uart: volatile/uart_wait()

1 files changed, 8 insertions, 2 deletions

diff --git a/uart.c b/uart.c
index fcc5783..feb9619 100644
--- a/uart.c
+++ b/uart.c
@@ -1,6 +1,6 @@
 #define TXBSIZE 128
-static char txbuf[TXBSIZE];
-static uint8_t txput = 0, txsend = 0;
+static volatile char txbuf[TXBSIZE];
+static volatile uint8_t txput = 0, txsend = 0;
 
 ISR(USART_RX_vect)
 {
@@ -19,6 +19,12 @@ ISR(USART_UDRE_vect)
 	}
 }
 
+static void uart_wait(void)
+{
+	while (txsend != txput)
+		asm volatile ("" : : : "memory");
+}
+
 static void _uart_putch(const char ch)
 {
 	txbuf[txput] = ch;