Fix read_fifo() better readout and more checks

read_fifo() used part of the frame buffer to readout non-frame data.
This results in incorrect readout of the fifo buffer but also the full
MTU could not be used.

Also added some more tests to check this and that the readout is a
multipule of 4 bytes.

embassy-net-adin1110/src/lib.rs

@@ -65,14 +65,16 @@ const FSC_LEN: usize = 4;
 const SPI_HEADER_LEN: usize = 2;
 /// SPI Header CRC length
 const SPI_HEADER_CRC_LEN: usize = 1;
-/// Frame Header,
+/// SPI Header Trun Around length
+const SPI_HEADER_TA_LEN: usize = 1;
+/// Frame Header length
 const FRAME_HEADER_LEN: usize = 2;
+/// Space for last bytes to create multipule 4 bytes on the end of a FIFO read/write.
+const SPI_SPACE_MULTIPULE: usize = 3;
 
 // P1 = 0x00, P2 = 0x01
 const PORT_ID_BYTE: u8 = 0x00;
 
-pub type Packet = Vec<u8, { SPI_HEADER_LEN + FRAME_HEADER_LEN + MTU + FSC_LEN + 1 + 4 }>;
-
 /// Type alias for the embassy-net driver for ADIN1110
 pub type Device<'d> = embassy_net_driver_channel::Device<'d, MTU>;
 
@@ -187,22 +189,24 @@ impl<SPI: SpiDevice> ADIN1110<SPI> {
     }
 
     /// Read out fifo ethernet packet memory received via the wire.
-    pub async fn read_fifo(&mut self, packet: &mut [u8]) -> AEResult<usize, SPI::Error> {
+    pub async fn read_fifo(&mut self, frame: &mut [u8]) -> AEResult<usize, SPI::Error> {
-        let mut tx_buf = Vec::<u8, 16>::new();
+        const HEAD_LEN: usize = SPI_HEADER_LEN + SPI_HEADER_CRC_LEN + SPI_HEADER_TA_LEN;
+        const TAIL_LEN: usize = FSC_LEN + SPI_SPACE_MULTIPULE;
 
-        // Size of the frame, also includes the appednded header.
+        let mut tx_buf = Vec::<u8, HEAD_LEN>::new();
-        let packet_size = self.read_reg(sr::RX_FSIZE).await? as usize;
 
-        // Packet read of write to the MAC packet buffer must be a multipul of 4!
+        // Size of the frame, also includes the `frame header` and `FSC`.
-        let read_size = packet_size.next_multiple_of(4);
+        let fifo_frame_size = self.read_reg(sr::RX_FSIZE).await? as usize;
 
-        if packet_size < (SPI_HEADER_LEN + FSC_LEN) {
+        if fifo_frame_size < ETH_MIN_LEN + FRAME_HEADER_LEN {
             return Err(AdinError::PACKET_TOO_SMALL);
         }
 
-        if read_size > packet.len() {
+        let packet_size = fifo_frame_size - FRAME_HEADER_LEN - FSC_LEN;
+
+        if packet_size > frame.len() {
             #[cfg(feature = "defmt")]
-            defmt::trace!("MAX: {} WANT: {}", packet.len(), read_size);
+            defmt::trace!("MAX: {} WANT: {}", frame.len(), packet_size);
             return Err(AdinError::PACKET_TOO_BIG);
         }
 
@@ -219,29 +223,28 @@ impl<SPI: SpiDevice> ADIN1110<SPI> {
         // Turn around byte, TODO: Unknown that this is.
         let _ = tx_buf.push(TURN_AROUND_BYTE);
 
-        let spi_packet = &mut packet[0..read_size];
+        let mut frame_header = [0, 0];
+        let mut fsc_and_extra = [0; TAIL_LEN];
 
-        assert_eq!(spi_packet.len() & 0x03, 0x00);
+        // Packet read of write to the MAC packet buffer must be a multipul of 4!
-
+        let tail_size = (fifo_frame_size & 0x03) + FSC_LEN;
-        let mut pkt_header = [0, 0];
-        let mut fsc = [0, 0, 0, 0];
 
         let mut spi_op = [
             Operation::Write(&tx_buf),
-            Operation::Read(&mut pkt_header),
+            Operation::Read(&mut frame_header),
-            Operation::Read(spi_packet),
+            Operation::Read(&mut frame[0..packet_size]),
-            Operation::Read(&mut fsc),
+            Operation::Read(&mut fsc_and_extra[0..tail_size]),
         ];
 
         self.spi.transaction(&mut spi_op).await.map_err(AdinError::Spi)?;
 
-        Ok(packet_size as usize)
+        Ok(packet_size)
     }
 
     /// Write to fifo ethernet packet memory send over the wire.
     pub async fn write_fifo(&mut self, frame: &[u8]) -> AEResult<(), SPI::Error> {
         const HEAD_LEN: usize = SPI_HEADER_LEN + SPI_HEADER_CRC_LEN + FRAME_HEADER_LEN;
-        const TAIL_LEN: usize = ETH_MIN_LEN - FSC_LEN + FSC_LEN + 1;
+        const TAIL_LEN: usize = ETH_MIN_LEN - FSC_LEN + FSC_LEN + SPI_SPACE_MULTIPULE;
 
         if frame.len() < (6 + 6 + 2) {
             return Err(AdinError::PACKET_TOO_SMALL);
@@ -1043,4 +1046,144 @@ mod tests {
 
         spi.done();
     }
+
+    #[futures_test::test]
+    async fn read_packet_from_fifo_packet_too_big_for_frame_buffer() {
+        // Configure expectations
+        let mut expectations = vec![];
+
+        // Read RX_SIZE reg
+        let rx_size: u32 = u32::try_from(ETH_MIN_LEN + FRAME_HEADER_LEN + FSC_LEN).unwrap();
+        let mut rx_size_vec = rx_size.to_be_bytes().to_vec();
+        rx_size_vec.push(crc8(&rx_size_vec));
+
+        expectations.push(SpiTransaction::write_vec(vec![128, 144, 79, TURN_AROUND_BYTE]));
+        expectations.push(SpiTransaction::read_vec(rx_size_vec));
+        expectations.push(SpiTransaction::flush());
+
+        let mut spi = SpiMock::new(&expectations);
+
+        let cs = CsPinMock::default();
+        let delay = MockDelay {};
+        let spi_dev = ExclusiveDevice::new(spi.clone(), cs, delay);
+
+        let mut spe = ADIN1110::new(spi_dev, true);
+
+        let mut frame = [0; MTU];
+
+        let ret = spe.read_fifo(&mut frame[0..ETH_MIN_LEN - 1]).await;
+        assert!(matches!(dbg!(ret), Err(AdinError::PACKET_TOO_BIG)));
+
+        spi.done();
+    }
+
+    #[futures_test::test]
+    async fn read_packet_from_fifo_packet_too_small() {
+        // Configure expectations
+        let mut expectations = vec![];
+
+        // This value is importen for this test!
+        assert_eq!(ETH_MIN_LEN, 64);
+
+        // Packet data, size = `ETH_MIN_LEN` - `FSC_LEN` - 1
+        let packet = [0; 64 - FSC_LEN - 1];
+
+        // Read RX_SIZE reg
+        let rx_size: u32 = u32::try_from(packet.len() + FRAME_HEADER_LEN + FSC_LEN).unwrap();
+        let mut rx_size_vec = rx_size.to_be_bytes().to_vec();
+        rx_size_vec.push(crc8(&rx_size_vec));
+
+        expectations.push(SpiTransaction::write_vec(vec![128, 144, 79, TURN_AROUND_BYTE]));
+        expectations.push(SpiTransaction::read_vec(rx_size_vec));
+        expectations.push(SpiTransaction::flush());
+
+        let mut spi = SpiMock::new(&expectations);
+
+        let cs = CsPinMock::default();
+        let delay = MockDelay {};
+        let spi_dev = ExclusiveDevice::new(spi.clone(), cs, delay);
+
+        let mut spe = ADIN1110::new(spi_dev, true);
+
+        let mut frame = [0; MTU];
+
+        let ret = spe.read_fifo(&mut frame).await;
+        assert!(matches!(dbg!(ret), Err(AdinError::PACKET_TOO_SMALL)));
+
+        spi.done();
+    }
+
+    #[futures_test::test]
+    async fn read_packet_to_fifo_check_spi_read_multipule_of_u32_valid_lengths() {
+        let packet_buffer = [0; MTU];
+        let mut frame = [0; MTU];
+        let mut expectations = std::vec::Vec::with_capacity(16);
+
+        // Packet data, size = `ETH_MIN_LEN` - `FSC_LEN`
+        for packet_size in [60, 61, 62, 63, 64, MTU - 4, MTU - 3, MTU - 2, MTU - 1, MTU] {
+            for crc_en in [false, true] {
+                expectations.clear();
+
+                let packet = &packet_buffer[0..packet_size];
+
+                // Read RX_SIZE reg
+                let rx_size: u32 = u32::try_from(packet.len() + FRAME_HEADER_LEN + FSC_LEN).unwrap();
+                let mut rx_size_vec = rx_size.to_be_bytes().to_vec();
+                if crc_en {
+                    rx_size_vec.push(crc8(&rx_size_vec));
+                }
+
+                // SPI Header with CRC
+                let mut rx_fsize = vec![128, 144, 79, TURN_AROUND_BYTE];
+                if !crc_en {
+                    // remove the CRC on idx 2
+                    rx_fsize.swap_remove(2);
+                }
+                expectations.push(SpiTransaction::write_vec(rx_fsize));
+                expectations.push(SpiTransaction::read_vec(rx_size_vec));
+                expectations.push(SpiTransaction::flush());
+
+                // Read RX reg, SPI Header with CRC
+                let mut rx_reg = vec![128, 145, 72, TURN_AROUND_BYTE];
+                if !crc_en {
+                    // remove the CRC on idx 2
+                    rx_reg.swap_remove(2);
+                }
+                expectations.push(SpiTransaction::write_vec(rx_reg));
+                // Frame Header
+                expectations.push(SpiTransaction::read_vec(vec![0, 0]));
+                // Packet data
+                expectations.push(SpiTransaction::read_vec(packet.to_vec()));
+
+                let packet_crc = ETH_FSC::new(packet);
+
+                let mut tail = std::vec::Vec::<u8>::with_capacity(100);
+
+                tail.extend_from_slice(&packet_crc.hton_bytes());
+
+                // Need extra bytes?
+                let pad = (packet_size + FSC_LEN + FRAME_HEADER_LEN) & 0x03;
+                if pad != 0 {
+                    // Packet FCS + optinal padding
+                    tail.resize(tail.len() + pad, DONT_CARE_BYTE);
+                }
+
+                expectations.push(SpiTransaction::read_vec(tail));
+                expectations.push(SpiTransaction::flush());
+
+                let mut spi = SpiMock::new(&expectations);
+
+                let cs = CsPinMock::default();
+                let delay = MockDelay {};
+                let spi_dev = ExclusiveDevice::new(spi.clone(), cs, delay);
+
+                let mut spe = ADIN1110::new(spi_dev, crc_en);
+
+                let ret = spe.read_fifo(&mut frame).await.expect("Error!");
+                assert_eq!(ret, packet_size);
+
+                spi.done();
+            }
+        }
+    }
 }