Add and use BlockCount and BlockIdx newtypes.

Author: qwandor

src/block.rs

@@ -0,0 +1,141 @@
+use core::ops::{Add, AddAssign, Sub, SubAssign};
+
+/// A device which can read and write whole numbers of blocks.
+///
+/// Blocks are also referred to as sectors in some contexts.
+pub trait BlockDevice<const BLOCK_SIZE: usize = 512> {
+	/// The error type returned by methods on this trait.
+	type Error;
+
+	/// Returns the size of the device in blocks.
+	fn block_count(&self) -> Result<BlockCount, Self::Error>;
+
+	/// Reads some number of blocks from the device, starting at `first_block_index`.
+	///
+	/// `first_block_index + blocks.len()` must not be greater than the size returned by
+	/// `block_count`.
+	fn read(
+		&mut self,
+		first_block_index: BlockIdx,
+		blocks: &mut [[u8; BLOCK_SIZE]],
+	) -> Result<(), Self::Error>;
+
+	/// Writes some number of blocks to the device, starting at `first_block_index`.
+	///
+	/// `first_block_index + blocks.len()` must not be greater than the size returned by
+	/// `block_count`.
+	fn write(
+		&mut self,
+		first_block_index: BlockIdx,
+		blocks: &[[u8; BLOCK_SIZE]],
+	) -> Result<(), Self::Error>;
+}
+
+/// The linear numeric address of a block (or sector).
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct BlockIdx(pub u64);
+
+impl BlockIdx {
+	/// Creates an iterator from the current `BlockIdx` through the given number of blocks.
+	pub fn range(self, num: BlockCount) -> BlockIter {
+		BlockIter::new(self, self + BlockCount(num.0))
+	}
+}
+
+impl From<BlockIdx> for u64 {
+	fn from(value: BlockIdx) -> Self {
+		value.0.into()
+	}
+}
+
+impl Add<BlockCount> for BlockIdx {
+	type Output = BlockIdx;
+
+	fn add(self, rhs: BlockCount) -> BlockIdx {
+		BlockIdx(self.0 + rhs.0)
+	}
+}
+
+impl AddAssign<BlockCount> for BlockIdx {
+	fn add_assign(&mut self, rhs: BlockCount) {
+		self.0 += rhs.0
+	}
+}
+
+impl Sub<BlockCount> for BlockIdx {
+	type Output = BlockIdx;
+
+	fn sub(self, rhs: BlockCount) -> BlockIdx {
+		BlockIdx(self.0 - rhs.0)
+	}
+}
+
+impl SubAssign<BlockCount> for BlockIdx {
+	fn sub_assign(&mut self, rhs: BlockCount) {
+		self.0 -= rhs.0
+	}
+}
+
+/// A number of blocks (or sectors).
+///
+/// This may be added to a [`BlockIdx`] to get another `BlockIdx`.
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct BlockCount(pub u64);
+
+impl Add<BlockCount> for BlockCount {
+	type Output = BlockCount;
+
+	fn add(self, rhs: BlockCount) -> BlockCount {
+		BlockCount(self.0 + rhs.0)
+	}
+}
+
+impl AddAssign<BlockCount> for BlockCount {
+	fn add_assign(&mut self, rhs: BlockCount) {
+		self.0 += rhs.0
+	}
+}
+
+impl Sub<BlockCount> for BlockCount {
+	type Output = BlockCount;
+
+	fn sub(self, rhs: BlockCount) -> BlockCount {
+		BlockCount(self.0 - rhs.0)
+	}
+}
+
+impl SubAssign<BlockCount> for BlockCount {
+	fn sub_assign(&mut self, rhs: BlockCount) {
+		self.0 -= rhs.0
+	}
+}
+
+/// An iterator returned from `Block::range`.
+pub struct BlockIter {
+	inclusive_end: BlockIdx,
+	current: BlockIdx,
+}
+
+impl BlockIter {
+	/// Creates a new `BlockIter`, from the given start block, through (and including) the given end
+	/// block.
+	pub const fn new(start: BlockIdx, inclusive_end: BlockIdx) -> BlockIter {
+		BlockIter {
+			inclusive_end,
+			current: start,
+		}
+	}
+}
+
+impl Iterator for BlockIter {
+	type Item = BlockIdx;
+	fn next(&mut self) -> Option<Self::Item> {
+		if self.current.0 >= self.inclusive_end.0 {
+			None
+		} else {
+			let this = self.current;
+			self.current += BlockCount(1);
+			Some(this)
+		}
+	}
+}

src/lib.rs

@@ -8,6 +8,8 @@
 #![deny(missing_docs)]
 #![deny(unsafe_code)]
 
+/// Types and traits for block devices.
+pub mod block;
 /// Currently contains [`OverlapIterator`]
 pub mod iter;
 /// Technology specific traits for NOR Flashes
@@ -53,34 +55,3 @@ pub trait Storage: ReadStorage {
 	/// and might as such do RMW operations at an undesirable performance impact.
 	fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error>;
 }
-
-/// A device which can read and write whole numbers of blocks.
-///
-/// Blocks are also referred to as sectors in some contexts.
-pub trait BlockDevice<const BLOCK_SIZE: usize = 512> {
-	/// The error type returned by methods on this trait.
-	type Error;
-
-	/// Returns the size of the device in blocks.
-	fn block_count(&self) -> Result<u64, Self::Error>;
-
-	/// Reads some number of blocks from the device, starting at `first_block_index`.
-	///
-	/// `first_block_index + blocks.len()` must not be greater than the size returned by
-	/// `block_count`.
-	fn read(
-		&mut self,
-		first_block_index: u64,
-		blocks: &mut [[u8; BLOCK_SIZE]],
-	) -> Result<(), Self::Error>;
-
-	/// Writes some number of blocks to the device, starting at `first_block_index`.
-	///
-	/// `first_block_index + blocks.len()` must not be greater than the size returned by
-	/// `block_count`.
-	fn write(
-		&mut self,
-		first_block_index: u64,
-		blocks: &[[u8; BLOCK_SIZE]],
-	) -> Result<(), Self::Error>;
-}