1 files changed, 153 insertions, 0 deletions
diff --git a/sw/picardy/src/cw.rs b/sw/picardy/src/cw.rs
index ce99e39..4ebebf9 100644
--- a/sw/picardy/src/cw.rs
+++ b/sw/picardy/src/cw.rs
@@ -33,3 +33,156 @@ impl CWPWM {
     }
 }
 
+#[derive(PartialEq, Eq, Clone, Copy)]
+enum MorseSign {
+    Dot,
+    Dash
+}
+
+impl MorseSign {
+    fn length(&self) -> u32 {
+        match self {
+            Self::Dot => 1,
+            Self::Dash => 3,
+        }
+    }
+
+    fn other(&self) -> Self {
+        match self {
+            Self::Dot => Self::Dash,
+            Self::Dash => Self::Dot,
+        }
+    }
+}
+
+fn other_pressed(sign: MorseSign, dot_pressed: bool, dash_pressed: bool) -> bool {
+    match sign {
+        MorseSign::Dot => dash_pressed,
+        MorseSign::Dash => dot_pressed,
+    }
+}
+
+#[derive(PartialEq, Eq, Clone, Copy)]
+enum KeyerState {
+    Idle,
+    Beep{current: MorseSign, next: Option<MorseSign>},
+    Pause{current: MorseSign, next: Option<MorseSign>},
+    LastPause{next: Option<MorseSign>},
+}
+
+pub struct Keyer {
+    // All durations are in ticks
+    dot_length : u32,
+    state : KeyerState,
+    time_last_state_change : u32,
+}
+
+impl Keyer {
+    pub fn new(wpm : u32, ticks_per_s: u32) -> Keyer {
+        /* PARIS standard: 20 words per minute = dot length of 60 ms, inversely proportional:
+         * 1 wpm = 1200 ms, 2 wpm = 600 ms */
+
+        Keyer{
+            dot_length : 1200 * ticks_per_s / (1000 * wpm),
+            state : KeyerState::Idle,
+            time_last_state_change : 0,
+        }
+    }
+    pub fn set_speed(&mut self, wpm : u32, ticks_per_s: u32) { self.dot_length = 1200 * ticks_per_s / (1000 * wpm) }
+
+    pub fn tick(&mut self, ticks_now: u32, dot_pressed: bool, dash_pressed: bool) -> bool {
+        let mut transmit = false;
+
+        let next_state = match self.state {
+            KeyerState::Idle => {
+                if dot_pressed {
+                    transmit = true;
+                    KeyerState::Beep{current: MorseSign::Dot, next: None}
+                }
+                else if dash_pressed {
+                    transmit = true;
+                    KeyerState::Beep{current: MorseSign::Dash, next: None}
+                }
+                else {
+                    KeyerState::Idle
+                }
+            },
+            KeyerState::Beep{current, next} => {
+                transmit = true;
+
+                let next = if other_pressed(current, dot_pressed, dash_pressed) {
+                    Some(current.other())
+                }
+                else {
+                    next
+                };
+
+                if self.time_last_state_change + self.dot_length * current.length() <= ticks_now {
+                    KeyerState::Pause{current, next}
+                }
+                else {
+                    KeyerState::Beep{current, next}
+                }
+            },
+            KeyerState::Pause{current, next} => {
+                let next = if other_pressed(current, dot_pressed, dash_pressed) {
+                    Some(current.other())
+                }
+                else {
+                    next
+                };
+
+                if self.time_last_state_change + self.dot_length <= ticks_now {
+                    match next {
+                        Some(state) => {
+                            transmit = true;
+                            KeyerState::Beep{current: state, next: None}
+                        },
+                        None => KeyerState::LastPause{next: None}
+                    }
+                }
+                else {
+                    KeyerState::Pause{current, next}
+                }
+            },
+            KeyerState::LastPause{next} => {
+                let next = if dot_pressed {
+                    Some(MorseSign::Dot)
+                }
+                else if dash_pressed {
+                    Some(MorseSign::Dash)
+                }
+                else {
+                    next
+                };
+
+                if self.time_last_state_change + self.dot_length <= ticks_now {
+                    KeyerState::LastPause{next}
+                }
+                else {
+                    match next {
+                        Some(MorseSign::Dot) => {
+                            transmit = true;
+                            KeyerState::Beep{current: MorseSign::Dot, next: None}
+                        },
+                        Some(MorseSign::Dash) => {
+                            transmit = true;
+                            KeyerState::Beep{current: MorseSign::Dash, next: None}
+                        },
+                        None => {
+                            KeyerState::Idle
+                        },
+                    }
+                }
+            },
+        };
+
+        if next_state != self.state {
+            self.time_last_state_change = ticks_now;
+            self.state = next_state;
+        }
+
+        transmit
+    }
+}
+