Maximum PC

I am working a simple OS, and have worked on the kernel and use GRUB as my bootloader. Now I want to program the PC speaker (not the sound card) to emit a POST-like series of beeps if something fails. Can anyone tell me why this code doesn't work?



If anyone want's to see outportb and inportb just ask, but I'm sure they work because the keyboard input/output is fine. The calling function does this (stripped version):


Don't worry, the speaker gets turned off later.

Nice.... I'm going to be of very little help here. Just curious to see how this turns out.

First, you've probably pissed of the programming gods by not using K&R, so don't expect debugging to be rational...

I am curious....

why ( a / b ) in this case?
int countdown = (1193180 / freq);

why caste to int? int / int == int
int high = (int)(countdown / 256);

I really don't understand what con_speaker is suppose to do. Wht does con mean? At first glance, I thought you were setting up a high and low frequency range or something - "//I think 131 is middle C". After reading into it, I get the impression you're setting up a timer to run over a certain time period. Is that right?

I am sorry if this seems like a stupid question, but what is K&R?

http://www.amazon.com/exec/obidos/tg/de ... 9?v=glance

A common programming style popularized by those two guys....


It tends to be shunned by C++ textbooks (why? I have no idea), but I've never seen a significant project or known of that doesn't use the K&R style either - all the free software uses K&R (linux, every bsd, etc), all the highest rated programmers at TC use it, the java programming sytle is similiar (minor change), and it is the prefered style of Stroustrup as well. Good company to keep.

The main benefit is that it saves vertical space on the screen (and in the books which often need the extra space even more... irony). You also know immediately from looking at the control structure line (ie the while in this case) whether you're dealing with a block or not. And in case you were wondering, that other style doesn't have a name - it isn't worthy!

*In all seriousness, it might have a name, but I'll be damned if I know anyone that uses that style that knows it.

"con" stood for "connect", but that wasn't really appropriate; what I really wanted to do was program timer two and use it to set the frequency on the speaker (but that's it, it doesn't really connect anything, more like initializes)... the cast to int? don't know about that one, just wanted to be safe (but you're right, totally unnecessary, since 'division' means 'integer division').

low and high is 'low order' and 'high order', because that's how you have to send it to the port (otherwise there is a much smaller range).

Yeah, my style is different (from both of them), but that's what happens when you learn by yourself; I might switch if it precludes me from getting a job.

speaker_on and speaker_off do exactly what they say...

The weird thing is, I tested it on an identical machine and the above code works...and I mean identical. Same BIOS, same BIOS settings, same everything, yet it doesn't play on my primary testing machine. Maybe some registers are getting trashed? Any insight would be helpful. (and yes, the speaker is enabled in the BIOS).

Okay, I've decided to learn "Stroustrup Style" or "K&R for C++", since that is fairly close to my current style (but I absolutely refuse to rewrite anything unless someone else wants it). Does anyone have a good book/something for teaching this style (I found a short one on http://www.research.att.com/~bs/bs_faq2.html but I want to know if there is more to it)?

See the linux kernel docs..... they have a short howto on using K&R. As far as good book, see the resources section and the book by Stroustrup, while it doesn't teach K&R, is written entirely in this style and is the most recommended C++ book in existance. You can also refer to the Java Coding style at Sun, which is essentially K&R as well.

Any progress on your project?

I r Python programmer (beware)

First, I think maybe try 400 instead of 131. Is 131 supposed to be the thue freq? as in 131 hetrz? That might be outside a PC speaker's range.

Forgive me if I am off the mark here. Also, can you ring the bell? Like ^g, just to confirm the speaker is working?

also " if (freq <= 15)" you should set to 20 (actually set it to 300 for a test). Most folks can't hear less than 20 and a PC speaker is not going to get near 20 in reality. You would just hear a "click" as it activates.

Also, what is the max on freq?

The above all assumes you are using hertz for freq.

Manta

Not only would a pc speaker not go down to 20 hertz, but most subwoofers can't either! I doubt a pc speaker can go below 100.

Good points.... so that's why JPL pays you the big bucks.

Hey Cplusplus have you seen my PM?

Heh - I am still waiting for a travel reimbursment from them

Manta

Thaks for helping me. The speaker just 'clicked' before, as you (meaning the collective you) expected.

As I suspected. Did you get it fixed?

Manta

Yeah, I just upped the frequency (in Hertz), and now I can hear it.

Kewl

Manta

Middle A (A4) is 440 Hz.

You can find the frequency of another note with this formula:

Freq. = ((2^(1/12))^s) * 440 Hz

Where Freq. is the freqeuncy of the note, and s is the number of half steps up from A4 the note is.

This can be expressed in C as:



To go up or down an octave, multiply or divide by two (respectively).