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CLK/Components/8272/i8272.cpp

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//
// i8272.cpp
// Clock Signal
//
// Created by Thomas Harte on 05/08/2017.
// Copyright 2017 Thomas Harte. All rights reserved.
//
#include "i8272.hpp"
#include "../../Outputs/Log.hpp"
using namespace Intel::i8272;
#define SetDataRequest() (main_status_ |= 0x80)
#define ResetDataRequest() (main_status_ &= ~0x80)
#define DataRequest() (main_status_ & 0x80)
#define SetDataDirectionToProcessor() (main_status_ |= 0x40)
#define SetDataDirectionFromProcessor() (main_status_ &= ~0x40)
#define DataDirectionToProcessor() (main_status_ & 0x40)
#define SetNonDMAExecution() (main_status_ |= 0x20)
#define ResetNonDMAExecution() (main_status_ &= ~0x20)
#define SetBusy() (main_status_ |= 0x10)
#define ResetBusy() (main_status_ &= ~0x10)
#define Busy() (main_status_ & 0x10)
#define SetAbnormalTermination() (status_[0] |= 0x40)
#define SetInvalidCommand() (status_[0] |= 0x80)
#define SetReadyChanged() (status_[0] |= 0xc0)
#define SetSeekEnd() (status_[0] |= 0x20)
#define SetEquipmentCheck() (status_[0] |= 0x10)
#define SetNotReady() (status_[0] |= 0x08)
#define SetSide2() (status_[0] |= 0x04)
#define SetEndOfCylinder() (status_[1] |= 0x80)
#define SetDataError() (status_[1] |= 0x20)
#define SetOverrun() (status_[1] |= 0x10)
#define SetNoData() (status_[1] |= 0x04)
#define SetNotWriteable() (status_[1] |= 0x02)
#define SetMissingAddressMark() (status_[1] |= 0x01)
#define SetControlMark() (status_[2] |= 0x40)
#define ClearControlMark() (status_[2] &= ~0x40)
#define ControlMark() (status_[2] & 0x40)
#define SetDataFieldDataError() (status_[2] |= 0x20)
#define SetWrongCyinder() (status_[2] |= 0x10)
#define SetScanEqualHit() (status_[2] |= 0x08)
#define SetScanNotSatisfied() (status_[2] |= 0x04)
#define SetBadCylinder() (status_[2] |= 0x02)
#define SetMissingDataAddressMark() (status_[2] |= 0x01)
namespace {
const uint8_t CommandReadData = 0x06;
const uint8_t CommandReadDeletedData = 0x0c;
const uint8_t CommandWriteData = 0x05;
const uint8_t CommandWriteDeletedData = 0x09;
const uint8_t CommandReadTrack = 0x02;
const uint8_t CommandReadID = 0x0a;
const uint8_t CommandFormatTrack = 0x0d;
const uint8_t CommandScanLow = 0x11;
const uint8_t CommandScanLowOrEqual = 0x19;
const uint8_t CommandScanHighOrEqual = 0x1d;
const uint8_t CommandRecalibrate = 0x07;
const uint8_t CommandSeek = 0x0f;
const uint8_t CommandSenseInterruptStatus = 0x08;
const uint8_t CommandSpecify = 0x03;
const uint8_t CommandSenseDriveStatus = 0x04;
}
i8272::i8272(BusHandler &bus_handler, Cycles clock_rate) :
Storage::Disk::MFMController(clock_rate),
bus_handler_(bus_handler) {
posit_event(static_cast<int>(Event8272::CommandByte));
}
ClockingHint::Preference i8272::preferred_clocking() {
const auto mfm_controller_preferred_clocking = Storage::Disk::MFMController::preferred_clocking();
if(mfm_controller_preferred_clocking != ClockingHint::Preference::None) return mfm_controller_preferred_clocking;
return is_sleeping_ ? ClockingHint::Preference::None : ClockingHint::Preference::JustInTime;
}
void i8272::run_for(Cycles cycles) {
Storage::Disk::MFMController::run_for(cycles);
if(is_sleeping_) return;
// check for an expired timer
if(delay_time_ > 0) {
if(cycles.as_integral() >= delay_time_) {
delay_time_ = 0;
posit_event(static_cast<int>(Event8272::Timer));
} else {
delay_time_ -= cycles.as_integral();
}
}
// update seek status of any drives presently seeking
if(drives_seeking_) {
int drives_left = drives_seeking_;
for(int c = 0; c < 4; c++) {
if(drives_[c].phase == Drive::Seeking) {
drives_[c].step_rate_counter += cycles.as_integral();
auto steps = drives_[c].step_rate_counter / (8000 * step_rate_time_);
drives_[c].step_rate_counter %= (8000 * step_rate_time_);
while(steps--) {
// Perform a step.
int direction = (drives_[c].target_head_position < drives_[c].head_position) ? -1 : 1;
LOG("Target " << PADDEC(0) << drives_[c].target_head_position << " versus believed " << static_cast<int>(drives_[c].head_position));
select_drive(c);
get_drive().step(Storage::Disk::HeadPosition(direction));
if(drives_[c].target_head_position >= 0) drives_[c].head_position += direction;
// Check for completion.
if(seek_is_satisfied(c)) {
drives_[c].phase = Drive::CompletedSeeking;
drives_seeking_--;
break;
}
}
drives_left--;
if(!drives_left) break;
}
}
}
// check for any head unloads
if(head_timers_running_) {
int timers_left = head_timers_running_;
for(int c = 0; c < 8; c++) {
int drive = (c >> 1);
int head = c&1;
if(drives_[drive].head_unload_delay[head] > 0) {
if(cycles.as_integral() >= drives_[drive].head_unload_delay[head]) {
drives_[drive].head_unload_delay[head] = 0;
drives_[drive].head_is_loaded[head] = false;
head_timers_running_--;
} else {
drives_[drive].head_unload_delay[head] -= cycles.as_integral();
}
timers_left--;
if(!timers_left) break;
}
}
}
// check for busy plus ready disabled
if(is_executing_ && !get_drive().get_is_ready()) {
posit_event(static_cast<int>(Event8272::NoLongerReady));
}
is_sleeping_ = !delay_time_ && !drives_seeking_ && !head_timers_running_;
if(is_sleeping_) update_clocking_observer();
}
void i8272::set_register(int address, uint8_t value) {
// don't consider attempted sets to the status register
if(!address) return;
// if not ready for commands, do nothing
if(!DataRequest() || DataDirectionToProcessor()) return;
if(expects_input_) {
input_ = value;
has_input_ = true;
ResetDataRequest();
} else {
// accumulate latest byte in the command byte sequence
command_.push_back(value);
posit_event(static_cast<int>(Event8272::CommandByte));
}
}
uint8_t i8272::get_register(int address) {
if(address) {
if(result_stack_.empty()) return 0xff;
uint8_t result = result_stack_.back();
result_stack_.pop_back();
if(result_stack_.empty()) posit_event(static_cast<int>(Event8272::ResultEmpty));
return result;
} else {
return main_status_;
}
}
#define BEGIN_SECTION() switch(resume_point_) { default:
#define END_SECTION() }
#define MS_TO_CYCLES(x) x * 8000
#define WAIT_FOR_EVENT(mask) resume_point_ = __LINE__; interesting_event_mask_ = static_cast<int>(mask); return; case __LINE__:
#define WAIT_FOR_TIME(ms) resume_point_ = __LINE__; interesting_event_mask_ = static_cast<int>(Event8272::Timer); delay_time_ = MS_TO_CYCLES(ms); is_sleeping_ = false; update_clocking_observer(); case __LINE__: if(delay_time_) return;
#define PASTE(x, y) x##y
#define CONCAT(x, y) PASTE(x, y)
#define FIND_HEADER() \
set_data_mode(DataMode::Scanning); \
CONCAT(find_header, __LINE__): WAIT_FOR_EVENT(static_cast<int>(Event::Token) | static_cast<int>(Event::IndexHole)); \
if(event_type == static_cast<int>(Event::IndexHole)) { index_hole_limit_--; } \
else if(get_latest_token().type == Token::ID) goto CONCAT(header_found, __LINE__); \
\
if(index_hole_limit_) goto CONCAT(find_header, __LINE__); \
CONCAT(header_found, __LINE__): (void)0;\
#define FIND_DATA() \
set_data_mode(DataMode::Scanning); \
CONCAT(find_data, __LINE__): WAIT_FOR_EVENT(static_cast<int>(Event::Token) | static_cast<int>(Event::IndexHole)); \
if(event_type == static_cast<int>(Event::Token)) { \
if(get_latest_token().type == Token::Byte || get_latest_token().type == Token::Sync) goto CONCAT(find_data, __LINE__); \
}
#define READ_HEADER() \
distance_into_section_ = 0; \
set_data_mode(DataMode::Reading); \
CONCAT(read_header, __LINE__): WAIT_FOR_EVENT(Event::Token); \
header_[distance_into_section_] = get_latest_token().byte_value; \
distance_into_section_++; \
if(distance_into_section_ < 6) goto CONCAT(read_header, __LINE__); \
#define SET_DRIVE_HEAD_MFM() \
active_drive_ = command_[1]&3; \
active_head_ = (command_[1] >> 2)&1; \
status_[0] = (command_[1]&7); \
select_drive(active_drive_); \
get_drive().set_head(active_head_); \
set_is_double_density(command_[0] & 0x40);
#define WAIT_FOR_BYTES(n) \
distance_into_section_ = 0; \
CONCAT(wait_bytes, __LINE__): WAIT_FOR_EVENT(Event::Token); \
if(get_latest_token().type == Token::Byte) distance_into_section_++; \
if(distance_into_section_ < (n)) goto CONCAT(wait_bytes, __LINE__);
#define LOAD_HEAD() \
if(!drives_[active_drive_].head_is_loaded[active_head_]) { \
drives_[active_drive_].head_is_loaded[active_head_] = true; \
WAIT_FOR_TIME(head_load_time_); \
} else { \
if(drives_[active_drive_].head_unload_delay[active_head_] > 0) { \
drives_[active_drive_].head_unload_delay[active_head_] = 0; \
head_timers_running_--; \
} \
}
#define SCHEDULE_HEAD_UNLOAD() \
if(drives_[active_drive_].head_is_loaded[active_head_]) {\
if(drives_[active_drive_].head_unload_delay[active_head_] == 0) { \
head_timers_running_++; \
is_sleeping_ = false; \
update_clocking_observer(); \
} \
drives_[active_drive_].head_unload_delay[active_head_] = MS_TO_CYCLES(head_unload_time_);\
}
void i8272::posit_event(int event_type) {
if(event_type == static_cast<int>(Event::IndexHole)) index_hole_count_++;
if(event_type == static_cast<int>(Event8272::NoLongerReady)) {
SetNotReady();
goto abort;
}
if(!(interesting_event_mask_ & event_type)) return;
interesting_event_mask_ &= ~event_type;
BEGIN_SECTION();
// Resets busy and non-DMA execution, clears the command buffer, sets the data mode to scanning and flows
// into wait_for_complete_command_sequence.
wait_for_command:
expects_input_ = false;
set_data_mode(Storage::Disk::MFMController::DataMode::Scanning);
ResetBusy();
ResetNonDMAExecution();
command_.clear();
// Sets the data request bit, and waits for a byte. Then sets the busy bit. Continues accepting bytes
// until it has a quantity that make up an entire command, then resets the data request bit and
// branches to that command.
wait_for_complete_command_sequence:
SetDataRequest();
SetDataDirectionFromProcessor();
WAIT_FOR_EVENT(Event8272::CommandByte)
SetBusy();
static const std::size_t required_lengths[32] = {
0, 0, 9, 3, 2, 9, 9, 2,
1, 9, 2, 0, 9, 6, 0, 3,
0, 9, 0, 0, 0, 0, 0, 0,
0, 9, 0, 0, 0, 9, 0, 0,
};
if(command_.size() < required_lengths[command_[0] & 0x1f]) goto wait_for_complete_command_sequence;
if(command_.size() == 9) {
cylinder_ = command_[2];
head_ = command_[3];
sector_ = command_[4];
size_ = command_[5];
}
ResetDataRequest();
status_[0] = status_[1] = status_[2] = 0;
// If this is not clearly a command that's safe to carry out in parallel to a seek, end all seeks.
switch(command_[0] & 0x1f) {
case CommandReadData:
case CommandReadDeletedData:
case CommandWriteData:
case CommandWriteDeletedData:
case CommandReadTrack:
case CommandReadID:
case CommandFormatTrack:
case CommandScanLow:
case CommandScanLowOrEqual:
case CommandScanHighOrEqual:
is_access_command_ = true;
break;
default:
is_access_command_ = false;
break;
}
if(is_access_command_) {
for(int c = 0; c < 4; c++) {
if(drives_[c].phase == Drive::Seeking) {
drives_[c].phase = Drive::NotSeeking;
drives_seeking_--;
}
}
// Establishes the drive and head being addressed, and whether in double density mode; populates the internal
// cylinder, head, sector and size registers from the command stream.
is_executing_ = true;
if(!dma_mode_) SetNonDMAExecution();
SET_DRIVE_HEAD_MFM();
LOAD_HEAD();
if(!get_drive().get_is_ready()) {
SetNotReady();
goto abort;
}
}
// Jump to the proper place.
switch(command_[0] & 0x1f) {
case CommandReadData:
case CommandReadDeletedData:
goto read_data;
case CommandWriteData:
case CommandWriteDeletedData:
goto write_data;
case CommandReadTrack: goto read_track;
case CommandReadID: goto read_id;
case CommandFormatTrack: goto format_track;
case CommandScanLow: goto scan_low;
case CommandScanLowOrEqual: goto scan_low_or_equal;
case CommandScanHighOrEqual: goto scan_high_or_equal;
case CommandRecalibrate: goto recalibrate;
case CommandSeek: goto seek;
case CommandSenseInterruptStatus: goto sense_interrupt_status;
case CommandSpecify: goto specify;
case CommandSenseDriveStatus: goto sense_drive_status;
default: goto invalid;
}
// Decodes drive, head and density, loads the head, loads the internal cylinder, head, sector and size registers,
// and searches for a sector that meets those criteria. If one is found, inspects the instruction in use and
// jumps to an appropriate handler.
read_write_find_header:
// Sets a maximum index hole limit of 2 then performs a find header/read header loop, continuing either until
// the index hole limit is breached or a sector is found with a cylinder, head, sector and size equal to the
// values in the internal registers.
index_hole_limit_ = 2;
// LOG("Seeking " << PADDEC(0) << cylinder_ << " " << head_ " " << sector_ << " " << size_);
find_next_sector:
FIND_HEADER();
if(!index_hole_limit_) {
// Two index holes have passed wihout finding the header sought.
// LOG("Not found");
SetNoData();
goto abort;
}
index_hole_count_ = 0;
// LOG("Header");
READ_HEADER();
if(index_hole_count_) {
// This implies an index hole was sighted within the header. Error out.
SetEndOfCylinder();
goto abort;
}
if(get_crc_generator().get_value()) {
// This implies a CRC error in the header; mark as such but continue.
SetDataError();
}
// LOG("Considering << PADHEX(2) << header_[0] << " " << header_[1] << " " << header_[2] << " " << header_[3] << " [" << get_crc_generator().get_value() << "]");
if(header_[0] != cylinder_ || header_[1] != head_ || header_[2] != sector_ || header_[3] != size_) goto find_next_sector;
// Branch to whatever is supposed to happen next
// LOG("Proceeding");
switch(command_[0] & 0x1f) {
case CommandReadData:
case CommandReadDeletedData:
goto read_data_found_header;
case CommandWriteData: // write data
case CommandWriteDeletedData: // write deleted data
goto write_data_found_header;
}
// Performs the read data or read deleted data command.
read_data:
LOG(PADHEX(2) << "Read [deleted] data ["
<< static_cast<int>(command_[2]) << " "
<< static_cast<int>(command_[3]) << " "
<< static_cast<int>(command_[4]) << " "
<< static_cast<int>(command_[5]) << " ... "
<< static_cast<int>(command_[6]) << " "
<< static_cast<int>(command_[8]) << "]");
read_next_data:
goto read_write_find_header;
// Finds the next data block and sets data mode to reading, setting an error flag if the on-disk deleted
// flag doesn't match the sort the command was looking for.
read_data_found_header:
FIND_DATA();
ClearControlMark();
if(event_type == static_cast<int>(Event::Token)) {
if(get_latest_token().type != Token::Data && get_latest_token().type != Token::DeletedData) {
// Something other than a data mark came next, impliedly an ID or index mark.
SetMissingAddressMark();
SetMissingDataAddressMark();
goto abort; // TODO: or read_next_data?
} else {
if((get_latest_token().type == Token::Data) != ((command_[0] & 0x1f) == CommandReadData)) {
if(!(command_[0]&0x20)) {
// SK is not set; set the error flag but read this sector before finishing.
SetControlMark();
} else {
// SK is set; skip this sector.
goto read_next_data;
}
}
}
} else {
// An index hole appeared before the data mark.
SetEndOfCylinder();
goto abort; // TODO: or read_next_data?
}
distance_into_section_ = 0;
set_data_mode(Reading);
// Waits for the next token, then supplies it to the CPU by: (i) setting data request and direction; and (ii) resetting
// data request once the byte has been taken. Continues until all bytes have been read.
//
// TODO: consider DTL.
read_data_get_byte:
WAIT_FOR_EVENT(static_cast<int>(Event::Token) | static_cast<int>(Event::IndexHole));
if(event_type == static_cast<int>(Event::Token)) {
result_stack_.push_back(get_latest_token().byte_value);
distance_into_section_++;
SetDataRequest();
SetDataDirectionToProcessor();
WAIT_FOR_EVENT(static_cast<int>(Event8272::ResultEmpty) | static_cast<int>(Event::Token) | static_cast<int>(Event::IndexHole));
}
switch(event_type) {
case static_cast<int>(Event8272::ResultEmpty): // The caller read the byte in time; proceed as normal.
ResetDataRequest();
if(distance_into_section_ < (128 << size_)) goto read_data_get_byte;
break;
case static_cast<int>(Event::Token): // The caller hasn't read the old byte yet and a new one has arrived
SetOverrun();
goto abort;
break;
case static_cast<int>(Event::IndexHole):
SetEndOfCylinder();
goto abort;
break;
}
// read CRC, without transferring it, then check it
WAIT_FOR_EVENT(Event::Token);
WAIT_FOR_EVENT(Event::Token);
if(get_crc_generator().get_value()) {
// This implies a CRC error in the sector; mark as such and temrinate.
SetDataError();
SetDataFieldDataError();
goto abort;
}
// check whether that's it: either the final requested sector has been read, or because
// a sector that was [/wasn't] marked as deleted when it shouldn't [/should] have been
if(sector_ != command_[6] && !ControlMark()) {
sector_++;
goto read_next_data;
}
// For a final result phase, post the standard ST0, ST1, ST2, C, H, R, N
goto post_st012chrn;
write_data:
LOG(PADHEX(2) << "Write [deleted] data ["
<< static_cast<int>(command_[2]) << " "
<< static_cast<int>(command_[3]) << " "
<< static_cast<int>(command_[4]) << " "
<< static_cast<int>(command_[5]) << " ... "
<< static_cast<int>(command_[6]) << " "
<< static_cast<int>(command_[8]) << "]");
if(get_drive().get_is_read_only()) {
SetNotWriteable();
goto abort;
}
write_next_data:
goto read_write_find_header;
write_data_found_header:
WAIT_FOR_BYTES(get_is_double_density() ? 22 : 11);
begin_writing(true);
write_id_data_joiner((command_[0] & 0x1f) == CommandWriteDeletedData, true);
SetDataDirectionFromProcessor();
SetDataRequest();
expects_input_ = true;
distance_into_section_ = 0;
write_loop:
WAIT_FOR_EVENT(Event::DataWritten);
if(!has_input_) {
SetOverrun();
goto abort;
}
write_byte(input_);
has_input_ = false;
distance_into_section_++;
if(distance_into_section_ < (128 << size_)) {
SetDataRequest();
goto write_loop;
}
LOG("Wrote " << PADDEC(0) << distance_into_section_ << " bytes");
write_crc();
expects_input_ = false;
WAIT_FOR_EVENT(Event::DataWritten);
end_writing();
if(sector_ != command_[6]) {
sector_++;
goto write_next_data;
}
goto post_st012chrn;
// Performs the read ID command.
read_id:
// Establishes the drive and head being addressed, and whether in double density mode.
LOG(PADHEX(2) << "Read ID [" << static_cast<int>(command_[0]) << " " << static_cast<int>(command_[1]) << "]");
// Sets a maximum index hole limit of 2 then waits either until it finds a header mark or sees too many index holes.
// If a header mark is found, reads in the following bytes that produce a header. Otherwise branches to data not found.
index_hole_limit_ = 2;
FIND_HEADER();
if(!index_hole_limit_) {
SetMissingAddressMark();
goto abort;
}
READ_HEADER();
// Sets internal registers from the discovered header and posts the standard ST0, ST1, ST2, C, H, R, N.
cylinder_ = header_[0];
head_ = header_[1];
sector_ = header_[2];
size_ = header_[3];
goto post_st012chrn;
// Performs read track.
read_track:
LOG(PADHEX(2) << "Read track ["
<< static_cast<int>(command_[2]) << " "
<< static_cast<int>(command_[3]) << " "
<< static_cast<int>(command_[4]) << " "
<< static_cast<int>(command_[5]) << "]");
// Wait for the index hole.
WAIT_FOR_EVENT(Event::IndexHole);
sector_ = 0;
index_hole_limit_ = 2;
// While not index hole again, stream all sector contents until EOT sectors have been read.
read_track_next_sector:
FIND_HEADER();
if(!index_hole_limit_) {
if(!sector_) {
SetMissingAddressMark();
goto abort;
} else {
goto post_st012chrn;
}
}
READ_HEADER();
FIND_DATA();
distance_into_section_ = 0;
SetDataDirectionToProcessor();
read_track_get_byte:
WAIT_FOR_EVENT(Event::Token);
result_stack_.push_back(get_latest_token().byte_value);
distance_into_section_++;
SetDataRequest();
// TODO: other possible exit conditions; find a way to merge with the read_data version of this.
WAIT_FOR_EVENT(static_cast<int>(Event8272::ResultEmpty));
ResetDataRequest();
if(distance_into_section_ < (128 << header_[2])) goto read_track_get_byte;
sector_++;
if(sector_ < command_[6]) goto read_track_next_sector;
goto post_st012chrn;
// Performs format [/write] track.
format_track:
LOG("Format track");
if(get_drive().get_is_read_only()) {
SetNotWriteable();
goto abort;
}
// Wait for the index hole.
WAIT_FOR_EVENT(Event::IndexHole);
index_hole_count_ = 0;
begin_writing(true);
// Write start-of-track.
write_start_of_track();
WAIT_FOR_EVENT(Event::DataWritten);
sector_ = 0;
format_track_write_sector:
write_id_joiner();
// Write the sector header, obtaining its contents
// from the processor.
SetDataDirectionFromProcessor();
SetDataRequest();
expects_input_ = true;
distance_into_section_ = 0;
format_track_write_header:
WAIT_FOR_EVENT(static_cast<int>(Event::DataWritten) | static_cast<int>(Event::IndexHole));
switch(event_type) {
case static_cast<int>(Event::IndexHole):
SetOverrun();
goto abort;
break;
case static_cast<int>(Event::DataWritten):
header_[distance_into_section_] = input_;
write_byte(input_);
has_input_ = false;
distance_into_section_++;
if(distance_into_section_ < 4) {
SetDataRequest();
goto format_track_write_header;
}
break;
}
LOG(PADHEX(2) << "W:"
<< static_cast<int>(header_[0]) << " "
<< static_cast<int>(header_[1]) << " "
<< static_cast<int>(header_[2]) << " "
<< static_cast<int>(header_[3]) << ", "
<< get_crc_generator().get_value());
write_crc();
// Write the sector body.
write_id_data_joiner(false, false);
write_n_bytes(128 << command_[2], command_[5]);
write_crc();
// Write the prescribed gap.
write_n_bytes(command_[4], get_is_double_density() ? 0x4e : 0xff);
// Consider repeating.
sector_++;
if(sector_ < command_[3] && !index_hole_count_)
goto format_track_write_sector;
// Otherwise, pad out to the index hole.
format_track_pad:
write_byte(get_is_double_density() ? 0x4e : 0xff);
WAIT_FOR_EVENT(static_cast<int>(Event::DataWritten) | static_cast<int>(Event::IndexHole));
if(event_type != static_cast<int>(Event::IndexHole)) goto format_track_pad;
end_writing();
cylinder_ = header_[0];
head_ = header_[1];
sector_ = header_[2] + 1;
size_ = header_[3];
goto post_st012chrn;
scan_low:
ERROR("Scan low unimplemented!!");
goto wait_for_command;
scan_low_or_equal:
ERROR("Scan low or equal unimplemented!!");
goto wait_for_command;
scan_high_or_equal:
ERROR("Scan high or equal unimplemented!!");
goto wait_for_command;
// Performs both recalibrate and seek commands. These commands occur asynchronously, so the actual work
// occurs in ::run_for; this merely establishes that seeking should be ongoing.
recalibrate:
seek:
{
int drive = command_[1]&3;
select_drive(drive);
// Increment the seeking count if this drive wasn't already seeking.
if(drives_[drive].phase != Drive::Seeking) {
drives_seeking_++;
is_sleeping_ = false;
update_clocking_observer();
}
// Set currently seeking, with a step to occur right now (yes, it sounds like jamming these
// in could damage your drive motor).
drives_[drive].phase = Drive::Seeking;
drives_[drive].step_rate_counter = 8000 * step_rate_time_;
drives_[drive].steps_taken = 0;
drives_[drive].seek_failed = false;
main_status_ |= 1 << (command_[1]&3);
// If this is a seek, set the processor-supplied target location; otherwise it is a recalibrate,
// which means resetting the current state now but aiming to hit '-1' (which the stepping code
// up in run_for understands to mean 'keep going until track 0 is active').
if(command_.size() > 2) {
drives_[drive].target_head_position = command_[2];
LOG(PADHEX(2) << "Seek to " << static_cast<int>(command_[2]));
} else {
drives_[drive].target_head_position = -1;
drives_[drive].head_position = 0;
LOG("Recalibrate");
}
// Check whether any steps are even needed; if not then mark as completed already.
if(seek_is_satisfied(drive)) {
drives_[drive].phase = Drive::CompletedSeeking;
drives_seeking_--;
}
}
goto wait_for_command;
// Performs sense interrupt status.
sense_interrupt_status:
LOG("Sense interrupt status");
{
// Find the first drive that is in the CompletedSeeking state.
int found_drive = -1;
for(int c = 0; c < 4; c++) {
if(drives_[c].phase == Drive::CompletedSeeking) {
found_drive = c;
break;
}
}
// If a drive was found, return its results. Otherwise return a single 0x80.
if(found_drive != -1) {
drives_[found_drive].phase = Drive::NotSeeking;
status_[0] = static_cast<uint8_t>(found_drive);
main_status_ &= ~(1 << found_drive);
SetSeekEnd();
result_stack_ = { drives_[found_drive].head_position, status_[0]};
} else {
result_stack_ = { 0x80 };
}
}
goto post_result;
// Performs specify.
specify:
// Just store the values, and terminate the command.
LOG("Specify");
step_rate_time_ = 16 - (command_[1] >> 4); // i.e. 1 to 16ms
head_unload_time_ = (command_[1] & 0x0f) << 4; // i.e. 16 to 240ms
head_load_time_ = command_[2] & ~1; // i.e. 2 to 254 ms in increments of 2ms
if(!head_unload_time_) head_unload_time_ = 16;
if(!head_load_time_) head_load_time_ = 2;
dma_mode_ = !(command_[2] & 1);
goto wait_for_command;
sense_drive_status:
LOG("Sense drive status");
{
int drive = command_[1] & 3;
select_drive(drive);
result_stack_= {
static_cast<uint8_t>(
(command_[1] & 7) | // drive and head number
0x08 | // single sided
(get_drive().get_is_track_zero() ? 0x10 : 0x00) |
(get_drive().get_is_ready() ? 0x20 : 0x00) |
(get_drive().get_is_read_only() ? 0x40 : 0x00)
)
};
}
goto post_result;
// Performs any invalid command.
invalid:
// A no-op, but posts ST0 (but which ST0?)
result_stack_ = {0x80};
goto post_result;
// Sets abnormal termination of the current command and proceeds to an ST0, ST1, ST2, C, H, R, N result phase.
abort:
end_writing();
SetAbnormalTermination();
goto post_st012chrn;
// Posts ST0, ST1, ST2, C, H, R and N as a result phase.
post_st012chrn:
SCHEDULE_HEAD_UNLOAD();
result_stack_ = {size_, sector_, head_, cylinder_, status_[2], status_[1], status_[0]};
goto post_result;
// Posts whatever is in result_stack_ as a result phase. Be aware that it is a stack, so the
// last thing in it will be returned first.
post_result:
LOGNBR(PADHEX(2) << "Result to " << static_cast<int>(command_[0] & 0x1f) << ", main " << static_cast<int>(main_status_) << "; ");
for(std::size_t c = 0; c < result_stack_.size(); c++) {
LOGNBR(" " << static_cast<int>(result_stack_[result_stack_.size() - 1 - c]));
}
LOGNBR(std::endl);
// Set ready to send data to the processor, no longer in non-DMA execution phase.
is_executing_ = false;
ResetNonDMAExecution();
SetDataRequest();
SetDataDirectionToProcessor();
// The actual stuff of unwinding result_stack_ is handled by ::get_register; wait
// until the processor has read all result bytes.
WAIT_FOR_EVENT(Event8272::ResultEmpty);
// Reset data direction and end the command.
goto wait_for_command;
END_SECTION()
}
bool i8272::seek_is_satisfied(int drive) {
return (drives_[drive].target_head_position == drives_[drive].head_position) ||
(drives_[drive].target_head_position == -1 && get_drive().get_is_track_zero());
}
void i8272::set_dma_acknowledge(bool dack) {
}
void i8272::set_terminal_count(bool tc) {
}
void i8272::set_data_input(uint8_t value) {
}
uint8_t i8272::get_data_output() {
return 0xff;
}
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