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CLK/Components/6526/6526.hpp
2023-05-10 16:02:18 -05:00

93 lines
2.4 KiB
C++

//
// 6526.h
// Clock Signal
//
// Created by Thomas Harte on 18/07/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#ifndef _526_h
#define _526_h
#include <cstdint>
#include "Implementation/6526Storage.hpp"
#include "../Serial/Line.hpp"
namespace MOS::MOS6526 {
enum Port {
A = 0,
B = 1
};
struct PortHandler {
/// Requests the current input value of @c port from the port handler.
uint8_t get_port_input([[maybe_unused]] Port port) {
return 0xff;
}
/// Sets the current output value of @c port; any bits marked as input will be supplied as 1s.
void set_port_output([[maybe_unused]] Port port, [[maybe_unused]] uint8_t value) {}
};
enum class Personality {
// The 6526, used in machines such as the C64, has a BCD time-of-day clock.
P6526,
// The 8250, used in the Amiga, provides a binary time-of-day clock.
P8250,
};
template <typename PortHandlerT, Personality personality> class MOS6526:
private MOS6526Storage,
private Serial::Line<true>::ReadDelegate
{
public:
MOS6526(PortHandlerT &port_handler) noexcept : port_handler_(port_handler) {
serial_input.set_read_delegate(this);
}
MOS6526(const MOS6526 &) = delete;
/// Writes @c value to the register at @c address. Only the low two bits of the address are decoded.
void write(int address, uint8_t value);
/// Fetches the value of the register @c address. Only the low two bits of the address are decoded.
uint8_t read(int address);
/// Pulses Phi2 to advance by the specified number of half cycles.
void run_for(const HalfCycles half_cycles);
/// Pulses the TOD input the specified number of times.
void advance_tod(int count);
/// @returns @c true if the interrupt output is active, @c false otherwise.
bool get_interrupt_line();
/// Sets the current state of the CNT input.
void set_cnt_input(bool active);
/// Provides both the serial input bit and an additional source of CNT.
Serial::Line<true> serial_input;
/// Sets the current state of the FLG input.
void set_flag_input(bool low);
private:
PortHandlerT &port_handler_;
TODStorage<personality == Personality::P8250> tod_;
template <int port> void set_port_output();
template <int port> uint8_t get_port_input();
void update_interrupts();
void posit_interrupt(uint8_t mask);
void advance_counters(int);
bool serial_line_did_produce_bit(Serial::Line<true> *line, int bit) final;
};
}
#include "Implementation/6526Implementation.hpp"
#endif /* _526_h */