save tests

Software/MainBoard/rust/src/hal/savegame_manager.rs

@@ -9,9 +9,10 @@ use crate::hal::shared_flash::MutexFlashStorage;
 
 /// Size of each save slot in bytes (16 KB).
 pub const SAVEGAME_SLOT_SIZE: usize = 16384;
-
+//keep a little of space at the end due to partition table offsets
+const SAFETY: usize = 5;
 /// Number of slots in the 8 MB storage partition.
-pub const SAVEGAME_SLOT_COUNT: usize = 8 * 1024 * 1024 / SAVEGAME_SLOT_SIZE; // 512
+pub const SAVEGAME_SLOT_COUNT: usize = (8 * 1024 * 1024) / SAVEGAME_SLOT_SIZE  - SAFETY; // 507
 
 /// Metadata about a single existing save slot, returned by [`SavegameManager::list_saves`].
 #[derive(Serialize, Debug, Clone)]
@@ -51,9 +52,15 @@ impl Flash for SavegameFlashAdapter<'_> {
     /// embedded-savegame calls this before writing to a slot, so we erase
     /// the entire `SAVEGAME_SLOT_SIZE` bytes so subsequent writes land on
     /// pre-erased (0xFF) pages.
+    /// Ensures addresses are aligned to ERASE_SIZE (4KB) boundaries.
     fn erase(&mut self, addr: u32) -> Result<(), Self::Error> {
+        const ERASE_SIZE: u32 = 4096;
+        // Align start address down to erase boundary
+        let aligned_start = (addr / ERASE_SIZE) * ERASE_SIZE;
+        // Align end address up to erase boundary
         let end = addr + SAVEGAME_SLOT_SIZE as u32;
-        NorFlash::erase(self.region, addr, end).map_err(SavegameFlashError)
+        let aligned_end = ((end + ERASE_SIZE - 1) / ERASE_SIZE) * ERASE_SIZE;
+        NorFlash::erase(self.region, aligned_start, aligned_end).map_err(SavegameFlashError)
     }
 }
 
@@ -91,9 +98,10 @@ impl SavegameManager {
     ///
     /// `scan()` advances the internal wear-leveling pointer to the latest valid
     /// slot before `append()` writes to the next free one.
+    /// Both operations are performed atomically on the same Storage instance.
     pub fn save(&mut self, data: &mut [u8]) -> FatResult<()> {
         let mut st = self.storage();
-        st.scan()?;
+        let _slot = st.scan()?;
         st.append(data)?;
         Ok(())
     }