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CLK/Storage/MassStorage/SCSI/TargetImplementation.hpp
2024-01-22 21:17:00 -05:00

280 lines
8.9 KiB
C++

//
// TargetImplementation.hpp
// Clock Signal
//
// Created by Thomas Harte on 19/08/2019.
// Copyright © 2019 Thomas Harte. All rights reserved.
//
#pragma once
template <typename Executor> Target<Executor>::Target(Bus &bus, int scsi_id) :
bus_(bus),
scsi_id_mask_(BusState(1 << scsi_id)),
scsi_bus_device_id_(bus.add_device()) {
bus.add_observer(this);
}
template <typename Executor> void Target<Executor>::scsi_bus_did_change(Bus *, BusState new_state, double time_since_change) {
/*
"The target determines that it is selected when the SEL# signal
and its SCSI ID bit are active and the BSY# and I#/O signals
are false. It then asserts the signal within a selection
abort time."
*/
// Wait for deskew, at the very least.
if(time_since_change < SCSI::DeskewDelay) return;
// A reset always takes precedence over anything else ongoing.
if(new_state & Line::Reset) {
phase_ = Phase::AwaitingSelection;
bus_state_ = DefaultBusState;
set_device_output(bus_state_);
return;
}
switch(phase_) {
/*
While awaiting selection the SCSI target is passively watching the bus waiting for its ID
to be set during a target selection. It will segue automatically from there to the command
phase regardless of its executor.
*/
case Phase::AwaitingSelection:
if(
(new_state & scsi_id_mask_) &&
((new_state & (Line::SelectTarget | Line::Busy | Line::Input)) == Line::SelectTarget)
) {
phase_ = Phase::Command;
command_.resize(0);
command_pointer_ = 0;
bus_state_ |= Line::Busy; // Initiate the command phase: request a command byte.
set_device_output(bus_state_);
}
break;
/*
In the command phase, the target will stream an appropriate number of bytes for the command
it is being offered, before giving the executor a chance to handle the command. If the target
supports this command, it becomes responsible for the appropriate next phase transition. If it
reports that it doesn't support that command, a suitable response is automatically dispatched.
*/
case Phase::Command:
// Wait for select to be disabled before beginning the control phase proper.
if((new_state & Line::SelectTarget)) return;
bus_state_ |= Line::Control;
switch(new_state & (Line::Request | Line::Acknowledge)) {
// If request and acknowledge are both enabled, grab a byte and cancel the request.
case Line::Request | Line::Acknowledge:
bus_state_ &= ~Line::Request;
if(command_.empty()) {
begin_command(uint8_t(new_state));
// TODO: if(command_.empty()) signal_error_somehow();
} else {
command_[command_pointer_] = uint8_t(new_state);
++command_pointer_;
if(command_pointer_ == command_.size()) {
if(!dispatch_command()) {
// This is just a guess for now; I don't know how SCSI
// devices are supposed to respond if they don't support
// a command.
terminate_command(Responder::Status::TaskAborted);
}
}
}
break;
// The reset of request has caused the initiator to reset acknowledge, so it is now
// safe to request the next byte.
case 0:
bus_state_ |= Line::Request;
break;
default: break;
}
set_device_output(bus_state_);
break;
case Phase::ReceivingData:
switch(new_state & (Line::Request | Line::Acknowledge)) {
case Line::Request | Line::Acknowledge:
bus_state_ &= ~Line::Request;
data_[data_pointer_] = uint8_t(new_state);
++data_pointer_;
break;
case 0:
if(data_pointer_ == data_.size()) {
next_function_(CommandState(command_, data_), *this);
} else {
bus_state_ |= Line::Request;
}
break;
}
set_device_output(bus_state_);
break;
case Phase::SendingData:
case Phase::SendingStatus:
case Phase::SendingMessage:
switch(new_state & (Line::Request | Line::Acknowledge)) {
case Line::Request | Line::Acknowledge:
bus_state_ &= ~(Line::Request | 0xff);
++data_pointer_;
break;
case 0:
if(
(phase_ == Phase::SendingMessage && data_pointer_ == 1) ||
(phase_ == Phase::SendingStatus && data_pointer_ == 1) ||
(phase_ == Phase::SendingData && data_pointer_ == data_.size())
) {
next_function_(CommandState(command_, data_), *this);
} else {
bus_state_ |= Line::Request;
bus_state_ &= ~0xff;
switch(phase_) {
case Phase::SendingData: bus_state_ |= data_[data_pointer_]; break;
case Phase::SendingStatus: bus_state_ |= BusState(status_); break;
default:
case Phase::SendingMessage: bus_state_ |= BusState(message_); break;
}
}
break;
}
set_device_output(bus_state_);
break;
}
}
template <typename Executor> void Target<Executor>::begin_command(uint8_t first_byte) {
// The logic below is valid for SCSI-1. TODO: other SCSIs.
switch(first_byte >> 5) {
default: break;
case 0: command_.resize(6); break; // Group 0 commands: 6 bytes long.
case 1: command_.resize(10); break; // Group 1 commands: 10 bytes long.
case 5: command_.resize(12); break; // Group 5 commands: 12 bytes long.
}
// Store the first byte if it was recognised.
if(!command_.empty()) {
command_[0] = first_byte;
command_pointer_ = 1;
}
}
namespace {
constexpr uint8_t G0(uint8_t opcode) { return 0x00 | opcode; }
constexpr uint8_t G1(uint8_t opcode) { return 0x20 | opcode; }
constexpr uint8_t G5(uint8_t opcode) { return 0xa0 | opcode; }
}
template <typename Executor> bool Target<Executor>::dispatch_command() {
CommandState arguments(command_, data_);
log_.info().append("---Command %02x---", command_[0]);
switch(command_[0]) {
default: return false;
case G0(0x00): return executor_.test_unit_ready(arguments, *this);
case G0(0x01): return executor_.rezero_unit(arguments, *this);
case G0(0x03): return executor_.request_sense(arguments, *this);
case G0(0x04): return executor_.format_unit(arguments, *this);
case G0(0x08): return executor_.read(arguments, *this);
case G0(0x0a): return executor_.write(arguments, *this);
case G0(0x0b): return executor_.seek(arguments, *this);
case G0(0x12): return executor_.inquiry(arguments, *this);
case G0(0x15): return executor_.mode_select(arguments, *this);
case G0(0x16): return executor_.reserve_unit(arguments, *this);
case G0(0x17): return executor_.release_unit(arguments, *this);
case G0(0x1a): return executor_.mode_sense(arguments, *this);
case G0(0x1c): return executor_.read_diagnostic(arguments, *this);
case G0(0x1d): return executor_.write_diagnostic(arguments, *this);
case G1(0x05): return executor_.read_capacity(arguments, *this);
case G1(0x08): return executor_.read(arguments, *this);
case G1(0x0a): return executor_.write(arguments, *this);
case G1(0x0e): return executor_.write_and_verify(arguments, *this);
case G1(0x0f): return executor_.verify(arguments, *this);
case G1(0x11): return executor_.search_data_equal(arguments, *this);
case G1(0x10): return executor_.search_data_high(arguments, *this);
case G1(0x12): return executor_.search_data_low(arguments, *this);
case G1(0x1c): return executor_.read_buffer(arguments, *this);
case G1(0x15): return executor_.mode_select(arguments, *this);
case G5(0x09): return executor_.set_block_limits(arguments, *this);
}
return false;
}
template <typename Executor> void Target<Executor>::send_data(std::vector<uint8_t> &&data, continuation next) {
// Data out phase: control and message all reset, input set.
bus_state_ &= ~(Line::Control | Line::Input | Line::Message);
bus_state_ |= Line::Input;
phase_ = Phase::SendingData;
next_function_ = next;
data_ = std::move(data);
data_pointer_ = 0;
set_device_output(bus_state_);
}
template <typename Executor> void Target<Executor>::receive_data(size_t length, continuation next) {
// Data out phase: control, input and message all reset.
bus_state_ &= ~(Line::Control | Line::Input | Line::Message);
phase_ = Phase::ReceivingData;
next_function_ = next;
data_.resize(length);
data_pointer_ = 0;
set_device_output(bus_state_);
}
template <typename Executor> void Target<Executor>::send_status(Status status, continuation next) {
// Status phase: message reset, control and input set.
bus_state_ &= ~(Line::Control | Line::Input | Line::Message);
bus_state_ |= Line::Input | Line::Control;
status_ = status;
phase_ = Phase::SendingStatus;
next_function_ = next;
data_pointer_ = 0;
set_device_output(bus_state_);
}
template <typename Executor> void Target<Executor>::send_message(Message message, continuation next) {
// Message in phase: message, control and input set.
bus_state_ |= Line::Message | Line::Control | Line::Input;
message_ = message;
phase_ = Phase::SendingMessage;
next_function_ = next;
data_pointer_ = 0;
set_device_output(bus_state_);
}
template <typename Executor> void Target<Executor>::end_command() {
// TODO: was this a linked command?
// Release all bus lines and return to awaiting selection.
phase_ = Phase::AwaitingSelection;
bus_state_ = DefaultBusState;
set_device_output(bus_state_);
log_.info().append("---Done---");
}