Optimize OverlapIterator

CHANGELOG.md

@@ -7,7 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## Unreleased
 
-No unreleased changes yet
+- Add `start()` and `end()` method to the `Region` trait.
+- Much faster `OverlapIterator`.
 
 ## [0.3.1] - 2023-12-04
 

embedded-storage-async/src/nor_flash.rs

@@ -102,17 +102,15 @@ impl Page {
 			size,
 		}
 	}
-
-	/// The end address of the page
-	const fn end(&self) -> u32 {
-		self.start + self.size as u32
-	}
 }
 
 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)
+	fn start(&self) -> u32 {
+		self.start
+	}
+
+	fn end(&self) -> u32 {
+		self.start + self.size as u32
 	}
 }
 

src/iter.rs

@@ -30,18 +30,15 @@ where
 	type Item = (&'a [u8], R, u32);
 
 	fn next(&mut self) -> Option<Self::Item> {
+		let mem_start = self.base_address;
+		let mem_end = self.base_address + self.memory.len() as u32;
 		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 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 as u32,
-				));
+			if mem_start < region.end() && mem_end >= region.start() {
+				let addr_start = core::cmp::max(mem_start, region.start());
+				let addr_end = core::cmp::min(mem_end, region.end());
+				let start = (addr_start - self.base_address) as usize;
+				let end = (addr_end - self.base_address) as usize;
+				return Some((&self.memory[start..end], region, addr_start));
 			}
 		}
 		None

src/lib.rs

@@ -15,8 +15,16 @@ pub mod nor_flash;
 
 /// A region denotes a contiguous piece of memory between two addresses.
 pub trait Region {
+	/// Start address of the region of `Self`
+	fn start(&self) -> u32;
+
+	/// End address of the region of `Self`
+	fn end(&self) -> u32;
+
 	/// Check if `address` is contained in the region of `Self`
-	fn contains(&self, address: u32) -> bool;
+	fn contains(&self, address: u32) -> bool {
+		(address >= self.start()) && (address < self.end())
+	}
 }
 
 /// Transparent read only storage trait

src/nor_flash.rs

@@ -202,17 +202,15 @@ impl Page {
 			size,
 		}
 	}
-
-	/// The end address of the page
-	const fn end(&self) -> u32 {
-		self.start + self.size as u32
-	}
 }
 
 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)
+	fn start(&self) -> u32 {
+		self.start
+	}
+
+	fn end(&self) -> u32 {
+		self.start + self.size as u32
 	}
 }