embedded-storage 0.1.0

/// Read only NOR flash trait.
pub trait ReadNorFlash {
	/// An enumeration of storage errors
	type Error;

	/// The minumum number of bytes the storage peripheral can read
	const READ_SIZE: usize;

	/// Read a slice of data from the storage peripheral, starting the read
	/// operation at the given address offset, and reading `bytes.len()` bytes.
	///
	/// This should throw an error in case `bytes.len()` will be larger than
	/// the peripheral end address.
	fn try_read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error>;

	/// The capacity of the peripheral in bytes.
	fn capacity(&self) -> usize;
}

/// NOR flash trait.
pub trait NorFlash: ReadNorFlash {
	/// The minumum number of bytes the storage peripheral can write
	const WRITE_SIZE: usize;

	/// The minumum number of bytes the storage peripheral can erase
	const ERASE_SIZE: usize;

	/// Erase the given storage range, clearing all data within `[from..to]`.
	/// The given range will contain all 1s afterwards.
	///
	/// This should return an error if the range is not aligned to a proper
	/// erase resolution
	/// If power is lost during erase, contents of the page are undefined.
	/// `from` and `to` must both be multiples of `ERASE_SIZE` and `from` <= `to`.
	fn try_erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error>;

	/// If power is lost during write, the contents of the written words are undefined,
	/// but the rest of the page is guaranteed to be unchanged.
	/// It is not allowed to write to the same word twice.
	/// `offset` and `bytes.len()` must both be multiples of `WRITE_SIZE`.
	fn try_write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error>;
}

/// Marker trait for NorFlash relaxing the restrictions on `write`.
///
/// Writes to the same word twice are now allowed. The result is the logical AND of the
/// previous data and the written data. That is, it is only possible to change 1 bits to 0 bits.
///
/// If power is lost during write:
/// - Bits that were 1 on flash and are written to 1 are guaranteed to stay as 1
/// - Bits that were 1 on flash and are written to 0 are undefined
/// - Bits that were 0 on flash are guaranteed to stay as 0
/// - Rest of the bits in the page are guaranteed to be unchanged
pub trait MultiwriteNorFlash: NorFlash {}