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71 lines
1.2 KiB
C++
71 lines
1.2 KiB
C++
//
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// IWM.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/05/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#include "IWM.hpp"
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#include <cstdio>
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using namespace Apple;
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IWM::IWM(int clock_rate) {
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}
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uint8_t IWM::read(int address) {
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access(address);
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// printf("IWM r %d (%02x)\n", address&0xf, q_switches_);
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switch(q_switches_) {
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default: return 0x00; // Undefined.
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case 0x20: return 0x00; // Data register.
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case 0x40:
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case 0x60:
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return (mode_&0x1f); // Status register.
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case 0x80:
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case 0xa0:
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return 0x80; // Handshake register.
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}
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}
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void IWM::write(int address, uint8_t input) {
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access(address);
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switch(q_switches_) {
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default:
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break;
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case 0xc0: // Write mode register.
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mode_ = input;
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break;
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case 0xd0: // Write data register.
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break;
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}
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}
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void IWM::access(int address) {
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switch(address & 0xf) {
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default:
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break;
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case 0x8: q_switches_ &= ~0x20; break;
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case 0x9: q_switches_ |= 0x20; break;
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case 0xc: q_switches_ &= ~0x40; break;
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case 0xd: q_switches_ |= 0x40; break;
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case 0xe: q_switches_ &= ~0x80; break;
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case 0xf: q_switches_ |= 0x80; break;
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}
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}
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void IWM::run_for(const Cycles cycles) {
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}
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