PCI-Express Source Code + Questions about fast drawing

[Jeko]

I need some source code about PCI-Express. Have you anything?

I change the video mode to 800x600x32 bits, but if I use 800x600x16 bits is it very faster?

In your opinion (for performance) is better 32 bits, 16 bits or 8 bits?
I think 8 bits, but I think its quality is too much low.
I need also some informations about drawing optimizations.
Sorry for the bad english and thank you for all!

[turtling]

My laptop is more than 2 times faster in 16 bits than 32 bits. It's a radeon xpress 200m. I think the problem has to do with the low clock frequency ( 333mhz) and that the card is shared memory with the main board.
If it's dedicated vram, 32 bits or 16 bits shouldn't make a big difference probably? But it sure do in a shared memory environment.

[Combuster]

the main problem is that of bandwidth: writing the same amount of pixels in 32 bit mode costs twice the amount of memory bandwidth as 16 bits (and 4x that of 8 bits).

On the other hand, doing calculations on packed 16-bit colors is more processor-intensive because it does not match a native processor data type, whereas 32-bit colors fit nicely into multimedia registers. What makes you suffer most depends on how you do things, but in general using 16 bit colors is less than 2x as fast as 32-bit modes.

If you want performance, use hardware accelleration (intels & voodoo's will do)

[Jeko]

If you want performance, use hardware accelleration (intels & voodoo's will do)

For this I need to write a lot of drivers.
I want to optimize performance with functions that works on the framebuffer.