Add serial transmit call

[~andy/csm213a-hw] / hw2 / serial_irq.c

diff --git a/hw2/serial_irq.c b/hw2/serial_irq.c
index e002ce94f49a07c96d7436612ab4cbaa014bc214..0f5106d8bda598b8bcbb0b91c55a443f6260a006 100644 (file)
--- a/hw2/serial_irq.c
+++ b/hw2/serial_irq.c
@@ -21,6 +21,7 @@ struct sirq_t {
        queue_t  xmt;\r
        queue_t  rcv;\r
        int      irq;\r
+       int      buffered;\r
 };\r
 \r
 /* Port data */\r
@@ -32,13 +33,18 @@ void sirq_handler(uint32_t _port, SerialIrq event)
        sirq_t *port = (sirq_t *)_port;\r
 \r
        // Handle transmit\r
-       if (event == TxIrq && port->xmt.rix != port->xmt.wix) {\r
-               int byte = port->xmt.buf[port->xmt.rix];\r
-               serial_putc(&port->uart, byte);\r
-               port->xmt.rix = (port->xmt.rix+1) % SIRQ_LEN;\r
-       } else {\r
-               serial_irq_set(&port->uart, TxIrq, 0);\r
-               port->irq = 0;\r
+       //   note: mbed seems to call TxIrq even it is not enabled,\r
+       //   so we need to manually prevent transmitting when the\r
+       //   port is set to buffered mode.\r
+       if (event == TxIrq && (port->irq || !port->buffered)) {\r
+               if (port->xmt.rix != port->xmt.wix) {\r
+                       int byte = port->xmt.buf[port->xmt.rix];\r
+                       serial_putc(&port->uart, byte);\r
+                       port->xmt.rix = (port->xmt.rix+1) % SIRQ_LEN;\r
+               } else {\r
+                       serial_irq_set(&port->uart, TxIrq, 0);\r
+                       port->irq = 0;\r
+               }\r
        }\r
 \r
        // Handle receive\r
@@ -50,11 +56,14 @@ void sirq_handler(uint32_t _port, SerialIrq event)
 }\r
 \r
 /* Open port */\r
-sirq_t *sirq_open(sirq_uart_t uart, PinName tx, PinName rx, int baud)\r
+sirq_t *sirq_open(sirq_uart_t uart, PinName tx, PinName rx, int baud, int buffered)\r
 {\r
        // Allocate port\r
        sirq_t *port = &sirq_ports[uart];\r
 \r
+       // Buffered ports only transmit on demand\r
+       port->buffered = buffered;\r
+\r
        // Configure port\r
        serial_init(&port->uart, tx, rx);\r
        serial_baud(&port->uart, baud);\r
@@ -71,10 +80,8 @@ void sirq_putc(sirq_t *port, int byte)
 {\r
        port->xmt.buf[port->xmt.wix] = byte;\r
        port->xmt.wix = (port->xmt.wix+1) % SIRQ_LEN;\r
-       if (!port->irq) {\r
-               port->irq = 1;\r
-               serial_irq_set(&port->uart, TxIrq, 1);\r
-       }\r
+       if (!port->buffered)\r
+               sirq_transmit(port);\r
 }\r
 \r
 /* Read byte from the port */\r
@@ -88,6 +95,15 @@ int sirq_getc(sirq_t *port)
        return byte;\r
 }\r
 \r
+/* Enable transmitter */\r
+void sirq_transmit(sirq_t *port)\r
+{\r
+       if (port->xmt.rix != port->xmt.wix && !port->irq) {\r
+               port->irq = 1;\r
+               serial_irq_set(&port->uart, TxIrq, 1);\r
+       }\r
+}\r
+\r
 /* Buffered write */\r
 void sirq_write(sirq_t *port, void *data, int len)\r
 {\r