2019-08-11 03:53:52 +00:00
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//
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// ncr5380.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 10/08/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#include "ncr5380.hpp"
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2019-08-12 00:55:20 +00:00
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#include "../../Outputs/Log.hpp"
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2019-08-11 03:53:52 +00:00
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using namespace NCR::NCR5380;
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2019-08-14 03:09:11 +00:00
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NCR5380::NCR5380() {
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device_id_ = bus_.add_device();
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}
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2019-08-11 03:53:52 +00:00
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void NCR5380::write(int address, uint8_t value) {
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2019-08-14 03:09:11 +00:00
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using Line = SCSI::Line;
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2019-08-12 00:55:20 +00:00
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switch(address & 7) {
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case 0:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 0] Set current SCSI bus state to " << PADHEX(2) << int(value));
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2019-08-14 03:09:11 +00:00
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data_bus_ = value;
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2019-08-12 00:55:20 +00:00
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break;
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2019-08-14 03:09:11 +00:00
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case 1: {
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 1] Initiator command register set: " << PADHEX(2) << int(value));
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2019-08-14 03:09:11 +00:00
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initiator_command_ = value;
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SCSI::BusState mask = SCSI::DefaultBusState;
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if(value & 0x80) mask &= ~Line::Reset;
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test_mode_ = !!(value & 0x40);
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/* bit 5 = differential enable if this were a 5381 */
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if(value & 0x10) mask &= ~Line::Acknowledge;
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if(value & 0x08) mask &= ~Line::Busy;
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if(value & 0x04) mask &= ~Line::SelectTarget;
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if(value & 0x02) mask &= ~Line::Attention;
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assert_data_bus_ = (value & 0x01);
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bus_output_ = (bus_output_ | Line::Reset | Line::Acknowledge | Line::Busy | Line::SelectTarget | Line::Attention) & mask;
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} break;
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2019-08-12 00:55:20 +00:00
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case 2:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 2] Set mode: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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mode_ = value;
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2019-08-14 03:09:11 +00:00
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// bit 7: 1 = use block mode DMA mode (if DMA mode is also enabled)
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// bit 6: 1 = be a SCSI target; 0 = be an initiator
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// bit 5: 1 = check parity
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// bit 4: 1 = generate an interrupt if parity checking is enabled and an error is found
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// bit 3: 1 = generate an interrupt when an EOP is received from the DMA controller
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// bit 2: 1 = generate an interrupt and reset low 6 bits of register 1 if an unexpected loss of Line::Busy occurs
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// bit 1: 1 = use DMA mode
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// bit 0: 1 = begin arbitration mode (device ID should be in register 0)
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/*
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Arbitration is accomplished using a bus-free filter to continuously monitor BSY.
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If BSY remains inactive for at least 400 nsec then the SCSI bus is considered free
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and arbitration may begin. Arbitration will begin if the bus is free, SEL is inactive
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and the ARBITRATION bit (port 2, bit 0) is active. Once arbitration has begun
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(BSY asserted), an arbitration delay of 2.2 /Lsec must elapse before the data bus
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can be examined to deter- mine if arbitration has been won. This delay must be
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implemented in the controlling software driver.
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*/
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2019-08-12 00:55:20 +00:00
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break;
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case 3:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 3] Set target command: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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break;
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case 4:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 4] Set select enabled: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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break;
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case 5:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 5] Start DMA send: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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break;
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case 6:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 6] Start DMA target receive: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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break;
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case 7:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 7] Start DMA initiator receive: " << PADHEX(2) << int(value));
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2019-08-12 00:55:20 +00:00
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break;
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}
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2019-08-14 03:09:11 +00:00
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// Data is output only if the data bus is asserted.
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if(assert_data_bus_) {
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bus_output_ &= data_bus_;
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} else {
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bus_output_ |= SCSI::Line::Data;
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}
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// In test mode, still nothing is output. Otherwise throw out
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// the current value of bus_output_.
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if(test_mode_) {
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bus_.set_device_output(device_id_, SCSI::DefaultBusState);
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} else {
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bus_.set_device_output(device_id_, bus_output_);
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}
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2019-08-11 03:53:52 +00:00
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}
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uint8_t NCR5380::read(int address) {
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2019-08-12 00:55:20 +00:00
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switch(address & 7) {
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case 0:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 0] Get current SCSI bus state");
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2019-08-14 03:09:11 +00:00
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return uint8_t(bus_.get_state());
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2019-08-12 00:55:20 +00:00
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case 1:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 1] Initiator command register get");
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2019-08-14 03:09:11 +00:00
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return initiator_command_;
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2019-08-12 00:55:20 +00:00
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case 2:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 2] Get mode");
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2019-08-12 00:55:20 +00:00
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return mode_;
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case 3:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 3] Get target command");
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2019-08-12 00:55:20 +00:00
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return 0xff;
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case 4:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 4] Get current bus state");
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2019-08-12 00:55:20 +00:00
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return 0xff;
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case 5:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 5] Get bus and status");
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2019-08-12 00:55:20 +00:00
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return 0x03;
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case 6:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 6] Get input data");
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2019-08-12 00:55:20 +00:00
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return 0xff;
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case 7:
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2019-08-12 02:43:25 +00:00
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LOG("[SCSI 7] Reset parity/interrupt");
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2019-08-12 00:55:20 +00:00
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return 0xff;
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}
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2019-08-11 03:53:52 +00:00
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return 0;
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}
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