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58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
//
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// DirectAccessDevice.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 17/08/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#include "DirectAccessDevice.hpp"
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using namespace SCSI;
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DirectAccessDevice::DirectAccessDevice(Bus &bus, int scsi_id) :
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bus_(bus),
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scsi_id_mask_(BusState(1 << scsi_id)),
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scsi_bus_device_id_(bus.add_device()) {
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bus.add_observer(this);
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}
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void DirectAccessDevice::scsi_bus_did_change(Bus *, BusState new_state) {
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/*
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"The target determines that it is selected when the SEL# signal
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and its SCSI ID bit are active and the BSY# and I#/O signals
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are false. It then asserts the signal within a selection abort
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time."
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*/
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switch(state_) {
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case State::Inactive:
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if(
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(new_state & scsi_id_mask_) &&
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((new_state & (Line::SelectTarget | Line::Busy | Line::Input)) == Line::SelectTarget)
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) {
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state_ = State::Selected;
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bus_state_ |= Line::Busy | Line::Request;
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bus_.set_device_output(scsi_bus_device_id_, bus_state_);
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}
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break;
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case State::Selected:
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switch(new_state & (Line::Request | Line::Acknowledge)) {
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case Line::Request | Line::Acknowledge:
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bus_state_ &= ~Line::Request;
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printf("Got %02x maybe?\n", bus_state_ & 0xff);
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break;
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case Line::Acknowledge:
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case 0:
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bus_state_ |= Line::Request;
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break;
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default: break;
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}
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bus_.set_device_output(scsi_bus_device_id_, bus_state_);
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break;
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}
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}
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