main menu: wrap around correctly

src/navigation/navigation.rs

@@ -8,13 +8,17 @@ use embassy_time::{Duration, Timer};
 const DEBOUNCE_DURATION_MILLIS: u64 = 100;
 
 pub trait Displayable {
-    fn display(&self, display: &mut PrimaryLcdDisplay<'static>) -> impl core::future::Future<Output = ()> + Send;
+    fn display(
+        &self,
+        display: &mut PrimaryLcdDisplay<'static>,
+    ) -> impl core::future::Future<Output = ()> + Send;
 }
 
 #[embassy_executor::task]
 pub async fn run(mut inputs: Inputs, display: &'static mut PrimaryLcdDisplay<'static>) {
     let mut state = MainMenu { selected: 0 };
 
+    state.display(display).await;
     log::info!("starting navigation");
     loop {
         log::info!("await button press");
@@ -32,7 +36,11 @@ pub async fn run(mut inputs: Inputs, display: &'static mut PrimaryLcdDisplay<'st
         let value = match selection {
             Either6::First(_) => {
                 log::info!("up pressed");
-                (state.selected.wrapping_sub(1)) % MAX_SELECTED
+                if (state.selected - 1) < 0 {
+                    MAX_SELECTED - 1
+                } else {
+                    state.selected - 1
+                }
             }
             Either6::Second(_) => {
                 log::info!("down pressed");