# mfsRamWriteFile

    Format:	s32 mfsRamWriteFile(MfsDirID dirID, void* buf, s32 offset,u32 len)
    Arguments:	dirID	Directory ID of file
    	*buf	Buffer in which data to be written is stored
    	offset	Write starting position
    	len	Size to be written
    Return value:Size of data that was written (a negative value is an error)
    Function:	Writes data to file
    Description:	This function writes data to the file specified by dirID.
    If the address specified by buf is not at a 16-byte boundary, the speed will decrease somewhat because the data is written after being copied to an internal buffer.
    If the offset value is greater than the file size, an error will occur.

    Main errors:
    	MFS_ERR_NOTFOUND Specified file not found
    	MFS_ERR_DEVICE	Device error
    			An error occurred in an internally called Leo function.
    Since a Leo function error is stored in the variable mfsError, check this variable to perform processing.
    	MFS_ERR_PROTECT	Write protected
    			The file attribute is write protected, or the volume attribute is write protected, or the parent directory is write protected.