Bugfixes

diff --git a/ROM2/sci.c b/ROM2/sci.c
index fe59f75..646e443 100644 (file)
--- 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 */
        }
 }
+