X-Git-Url: https://git.ucc.asn.au/?p=uccvend-snackrom.git;a=blobdiff_plain;f=ROM2%2Fsci.c;h=646e443ca4cb4077226b394836fe27e2f321b582;hp=fe59f75b1b6c478a9cfaa5d5e7ebbbec1ce77e4a;hb=74fa3423b3feafe4877c3bfc819462e80797ed3a;hpb=b0e717fbd07189603c7fcc51f55bc6f67119ead3

diff --git a/ROM2/sci.c b/ROM2/sci.c
index fe59f75..646e443 100644
--- a/ROM2/sci.c
+++ b/ROM2/sci.c
@@ -113,10 +113,14 @@ void serial_rti() { /* called every 6.6 ms */
 
 /* for gdb compatibility */
 int serial_readchar(u8 timeout) {
+	int ret;
 	sci_timer = timeout * 152;
 	while (sci_timer && sci_rx_buf_ptr_start == sci_rx_buf_ptr); /* spin */
 	if (sci_timer == 0) return SERIAL_TIMEOUT;
-	return sci_rx_buf[sci_rx_buf_ptr_start++];
+	ret = sci_rx_buf[sci_rx_buf_ptr_start];
+	sci_rx_buf_ptr_start++;
+	sci_rx_buf_ptr_start %= BUFFER_LEN;
+	return ret;
 }
 
 void serial_write(const char *str, int len) {
@@ -127,3 +131,4 @@ void serial_write(const char *str, int len) {
 		_io_ports[M6811_SCDR] = *c; /* send byte */
 	}
 }
+