From dc3b83f9c83ac9316c0e623af1726fe975557ad3 Mon Sep 17 00:00:00 2001
From: Adam Greig <adam@adamgreig.com>
Date: Fri, 18 Apr 2025 14:42:16 +0100
Subject: [PATCH] STM32: Change CAN data() to return slice with correct length

---
 embassy-stm32/src/can/fd/peripheral.rs |  2 +-
 embassy-stm32/src/can/frame.rs         | 18 ++++++++----------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/embassy-stm32/src/can/fd/peripheral.rs b/embassy-stm32/src/can/fd/peripheral.rs
index 39c4112ad..014f31c87 100644
--- a/embassy-stm32/src/can/fd/peripheral.rs
+++ b/embassy-stm32/src/can/fd/peripheral.rs
@@ -190,7 +190,7 @@ impl Registers {
                 DataLength::Fdcan(len) => len,
                 DataLength::Classic(len) => len,
             };
-            if len as usize > ClassicData::MAX_DATA_LEN {
+            if len as usize > 8 {
                 return None;
             }
 
diff --git a/embassy-stm32/src/can/frame.rs b/embassy-stm32/src/can/frame.rs
index f621b8bd5..a1d773f2c 100644
--- a/embassy-stm32/src/can/frame.rs
+++ b/embassy-stm32/src/can/frame.rs
@@ -104,15 +104,13 @@ pub trait CanHeader: Sized {
 #[derive(Debug, Copy, Clone)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct ClassicData {
-    pub(crate) bytes: [u8; Self::MAX_DATA_LEN],
+    pub(crate) bytes: [u8; 8],
 }
 
 impl ClassicData {
-    pub(crate) const MAX_DATA_LEN: usize = 8;
     /// Creates a data payload from a raw byte slice.
     ///
-    /// Returns `None` if `data` is more than 64 bytes (which is the maximum) or
-    /// cannot be represented with an FDCAN DLC.
+    /// Returns `FrameCreateError` if `data` is more than 8 bytes (which is the maximum).
     pub fn new(data: &[u8]) -> Result<Self, FrameCreateError> {
         if data.len() > 8 {
             return Err(FrameCreateError::InvalidDataLength);
@@ -211,12 +209,12 @@ impl Frame {
 
     /// Get reference to data
     pub fn data(&self) -> &[u8] {
-        &self.data.raw()
+        &self.data.raw()[..self.can_header.len as usize]
     }
 
     /// Get mutable reference to data
     pub fn data_mut(&mut self) -> &mut [u8] {
-        self.data.raw_mut()
+        &mut self.data.raw_mut()[..self.can_header.len as usize]
     }
 
     /// Get priority of frame
@@ -260,7 +258,7 @@ impl embedded_can::Frame for Frame {
         self.can_header.len as usize
     }
     fn data(&self) -> &[u8] {
-        &self.data.raw()
+        &self.data()
     }
 }
 
@@ -405,12 +403,12 @@ impl FdFrame {
 
     /// Get reference to data
     pub fn data(&self) -> &[u8] {
-        &self.data.raw()
+        &self.data.raw()[..self.can_header.len as usize]
     }
 
     /// Get mutable reference to data
     pub fn data_mut(&mut self) -> &mut [u8] {
-        self.data.raw_mut()
+        &mut self.data.raw_mut()[..self.can_header.len as usize]
     }
 }
 
@@ -448,7 +446,7 @@ impl embedded_can::Frame for FdFrame {
         self.can_header.len as usize
     }
     fn data(&self) -> &[u8] {
-        &self.data.raw()
+        &self.data()
     }
 }