fix buffer index calculation

they take a bit field as an argument, and then immediately use a clz instruction to convert it back to an index for some reason

README.md

@@ -24,6 +24,8 @@ When using the FDCAN peripheral (H7 series), you also need to define
 `FTCAN_NUM_FILTERS` (and set it to the value of "Std Filters Nbr" you configured
 in your `.ioc`).
 
+If you want to use the dedicated buffers of the FDCAN, you must additionally define `FTCAN_NUM_TX_BUFFERS` (set to value of "Tx Buffers Nbr" in CubeMX).
+
 If you use
 [VSCode with the stm-32-for-vscode extension](https://podio.com/fasttubede/modulubergreifend/apps/tech-tutorials/items/57),
 you can add these definitions in the `STM32-for-VSCode-config.yaml` file, e.g.:
@@ -33,6 +35,7 @@ you can add these definitions in the `STM32-for-VSCode-config.yaml` file, e.g.:
 cDefinitions:
   - STM32H7
   - FTCAN_NUM_FILTERS=32
+  - FTCAN_NUM_TX_BUFFERS=10 # optional, only if using dedicated tx buffers
 ```
 
 ## Usage

can-halal.c

@@ -100,48 +100,51 @@ HAL_StatusTypeDef ftcan_init(FDCAN_HandleTypeDef *handle) {
   return HAL_FDCAN_Start(hcan);
 }
 
-HAL_StatusTypeDef ftcan_transmit(uint16_t id, const uint8_t *data,
-                                 size_t datalen) {
-  static FDCAN_TxHeaderTypeDef header;
-  header.Identifier = id;
-  header.IdType = FDCAN_STANDARD_ID;
-  header.TxFrameType = FDCAN_DATA_FRAME;
+static FDCAN_TxHeaderTypeDef * fdcan_initialize_tx_header(FDCAN_TxHeaderTypeDef * header, uint16_t id, size_t datalen) {
+  header->Identifier = id;
+  header->IdType = FDCAN_STANDARD_ID;
+  header->TxFrameType = FDCAN_DATA_FRAME;
   switch (datalen) {
   case 0:
-    header.DataLength = FDCAN_DLC_BYTES_0;
+    header->DataLength = FDCAN_DLC_BYTES_0;
     break;
   case 1:
-    header.DataLength = FDCAN_DLC_BYTES_1;
+    header->DataLength = FDCAN_DLC_BYTES_1;
     break;
   case 2:
-    header.DataLength = FDCAN_DLC_BYTES_2;
+    header->DataLength = FDCAN_DLC_BYTES_2;
     break;
   case 3:
-    header.DataLength = FDCAN_DLC_BYTES_3;
+    header->DataLength = FDCAN_DLC_BYTES_3;
     break;
   case 4:
-    header.DataLength = FDCAN_DLC_BYTES_4;
+    header->DataLength = FDCAN_DLC_BYTES_4;
     break;
   case 5:
-    header.DataLength = FDCAN_DLC_BYTES_5;
+    header->DataLength = FDCAN_DLC_BYTES_5;
     break;
   case 6:
-    header.DataLength = FDCAN_DLC_BYTES_6;
+    header->DataLength = FDCAN_DLC_BYTES_6;
     break;
   case 7:
-    header.DataLength = FDCAN_DLC_BYTES_7;
+    header->DataLength = FDCAN_DLC_BYTES_7;
     break;
   case 8:
   default:
-    header.DataLength = FDCAN_DLC_BYTES_8;
+    header->DataLength = FDCAN_DLC_BYTES_8;
     break;
   }
-  header.ErrorStateIndicator = FDCAN_ESI_PASSIVE;
-  header.BitRateSwitch = FDCAN_BRS_OFF;
-  header.FDFormat = FDCAN_CLASSIC_CAN;
-  header.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
+  header->ErrorStateIndicator = FDCAN_ESI_PASSIVE;
+  header->BitRateSwitch = FDCAN_BRS_OFF;
+  header->FDFormat = FDCAN_CLASSIC_CAN;
+  header->TxEventFifoControl = FDCAN_NO_TX_EVENTS;
 
-  return HAL_FDCAN_AddMessageToTxFifoQ(hcan, &header, data);
+  return header;
+}
+
+HAL_StatusTypeDef ftcan_transmit(uint16_t id, const uint8_t *data, size_t datalen) {
+    static FDCAN_TxHeaderTypeDef header;
+    return HAL_FDCAN_AddMessageToTxFifoQ(hcan, fdcan_initialize_tx_header(&header, id, datalen), data);
 }
 
 HAL_StatusTypeDef ftcan_add_filter(uint16_t id, uint16_t mask) {
@@ -217,6 +220,26 @@ void HAL_FDCAN_RxFifo0Callback(FDCAN_HandleTypeDef *handle,
 
   ftcan_msg_received_cb(header.Identifier, datalen, data);
 }
+
+HAL_StatusTypeDef ftcan_get_tx_queue_length(uint32_t *length) {
+  if (length == NULL) {
+    return HAL_ERROR;
+  }
+  *length = HAL_FDCAN_GetTxFifoFreeLevel(hcan);
+  return HAL_OK;
+}
+
+#if FTCAN_NUM_TX_BUFFERS
+static_assert(FDCAN_TX_BUFFER11 == 1 << 11 && FDCAN_TX_BUFFER21 == 1 << 21, "Your HAL version has a different definition for the transmit buffer indices. Please update your HAL version or change the code below.");
+
+HAL_StatusTypeDef ftcan_transmit_buffer(uint16_t id, const uint8_t *data, size_t datalen, uint32_t buffer_index) {
+    static FDCAN_TxHeaderTypeDef header;
+    if (buffer_index >= FTCAN_NUM_TX_BUFFERS) {
+        return HAL_ERROR;
+    }
+    return HAL_FDCAN_AddMessageToTxBuffer(hcan, fdcan_initialize_tx_header(&header, id, datalen), data, 1 << buffer_index);
+}
+#endif // FTCAN_NUM_TX_BUFFERS
 #endif
 
 __weak void ftcan_msg_received_cb(uint16_t id, size_t datalen,
@@ -271,4 +294,4 @@ uint8_t *ftcan_marshal_unsigned(uint8_t *data, uint64_t val, size_t num_bytes) {
 
 uint8_t *ftcan_marshal_signed(uint8_t *data, int64_t val, size_t num_bytes) {
   return ftcan_marshal_unsigned(data, val, num_bytes);
-}
+}

can-halal.h

@@ -41,6 +41,13 @@ HAL_StatusTypeDef ftcan_init(FDCAN_HandleTypeDef *handle);
 #error "Unknown CAN peripheral"
 #endif
 
+#if defined(FTCAN_IS_FDCAN) && defined(FTCAN_NUM_TX_BUFFERS)
+static_assert(FTCAN_NUM_TX_BUFFERS > 0,
+               "If you want to use the dedicated transmit buffers, you must define FTCAN_NUM_TX_BUFFERS as configured in CubeMX (at least 1).");
+
+HAL_StatusTypeDef ftcan_transmit_buffer(uint16_t id, const uint8_t *data, size_t datalen, uint32_t buffer_index);
+#endif // FTCAN_IS_FDCAN && FTCAN_NUM_TX_BUFFERS
+
 HAL_StatusTypeDef ftcan_transmit(uint16_t id, const uint8_t *data,
                                  size_t datalen);