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Improve terminology, add more documentation.

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This commit is contained in:
Thomas Harte 2024-03-23 21:12:01 -04:00
parent ccfc389274
commit 3cf262d1f7
1 changed files with 29 additions and 26 deletions
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55
Machines/Acorn/Archimedes/Keyboard.hpp
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@ -33,33 +33,33 @@ struct Keyboard {
if(serial_.events(KeyboardParty) & HalfDuplexSerial::Receive) {
const auto reset = [&]() {
serial_.output(KeyboardParty, HRST);
phase_ = Phase::Idle;
state_ = State::Idle;
};
const uint8_t input = serial_.input(KeyboardParty);
// A reset command is always accepted, usurping any other state.
if(input == HRST) {
phase_ = Phase::ExpectingRAK1;
state_ = State::ExpectingRAK1;
event_queue_.clear();
serial_.output(KeyboardParty, HRST);
return;
}
switch(phase_) {
case Phase::ExpectingACK:
switch(state_) {
case State::ExpectingACK:
if(input != NACK && input != SMAK && input != MACK && input != SACK) {
reset();
break;
}
phase_ = Phase::Idle;
state_ = State::Idle;
[[fallthrough]];
case Phase::Idle:
case State::Idle:
switch(input) {
case RQID: // Post keyboard ID.
serial_.output(KeyboardParty, 0x81); // Declare this to be a UK keyboard.
phase_ = Phase::Idle;
state_ = State::Idle;
break;
case PRST: // "1-byte command, does nothing."
@ -98,31 +98,31 @@ struct Keyboard {
}
break;
case Phase::ExpectingRAK1:
case State::ExpectingRAK1:
if(input != RAK1) {
reset();
break;
}
serial_.output(KeyboardParty, input);
phase_ = Phase::ExpectingRAK2;
state_ = State::ExpectingRAK2;
break;
case Phase::ExpectingRAK2:
case State::ExpectingRAK2:
if(input != RAK2) {
reset();
break;
}
serial_.output(KeyboardParty, input);
phase_ = Phase::ExpectingACK;
state_ = State::ExpectingACK;
break;
case Phase::ExpectingBACK:
case State::ExpectingBACK:
if(input != BACK) {
reset();
break;
}
dequeue_next();
phase_ = Phase::ExpectingACK;
state_ = State::ExpectingACK;
break;
}
@ -131,8 +131,8 @@ struct Keyboard {
}
void consider_dequeue() {
if(phase_ == Phase::Idle && dequeue_next()) {
phase_ = Phase::ExpectingBACK;
if(state_ == State::Idle && dequeue_next()) {
state_ = State::ExpectingBACK;
}
}
@ -143,13 +143,16 @@ private:
bool scan_keyboard_ = false;
bool scan_mouse_ = false;
enum class Phase {
ExpectingRAK1,
ExpectingRAK2,
ExpectingBACK,
ExpectingACK,
Idle,
} phase_ = Phase::Idle;
enum class State {
ExpectingRAK1, // Post a RAK1 and proceed to ExpectingRAK2 if RAK1 is received; otherwise request a reset.
ExpectingRAK2, // Post a RAK2 and proceed to ExpectingACK if RAK2 is received; otherwise request a reset.
ExpectingACK, // Process NACK, SACK, MACK or SMAK if received; otherwise request a reset.
Idle, // Process any of: NACK, SACK, MACK, SMAK, RQID, RQMP, RQPD or LEDS if received; also
// unilaterally begin post a byte pair enqueued but not yet sent if any are waiting.
ExpectingBACK, // Dequeue and post one further byte if BACK is received; otherwise request a reset.
} state_ = State::Idle;
std::vector<uint8_t> event_queue_;
void enqueue(uint8_t first, uint8_t second) {
@ -173,10 +176,10 @@ private:
static constexpr uint8_t RQMP = 0b0010'0010; // Request for mouse data.
static constexpr uint8_t BACK = 0b0011'1111; // Acknowledge for first keyboard data byte pair.
static constexpr uint8_t NACK = 0b0011'0000; // Acknowledge for last keyboard data byte pair, selects scan/mouse mode.
static constexpr uint8_t SACK = 0b0011'0001; // Last data byte acknowledge.
static constexpr uint8_t MACK = 0b0011'0010; // Last data byte acknowledge.
static constexpr uint8_t SMAK = 0b0011'0011; // Last data byte acknowledge.
static constexpr uint8_t NACK = 0b0011'0000; // Acknowledge for last keyboard data byte pair, disables both scanning and mouse.
static constexpr uint8_t SACK = 0b0011'0001; // Last data byte acknowledge, enabling scanning but disabling mouse.
static constexpr uint8_t MACK = 0b0011'0010; // Last data byte acknowledge, disabling scanning but enabling mouse.
static constexpr uint8_t SMAK = 0b0011'0011; // Last data byte acknowledge, enabling scanning and mouse.
static constexpr uint8_t PRST = 0b0010'0001; // Does nothing.
};