X-Git-Url: http://pileus.org/git/?p=~andy%2Fcsm213a-hw;a=blobdiff_plain;f=hw2%2Fserial_irq.c;fp=hw2%2Fserial_irq.c;h=0f5106d8bda598b8bcbb0b91c55a443f6260a006;hp=e002ce94f49a07c96d7436612ab4cbaa014bc214;hb=af693a35ec651f1264e5332d30eca558e07a188f;hpb=a8fb9b5f585f2cd1d163e37269b6b44ad937c1b2

diff --git a/hw2/serial_irq.c b/hw2/serial_irq.c
index e002ce9..0f5106d 100644
--- a/hw2/serial_irq.c
+++ b/hw2/serial_irq.c
@@ -21,6 +21,7 @@ struct sirq_t {
 	queue_t  xmt;
 	queue_t  rcv;
 	int      irq;
+	int      buffered;
 };
 
 /* Port data */
@@ -32,13 +33,18 @@ void sirq_handler(uint32_t _port, SerialIrq event)
 	sirq_t *port = (sirq_t *)_port;
 
 	// Handle transmit
-	if (event == TxIrq && port->xmt.rix != port->xmt.wix) {
-		int byte = port->xmt.buf[port->xmt.rix];
-		serial_putc(&port->uart, byte);
-		port->xmt.rix = (port->xmt.rix+1) % SIRQ_LEN;
-	} else {
-		serial_irq_set(&port->uart, TxIrq, 0);
-		port->irq = 0;
+	//   note: mbed seems to call TxIrq even it is not enabled,
+	//   so we need to manually prevent transmitting when the
+	//   port is set to buffered mode.
+	if (event == TxIrq && (port->irq || !port->buffered)) {
+		if (port->xmt.rix != port->xmt.wix) {
+			int byte = port->xmt.buf[port->xmt.rix];
+			serial_putc(&port->uart, byte);
+			port->xmt.rix = (port->xmt.rix+1) % SIRQ_LEN;
+		} else {
+			serial_irq_set(&port->uart, TxIrq, 0);
+			port->irq = 0;
+		}
 	}
 
 	// Handle receive
@@ -50,11 +56,14 @@ void sirq_handler(uint32_t _port, SerialIrq event)
 }
 
 /* Open port */
-sirq_t *sirq_open(sirq_uart_t uart, PinName tx, PinName rx, int baud)
+sirq_t *sirq_open(sirq_uart_t uart, PinName tx, PinName rx, int baud, int buffered)
 {
 	// Allocate port
 	sirq_t *port = &sirq_ports[uart];
 
+	// Buffered ports only transmit on demand
+	port->buffered = buffered;
+
 	// Configure port
 	serial_init(&port->uart, tx, rx);
 	serial_baud(&port->uart, baud);
@@ -71,10 +80,8 @@ void sirq_putc(sirq_t *port, int byte)
 {
 	port->xmt.buf[port->xmt.wix] = byte;
 	port->xmt.wix = (port->xmt.wix+1) % SIRQ_LEN;
-	if (!port->irq) {
-		port->irq = 1;
-		serial_irq_set(&port->uart, TxIrq, 1);
-	}
+	if (!port->buffered)
+		sirq_transmit(port);
 }
 
 /* Read byte from the port */
@@ -88,6 +95,15 @@ int sirq_getc(sirq_t *port)
 	return byte;
 }
 
+/* Enable transmitter */
+void sirq_transmit(sirq_t *port)
+{
+	if (port->xmt.rix != port->xmt.wix && !port->irq) {
+		port->irq = 1;
+		serial_irq_set(&port->uart, TxIrq, 1);
+	}
+}
+
 /* Buffered write */
 void sirq_write(sirq_t *port, void *data, int len)
 {