |= (page & bits(22, 12)) >> 12;
|
|
break;
|
|
|
|
case PageSize::kb8:
|
|
// 8kb:
|
|
// A[0] -> PPN[6]; A[6:1] -> PPN[5:0]
|
|
// A[11:10] -> LPN[11:10]; A[22:13] -> LPN[9:0] i.e. 4096 logical pages
|
|
physical = (page & bits(0, 0)) << 6;
|
|
physical |= (page & bits(6, 1)) >> 1;
|
|
|
|
physical <<= 13;
|
|
|
|
logical = page & bits(11, 10);
|
|
logical |= (page & bits(22, 13)) >> 13;
|
|
break;
|
|
|
|
case PageSize::kb16:
|
|
// 16kb:
|
|
// A[1:0] -> PPN[6:5]; A[6:2] -> PPN[4:0]
|
|
// A[11:10] -> LPN[10:9]; A[22:14] -> LPN[8:0] i.e. 2048 logical pages
|
|
physical = (page & bits(1, 0)) << 5;
|
|
physical |= (page & bits(6, 2)) >> 2;
|
|
|
|
physical <<= 14;
|
|
|
|
logical = (page & bits(11, 10)) >> 1;
|
|
logical |= (page & bits(22, 14)) >> 14;
|
|
break;
|
|
|
|
case PageSize::kb32:
|
|
// 32kb:
|
|
// A[1] -> PPN[6]; A[2] -> PPN[5]; A[0] -> PPN[4]; A[6:3] -> PPN[6:3]
|
|
// A[11:10] -> LPN[9:8]; A[22:15] -> LPN[7:0] i.e. 1024 logical pages
|
|
physical = (page & bits(1, 1)) << 5;
|
|
physical |= (page & bits(2, 2)) << 3;
|
|
physical |= (page & bits(0, 0)) << 4;
|
|
physical |= page & bits(6, 3);
|
|
|
|
physical <<= 15;
|
|
|
|
logical = (page & bits(11, 10)) >> 2;
|
|
logical |= (page & bits(22, 15)) >> 15;
|
|
break;
|
|
}
|
|
|
|
// TODO: consider clashes.
|
|
// TODO: what if there's less than 4mb present?
|
|
mapping_[logical].target = &ram_[physical];
|
|
mapping_[logical].protection_level = (page >> 8) & 3;
|
|
}
|
|
}
|
|
};
|
|
|
|
class ConcreteMachine:
|
|
public Machine,
|
|
public MachineTypes::MediaTarget,
|
|
public MachineTypes::TimedMachine,
|
|
public MachineTypes::ScanProducer
|
|
{
|
|
// TODO: pick a sensible clock rate; this is just code for '20 MIPS, please'.
|
|
static constexpr int ClockRate = 20'000'000;
|
|
|
|
// Timers tick at 2Mhz, so figure out the proper divider for that.
|
|
static constexpr int TimerTarget = ClockRate / 2'000'000;
|
|
int timer_divider_ = TimerTarget;
|
|
|
|
public:
|
|
ConcreteMachine(
|
|
const Analyser::Static::Target &target,
|
|
const ROMMachine::ROMFetcher &rom_fetcher
|
|
) {
|
|
set_clock_rate(ClockRate);
|
|
|
|
constexpr ROM::Name risc_os = ROM::Name::AcornRISCOS319;
|
|
ROM::Request request(risc_os);
|
|
auto roms = rom_fetcher(request);
|
|
if(!request.validate(roms)) {
|
|
throw ROMMachine::Error::MissingROMs;
|
|
}
|
|
|
|
executor_.bus.set_rom(roms.find(risc_os)->second);
|
|
insert_media(target.media);
|
|
}
|
|
|
|
private:
|
|
|
|
// MARK: - ScanProducer.
|
|
void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
|
|
(void)scan_target;
|
|
}
|
|
Outputs::Display::ScanStatus get_scaled_scan_status() const override {
|
|
return Outputs::Display::ScanStatus();
|
|
}
|
|
|
|
// MARK: - TimedMachine.
|
|
void run_for(Cycles cycles) override {
|
|
static uint32_t last_pc = 0;
|
|
|
|
auto instructions = cycles.as<int>();
|
|
|
|
while(instructions) {
|
|
auto run_length = std::min(timer_divider_, instructions);
|
|
instructions -= run_length;
|
|
timer_divider_ -= run_length;
|
|
|
|
while(run_length--) {
|
|
uint32_t instruction;
|
|
if(!executor_.bus.read(executor_.pc(), instruction, executor_.registers().mode(), false)) {
|
|
logger.info().append("Prefetch abort at %08x; last good was at %08x", executor_.pc(), last_pc);
|
|
executor_.prefetch_abort();
|
|
|
|
// TODO: does a double abort cause a reset?
|
|
executor_.bus.read(executor_.pc(), instruction, executor_.registers().mode(), false);
|
|
} else {
|
|
last_pc = executor_.pc();
|
|
}
|
|
// TODO: pipeline prefetch?
|
|
|
|
static bool log = false;
|
|
if(log) {
|
|
logger.info().append("%08x: %08x [r0:%08x]", executor_.pc(), instruction, executor_.registers()[0]);
|
|
}
|
|
InstructionSet::ARM::execute<arm_model>(instruction, executor_);
|
|
}
|
|
|
|
if(!timer_divider_) {
|
|
executor_.bus.tick_timers();
|
|
timer_divider_ = TimerTarget;
|
|
}
|
|
}
|
|
|
|
|
|
}
|
|
|
|
// MARK: - MediaTarget
|
|
bool insert_media(const Analyser::Static::Media &) override {
|
|
// int c = 0;
|
|
// for(auto &disk : media.disks) {
|
|
// fdc_.set_disk(disk, c);
|
|
// c++;
|
|
// if(c == 4) break;
|
|
// }
|
|
// return true;
|
|
return false;
|
|
}
|
|
|
|
// MARK: - ARM execution
|
|
static constexpr auto arm_model = InstructionSet::ARM::Model::ARMv2;
|
|
InstructionSet::ARM::Executor<arm_model, Memory> executor_;
|
|
};
|
|
|
|
}
|
|
|
|
using namespace Archimedes;
|
|
|
|
std::unique_ptr<Machine> Machine::Archimedes(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
|
|
return std::make_unique<ConcreteMachine>(*target, rom_fetcher);
|
|
}
|