Make RmwNorFlashStorage::new take a mutable merge_buffer, that must be atleast EraseSize long. Introduce RmwMultiwriteNorFlashStorage

Author: MathiasKoch

src/nor_flash.rs

@@ -1,4 +1,7 @@
-use crate::{iter::IterableByOverlaps, ReadStorage, Region, Storage};
+use crate::{
+	iter::{IterableByOverlaps, OverlapIterator},
+	ReadStorage, Region, Storage,
+};
 
 /// Read only NOR flash trait.
 pub trait ReadNorFlash {
@@ -77,117 +80,143 @@ impl Page {
 }
 
 impl Region for Page {
+	/// Checks if an address offset is contained within the page
 	fn contains(&self, address: u32) -> bool {
 		(self.start <= address) && (self.end() > address)
 	}
 }
 
 ///
-pub struct RmwNorFlashStorage<S>(S);
+pub struct RmwNorFlashStorage<'a, S> {
+	storage: S,
+	merge_buffer: &'a mut [u8],
+}
 
-impl<S> RmwNorFlashStorage<S> {
+impl<'a, S> RmwNorFlashStorage<'a, S>
+where
+	S: NorFlash,
+{
 	/// Instantiate a new generic `Storage` from a `NorFlash` peripheral
-	pub fn new(nor_flash: S) -> Self {
-		Self(nor_flash)
+	///
+	/// **NOTE** This will panic if the provided merge buffer,
+	/// is smaller than the erase size of the flash peripheral
+	pub fn new(nor_flash: S, merge_buffer: &'a mut [u8]) -> Self {
+		if merge_buffer.len() < S::ERASE_SIZE {
+			panic!("Merge buffer is too small");
+		}
+
+		Self {
+			storage: nor_flash,
+			merge_buffer,
+		}
 	}
 }
 
-impl<S> ReadStorage for RmwNorFlashStorage<S>
+impl<'a, S> ReadStorage for RmwNorFlashStorage<'a, S>
 where
 	S: ReadNorFlash,
 {
 	type Error = S::Error;
 
 	fn try_read(&mut self, address: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
 		// Nothing special to be done for reads
-		self.0.try_read(address, bytes)
+		self.storage.try_read(address, bytes)
 	}
 
 	fn capacity(&self) -> usize {
-		self.0.capacity()
+		self.storage.capacity()
 	}
 }
 
-impl<S> Storage for RmwNorFlashStorage<S>
+impl<'a, S> Storage for RmwNorFlashStorage<'a, S>
 where
 	S: NorFlash,
-	// [u8; S::ERASE_SIZE]: Sized,
 {
 	fn try_write(&mut self, address: u32, bytes: &[u8]) -> Result<(), Self::Error> {
 		// Perform read/modify/write operations on the byte slice.
-		let last_page = (self.0.capacity() / S::ERASE_SIZE) - 1;
+		let last_page = (self.storage.capacity() / S::ERASE_SIZE) - 1;
 
 		// `data` is the part of `bytes` contained within `page`,
 		// and `addr` in the address offset of `page` + any offset into the page as requested by `address`
 		for (data, page, addr) in (0..last_page as u32)
 			.map(move |i| Page::new(i, S::ERASE_SIZE))
 			.overlaps(bytes, address)
 		{
-			let merge_buffer = &mut [0u8; 2048];
 			let offset_into_page = addr.saturating_sub(page.start) as usize;
 
-			self.try_read(page.start, merge_buffer)?;
+			self.storage.try_read(page.start, self.merge_buffer)?;
 
 			// If we cannot write multiple times to the same page, we will have to erase it
-			self.0.try_erase(page.start, page.end())?;
-			merge_buffer
+			self.storage.try_erase(page.start, page.end())?;
+			self.merge_buffer
 				.iter_mut()
 				.skip(offset_into_page)
 				.zip(data)
 				.for_each(|(byte, input)| *byte = *input);
-			self.0.try_write(page.start, merge_buffer)?;
+			self.storage.try_write(page.start, self.merge_buffer)?;
 		}
 		Ok(())
 	}
 }
 
-// FIXME: Requires specialization to take advantage of MultiwriteNorFlash?
-// impl<S: MultiwriteNorFlash> Storage for RmwNorFlashStorage<S> {
-// 	type Error = S::Error;
-
-// 	fn try_read(&mut self, address: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
-// 		// Nothing special to be done for reads
-// 		self.0.try_read(address, bytes)
-// 	}
-
-// 	fn try_write(&mut self, address: u32, bytes: &[u8]) -> Result<(), Self::Error> {
-// 		// Perform read/modify/write operations on the byte slice.
-// 		let erase_size = self.0.erase_size();
-// 		let last_page = (self.0.capacity() / erase_size) - 1;
-
-// 		// `data` is the part of `bytes` contained within `page`,
-// 		// and `addr` in the address offset of `page` + any offset into the page as requested by `address`
-// 		for (data, page, addr) in (0..last_page)
-// 			.map(move |i| Page::new(i, erase_size))
-// 			.overlaps(bytes, address)
-// 		{
-// 			let merge_buffer = &mut [0u8; MAX_PAGE_SIZE][0..erase_size as usize];
-// 			let offset_into_page = addr.saturating_sub(page.start) as usize;
-
-// 			self.try_read(page.start, merge_buffer)?;
-
-// 			let rhs = &merge_buffer[offset_into_page..];
-// 			let is_subset =
-// 			 	data.len() < rhs.len() && data.iter().zip(rhs.iter()).all(|(a, b)| (*a | *b) == *b);
-
-// 			// Check if we can write the data block directly, under the limitations imposed by NorFlash:
-// 			// - We can only change 1's to 0's
-// 			if is_subset {
-// 				self.0.try_write(addr, data)?;
-// 			} else {
-// 				self.0.try_erase(page.start, page.end())?;
-// 				merge_buffer
-// 					.iter_mut()
-// 					.skip(offset_into_page)
-// 					.zip(data)
-// 					.for_each(|(byte, input)| *byte = *input);
-// 				self.0.try_write(page.start, merge_buffer)?;
-// 			}
-// 		}
-// 		Ok(())
-// 	}
-
-// 	fn capacity(&self) -> u32 {
-// 		self.0.capacity()
-// 	}
-// }
+///
+pub struct RmwMultiwriteNorFlashStorage<'a, S> {
+	storage: S,
+	merge_buffer: &'a mut [u8],
+}
+
+impl<'a, S> ReadStorage for RmwMultiwriteNorFlashStorage<'a, S>
+where
+	S: ReadNorFlash,
+{
+	type Error = S::Error;
+
+	fn try_read(&mut self, address: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
+		// Nothing special to be done for reads
+		self.storage.try_read(address, bytes)
+	}
+
+	fn capacity(&self) -> usize {
+		self.storage.capacity()
+	}
+}
+
+impl<'a, S> Storage for RmwMultiwriteNorFlashStorage<'a, S>
+where
+	S: NorFlash,
+{
+	fn try_write(&mut self, address: u32, bytes: &[u8]) -> Result<(), Self::Error> {
+		// Perform read/modify/write operations on the byte slice.
+		let last_page = (self.storage.capacity() / S::ERASE_SIZE) - 1;
+
+		// `data` is the part of `bytes` contained within `page`,
+		// and `addr` in the address offset of `page` + any offset into the page as requested by `address`
+		for (data, page, addr) in (0..last_page as u32)
+			.map(move |i| Page::new(i, S::ERASE_SIZE))
+			.overlaps(bytes, address)
+		{
+			let offset_into_page = addr.saturating_sub(page.start) as usize;
+
+			self.storage.try_read(page.start, self.merge_buffer)?;
+
+			let rhs = &self.merge_buffer[offset_into_page..];
+			let is_subset =
+				data.len() < rhs.len() && data.iter().zip(rhs.iter()).all(|(a, b)| (*a | *b) == *b);
+
+			// Check if we can write the data block directly, under the limitations imposed by NorFlash:
+			// - We can only change 1's to 0's
+			if is_subset {
+				self.storage.try_write(addr, data)?;
+			} else {
+				self.storage.try_erase(page.start, page.end())?;
+				self.merge_buffer
+					.iter_mut()
+					.skip(offset_into_page)
+					.zip(data)
+					.for_each(|(byte, input)| *byte = *input);
+				self.storage.try_write(page.start, self.merge_buffer)?;
+			}
+		}
+		Ok(())
+	}
+}