implement simple card storage retreival

src/storage/store.rs

@@ -0,0 +1,40 @@
+use embedded_storage::nor_flash::NorFlash;
+use embedded_storage::nor_flash::ReadNorFlash;
+use esp_storage::{FlashStorage, FlashStorageError};
+
+pub type StoreError = FlashStorageError;
+
+const FLASH_ADDR: u32 = 0x9000;
+
+const INITIALIZATION_SIZE: usize = 0x1004;
+const FLASH_INITIALIZE_MAGIC: u32 = 0xde6de6de;
+
+pub struct Store {
+    pub storage: FlashStorage<'static>,
+}
+
+fn initialize_flash(storage: &mut FlashStorage) -> Result<(), StoreError> {
+    let zeros: [u8; INITIALIZATION_SIZE] = [0; INITIALIZATION_SIZE];
+    storage.write(FLASH_ADDR, &zeros)?;
+    storage.write(FLASH_ADDR, &FLASH_INITIALIZE_MAGIC.to_ne_bytes())?;
+    Ok(())
+}
+
+impl Store {
+    pub fn new(flash: esp_hal::peripherals::FLASH<'static>) -> Result<Self, StoreError> {
+        let mut storage = FlashStorage::new(flash);
+
+        let mut magic: [u8; 4] = [0, 0, 0, 0];
+        storage.read(FLASH_ADDR, &mut magic)?;
+
+        if (u32::from_ne_bytes(magic)) != FLASH_INITIALIZE_MAGIC {
+            initialize_flash(&mut storage)?;
+        }
+
+        Ok(Self { storage })
+    }
+
+    pub fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), StoreError> {
+        self.storage.read(FLASH_ADDR + offset, bytes)
+    }
+}