Add function comments to detail the expected parameters and return values of a FileStream

cocos/platform/CCFileStream.h

@@ -19,14 +19,54 @@ public:
         APPEND,
     };
 
+    /**
+    *  Open a file
+    *  @param path file to open
+    *  @param mode File open mode, being READ | WRITE | APPEND
+    *  @return true if successful, false if not
+    */
     virtual bool open(const std::string& path, FileStream::Mode mode) = 0;
+
+    /**
+    *  Close a file stream
+    *  @return 0 if successful, -1 if not
+    */
     virtual int close() = 0;
 
+    /**
+    *  Seek to position in a file stream
+    *  @param offset how many bytes to move within the stream
+    *  @param origin SEEK_SET | SEEK_CUR | SEEK_END
+    *  @return 0 if successful, -1 if not
+    */
     virtual int seek(long offset, int origin) = 0;
+
+    /**
+    *  Read data from file stream
+    *  @param buf pointer to data
+    *  @param size the amount of data to read in bytes
+    *  @return amount of data read successfully, -1 if error
+    */
     virtual int read(void* buf, unsigned int size) = 0;
 
+    /**
+    *  Write data to file stream
+    *  @param buf pointer to data
+    *  @param size the amount of data to write in bytes
+    *  @return amount of data written successfully, -1 if error
+    */
     virtual int write(const void* buf, unsigned int size) = 0;
+
+    /**
+    *  Get the current position in the file stream
+    *  @return current position, -1 if error
+    */
     virtual int tell() = 0;
+
+    /**
+    *  Get status of file stream
+    *  @return true if open, false if closed
+    */
     virtual bool isOpen() const = 0;
 
     virtual operator bool() const { return isOpen(); }