cdcacm: added FIONREAD and FIONWRITE to cdcacm driver

based on serial.c implementation

1 files changed, 48 insertions, 0 deletions

diff --git a/nuttx/drivers/usbdev/cdcacm.c b/nuttx/drivers/usbdev/cdcacm.c
index ec3dcd333..2584ce428 100644
--- a/nuttx/drivers/usbdev/cdcacm.c
+++ b/nuttx/drivers/usbdev/cdcacm.c
@@ -1939,6 +1939,54 @@ static int cdcuart_ioctl(FAR struct file *filep,int cmd,unsigned long arg)
           break;
 #endif
 
+          case FIONREAD:
+          {
+            int count;
+            irqstate_t state = irqsave();
+
+            /* determine the number of bytes available in the buffer */
+
+            if (serdev->recv.tail <= serdev->recv.head)
+              { 
+                count = serdev->recv.head - serdev->recv.tail;
+              }
+            else
+              {
+                count = serdev->recv.size - (serdev->recv.tail - serdev->recv.head);
+              }
+
+            irqrestore(state);
+
+            *(int *)arg = count;
+            ret = 0;
+
+            break;
+          }
+
+          case FIONWRITE:
+          {
+            int count;
+            irqstate_t state = irqsave();
+
+            /* determine the number of bytes free in the buffer */
+
+            if (serdev->xmit.head < serdev->xmit.tail)
+              { 
+                count = serdev->xmit.tail - serdev->xmit.head - 1;
+              }
+            else
+              {
+                count = serdev->xmit.size - (serdev->xmit.head - serdev->xmit.tail) - 1;
+              }
+
+            irqrestore(state);
+
+            *(int *)arg = count;
+            ret = 0;
+
+            break;
+          }
+
     default:
             
             ret = -ENOSYS;