Rework NorFlash & Storage traits

Cargo.toml

@@ -13,8 +13,3 @@ documentation = "https://docs.rs/embedded-storage"
 readme = "README.md"
 keywords = ["storage"]
 categories = ["embedded", "hardware-support", "no-std"]
-
-[dependencies]
-nb = "1"
-no-std-net = "0.4"
-heapless = "^0.5"

src/iter.rs

@@ -1,4 +1,4 @@
-use crate::{Address, Region};
+use crate::Region;
 
 /// Iterator producing block-region pairs, where each memory block maps to each
 /// region.
@@ -9,7 +9,7 @@ where
 {
 	memory: &'a [u8],
 	regions: I,
-	base_address: Address,
+	base_address: u32,
 }
 
 /// Trait allowing us to automatically add an `overlaps` function to all iterators over [`Region`]
@@ -19,25 +19,29 @@ where
 	I: Iterator<Item = R>,
 {
 	/// Obtain an [`OverlapIterator`] over a subslice of `memory` that overlaps with the region in `self`
-	fn overlaps(self, memory: &'a [u8], base_address: Address) -> OverlapIterator<R, I>;
+	fn overlaps(self, memory: &'a [u8], base_address: u32) -> OverlapIterator<R, I>;
 }
 
 impl<'a, R, I> Iterator for OverlapIterator<'a, R, I>
 where
 	R: Region,
 	I: Iterator<Item = R>,
 {
-	type Item = (&'a [u8], R, Address);
+	type Item = (&'a [u8], R, u32);
 
 	fn next(&mut self) -> Option<Self::Item> {
 		while let Some(region) = self.regions.next() {
 			//  TODO: This might be possible to do in a smarter way?
 			let mut block_range = (0..self.memory.len())
-				.skip_while(|index| !region.contains(self.base_address + *index))
-				.take_while(|index| region.contains(self.base_address + *index));
+				.skip_while(|index| !region.contains(self.base_address + *index as u32))
+				.take_while(|index| region.contains(self.base_address + *index as u32));
 			if let Some(start) = block_range.next() {
 				let end = block_range.last().unwrap_or(start) + 1;
-				return Some((&self.memory[start..end], region, self.base_address + start));
+				return Some((
+					&self.memory[start..end],
+					region,
+					self.base_address + start as u32,
+				));
 			}
 		}
 		None
@@ -50,7 +54,7 @@ where
 	R: Region,
 	I: Iterator<Item = R>,
 {
-	fn overlaps(self, memory: &'a [u8], base_address: Address) -> OverlapIterator<R, I> {
+	fn overlaps(self, memory: &'a [u8], base_address: u32) -> OverlapIterator<R, I> {
 		OverlapIterator {
 			memory,
 			regions: self,

src/lib.rs

@@ -2,169 +2,45 @@
 //!
 //! Storage traits to allow on and off board storage devices to read and write
 //! data.
-//!
-//! Implementation based on `Cuervo`s great work in
-//! https://www.ecorax.net/as-above-so-below-1/ and
-//! https://www.ecorax.net/as-above-so-below-2/
 
 #![no_std]
 #![deny(missing_docs)]
 #![deny(unsafe_code)]
 
-use core::ops::{Add, Sub};
-use heapless::{consts::*, Vec};
-use nb;
-
 /// Currently contains [`OverlapIterator`]
 pub mod iter;
-
-/// An address denotes the read/write address of a single word.
-#[derive(Default, Copy, Clone, Debug, PartialOrd, PartialEq, Eq, Ord)]
-pub struct Address(pub u32);
-
-impl Add<usize> for Address {
-	type Output = Self;
-
-	fn add(self, rhs: usize) -> Self::Output {
-		Address(self.0 + rhs as u32)
-	}
-}
-
-impl Add<isize> for Address {
-	type Output = Self;
-
-	fn add(self, rhs: isize) -> Self::Output {
-		Address((self.0 as isize + rhs) as u32)
-	}
-}
-impl Sub<usize> for Address {
-	type Output = Self;
-
-	fn sub(self, rhs: usize) -> Self::Output {
-		Address(self.0 - rhs as u32)
-	}
-}
-
-impl Sub<isize> for Address {
-	type Output = Self;
-
-	fn sub(self, rhs: isize) -> Self::Output {
-		Address((self.0 as isize - rhs) as u32)
-	}
-}
-
-impl Sub<Address> for Address {
-	type Output = Self;
-
-	fn sub(self, rhs: Address) -> Self::Output {
-		Address(self.0 - rhs.0)
-	}
-}
+/// Technology specific traits for NOR Flashes
+pub mod nor_flash;
 
 /// A region denotes a contiguous piece of memory between two addresses.
 pub trait Region {
 	/// Check if `address` is contained in the region of `Self`
-	fn contains(&self, address: Address) -> bool;
+	fn contains(&self, address: u32) -> bool;
 }
 
-/// Transparent storage trait
-pub trait ReadWriteStorage {
+/// Transparent read only storage trait
+pub trait ReadStorage {
 	/// An enumeration of storage errors
 	type Error;
 
 	/// Read a slice of data from the storage peripheral, starting the read
-	/// operation at the given address, and reading until end address
-	/// (`self.range().1`) or buffer length, whichever comes first.
-	fn try_read(&mut self, address: Address, bytes: &mut [u8]) -> nb::Result<(), Self::Error>;
-
-	/// Write a slice of data to the storage peripheral, starting the write
-	/// operation at the given address.
-	fn try_write(&mut self, address: Address, bytes: &[u8]) -> nb::Result<(), Self::Error>;
-
-	/// The range of possible addresses within the peripheral.
+	/// operation at the given address offset, and reading `bytes.len()` bytes.
 	///
-	/// (start_addr, end_addr)
-	fn range(&self) -> (Address, Address);
+	/// This should throw an error in case `bytes.len()` will be larger than
+	/// `self.capacity() - offset`.
+	fn try_read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error>;
 
-	/// Erase the given storage range, clearing all data within `[from..to]`.
-	fn try_erase(&mut self, from: Address, to: Address) -> nb::Result<(), Self::Error>;
+	/// The capacity of the storage peripheral in bytes.
+	fn capacity(&self) -> usize;
 }
 
-/// NOR flash region trait.
-pub trait NorFlashRegion {
-	/// The range of possible addresses within the region.
-	///
-	/// (start_addr, end_addr)
-	fn range(&self) -> (Address, Address);
-	/// Maximum number of bytes that can be written at once.
-	fn page_size(&self) -> usize;
-	/// List of avalable erase sizes in this region.
-	/// Should be sorted in ascending order.
-	/// Currently limited to 5 sizes, but could be increased if necessary.
-	fn erase_sizes(&self) -> Vec<usize, U5>;
-}
-
-/// Blanket implementation for all types implementing [`NorFlashRegion`]
-impl<T: NorFlashRegion> Region for T {
-	fn contains(&self, address: Address) -> bool {
-		let (start, end) = self.range();
-		address.0 >= start.0 && address.0 < end.0
-	}
-}
-
-/// NOR flash storage trait
-pub trait NorFlash {
-	/// An enumeration of storage errors
-	type Error;
-	/// Region type
-	type Region: NorFlashRegion;
-
-	/// Read a slice of data from the storage peripheral, starting the read
-	/// operation at the given address, and reading until end address
-	/// (`self.range().1`) or buffer length, whichever comes first.
-	fn try_read(&mut self, address: Address, bytes: &mut [u8]) -> nb::Result<(), Self::Error>;
-
+/// Transparent read/write storage trait
+pub trait Storage: ReadStorage {
 	/// Write a slice of data to the storage peripheral, starting the write
-	/// operation at the given address.
-	///
-	/// Since this is done on a NOR flash all bytes are anded with the current
-	/// content in the flash. This means no 0s can to turned into 1s this way.
-	fn try_write(&mut self, address: Address, bytes: &[u8]) -> nb::Result<(), Self::Error>;
-
-	/// 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
-	fn try_erase(&mut self, from: Address, to: Address) -> nb::Result<(), Self::Error>;
-
-	/// Get all distinct memory reagions. These must not overlap, but can be disjoint.
-	/// Most chips will return a single region, but some chips have regions with
-	/// different erase sizes.
-	/// Currently limited to 4 regions, but could be increased if necessary
-	fn regions(&self) -> Vec<Self::Region, U4>;
-}
-
-/// Marker trait for NOR flashes with uniform erase and page sizes across the whole
-/// address range
-pub trait UniformNorFlash {}
-
-/// Blanket implementation for all types implementing [`NorFlash`] and [`UniformNorFlash`]
-impl<T: NorFlash + UniformNorFlash> NorFlashRegion for T {
-	/// The range of possible addresses within the peripheral.
+	/// operation at the given address offset (between 0 and `self.capacity()`).
 	///
-	/// (start_addr, end_addr)
-	fn range(&self) -> (Address, Address) {
-		self.regions()[0].range()
-	}
-	/// Maximum number of bytes that can be written at once.
-	fn page_size(&self) -> usize {
-		self.regions()[0].page_size()
-	}
-	/// List of avalable erase sizes in this region.
-	/// Should be sorted in ascending order.
-	/// Currently limited to 5 sizes, but could be increased if necessary.
-	fn erase_sizes(&self) -> Vec<usize, U5> {
-		self.regions()[0].erase_sizes()
-	}
+	/// **NOTE:**
+	/// This function will automatically erase any pages necessary to write the given data,
+	/// and might as such do RMW operations at an undesirable performance impact.
+	fn try_write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error>;
 }

src/nor_flash.rs

@@ -0,0 +1,54 @@
+/// 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 {}