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94 lines
2.2 KiB
C++
94 lines
2.2 KiB
C++
//
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// 6522.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/06/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#ifndef _522_hpp
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#define _522_hpp
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#include <cstdint>
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#include <cstdio>
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namespace MOS {
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template <class T> class MOS6522 {
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public:
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MOS6522() :
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_data_direction{0, 0},
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_timer_is_running{false, false}
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{}
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void set_register(int address, uint8_t value)
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{
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printf("6522: %d <- %02x\n", address, value);
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address &= 0xf;
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switch(address)
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{
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// Timer 1
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case 0x06: case 0x04: _interval_timer_latch[0] = (_interval_timer_latch[0]&0xff00) | value; break;
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case 0x05: case 0x07:
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_interval_timer_latch[0] = (_interval_timer_latch[0]&0x00ff) | (uint16_t)(value << 8);
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// TODO: clear interrupt flag
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if(address == 0x05)
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{
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_interval_timer[0] = _interval_timer_latch[0];
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_timer_is_running[0] = true;
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}
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break;
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// Timer 2
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case 0x08: _interval_timer_latch[1] = value; break;
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case 0x09:
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// TODO: clear interrupt flag
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_interval_timer[1] = _interval_timer_latch[1] | (uint16_t)(value << 8);
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_timer_is_running[1] = true;
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break;
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case 0x11: _auxiliary_control_register = value; break;
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}
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}
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uint8_t get_register(int address)
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{
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printf("6522: %d\n", address);
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address &= 0xf;
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switch(address)
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{
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// Timer 1
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case 0x04:
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// TODO: clear interrupt flag
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return _interval_timer[0] & 0x00ff;
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case 0x05: return _interval_timer[0] >> 8;
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case 0x06: return _interval_timer_latch[0] & 0x00ff;
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case 0x07: return _interval_timer_latch[0] >> 8;
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}
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return 0xff;
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}
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void run_for_cycles(unsigned int number_of_cycles)
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{
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_interval_timer[0] -= number_of_cycles;
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_interval_timer[1] -= number_of_cycles;
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// TODO: interrupts, potentially reload of the first timer, other status effects
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}
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private:
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uint16_t _interval_timer[2], _interval_timer_latch[2];
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uint8_t _shift_register;
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uint8_t _input_latch[2];
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uint8_t _data_direction[2];
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bool _timer_is_running[2];
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uint8_t _interrupt_flag_register, _interrupt_enable_register;
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uint8_t _peripheral_control_register, _auxiliary_control_register;
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};
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}
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#endif /* _522_hpp */
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