sync the comments of serialportlib library class with Mde Library Spec.

[mirror_edk2.git] / MdePkg / Library / SerialPortLibNull / SerialPortLibNull.c

diff --git a/MdePkg/Library/SerialPortLibNull/SerialPortLibNull.c b/MdePkg/Library/SerialPortLibNull/SerialPortLibNull.c
index 79b4e925ed2b86a2ce5e9cbffa6d42079cc41b06..e6b3c63365f6128fff92e373b9fc9e5d07c5d4f8 100644 (file)
--- a/MdePkg/Library/SerialPortLibNull/SerialPortLibNull.c
+++ b/MdePkg/Library/SerialPortLibNull/SerialPortLibNull.c
@@ -19,9 +19,14 @@
 #include <Library/SerialPortLib.h>\r
 \r
 /**\r
-  Programmed hardware of Serial port.\r
-\r
-  @return    Always return RETURN_UNSUPPORTED.\r
+  Initialize the serial device hardware.\r
+  \r
+  If no initialization is required, then return RETURN_SUCCESS.\r
+  If the serial device was successfuly initialized, then return RETURN_SUCCESS.\r
+  If the serial device could not be initialized, then return RETURN_DEVICE_ERROR.\r
+  \r
+  @retval RETURN_SUCCESS        The serial device was initialized.\r
+  @retval RETURN_DEVICE_ERROR   The serail device could not be initialized.\r
 \r
 **/\r
 RETURN_STATUS\r
@@ -34,12 +39,22 @@ SerialPortInitialize (
 }\r
 \r
 /**\r
-  Write data to serial device.\r
+  Write data from buffer to serial device. \r
+ \r
+  Writes NumberOfBytes data bytes from Buffer to the serial device.  \r
+  The number of bytes actually written to the serial device is returned.\r
+  If the return value is less than NumberOfBytes, then the write operation failed.\r
+\r
+  If Buffer is NULL, then ASSERT(). \r
+\r
+  If NumberOfBytes is zero, then return 0.\r
 \r
-  @param  Buffer           Point of data buffer which need to be writed.\r
-  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.\r
+  @param  Buffer           Pointer to the data buffer to be written.\r
+  @param  NumberOfBytes    Number of bytes to written to the serial device.\r
 \r
-  @retval 0                No data is to be written.\r
+  @retval 0                NumberOfBytes is 0.\r
+  @retval >0               The number of bytes written to the serial device.  \r
+                           If this value is less than NumberOfBytes, then the read operation failed.\r
 \r
 **/\r
 UINTN\r
@@ -54,13 +69,14 @@ SerialPortWrite (
 \r
 \r
 /**\r
-  Read data from serial device and save the datas in buffer.\r
+  Reads data from a serial device into a buffer.\r
 \r
-  @param  Buffer           Point of data buffer, which contains the data\r
-                           returned from the serial device.\r
-  @param  NumberOfBytes    Number of bytes which will be read.\r
+  @param  Buffer           Pointer to the data buffer to store the data read from the serial device.\r
+  @param  NumberOfBytes    Number of bytes to read from the serial device.\r
 \r
-  @retval 0                No data is to be read.\r
+  @retval 0                NumberOfBytes is 0.\r
+  @retval >0               The number of bytes read from the serial device.  \r
+                           If this value is less than NumberOfBytes, then the read operation failed.\r
 \r
 **/\r
 UINTN\r