Use libieee1284 instead of native port-mapped I/O about covox-music-player

[yeokm1]

@volkertb Thanks so much for your effort! I honestly didn't expect anyone to be using this project.

At that time when I started this project, I don't think the CVX4 was available yet. I agree with you that is good way to have an off-the-shelf Covox experience.

I'll need some time to review your request and test the code. I have to fire up my retro PC for a start! I have a CVX4 as well so I'll test with that too.

I don't have a non-x86 system with a parallel port though to test the cross-platform aspects but I believe it should work.

[volkertb]

@yeokm1 Well, I tested this change in a QEMU VM with an emulated parallel port. It seemed to work, although it did still require sudo privileges. 😅 Instead of an x86-specific I/O port, the device name was parport0.

See the screenshot below.

I did need to run it with sudo privileges to output anything to it, though. Also, I'm not sure if the audio is actually working, since the emulated parallel port wasn't routed to an actual physical parallel port on the host. Also, the number of skipped frames is quite high. But that might have something to do with the emulated parallel port and my (failed) attempt to have QEMU dump the output of the emulated parallel port to a file. Testing this with actual hardware is better, of course.

I currently don't have an LPT DAC to test this with. I'll probably order a CVX4, the Covox clone I mentioned in my addition to the README. And I have another computer with a physical parallel port that I can test this with.

Also, I might soon be able to test this with a Ultrasparc workstation as well. That way, we'll know for sure whether the code is cross-platform with this change. 😄

Oh, and libieee1284 is also supposed to be cross-platform in terms of operating systems, not just CPU architecture. It should therefore make it easier to port this project to other operating systems in the future, should you be interested in that.