[prog] C help - assembly and ports

[Akkana Peck]

Laylaa writes:
> I was hoping somebody could direct me to appropriate tutorials or
> resources so I can quickly teach myself so I can teach my students.

Since I haven't seen any other answers posted ...

Both of the topics you mentioned (embedded assembly language and
accessing serial/parallel ports) are specific to the compiler and
operating system you're using, and aren't part of the C language
at all. (Which might explain why you don't remember them from your
past C experience.)

Assembly language seems to be compiler specific: I've seen several
different syntaxes for embedding assembly into a C program. I've
never had occasion to do that in VC++, but it's probably documented
(maybe a #pragma directive?)

> The other topic is port access, that is writing programs that do I/O
> to ports. This I have no clue about. It's stuff I wouldn't mind
> learning but I have no idea how etc. I barely remember the difference
> between parallel and serial ports.

On Linux, serial and parallel ports are just devices, accessed via
a pathname in the file system, e.g. /dev/ttyS1 or /dev/lp0 or
whatever. You can read from or write to the resulting file
descriptor (you probably do want to use low-level writes and
file descriptors, not stdio buffered writes and file pointers)
and you can also make some device-specific calls to them, usually
using the ioctl() system call.

But if you're using MSVC++, you aren't using Linux anyway, so what
you're actually asking is how to do this on Windows. I think it's
similar, only you open a different filename (COM1: or LP1: or something
like that? It's been a long long time ...) And I think ioctls work on
Windows too, but the specific codes you pass in might be different.

> Anywayz, I hope this is the appropriate list and I hope somebody can
> help/point me somewhere helpful. I did try googling but sometimes it's
> hard when you're not too sure what you're looking for. I will also try
> looking through the archives...but, are they searchable?

Since you really need Windows specific answers in both cases, I
suspect most of what you find in the Linuxchix archives wouldn't
be terribly helpful. But knowing that much might help you in
constructing more helpful google queries. Good luck!

	...Akkana