dateandtime.tex

嵌入式文件系统 EFSL 0.3.5 / 嵌入式文件系统 EFSL 0.3.5

\label{dateandtime}
The EFSL library supports setting and updating all date and time fields
supported by the filesystem. In order to do this the library must 
know the current time and date at all times. Since it has to run everywhere,
there is no standard mechanism to get the date/time, and some systems do
not have a clock.

With default configuration there is no date or time support, you have to
turn it on manually in the configuration file \filename{config.h}.
You will have to uncomment the field named \code{\#define DATE\_TIME\_SUPPORT},
in order to activate date/time support.

Furthermore you will have to provide the library with date and time information.
A set of defines was used for this, when date/time support is not enabled,
the defines automatically return \code{0x0000} for all time and date fields,
so there is no performance suffer when you do not need date/time support.
If you do need it you will have to provide 6 functions to the library
that will tell it the time. Since these functions may get called often,
it is highly recommended that you cache the time result somewhere so
you can serve the library directly from ram. If you do not do this and
your RTC request take a lot of time, you may suffer large losses in read
or write operations depending on your hardware.

The six functions are:
\begin{itemize}
    \item\code{euint16 efsl\_getYear(void)} 
    \item\code{euint8 efsl\_getMonth(void)} 
    \item\code{euint8 efsl\_getDay(void)} 
    \item\code{euint8 efsl\_getHour(void)} 
    \item\code{euint8 efsl\_getMinute(void)} 
    \item\code{euint8 efsl\_getSecond(void)}
\end{itemize}
Internally the library will recalculate these numbers to match the
filesystem that is currently in use.