print correctly BCD CMOS RTC values

[alberinfo]

hi,
i'm trying to implement a rtc with cmos(it isn't updated in github)i can get the values, but when i try to print it i only get something buggy.when i was reading some other post, i understood that this is cause it is in BCD and not as int values, so i have to convert it, but the only two abiavle ways that can compile with my code, doesn't work, they just display the same.how can i convert a BCD to a int value?

[alexfru]

https://en.wikipedia.org/wiki/Binary-coded_decimal

[alberinfo]

thanks, but this actually didn't work for me.

[alexfru]

thanks, but this actually didn't work for me.

How so? Elaborate please.

[alberinfo]

i didn't see anything to 'convert' BCD to INT, also the only two ways that i see that are:

Code: Select all

(((hour & 0xF0) >> 4) < 10)

and:

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((hour & 0xF0) >> 4) * 10 + (hour & 0x0F)

makes the same result as the image above

[alexfru]

Then, perhaps, the problem is not in conversion but in reading the values from the chip or your prgram being somehow broken (not read from disk correctly, not having correct values in e.g. segment registers).

[thomtl]

CMOS Please look at the wiki before posting.

[sortie]

You can look at how I've implemented it: https://gitlab.com/sortix/sortix/blob/m ... y/cmos.cpp

That should be a readable & good example. It also avoids race conditions when the value is being updated.

[alberinfo]

thanks, but either the CMOS method or the method provided by sortie didnt work, still displaying the 'S' in the screen

[alexfru]

thanks, but either the CMOS method or the method provided by sortie didnt work, still displaying the 'S' in the screen

Can you test separately:

• single character printing
• string printing
• conversion of integer to hex digits and hex chars ('0'-'9','A'-'F')
• conversion of integer to decimal digits and chars ('0'-'9')
• conversion from BCD to integer

[thomtl]

Could you post your source, since your github is severely outdated.

[alberinfo]

i've updated it, but anyway, i don't know what or why fails

[thomtl]

You've swapped around your outb functions, the correct syntax for you outb function is

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void outb(word port, word value);

and you're using

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void outb(word value, word port);

also you should really reorganise your project a good example for this is Meaty_Skeleton.
And because you have copied and pasted so much code by @pvc there are 2 outb functions outb and outportb, OSDev is more than just copying code from others it's about writing code yourself and creating your own OS.

[alberinfo]

i see in the outportb function that is first the port and then the data as you say.

[thomtl]

Please read my edit