backported changes from official ataradov vcp repository

Author: majbthrd

example-apps/vcp/uart.c

@@ -218,7 +218,7 @@ void UART_SERCOM_IRQ_HANDLER(void)
     }
     else
     {
-      UART_SERCOM->USART.DATA.reg = uart_tx_fifo.data[uart_tx_fifo.rd];;
+      UART_SERCOM->USART.DATA.reg = uart_tx_fifo.data[uart_tx_fifo.rd];
       uart_tx_fifo.rd = (uart_tx_fifo.rd + 1) % UART_BUF_SIZE;
     }
   }

example-apps/vcp/usb_descriptors.c

@@ -171,6 +171,3 @@ const char *const usb_strings[] =
   [USB_STR_PRODUCT]       = "Virtual COM-Port",
   [USB_STR_SERIAL_NUMBER] = usb_serial_number,
 };
-
-alignas(4) uint8_t usb_string_descriptor_buffer[64];
-

example-apps/vcp/usb_descriptors.h

@@ -72,7 +72,6 @@ extern const usb_configuration_hierarchy_t usb_configuration_hierarchy;
 extern const usb_string_descriptor_zero_t usb_string_descriptor_zero;
 extern const char *const usb_strings[];
 extern char usb_serial_number[16];
-extern uint8_t usb_string_descriptor_buffer[64];
 
 #endif // _USB_DESCRIPTORS_H_
 

example-apps/vcp/usb_std.c

@@ -28,6 +28,7 @@
 
 /*- Includes ----------------------------------------------------------------*/
 #include <stdbool.h>
+#include <stdalign.h>
 #include <string.h>
 #include "utils.h"
 #include "usb.h"
@@ -100,20 +101,22 @@ bool usb_handle_standard_request(usb_request_t *request)
         else if (index < USB_STR_COUNT)
         {
           const char *str = usb_strings[index];
-          int len;
+          int len = strlen(str);
+          int size = len*2 + 2;
+          alignas(4) uint8_t buf[size];
 
-          for (len = 0; *str; len++, str++)
+          buf[0] = size;
+          buf[1] = USB_STRING_DESCRIPTOR;
+
+          for (int i = 0; i < len; i++)
           {
-            usb_string_descriptor_buffer[2 + len*2] = *str;
-            usb_string_descriptor_buffer[3 + len*2] = 0;
+            buf[2 + i*2] = str[i];
+            buf[3 + i*2] = 0;
           }
 
-          usb_string_descriptor_buffer[0] = len*2 + 2;
-          usb_string_descriptor_buffer[1] = USB_STRING_DESCRIPTOR;
-
-          length = LIMIT(length, usb_string_descriptor_buffer[0]);
+          length = LIMIT(length, size);
 
-          usb_control_send(usb_string_descriptor_buffer, length);
+          usb_control_send(buf, length);
         }
         else
         {