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/*
Copyright (C) 2020-2022 Rafal Michalski
This file is part of SPECTRUSTY, a Rust library for building emulators.
For the full copyright notice, see the lib.rs file.
*/
//! *ZX Net* coders for the ZX Interface 1.
use core::mem;
use std::time::{Instant};
#[allow(unused_imports)]
use log::{error, warn, info, debug, trace};
use spectrusty_core::clock::{FTs, TimestampOps};
pub use super::zxnet_udp::*;
const CPU_HZ: f32 = 3_500_000.0;
/// This trait is being used by [ZxNet] to send and receive ZX-NET packets to and from remote parties.
pub trait ZxNetSocket {
/// Should return a view of the current packet being composed or received.
fn packet_data(&self) -> &[u8];
/// Signals that the new packet will be composed for sending.
fn begin_packet(&mut self);
/// Adds a `byte` to the packet data. Should return the size of the packet data after appending `byte`.
fn push_byte(&mut self, byte: u8) -> usize;
/// Should return the index of the next byte to be pushed to the outbound data packet.
/// This is the same as the byte size of the composed data packet so far.
fn outbound_index(&self) -> usize;
/// Should send the composed packet to the remote party.
fn send_packet(&mut self);
/// Should optionally wait and get the confirmation from the remote party.
/// Returns `true` if the remote party confirmed the received packet.
fn recv_accept(&mut self) -> bool;
/// Should receive a data packet from the remote party.
/// Returns `true` if the remote party has sent the next data packet.
fn recv_packet(&mut self) -> bool;
/// Gets the next byte from the last received data packet.
/// Returns `None` if there are no more bytes to be returned.
fn pull_byte(&mut self) -> Option<u8>;
/// Should return the index of the next byte to be pulled from the outbound data packet.
fn inbound_index(&self) -> usize;
/// Should send the confirmation of the received packet to the remote party.
fn send_accept(&mut self);
}
/// Implementation of this struct decodes and encodes ZX-NET packets from Spectrum's I/O port signals.
///
/// An implementation of [ZxNetSocket] should be provided as its `S` type parameter.
#[derive(Debug)]
pub struct ZxNet<T, S> {
/// Direct access to the underlying [ZxNetSocket] implementation.
pub socket: S,
event_ts: T,
dir_io: NetDir,
io: NetState,
net_state: bool
}
/// A helper struct for reading ZX-NET header information.
#[repr(C, packed)]
pub struct ZxNetHead {
/// `NCIRIS` The destination station number.
pub dest: u8,
/// `NCSELF` This Spectrum's station number.
pub ours: u8,
/// `NCNUMB` The block number.
pub serial: [u8;2],
/// `NCTYPE` The packet type code . 0 data, 1 EOF
pub eof: u8,
/// `NCOBL` Number of bytes in data block.
pub size: u8,
/// `NCDCS` The data checksum.
pub dchk: u8,
/// `NCHCS` The header checksum.
pub hchk: u8,
}
pub(super) const HEAD_SIZE: usize = mem::size_of::<ZxNetHead>();
/// A trait for converting data to references of [ZxNetHead].
pub trait DataAsZxNetHead {
/// Converts a reference to a data packet to a reference of [ZxNetHead].
fn as_zxnet_header(&self) -> &ZxNetHead;
}
impl DataAsZxNetHead for [u8] {
/// # Panics
/// Panics if the slice length is less than the size of the [ZxNetHead] struct.
fn as_zxnet_header(&self) -> &ZxNetHead {
let head = &self[..mem::size_of::<ZxNetHead>()];
let ptr = head.as_ptr() as *const ZxNetHead;
unsafe { &*ptr }
}
}
// const REST_DELAY: u32 = 6912 + 250; // input
// const SCOUT_WAIT_MAX: u32 = 47250;
const INPAK_WAIT_MAX: FTs = 8925;
const OUTPAK_START_DELAY: FTs = 110;
const BIT_DELAY: FTs = 60;
const REST_DELAY_THRESHOLD: FTs = 64;
const PROBE_DELAY_MIN: FTs = 65;
const PROBE_DELAY_MAX: FTs = 130;
const BYTE_DELAY: FTs = 120;
const BROADCAST_DATA_DELAY: i32 = 530;
// const MAX_PACKET_SIZE: usize = 256 + BODY_INDEX;
#[derive(Clone, Copy, Debug, PartialEq)]
enum NetDir {
Inbound,
Outbound
}
#[derive(Clone, Copy, Debug, PartialEq)]
enum NetState {
Idle(u8),
InputScout,
InputStart,
InputData(u8),
OutputScout,
OutputStart,
OutputData(u8),
OutputStop(u8),
OutputEnd
}
// https://scratchpad.fandom.com/wiki/ZX_Net
// scout: 1 x x x x x x x 0
//(2.5ms) 1 [ 0 x x x x x x x x 1 * bytes ] 0
impl<T: TimestampOps, S: ZxNetSocket> ZxNet<T, S> {
pub fn send_state(&mut self, net: bool, timestamp: T) {
match self.io {
NetState::Idle(..) => {
// println!("set scout: {} {} {}", net, V::vts_diff(self.event_ts, timestamp), V::vts_to_tstates(timestamp));
self.net_state = net;
self.io = NetState::OutputScout;
}
NetState::OutputScout if net && !self.net_state => { // OUTPAK will start
// println!("OUTPAK start from scout");
self.socket.begin_packet();
self.dir_io = NetDir::Outbound;
self.event_ts = timestamp + OUTPAK_START_DELAY;
self.io = NetState::OutputStart;
}
NetState::OutputScout => {
// println!("fake scout");
self.net_state = false;
self.io = NetState::Idle(0);
}
NetState::InputData(0) if net && timestamp >= self.event_ts => { // reply or body packet out OUTPAK
// println!("reply or body packet OUTPAK: {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp + OUTPAK_START_DELAY;
self.io = NetState::OutputStart;
}
NetState::OutputStart if !net && timestamp < self.event_ts => {
// println!("OUTPAK start: {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp + BIT_DELAY;
self.io = NetState::OutputData(0x80);
}
NetState::OutputData(bits) if timestamp < self.event_ts => {
let next_bits = ((bits & !1)| u8::from(net)).rotate_right(1);
self.event_ts = timestamp + BIT_DELAY;
self.io = if bits & 1 == 1 {
NetState::OutputStop(next_bits)
}
else {
NetState::OutputData(next_bits)
};
}
NetState::OutputStop(byte) if net && timestamp < self.event_ts => {
// println!("OUTPAK stop: {:02x}", byte);
match self.dir_io {
NetDir::Inbound if byte == 1 => {
// println!("got send resp 1");
if self.socket.inbound_index() == HEAD_SIZE {
// let now = Instant::now();
self.socket.send_accept();
// println!("sent accept in {:?}", now.elapsed());
}
self.io = NetState::OutputEnd;
}
NetDir::Inbound => {
// println!("this should be 1");
self.net_state = false;
self.io = NetState::Idle(0); // end of packet transmission
}
NetDir::Outbound => {
let len = self.socket.push_byte(byte);
self.io = if len == HEAD_SIZE {
// println!("outbound header end");
NetState::OutputEnd
}
else if len > HEAD_SIZE
&& len - HEAD_SIZE == self.socket.packet_data().as_zxnet_header().size as usize {
// println!("outbound data end");
self.socket.send_packet();
NetState::OutputEnd
}
else {
NetState::OutputStart
}
}
}
self.event_ts = timestamp + BYTE_DELAY;
}
NetState::OutputEnd if !net && timestamp < self.event_ts => { // end outpack
self.event_ts = timestamp; // TODO: SOME TIMEOUT
let head = self.socket.packet_data().as_zxnet_header();
match self.dir_io {
NetDir::Inbound => { // end of outpak resp
self.io = if self.socket.inbound_index() == head.size as usize + HEAD_SIZE {
self.net_state = false;
// println!("end of response and transmission");
NetState::Idle(0) // end of packet transmission
}
else {
// println!("end of response expecting more data");
self.net_state = true;
NetState::InputScout // expect DATA
}
}
NetDir::Outbound => {
self.io = if self.socket.outbound_index() == head.size as usize + HEAD_SIZE {
if head.dest == 0 { // BROADCAST - no response checking
// println!("end of BROADCAST");
self.net_state = false;
NetState::Idle(0) // end of packet transmission
}
else {
// println!("check remote response");
self.net_state = false;
NetState::InputScout // expect CHECK RESP need to fetch acceptance
}
}
else if head.dest == 0 { // BROADCAST - no response checking
// println!("BROADCAST: no check");
self.net_state = false;
NetState::InputData(0) // expect next OUTPAK
}
else {
// println!("check immediate response");
self.net_state = true;
NetState::InputScout // expect CHECK RESP
}
}
}
}
_ => { // something wrong, let scout routine know it's not the right moment
// println!("OUTPUT something wrong: {:?} {:?} {} {}", net, self.io, V::vts_to_tstates(timestamp), V::vts_diff(self.event_ts, timestamp));
self.io = NetState::Idle(0);
self.net_state = false;
}
}
}
pub fn poll_state(&mut self, timestamp: T) -> bool {
match self.io {
NetState::Idle(cnt) => {
if timestamp >= self.event_ts {
match timestamp.diff_from(self.event_ts) as FTs {
0..=REST_DELAY_THRESHOLD => {
// println!("IDLE REST: {} {}", V::vts_diff(self.event_ts, timestamp), cnt);
self.event_ts = timestamp;
self.io = NetState::Idle(cnt.saturating_add(1));
}
PROBE_DELAY_MIN..=PROBE_DELAY_MAX if cnt < 191 => { // WAIT SCOUT
// let now = Instant::now();
if self.socket.recv_packet() {
// println!("{} got packet let it REST: {} {:?} {:?}", cnt,
// self.socket.packet_data().len(), now.elapsed(), &self.socket.packet_data()[0..8]);
// got a packet, so regardless of what spectrums wants we will try to shove it
self.event_ts = timestamp;
self.io = NetState::InputScout;
self.dir_io = NetDir::Inbound;
self.net_state = true;
}
else {
// println!("READ PROBE: {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp;
}
}
_ => {
self.event_ts = timestamp;
self.io = NetState::Idle(0);
self.net_state = false;
}
}
}
else if cnt != 0 {
self.io = NetState::Idle(0);
}
}
NetState::OutputScout => {
// println!("verify scout");
self.io = NetState::Idle(0);
}
NetState::InputScout if self.net_state => { // Spectrum ignores scout (maybe set a scout grace time...)
// println!("SCOUT -> INPAK: {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp;
self.io = NetState::InputStart;
}
NetState::InputScout => {
let now = Instant::now();
if self.socket.recv_accept() {
// println!("got accept: {} {:?}", V::vts_diff(self.event_ts, timestamp), now.elapsed());
self.event_ts = timestamp;
self.io = NetState::InputStart;
self.net_state = true;
}
else {
// println!("NO ACCEPT!");
self.setup_event_time(timestamp, now);
self.io = NetState::Idle(0);
}
}
NetState::InputStart => { // if this happens, something is wrong, so discard packet and go to idle
// println!("INPAK no wait detected!");
self.event_ts = timestamp + INPAK_WAIT_MAX;
self.io = NetState::Idle(0);
self.net_state = false;
}
NetState::InputData(byte) => {
self.net_state = if timestamp < self.event_ts {
self.event_ts = timestamp + BIT_DELAY;
self.io = NetState::InputData(byte >> 1);
byte & 1 == 1
}
else if timestamp.diff_from(self.event_ts) <= BROADCAST_DATA_DELAY {
// println!("INPUT DATA BROADCAST?: {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp;
self.io = NetState::InputStart;
true
}
else {
// println!("INPUT DATA > IDLE: {}", V::vts_diff(self.event_ts, timestamp));
self.io = NetState::Idle(0);
false
};
}
_ => { // unexpected during output
// println!("INPUT something wrong: {:?} {} {}", self.io, V::vts_to_tstates(timestamp), V::vts_diff(self.event_ts, timestamp));
self.io = NetState::Idle(0);
self.net_state = false;
}
}
self.net_state // set by whatever Spectrum writes
}
pub fn wait_data(&mut self, timestamp: T) {
// println!("wait: {}", V::vts_to_tstates(timestamp));
if let Some(byte) = match (self.io, self.dir_io) { // Spectrum wants a byte
(NetState::InputStart, NetDir::Outbound) => Some(1),
(NetState::InputStart, NetDir::Inbound) => self.socket.pull_byte(),
(NetState::InputData(0), NetDir::Inbound) if timestamp > self.event_ts &&
timestamp < self.event_ts + BIT_DELAY => {
// the whole byte has been transerred
self.socket.pull_byte()
}
_ => None
}
{
// println!("WAIT -> BYTE [{}] {}", byte, V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp + 2*BIT_DELAY;
self.io = NetState::InputData(byte);
}
else {
// println!("bogus WAIT {}", V::vts_diff(self.event_ts, timestamp));
self.event_ts = timestamp + INPAK_WAIT_MAX;
self.io = NetState::Idle(0);
self.net_state = false;
}
}
pub fn next_frame(&mut self, eof_timestamp: T) {
self.event_ts = self.event_ts.saturating_sub(eof_timestamp);
}
fn setup_event_time(&mut self, timestamp: T, start: Instant) {
let elapsed = start.elapsed().as_secs_f32();
let elapsed_ts = (elapsed * CPU_HZ).round() as FTs;
// println!("waited: {} {}", elapsed_ts, elapsed);
self.event_ts = timestamp + elapsed_ts;
}
}
impl<T: Default, S: Default> Default for ZxNet<T, S> {
fn default() -> Self {
let socket = S::default();
let event_ts = T::default();
let net_state = false;
let dir_io = NetDir::Inbound;
let io = NetState::Idle(0);
ZxNet { socket, event_ts, net_state, dir_io, io }
}
}