[USB CDC] Fixed possible transmitting error

Author: makarenya

cores/arduino/stm32/usb/cdc/cdc_queue.c

@@ -73,19 +73,17 @@ void CDC_TransmitQueue_Enqueue(CDC_TransmitQueue_TypeDef *queue, const uint8_t *
 
 // Read flat block from queue (biggest as possible, but max CDC_QUEUE_MAX_PACKET_SIZE).
 uint8_t *CDC_TransmitQueue_ReadBlock(CDC_TransmitQueue_TypeDef *queue, uint16_t *size) {
-  uint16_t readPos = queue->read;
   if (queue->write >= queue->read) {
     *size = queue->write - queue->read;
-    queue->read = queue->write;
-  } else if ((uint16_t)(CDC_TRANSMIT_QUEUE_BUFFER_SIZE - queue->read) > CDC_QUEUE_MAX_PACKET_SIZE) {
-    // limit to max packet size
-    *size = CDC_QUEUE_MAX_PACKET_SIZE;
-    queue->read += CDC_QUEUE_MAX_PACKET_SIZE;
   } else {
     *size = CDC_TRANSMIT_QUEUE_BUFFER_SIZE - queue->read;
-    queue->read = 0;
   }
-  return &queue->buffer[readPos];
+  queue->reserved = *size;
+  return &queue->buffer[queue->read];
+}
+
+void CDC_TransmitQueue_CommitRead(CDC_TransmitQueue_TypeDef *queue) {
+  queue->read = (queue->read + queue->reserved) % CDC_TRANSMIT_QUEUE_BUFFER_SIZE;
 }
 
 // Initialize read and write position of queue.

cores/arduino/stm32/usb/cdc/cdc_queue.h

@@ -52,13 +52,14 @@
 #else
 #define CDC_QUEUE_MAX_PACKET_SIZE USB_FS_MAX_PACKET_SIZE
 #endif
-#define CDC_TRANSMIT_QUEUE_BUFFER_SIZE ((uint16_t)(CDC_QUEUE_MAX_PACKET_SIZE))
+#define CDC_TRANSMIT_QUEUE_BUFFER_SIZE ((uint16_t)(CDC_QUEUE_MAX_PACKET_SIZE * 2))
 #define CDC_RECEIVE_QUEUE_BUFFER_SIZE ((uint16_t)(CDC_QUEUE_MAX_PACKET_SIZE * 2))
 
 typedef struct {
   uint8_t buffer[CDC_TRANSMIT_QUEUE_BUFFER_SIZE];
   volatile uint16_t write;
   volatile uint16_t read;
+  volatile uint16_t reserved;
 } CDC_TransmitQueue_TypeDef;
 
 typedef struct {
@@ -73,6 +74,7 @@ int CDC_TransmitQueue_WriteSize(CDC_TransmitQueue_TypeDef* queue);
 int CDC_TransmitQueue_ReadSize(CDC_TransmitQueue_TypeDef* queue);
 void CDC_TransmitQueue_Enqueue(CDC_TransmitQueue_TypeDef* queue, const uint8_t* buffer, uint32_t size);
 uint8_t* CDC_TransmitQueue_ReadBlock(CDC_TransmitQueue_TypeDef* queue, uint16_t* size);
+void CDC_TransmitQueue_CommitRead(CDC_TransmitQueue_TypeDef *queue);
 
 void CDC_ReceiveQueue_Init(CDC_ReceiveQueue_TypeDef* queue);
 int CDC_ReceiveQueue_ReadSize(CDC_ReceiveQueue_TypeDef* queue);

cores/arduino/stm32/usb/cdc/usbd_cdc_if.c

@@ -211,6 +211,7 @@ static int8_t USBD_CDC_Receive (uint8_t* Buf, uint32_t *Len) {
 
 
 static int8_t USBD_CDC_Transferred (void) {
+  CDC_TransmitQueue_CommitRead(&TransmitQueue);
   CDC_continue_transmit();
   return (USBD_OK);
 }