mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-03 08:05:40 +00:00
338 lines
10 KiB
C++
338 lines
10 KiB
C++
//
|
||
// Macintosh.cpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 03/05/2019.
|
||
// Copyright © 2019 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#include "Macintosh.hpp"
|
||
|
||
#include <array>
|
||
|
||
#include "Keyboard.hpp"
|
||
#include "RealTimeClock.hpp"
|
||
#include "Video.hpp"
|
||
|
||
#include "../../CRTMachine.hpp"
|
||
|
||
#include "../../../Processors/68000/68000.hpp"
|
||
#include "../../../Components/6522/6522.hpp"
|
||
#include "../../../Components/DiskII/IWM.hpp"
|
||
|
||
#include "../../Utility/MemoryPacker.hpp"
|
||
|
||
namespace {
|
||
|
||
const int CLOCK_RATE = 7833600;
|
||
|
||
}
|
||
|
||
namespace Apple {
|
||
namespace Macintosh {
|
||
|
||
class ConcreteMachine:
|
||
public Machine,
|
||
public CRTMachine::Machine,
|
||
public CPU::MC68000::BusHandler {
|
||
public:
|
||
ConcreteMachine(const ROMMachine::ROMFetcher &rom_fetcher) :
|
||
mc68000_(*this),
|
||
video_(ram_.data()),
|
||
via_(via_port_handler_),
|
||
via_port_handler_(*this, clock_, keyboard_),
|
||
iwm_(CLOCK_RATE) {
|
||
|
||
// Grab a copy of the ROM and convert it into big-endian data.
|
||
const auto roms = rom_fetcher("Macintosh", { "mac128k.rom" });
|
||
if(!roms[0]) {
|
||
throw ROMMachine::Error::MissingROMs;
|
||
}
|
||
roms[0]->resize(64*1024);
|
||
Memory::PackBigEndian16(*roms[0], rom_.data());
|
||
|
||
// The Mac runs at 7.8336mHz.
|
||
set_clock_rate(double(CLOCK_RATE));
|
||
}
|
||
|
||
void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
|
||
video_.set_scan_target(scan_target);
|
||
}
|
||
|
||
Outputs::Speaker::Speaker *get_speaker() override {
|
||
return nullptr;
|
||
}
|
||
|
||
void run_for(const Cycles cycles) override {
|
||
mc68000_.run_for(cycles);
|
||
}
|
||
|
||
using Microcycle = CPU::MC68000::Microcycle;
|
||
|
||
HalfCycles perform_bus_operation(const Microcycle &cycle, int is_supervisor) {
|
||
time_since_video_update_ += cycle.length;
|
||
time_since_iwm_update_ += cycle.length;
|
||
|
||
// The VIA runs at one-tenth of the 68000's clock speed, in sync with the E clock.
|
||
// See: Guide to the Macintosh Hardware Family p149 (PDF p188).
|
||
via_clock_ += cycle.length;
|
||
via_.run_for(via_clock_.divide(HalfCycles(10)));
|
||
|
||
// The keyboard also has a clock, albeit a very slow one.
|
||
// Its clock and data lines are connected to the VIA.
|
||
keyboard_clock_ += cycle.length;
|
||
auto keyboard_ticks = keyboard_clock_.divide(HalfCycles(CLOCK_RATE / 100000));
|
||
if(keyboard_ticks > HalfCycles(0)) {
|
||
keyboard_.run_for(keyboard_ticks);
|
||
via_.set_control_line_input(MOS::MOS6522::Port::B, MOS::MOS6522::Line::Two, keyboard_.get_data());
|
||
via_.set_control_line_input(MOS::MOS6522::Port::B, MOS::MOS6522::Line::One, keyboard_.get_clock());
|
||
}
|
||
|
||
// TODO: SCC is a divide-by-two.
|
||
|
||
// Consider updating the real-time clock.
|
||
real_time_clock_ += cycle.length;
|
||
auto ticks = real_time_clock_.divide_cycles(Cycles(CLOCK_RATE)).as_int();
|
||
while(ticks--) {
|
||
clock_.update();
|
||
// TODO: leave a delay between toggling the input rather than using this coupled hack.
|
||
via_.set_control_line_input(MOS::MOS6522::Port::A, MOS::MOS6522::Line::Two, true);
|
||
via_.set_control_line_input(MOS::MOS6522::Port::A, MOS::MOS6522::Line::Two, false);
|
||
}
|
||
|
||
// Update interrupt input. TODO: move this into a VIA/etc delegate callback?
|
||
mc68000_.set_interrupt_level( (via_.get_interrupt_line() ? 1 : 0) );
|
||
|
||
// A null cycle leaves nothing else to do.
|
||
if(cycle.operation) {
|
||
auto word_address = cycle.word_address();
|
||
|
||
// Everything above E0 0000 is signalled as being on the peripheral bus.
|
||
mc68000_.set_is_peripheral_address(word_address >= 0x700000);
|
||
|
||
if(word_address >= 0x400000) {
|
||
if(cycle.data_select_active()) {
|
||
|
||
const int register_address = word_address >> 8;
|
||
|
||
switch(word_address & 0x78f000) {
|
||
case 0x70f000:
|
||
// VIA accesses are via address 0xefe1fe + register*512,
|
||
// which at word precision is 0x77f0ff + register*256.
|
||
if(cycle.operation & Microcycle::Read) {
|
||
cycle.value->halves.low = via_.get_register(register_address);
|
||
if(cycle.operation & Microcycle::SelectWord) cycle.value->halves.high = 0xff;
|
||
} else {
|
||
via_.set_register(register_address, cycle.value->halves.low);
|
||
}
|
||
break;
|
||
|
||
case 0x68f000:
|
||
// The IWM; this is a purely polled device, so can be run on demand.
|
||
iwm_.run_for(time_since_iwm_update_.flush_cycles());
|
||
if(cycle.operation & Microcycle::Read) {
|
||
cycle.value->halves.low = iwm_.read(register_address);
|
||
if(cycle.operation & Microcycle::SelectWord) cycle.value->halves.high = 0xff;
|
||
} else {
|
||
iwm_.write(register_address, cycle.value->halves.low);
|
||
}
|
||
break;
|
||
|
||
default:
|
||
if(cycle.operation & Microcycle::Read) {
|
||
cycle.value->halves.low = 0xff;
|
||
if(cycle.operation & Microcycle::SelectWord) cycle.value->halves.high = 0xff;
|
||
}
|
||
break;
|
||
}
|
||
}
|
||
} else {
|
||
if(cycle.data_select_active()) {
|
||
uint16_t *memory_base = nullptr;
|
||
auto operation = cycle.operation;
|
||
|
||
// When ROM overlay is enabled, the ROM begins at both $000000 and $400000,
|
||
// and RAM is available at $600000.
|
||
//
|
||
// Otherwise RAM is mapped at $000000 and ROM from $400000.
|
||
if(
|
||
(ROM_is_overlay_ && word_address >= 0x300000) ||
|
||
(!ROM_is_overlay_ && word_address < 0x200000)
|
||
) {
|
||
memory_base = ram_.data();
|
||
word_address %= ram_.size();
|
||
} else {
|
||
memory_base = rom_.data();
|
||
word_address %= rom_.size();
|
||
|
||
// Disallow writes to ROM.
|
||
if(!(operation & Microcycle::Read)) operation = 0;
|
||
}
|
||
|
||
switch(operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read | Microcycle::InterruptAcknowledge)) {
|
||
default:
|
||
break;
|
||
|
||
case Microcycle::SelectWord | Microcycle::Read:
|
||
cycle.value->full = memory_base[word_address];
|
||
break;
|
||
case Microcycle::SelectByte | Microcycle::Read:
|
||
cycle.value->halves.low = uint8_t(memory_base[word_address] >> cycle.byte_shift());
|
||
break;
|
||
case Microcycle::SelectWord:
|
||
memory_base[word_address] = cycle.value->full;
|
||
break;
|
||
case Microcycle::SelectByte:
|
||
memory_base[word_address] = uint16_t(
|
||
(cycle.value->halves.low << cycle.byte_shift()) |
|
||
(memory_base[word_address] & cycle.untouched_byte_mask())
|
||
);
|
||
break;
|
||
}
|
||
} else {
|
||
// TODO: add delay if this is a RAM access and video blocks it momentarily.
|
||
// "Each [video] fetch took two cycles out of eight"
|
||
}
|
||
}
|
||
}
|
||
|
||
/*
|
||
Normal memory map:
|
||
|
||
000000: RAM
|
||
400000: ROM
|
||
9FFFF8+: SCC read operations
|
||
BFFFF8+: SCC write operations
|
||
DFE1FF+: IWM
|
||
EFE1FE+: VIA
|
||
*/
|
||
|
||
return HalfCycles(0);
|
||
}
|
||
|
||
void flush() {
|
||
video_.run_for(time_since_video_update_.flush());
|
||
}
|
||
|
||
void set_rom_is_overlay(bool rom_is_overlay) {
|
||
ROM_is_overlay_ = rom_is_overlay;
|
||
}
|
||
|
||
void set_use_alternate_screen_buffer(bool use_alternate_screen_buffer) {
|
||
video_.set_use_alternate_screen_buffer(use_alternate_screen_buffer);
|
||
}
|
||
|
||
private:
|
||
class VIAPortHandler: public MOS::MOS6522::PortHandler {
|
||
public:
|
||
VIAPortHandler(ConcreteMachine &machine, RealTimeClock &clock, Keyboard &keyboard) :
|
||
machine_(machine), clock_(clock), keyboard_(keyboard) {}
|
||
|
||
using Port = MOS::MOS6522::Port;
|
||
using Line = MOS::MOS6522::Line;
|
||
|
||
void set_port_output(Port port, uint8_t value, uint8_t direction_mask) {
|
||
/*
|
||
Peripheral lines: keyboard data, interrupt configuration.
|
||
(See p176 [/215])
|
||
*/
|
||
switch(port) {
|
||
case Port::A:
|
||
/*
|
||
Port A:
|
||
b7: [input] SCC wait/request (/W/REQA and /W/REQB wired together for a logical OR)
|
||
b6: 0 = alternate screen buffer, 1 = main screen buffer
|
||
b5: floppy disk SEL state control (upper/lower head "among other things")
|
||
b4: 1 = use ROM overlay memory map, 0 = use ordinary memory map
|
||
b3: 0 = use alternate sound buffer, 1 = use ordinary sound buffer
|
||
b2–b0: audio output volume
|
||
*/
|
||
// printf("6522 A: %02x\n", value);
|
||
|
||
machine_.set_use_alternate_screen_buffer(!(value & 0x40));
|
||
machine_.set_rom_is_overlay(!!(value & 0x10));
|
||
break;
|
||
|
||
case Port::B:
|
||
/*
|
||
Port B:
|
||
b7: 0 = sound enabled, 1 = sound disabled
|
||
b6: [input] 0 = video beam in visible portion of line, 1 = outside
|
||
b5: [input] mouse y2
|
||
b4: [input] mouse x2
|
||
b3: [input] 0 = mouse button down, 1 = up
|
||
b2: 0 = real-time clock enabled, 1 = disabled
|
||
b1: clock's data-clock line
|
||
b0: clock's serial data line
|
||
*/
|
||
if(value & 0x4) clock_.abort();
|
||
else clock_.set_input(!!(value & 0x2), !!(value & 0x1));
|
||
break;
|
||
}
|
||
}
|
||
|
||
uint8_t get_port_input(Port port) {
|
||
switch(port) {
|
||
case Port::A:
|
||
// printf("6522 r A\n");
|
||
return 0xff;
|
||
|
||
case Port::B:
|
||
// printf("6522 r B\n");
|
||
return (clock_.get_data() ? 0x02 : 0x00);
|
||
}
|
||
}
|
||
|
||
void set_control_line_output(Port port, Line line, bool value) {
|
||
/*
|
||
Keyboard wiring (I believe):
|
||
CB2 = data (output)
|
||
CB1 = clock (input)
|
||
|
||
CA2 is used for receiving RTC interrupts.
|
||
CA1 is used for receiving vsync maybe?
|
||
*/
|
||
if(port == Port::B && line == Line::Two) keyboard_.set_input(value);
|
||
// printf("6522 line %c%d: %c\n", port ? 'B' : 'A', int(line), value ? 't' : 'f');
|
||
}
|
||
|
||
private:
|
||
ConcreteMachine &machine_;
|
||
RealTimeClock &clock_;
|
||
Keyboard &keyboard_;
|
||
};
|
||
|
||
std::array<uint16_t, 32*1024> rom_;
|
||
std::array<uint16_t, 64*1024> ram_;
|
||
|
||
CPU::MC68000::Processor<ConcreteMachine, true> mc68000_;
|
||
Video video_;
|
||
|
||
RealTimeClock clock_;
|
||
Keyboard keyboard_;
|
||
|
||
MOS::MOS6522::MOS6522<VIAPortHandler> via_;
|
||
VIAPortHandler via_port_handler_;
|
||
|
||
Apple::IWM iwm_;
|
||
|
||
HalfCycles via_clock_;
|
||
HalfCycles real_time_clock_;
|
||
HalfCycles keyboard_clock_;
|
||
HalfCycles time_since_video_update_;
|
||
HalfCycles time_since_iwm_update_;
|
||
|
||
bool ROM_is_overlay_ = true;
|
||
};
|
||
|
||
}
|
||
}
|
||
|
||
using namespace Apple::Macintosh;
|
||
|
||
Machine *Machine::Macintosh(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
|
||
return new ConcreteMachine(rom_fetcher);
|
||
}
|
||
|
||
Machine::~Machine() {}
|