Rewrite filter id to be more convenient and failsafe.

Author: aentinger

libraries/Arduino_CAN/examples/CANReadFilter/CANReadFilter.ino

@@ -42,12 +42,14 @@ void setup()
   CAN.setFilterMask_Extended(CAN_FILTER_MASK_EXTENDED);
   CAN.setFilterMask_Standard(CAN_FILTER_MASK_STANDARD);
 
-  for (int c=16; c <= 23; c++) {
-    CAN.setMailboxID(c, 0x0100);
+  for (int mailbox = 0; mailbox < R7FA4M1_CAN::CAN_MAX_EXTENDED_MAILBOXES; mailbox++)
+  {
+    CAN.setFilterId_Extended(mailbox, 0x0100);
   }
 
-  for (int c=24; c <= 31; c++) {
-    CAN.setMailboxID(c, 0x10);
+  for (int mailbox = 0; mailbox < R7FA4M1_CAN::CAN_MAX_STANDARD_MAILBOXES; mailbox++)
+  {
+    CAN.setFilterId_Standard(mailbox, 0x10);
   }
 
   if (!CAN.begin(CanBitRate::BR_250k))

libraries/Arduino_CAN/src/R7FA4M1_CAN.cpp

@@ -200,11 +200,23 @@ void R7FA4M1_CAN::setFilterMask_Extended(uint32_t const mask)
   _can_mailbox_mask[5] = mask;
 }
 
-void R7FA4M1_CAN::setMailboxID(size_t const mailbox, uint32_t const id)
+void R7FA4M1_CAN::setFilterId_Standard(size_t const mailbox, uint32_t const id)
 {
-	_can_mailbox[mailbox].mailbox_id = id;
+  if (mailbox > CAN_MAX_STANDARD_MAILBOXES)
+    return;
+
+  size_t const mailbox_idx = CAN_MAX_STANDARD_MAILBOX_OFFSET + mailbox;
+  _can_mailbox[mailbox_idx].mailbox_id = id;
 }
 
+void R7FA4M1_CAN::setFilterId_Extended(size_t const mailbox, uint32_t const id)
+{
+  if (mailbox > CAN_MAX_EXTENDED_MAILBOXES)
+    return;
+
+  size_t const mailbox_idx = CAN_MAX_EXTENDED_MAILBOX_OFFSET + mailbox;
+  _can_mailbox[mailbox_idx].mailbox_id = id;
+}
 
 int R7FA4M1_CAN::enableInternalLoopback()
 {

libraries/Arduino_CAN/src/R7FA4M1_CAN.h

@@ -56,7 +56,8 @@ class R7FA4M1_CAN final : public HardwareCAN
 
   void setFilterMask_Standard(uint32_t const mask);
   void setFilterMask_Extended(uint32_t const mask);
-  void setMailboxID(size_t const mailbox, uint32_t const id);
+  void setFilterId_Standard(size_t const mailbox, uint32_t const id);
+  void setFilterId_Extended(size_t const mailbox, uint32_t const id);
 
   int enableInternalLoopback();
   int disableInternalLoopback();
@@ -73,9 +74,13 @@ class R7FA4M1_CAN final : public HardwareCAN
   /* This function is used by the library and should NOT be called by the user. */
   void onCanCallback(can_callback_args_t * p_args);
 
+  static size_t constexpr CAN_MAX_STANDARD_MAILBOXES = 8U;
+  static size_t constexpr CAN_MAX_EXTENDED_MAILBOXES = 8U;
 
 private:
   static size_t constexpr CAN_MAX_NO_MAILBOXES = 32U;
+  static size_t constexpr CAN_MAX_STANDARD_MAILBOX_OFFSET = 24U;
+  static size_t constexpr CAN_MAX_EXTENDED_MAILBOX_OFFSET = 16U;
 
   int const _can_tx_pin;
   int const _can_rx_pin;