Add ReadNorFlash::read_if_not_empty

Author: bugadani

src/nor_flash.rs

@@ -68,6 +68,24 @@ pub trait ReadNorFlash: ErrorType {
 	/// can use the [`check_read`] helper function.
 	fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error>;
 
+	/// Read a slice of data from the storage peripheral, starting the read
+	/// operation at the given address offset, and reading `bytes.len()` bytes.
+	///
+	/// The function returns `Ok(true)` if the data is considered to be non-empty.
+	/// The value of `bytes` should not be considered reliable if the function returns `Ok(false)`.
+	///
+	/// This function is useful for devices that offer transparent flash encryption,
+	/// and for devices where the erased byte value is not `0xFF`.
+	///
+	/// # Errors
+	///
+	/// Returns an error if the arguments are not aligned or out of bounds. The implementation
+	/// can use the [`check_read`] helper function.
+	fn read_if_not_empty(&mut self, offset: u32, bytes: &mut [u8]) -> Result<bool, Self::Error> {
+		self.read(offset, bytes)?;
+		Ok(!bytes.iter().all(|&b| b == 0xFF))
+	}
+
 	/// The capacity of the peripheral in bytes.
 	fn capacity(&self) -> usize;
 }