Added non-blocking get/put_byte routines.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8556 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 25 insertions, 0 deletions

diff --git a/firmware/export/usb_serial.h b/firmware/export/usb_serial.h
index 5daefeeff2..32bb8525b4 100644
--- a/firmware/export/usb_serial.h
+++ b/firmware/export/usb_serial.h
@@ -22,5 +22,7 @@
 void usb_serial_init(void);
 void usb_serial_put_byte(int b);
 int usb_serial_get_byte(void);
+int usb_serial_try_put_byte(int b);
+int usb_serial_try_get_byte(void);
 
 #endif
diff --git a/firmware/usb_serial.c b/firmware/usb_serial.c
index acf19e3b1a..0c4fb9d896 100644
--- a/firmware/usb_serial.c
+++ b/firmware/usb_serial.c
@@ -1081,6 +1081,17 @@ int usb_serial_get_byte(void)
     return fifo_get_byte(&serial_in_fifo);
 }
 
+int usb_serial_try_get_byte(void)
+{
+    int r;
+    if (fifo_empty(&serial_in_fifo))
+        r = -1;
+    else
+        r = fifo_get_byte(&serial_in_fifo);
+    usb_serial_handle();
+    return r;
+}
+
 /*
   Not used:
 static int usb_serial_out_full(void)
@@ -1097,6 +1108,18 @@ void usb_serial_put_byte(int b)
     usb_serial_handle();
 }
 
+int usb_serial_try_put_byte(int b)
+{
+    int r = -1;
+    if (!fifo_full(&serial_out_fifo))
+    {
+        fifo_put_byte(&serial_out_fifo, b);
+        r = 0;
+    }
+    usb_serial_handle();
+    return r;
+}
+
 void usb_serial_init(void)
 {
     fifo_init(&serial_in_fifo);