minor improvements to driver

- updated docs
- added types

src/embedded_io.rs

@@ -0,0 +1,3 @@
+mod device;
+mod head;
+mod error;

src/embedded_io/device.rs

@@ -0,0 +1,78 @@
+use embedded_hal::i2c::I2c;
+use embedded_io::{ErrorType, Read, Seek, Write};
+
+use crate::{
+    MB85RC,
+    embedded_io::{error::MB85RCErrorType, head::Head},
+};
+
+pub struct EmbedIODev<T: I2c, const N: u64> {
+    dev: crate::MB85RC<T>,
+    head: Head<N>,
+}
+
+impl<T: I2c, const N: u64> EmbedIODev<T, N> {
+    pub fn new(mb85rc: MB85RC<T>) -> Self {
+        Self {
+            dev: mb85rc,
+            head: Head::new(),
+        }
+    }
+}
+
+impl<T: I2c, const N: u64> ErrorType for EmbedIODev<T, N> {
+    type Error = MB85RCErrorType<T::Error>;
+}
+
+impl<T: I2c, const N: u64> Read for EmbedIODev<T, N> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        match self.head.memory_address() {
+            Some(addr) => self
+                .dev
+                .sequential_read(&addr, buf)
+                .map_err(MB85RCErrorType::I2c)
+                .map(|_| {
+                    self.head.advance(buf.len());
+                    buf.len()
+                }),
+            None => Err(MB85RCErrorType::InvalidPosition),
+        }
+    }
+}
+
+impl<T: I2c, const N: u64> Write for EmbedIODev<T, N> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        // From trait doc: Implementations must not return Ok(0) unless buf is empty.
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
+        // match self.head.memory_address() {
+        //     Some(addr) => self
+        //         .dev
+        //         .write_page(&addr, buf)
+        //         .map_err(MB85RCErrorType::I2c)
+        //         .map(|_| {
+        //             self.head.advance(buf.len());
+        //             buf.len()
+        //         }),
+        //     None => Err(MB85RCErrorType::InvalidPosition),
+        // }
+
+        todo!()
+    }
+
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        // We can't really flush here.
+        Ok(())
+    }
+}
+
+impl<T: I2c, const N: u64> Seek for EmbedIODev<T, N> {
+    fn seek(&mut self, pos: embedded_io::SeekFrom) -> Result<u64, Self::Error> {
+        self.head
+            .seek(pos)
+            .ok_or(MB85RCErrorType::InvalidPosition)?;
+        Ok(self.head.into())
+    }
+}

src/embedded_io/error.rs

@@ -0,0 +1,17 @@
+use embedded_hal::i2c;
+use embedded_io::Error;
+
+#[derive(Debug)]
+pub enum MB85RCErrorType<T: i2c::Error> {
+    I2c(T),
+    InvalidPosition,
+}
+
+impl<T: i2c::Error> Error for MB85RCErrorType<T> {
+    fn kind(&self) -> embedded_io::ErrorKind {
+        match self {
+            MB85RCErrorType::I2c(_) => embedded_io::ErrorKind::Other,
+            MB85RCErrorType::InvalidPosition => embedded_io::ErrorKind::Other,
+        }
+    }
+}

src/embedded_io/head.rs

@@ -0,0 +1,217 @@
+use embedded_io::SeekFrom;
+
+/// moveable Read/Write head
+/// Capped at `N`
+/// Does not allow overflow
+#[derive(Clone, Copy, Default)]
+pub struct Head<const N: u64>(u64);
+
+impl<const N: u64> Head<N> {
+    pub fn new() -> Self {
+        Self(0)
+    }
+
+    pub fn seek(&mut self, pos: SeekFrom) -> Option<u64> {
+        match pos {
+            SeekFrom::Start(offset) => match self.0.checked_add(offset).filter(|&sum| sum <= N) {
+                Some(new_pos) => {
+                    self.0 = new_pos;
+                    Some(new_pos)
+                }
+                None => None,
+            },
+            SeekFrom::End(offset) => {
+                // Do not allow seek over the end
+                if offset > 0 {
+                    return None;
+                }
+
+                self.0 = N - offset.unsigned_abs();
+
+                Some(self.0)
+            }
+            SeekFrom::Current(offset) => {
+                let new_pos = if offset > 0 {
+                    self.0.checked_add(offset.unsigned_abs())
+                } else {
+                    self.0.checked_sub(offset.unsigned_abs())
+                };
+
+                match new_pos {
+                    Some(pos) => {
+                        if pos > N {
+                            None
+                        } else {
+                            self.0 = pos;
+                            Some(self.0)
+                        }
+                    }
+                    None => None,
+                }
+            }
+        }
+    }
+
+    /// Move the head forward when reading files.
+    /// Expected to not overflow. If it does it is capped at `N`.
+    pub fn advance(&mut self, bytes: usize) {
+        match self.0.checked_add(bytes as u64) {
+            Some(sum) => {
+                if sum > N {
+                    self.0 = N
+                } else {
+                    self.0 = sum;
+                }
+            }
+            None => self.0 = N,
+        }
+    }
+
+    /// Convert to a 2 byte memory address used by the i2c interface.
+    pub fn memory_address(&self) -> Option<[u8; 2]> {
+        if self.0 > u16::MAX as u64 {
+            return None;
+        }
+
+        let addr16 = self.0 as u16;
+        let high = (addr16 >> 8) as u8;
+        let low = (addr16 & 0xFF) as u8;
+
+        Some([high, low])
+    }
+}
+
+impl<const N: u64> From<Head<N>> for u64 {
+    fn from(head: Head<N>) -> Self {
+        head.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn create() {
+        let head: Head<65_535> = Head::new();
+        let inner: u64 = head.into();
+        assert_eq!(inner, 0u64);
+    }
+
+    #[test]
+    fn seek_start() {
+        let mut head: Head<65_535> = Head::new();
+        let res = head.seek(SeekFrom::Start(1337));
+
+        let inner: u64 = head.into();
+        assert_eq!(inner, 1337u64);
+        assert_eq!(res, Some(inner));
+    }
+
+    #[test]
+    fn seek_current_forward() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(1337));
+
+        let res = head.seek(SeekFrom::Current(3));
+
+        let inner: u64 = head.into();
+        assert_eq!(inner, 1340u64);
+        assert_eq!(res, Some(inner));
+    }
+
+    #[test]
+    fn seek_current_back() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(1337));
+
+        let res = head.seek(SeekFrom::Current(-337));
+
+        let inner: u64 = head.into();
+        assert_eq!(inner, 1000u64);
+        assert_eq!(res, Some(inner));
+    }
+
+    #[test]
+    fn seek_current_zero() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(1337));
+
+        let res = head.seek(SeekFrom::Current(0));
+
+        let inner: u64 = head.into();
+        assert_eq!(inner, 1337u64);
+        assert_eq!(res, Some(inner));
+    }
+
+    #[test]
+    fn seek_end() {
+        let mut head: Head<65_535> = Head::new();
+        let res = head.seek(SeekFrom::End(-10));
+
+        let inner: u64 = head.into();
+        assert_eq!(inner, 65_535 - 10);
+        assert_eq!(res, Some(inner));
+    }
+
+    #[test]
+    fn seek_end_overflow() {
+        let mut head: Head<65_535> = Head::new();
+        let res = head.seek(SeekFrom::End(10));
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn seek_invalid_overflow() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(65_535 - 5));
+
+        let res = head.seek(SeekFrom::Current(10));
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn seek_invalid_underflow() {
+        let mut head: Head<65_535> = Head::new();
+
+        let res = head.seek(SeekFrom::Current(-1));
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn convert_zero() {
+        let head: Head<65_535> = Head::new();
+        let addr = head.memory_address();
+
+        assert_eq!(addr, Some([0, 0]));
+    }
+
+    #[test]
+    fn convert_1_byte() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(50));
+
+        let addr = head.memory_address();
+
+        assert_eq!(addr, Some([0, 50]));
+    }
+
+    #[test]
+    fn convert_2_bytes() {
+        let mut head: Head<65_535> = Head::new();
+        let _ = head.seek(SeekFrom::Start(260));
+
+        let addr = head.memory_address();
+
+        assert_eq!(addr, Some([1, 4]));
+    }
+
+    #[test]
+    fn convert_invalid() {
+        let mut head: Head<4_294_967_295> = Head::new(); // Needs to be more then u16::MAX 
+        let _ = head.seek(SeekFrom::Start(65_536)); // One more then u16::MAX
+
+        let addr = head.memory_address();
+        assert!(addr.is_none());
+    }
+}

src/lib.rs

@@ -1,12 +1,19 @@
 #![no_std]
 
+//! The `MemoryAddress` are two bit.
+//! For the 16Kb version 11 bit are used.
+//! For the 256Kb version 16 bit are used.
+//! For the 64Kb version 16 bit are used.
+
 use core::result::Result;
 use embedded_hal::i2c::{I2c, SevenBitAddress};
 
-const DEVICE_ADDRESS: u8 = 0b10100000;
-const DEVICE_ADDRESS_CODE: u8 = 0b00000000;
-const DEVICE_W: u8 = 0b00000000;
-const DEVICE_R: u8 = 0b00000001;
+mod async_hal;
+mod embedded_io;
+
+
+/// [High,Low]
+type MemoryAddress = [u8; 2];
 
 pub struct MB85RC<T: I2c<SevenBitAddress>> {
     i2c: T,
@@ -20,11 +27,7 @@ impl<T: I2c> MB85RC<T> {
 
     /// The Device ID command reads fixed Device ID. The size of Device ID is 3 bytes and consists of manufacturer
     /// ID and product ID.
-    ///  # Arguments
-    /// * `self` - A mutable reference to the MB85RC instance.
-    /// # Returns
-    /// * `Result<[u8; 3], Error>` - Device ID is 3 bytes and consists of manufacturer ID and product ID
-    pub fn get_device_id(&mut self) -> Result<[u8; 3], T::Error> {
+      pub fn get_device_id(&mut self) -> Result<[u8; 3], T::Error> {
         let mut buffer: [u8; 3] = [0, 0, 0];
         let reserved_slave_address = 0x7C; // Reserved Slave ID F9H without last bit, because wrte address adds this bit 
         let payload = [0xA0]; // Device Address + read bit (write bit works also, because R/W code are “Don't care” value)
@@ -35,17 +38,9 @@ impl<T: I2c> MB85RC<T> {
     }
 
     /// Write bit on the specified memory address
-    /// # Arguments
-    /// * `self` - A mutable reference to the MB85RC instance.
-    /// * `memory_address` - The memory address to write to.
-    /// * `data` - The data byte to write.
-    /// # Returns
-    /// * `Result<u8, T::Error>`
-    pub fn byte_write(&mut self, memory_address: [u8; 2], data: u8) -> Result<u8, T::Error> {
+    pub fn byte_write(&mut self, memory_address: &MemoryAddress, data: u8) -> Result<(), T::Error> {
         let payload = [memory_address[0], memory_address[1], data];
-        self.i2c.write(self.address, &payload)?;
-
-        Ok(data)
+        self.i2c.write(self.address, &payload)
     }
 
     /// If additional 8 bits are continuously sent after the same command (except stop condition) as Byte Write, a
@@ -54,34 +49,21 @@ impl<T: I2c> MB85RC<T> {
     /// of the memory address that was written first. Because FRAM performs the high-speed write operations, the
     /// data will be written to FRAM right after the ACK response finished.
     /// array 32KB
-    /// # Arguments
-    /// * `self` - A mutable reference to the MB85RC instance.
-    /// * `memory_address` - The memory address to write to.
-    /// * `data` - The data bytes to write max 32KB.
-    /// # Returns
-    /// * `Result<(), T::Error>`
     pub fn write_page(
         &mut self,
-        memory_address: [u8; 2],
-        data: &mut [u8; 32000],
+        memory_address: &MemoryAddress,
+        data: &[u8],
     ) -> Result<(), T::Error> {
         let mut payload = [0u8; 32002];
         payload[0] = memory_address[0];
         payload[1] = memory_address[1];
         payload[2..].copy_from_slice(data);
-        self.i2c.write(self.address, &payload)?;
-
-        Ok(())
+        self.i2c.write(self.address, &payload[..2 + data.len()])
     }
 
     /// The one byte of data from the memory address saved in the memory address buffer can be read out
     /// synchronously
-    /// # Arguments
-    /// * `self` - A mutable reference to the MB85RC instance.
-    /// * `memory_address` - The memory address to read from.
-    /// # Returns
-    /// * `Result<u8, Error>` - The byte read from the specified
-    pub fn random_read(&mut self, memory_address: &[u8; 2]) -> Result<u8, T::Error> {
+    pub fn random_read(&mut self, memory_address: &MemoryAddress) -> Result<u8, T::Error> {
         let mut buffer: [u8; 1] = [0];
         self.i2c
             .write_read(self.address, memory_address, &mut buffer)?;
@@ -95,19 +77,11 @@ impl<T: I2c> MB85RC<T> {
     /// command. If the end of the memory address space is reached, the internal read
     /// address automatically rolls over to the first memory address (0x0000) and continues
     /// reading.
-    /// # Arguments
-    /// * `self` - A mutable reference to the MB85RC instance.
-    /// * `memory_address` - The memory address to read from.
-    /// * `buffer` - buffer to write the payload data
-    /// # Return
-    /// * `Result<&'a mut [u8], T::Error>` - Pointer to the array with the read data
-    pub fn sequential_read<'a>(
+    pub fn sequential_read(
         &mut self,
-        memory_address: &[u8; 2],
-        buffer: &'a mut [u8],
-    ) -> Result<&'a mut [u8], T::Error> {
-        self.i2c.write_read(self.address, memory_address, buffer)?;
-
-        Ok(buffer)
+        memory_address: &MemoryAddress,
+        buffer: &mut [u8],
+    ) -> Result<(), T::Error> {
+        self.i2c.write_read(self.address, memory_address, buffer)
     }
 }