Last time I used C/C++ was several years ago, so I forgot most of what I knew then... What I need is hopefully very simple: a program that reads input (or writes) from LPT n times per second, where n is frequency (4-22 Khz, but this is less relevant). I have problems finding solutions for this problem on the internet, but I believe this is simply because I do not know how to ask google properly I suppose I should use the int_inp() function to read data and int_outp() to write, which is fairly simple (if there is a better solution, please let me know), so the only problem would be timing the executing of the function properly. Thanks to everybody in advance!
Communicating with LPT is implementation dependent. So is the ability to exercise precise time control at 22 Khz. If it's critical, you're going to have to, at least, get down to driver level. For a modern desktop multi-processing system, you might even need some hardware support.