Problem with VESA

Jeko · Post by **Jeko** » Mon Oct 02, 2006 12:20 pm

I'm programming with VESA. I have encountered a problem. In bochs is all normal, but when i try the kernel on my real computer the image is moved right. I think maybe it is due that my computer has 32 bit vbe, while bochs has 24 bit.

carbonBased · Post by **carbonBased** » Mon Oct 02, 2006 7:09 pm

Can you post pictures?

The bits per pixel is definitly relevant... however, if you were skewing the basic size of a pixel, then your colours would be all off, as well.

--Jeff

gaf · Post by **gaf** » Tue Oct 03, 2006 5:43 am

And this is nothing that you could fix with the small buttons below your screen ?

Jeko · Post by **Jeko** » Tue Oct 03, 2006 7:23 am

carbonBased wrote:Can you post pictures?

The bits per pixel is definitly relevant

I know this. I have developed two function for drawing pixels in 32bit or 24bit.

For 32bit:
blue; green; red; alpha

For 24bit:
blue; green; red

When I try my kernel on my computer, the image is moved right.

Jeko · Post by **Jeko** » Tue Oct 03, 2006 7:51 am

this is an example of bochs and real:
Bochs:

Real PC:

mrkaktus · Post by **mrkaktus** » Wed Oct 04, 2006 12:06 pm

Are you using double or tripple buffering ? Maybe you set wrong adress of beginning second or third buffer. Are you using linear or buffered interface?

carbonBased · Post by **carbonBased** » Wed Oct 04, 2006 1:27 pm

MarkOS wrote: When I try my kernel on my computer, the image is moved right.

Oh... I originally misread. Gaf's right, just move the image over via you're monitor's correction keys.

Any shifting is usually caused by the sync rates and pixel clock used, and it's definitly not uncommon to have to adjust.

--Jeff

Jeko · Post by **Jeko** » Thu Oct 05, 2006 9:15 am

carbonBased wrote: Oh... I originally misread. Gaf's right, just move the image over via you're monitor's correction keys.

I already try this. Unfortunately it not works! If only it were so easy!

Dex · Post by **Dex** » Thu Oct 05, 2006 10:14 am

Here's something to check:
1. Do you hard code screen width or do you use "BytesPerScanLine" ?, as they are not always the same, if so use "BytesPerScanLine".
2. Are your gdt 0 based ?, if not these could be added to offset.
3. Are you multiplying by the bpp, eg: 3 for 24bit and 4 for 32bits ?.
4. Do you live on the side of a hill ?.

Jeko · Post by **Jeko** » Thu Oct 05, 2006 10:26 am

1 Yes
2 I don't understand
3 Yes
4 No!

Jeko · Post by **Jeko** » Fri Oct 06, 2006 8:08 am

I solved the problem

Dex · Post by **Dex** » Fri Oct 06, 2006 9:45 am

MarkOS wrote:I solved the problem

You should put what it was, so others with same problem can try it.

Jeko · Post by **Jeko** » Mon Oct 09, 2006 7:20 am

It's a stupid thing! I can't write to the text video memory.