1 files changed, 228 insertions, 0 deletions

diff --git a/embassy-embedded-hal/src/flash/concat_flash.rs b/embassy-embedded-hal/src/flash/concat_flash.rs
new file mode 100644
index 000000000..1ea84269c
--- /dev/null
+++ b/embassy-embedded-hal/src/flash/concat_flash.rs
@@ -0,0 +1,228 @@
+use embedded_storage::nor_flash::{ErrorType, NorFlash, NorFlashError, ReadNorFlash};
+#[cfg(feature = "nightly")]
+use embedded_storage_async::nor_flash::{NorFlash as AsyncNorFlash, ReadNorFlash as AsyncReadNorFlash};
+
+/// Convenience helper for concatenating two consecutive flashes into one.
+/// This is especially useful if used with "flash regions", where one may
+/// want to concatenate multiple regions into one larger region.
+pub struct ConcatFlash<First, Second>(First, Second);
+
+impl<First, Second> ConcatFlash<First, Second> {
+    /// Create a new flash that concatenates two consecutive flashes.
+    pub fn new(first: First, second: Second) -> Self {
+        Self(first, second)
+    }
+}
+
+const fn get_read_size(first_read_size: usize, second_read_size: usize) -> usize {
+    if first_read_size != second_read_size {
+        panic!("The read size for the concatenated flashes must be the same");
+    }
+    first_read_size
+}
+
+const fn get_write_size(first_write_size: usize, second_write_size: usize) -> usize {
+    if first_write_size != second_write_size {
+        panic!("The write size for the concatenated flashes must be the same");
+    }
+    first_write_size
+}
+
+const fn get_max_erase_size(first_erase_size: usize, second_erase_size: usize) -> usize {
+    let max_erase_size = if first_erase_size > second_erase_size {
+        first_erase_size
+    } else {
+        second_erase_size
+    };
+    if max_erase_size % first_erase_size != 0 || max_erase_size % second_erase_size != 0 {
+        panic!("The erase sizes for the concatenated flashes must have have a gcd equal to the max erase size");
+    }
+    max_erase_size
+}
+
+impl<First, Second, E> ErrorType for ConcatFlash<First, Second>
+where
+    First: ErrorType<Error = E>,
+    Second: ErrorType<Error = E>,
+    E: NorFlashError,
+{
+    type Error = E;
+}
+
+impl<First, Second, E> ReadNorFlash for ConcatFlash<First, Second>
+where
+    First: ReadNorFlash<Error = E>,
+    Second: ReadNorFlash<Error = E>,
+    E: NorFlashError,
+{
+    const READ_SIZE: usize = get_read_size(First::READ_SIZE, Second::READ_SIZE);
+
+    fn read(&mut self, mut offset: u32, mut bytes: &mut [u8]) -> Result<(), E> {
+        if offset < self.0.capacity() as u32 {
+            let len = core::cmp::min(self.0.capacity() - offset as usize, bytes.len());
+            self.0.read(offset, &mut bytes[..len])?;
+            offset += len as u32;
+            bytes = &mut bytes[len..];
+        }
+
+        if !bytes.is_empty() {
+            self.1.read(offset - self.0.capacity() as u32, bytes)?;
+        }
+
+        Ok(())
+    }
+
+    fn capacity(&self) -> usize {
+        self.0.capacity() + self.1.capacity()
+    }
+}
+
+impl<First, Second, E> NorFlash for ConcatFlash<First, Second>
+where
+    First: NorFlash<Error = E>,
+    Second: NorFlash<Error = E>,
+    E: NorFlashError,
+{
+    const WRITE_SIZE: usize = get_write_size(First::WRITE_SIZE, Second::WRITE_SIZE);
+    const ERASE_SIZE: usize = get_max_erase_size(First::ERASE_SIZE, Second::ERASE_SIZE);
+
+    fn write(&mut self, mut offset: u32, mut bytes: &[u8]) -> Result<(), E> {
+        if offset < self.0.capacity() as u32 {
+            let len = core::cmp::min(self.0.capacity() - offset as usize, bytes.len());
+            self.0.write(offset, &bytes[..len])?;
+            offset += len as u32;
+            bytes = &bytes[len..];
+        }
+
+        if !bytes.is_empty() {
+            self.1.write(offset - self.0.capacity() as u32, bytes)?;
+        }
+
+        Ok(())
+    }
+
+    fn erase(&mut self, mut from: u32, to: u32) -> Result<(), E> {
+        if from < self.0.capacity() as u32 {
+            let to = core::cmp::min(self.0.capacity() as u32, to);
+            self.0.erase(from, to)?;
+            from = self.0.capacity() as u32;
+        }
+
+        if from < to {
+            self.1
+                .erase(from - self.0.capacity() as u32, to - self.0.capacity() as u32)?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(feature = "nightly")]
+impl<First, Second, E> AsyncReadNorFlash for ConcatFlash<First, Second>
+where
+    First: AsyncReadNorFlash<Error = E>,
+    Second: AsyncReadNorFlash<Error = E>,
+    E: NorFlashError,
+{
+    const READ_SIZE: usize = get_read_size(First::READ_SIZE, Second::READ_SIZE);
+
+    async fn read(&mut self, mut offset: u32, mut bytes: &mut [u8]) -> Result<(), E> {
+        if offset < self.0.capacity() as u32 {
+            let len = core::cmp::min(self.0.capacity() - offset as usize, bytes.len());
+            self.0.read(offset, &mut bytes[..len]).await?;
+            offset += len as u32;
+            bytes = &mut bytes[len..];
+        }
+
+        if !bytes.is_empty() {
+            self.1.read(offset - self.0.capacity() as u32, bytes).await?;
+        }
+
+        Ok(())
+    }
+
+    fn capacity(&self) -> usize {
+        self.0.capacity() + self.1.capacity()
+    }
+}
+
+#[cfg(feature = "nightly")]
+impl<First, Second, E> AsyncNorFlash for ConcatFlash<First, Second>
+where
+    First: AsyncNorFlash<Error = E>,
+    Second: AsyncNorFlash<Error = E>,
+    E: NorFlashError,
+{
+    const WRITE_SIZE: usize = get_write_size(First::WRITE_SIZE, Second::WRITE_SIZE);
+    const ERASE_SIZE: usize = get_max_erase_size(First::ERASE_SIZE, Second::ERASE_SIZE);
+
+    async fn write(&mut self, mut offset: u32, mut bytes: &[u8]) -> Result<(), E> {
+        if offset < self.0.capacity() as u32 {
+            let len = core::cmp::min(self.0.capacity() - offset as usize, bytes.len());
+            self.0.write(offset, &bytes[..len]).await?;
+            offset += len as u32;
+            bytes = &bytes[len..];
+        }
+
+        if !bytes.is_empty() {
+            self.1.write(offset - self.0.capacity() as u32, bytes).await?;
+        }
+
+        Ok(())
+    }
+
+    async fn erase(&mut self, mut from: u32, to: u32) -> Result<(), E> {
+        if from < self.0.capacity() as u32 {
+            let to = core::cmp::min(self.0.capacity() as u32, to);
+            self.0.erase(from, to).await?;
+            from = self.0.capacity() as u32;
+        }
+
+        if from < to {
+            self.1
+                .erase(from - self.0.capacity() as u32, to - self.0.capacity() as u32)
+                .await?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use embedded_storage::nor_flash::{NorFlash, ReadNorFlash};
+
+    use super::ConcatFlash;
+    use crate::flash::mem_flash::MemFlash;
+
+    #[test]
+    fn can_write_and_read_across_flashes() {
+        let first = MemFlash::<64, 16, 4>::default();
+        let second = MemFlash::<64, 64, 4>::default();
+        let mut f = ConcatFlash::new(first, second);
+
+        f.write(60, &[0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88]).unwrap();
+
+        assert_eq!(&[0x11, 0x22, 0x33, 0x44], &f.0.mem[60..]);
+        assert_eq!(&[0x55, 0x66, 0x77, 0x88], &f.1.mem[0..4]);
+
+        let mut read_buf = [0; 8];
+        f.read(60, &mut read_buf).unwrap();
+
+        assert_eq!(&[0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88], &read_buf);
+    }
+
+    #[test]
+    fn can_erase_across_flashes() {
+        let first = MemFlash::<128, 16, 4>::new(0x00);
+        let second = MemFlash::<128, 64, 4>::new(0x00);
+        let mut f = ConcatFlash::new(first, second);
+
+        f.erase(64, 192).unwrap();
+
+        assert_eq!(&[0x00; 64], &f.0.mem[0..64]);
+        assert_eq!(&[0xff; 64], &f.0.mem[64..128]);
+        assert_eq!(&[0xff; 64], &f.1.mem[0..64]);
+        assert_eq!(&[0x00; 64], &f.1.mem[64..128]);
+    }
+}