aux_serial: Moved all the transmit logic into aux_serial.c and cleaned up in usb_serial.c

src/platforms/common/aux_serial.c

@@ -37,6 +37,8 @@
 #if defined(STM32F0) || defined(STM32F1) || defined(STM32F3) || defined(STM32F4)
 static char aux_serial_transmit_buffer[2U][TX_BUF_SIZE];
 static uint8_t aux_serial_transmit_buffer_index;
+/* Active buffer part used capacity */
+static uint8_t buf_tx_act_sz;
 #elif defined(LM4F)
 static char aux_serial_transmit_buffer[FIFO_SIZE];
 #endif
@@ -87,6 +89,11 @@ char *aux_serial_current_transmit_buffer(void)
 	return aux_serial_transmit_buffer[aux_serial_transmit_buffer_index];
 }
 
+size_t aux_serial_transmit_buffer_fullness(void)
+{
+	return buf_tx_act_sz;
+}
+
 /*
  * Changes USBUSART TX buffer in which data is accumulated from USB.
  * Filled buffer is submitted to DMA for transfer.
@@ -102,10 +109,35 @@ void aux_serial_switch_transmit_buffers(void)
 	buf_tx_act_sz = 0;
 	aux_serial_transmit_buffer_index ^= 1;
 }
-#elif defined(LM4F)
 
+void aux_serial_send(const size_t len)
+{
+	buf_tx_act_sz += len;
+
+	/* If DMA is idle, schedule new transfer */
+	if (len && tx_trfr_cplt)
+	{
+		tx_trfr_cplt = false;
+		aux_serial_switch_transmit_buffers();
+
+		/* Enable LED */
+		usbuart_set_led_state(TX_LED_ACT, true);
+	}
+}
+#elif defined(LM4F)
 char *aux_serial_current_transmit_buffer(void)
 {
 	return aux_serial_transmit_buffer;
 }
+
+size_t aux_serial_transmit_buffer_fullness(void)
+{
+	return 0;
+}
+
+void aux_serial_send(const size_t len)
+{
+	for(size_t i = 0; i < len; ++i)
+		uart_send_blocking(USBUART, aux_serial_transmit_buffer[i]);
+}
 #endif

src/platforms/common/aux_serial.h

@@ -20,15 +20,22 @@
 #ifndef AUX_SERIAL_H
 #define AUX_SERIAL_H
 
+#include <stddef.h>
 #include <libopencm3/usb/usbd.h>
 #include <libopencm3/usb/cdc.h>
 
 void aux_serial_init(void);
 void aux_serial_set_encoding(struct usb_cdc_line_coding *coding);
-char *aux_serial_current_transmit_buffer(void);
 
 #if defined(STM32F0) || defined(STM32F1) || defined(STM32F3) || defined(STM32F4)
 void aux_serial_switch_transmit_buffers(void);
 #endif
 
+/* Get the current transmit buffer to stage data into */
+char *aux_serial_current_transmit_buffer(void);
+/* Get how full the current transmit buffer is */
+size_t aux_serial_transmit_buffer_fullness(void);
+/* Send a number of bytes staged into the current transmit bufer */
+void aux_serial_send(size_t len);
+
 #endif /*AUX_SERIAL_H*/

src/platforms/common/usb_serial.c

@@ -311,50 +311,23 @@ static void debug_uart_send_callback(usbd_device *dev, uint8_t ep)
 #ifndef ENABLE_RTT
 static void debug_uart_receive_callback(usbd_device *dev, uint8_t ep)
 {
-	char *const transmit_buffer = aux_serial_current_transmit_buffer()
-#if defined(STM32F0) || defined(STM32F1) || defined(STM32F3) || defined(STM32F4)
-	                              + buf_tx_act_sz
-#endif
-		;
-
+	char *const transmit_buffer = aux_serial_current_transmit_buffer() + aux_serial_transmit_buffer_fullness();
 	const uint16_t len = usbd_ep_read_packet(dev, ep, transmit_buffer, CDCACM_PACKET_SIZE);
 
-#if defined(STM32F0) || defined(STM32F1) || defined(STM32F3) || defined(STM32F4)
-	usbd_ep_nak_set(dev, ep, 1);
-
 #if defined(BLACKMAGIC)
 	/* Don't bother if uart is disabled.
 	 * This will be the case on mini while we're being debugged.
 	 */
-	if(!(RCC_APB2ENR & RCC_APB2ENR_USART1EN) &&
-	   !(RCC_APB1ENR & RCC_APB1ENR_USART2EN))
-	{
-		usbd_ep_nak_set(dev, ep, 0);
+	if (!(RCC_APB2ENR & RCC_APB2ENR_USART1EN) && !(RCC_APB1ENR & RCC_APB1ENR_USART2EN))
 		return;
-	}
 #endif
 
-	if (len)
-	{
-		buf_tx_act_sz += len;
+	aux_serial_send(len);
 
-		/* If DMA is idle, schedule new transfer */
-		if (tx_trfr_cplt)
-		{
-			tx_trfr_cplt = false;
-			aux_serial_switch_transmit_buffers();
-
-			/* Enable LED */
-			usbuart_set_led_state(TX_LED_ACT, true);
-		}
-	}
-
-	/* Enable USBUART TX packet reception if buffer has enough space */
-	if (TX_BUF_SIZE - buf_tx_act_sz >= CDCACM_PACKET_SIZE)
-		usbd_ep_nak_set(dev, ep, 0);
-#elif defined(LM4F)
-	for(uint16_t i = 0; i < len; i++)
-		uart_send_blocking(USBUART, transmit_buffer[i]);
+#if defined(STM32F0) || defined(STM32F1) || defined(STM32F3) || defined(STM32F4)
+	/* Disable USBUART TX packet reception if buffer does not have enough space */
+	if (TX_BUF_SIZE - aux_serial_transmit_buffer_fullness() < CDCACM_PACKET_SIZE)
+		usbd_ep_nak_set(dev, ep, 1);
 #endif
 }
 #endif

src/platforms/common/usbuart.h

@@ -41,8 +41,6 @@ void debug_uart_run(void);
 #define RX_FIFO_SIZE (USART_DMA_BUF_SIZE)
 #define TX_BUF_SIZE (USART_DMA_BUF_SIZE)
 
-/* Active buffer part used capacity */
-extern uint8_t buf_tx_act_sz;
 /* TX transfer complete */
 extern bool tx_trfr_cplt;
 /* RX Fifo buffer with space for copy fn overrun */

src/platforms/stm32/usbuart.c

@@ -49,8 +49,6 @@
 #define DMA_CGIF DMA_IFCR_CGIF_BIT
 #endif
 
-/* Active buffer part used capacity */
-uint8_t buf_tx_act_sz;
 /* TX transfer complete */
 bool tx_trfr_cplt = true;
 /* RX Fifo buffer with space for copy fn overrun */
@@ -257,7 +255,7 @@ void USBUSART2_ISR(void)
 	/* If new buffer is ready, continue transmission.			\
 	 * Otherwise report transfer completion.				\
 	 */									\
-	if (buf_tx_act_sz)							\
+	if (aux_serial_transmit_buffer_fullness())							\
 	{									\
 		aux_serial_switch_transmit_buffers();					\
 		usbd_ep_nak_set(usbdev, CDCACM_UART_ENDPOINT, 0);		\