how fast are my blits?

Blitting a 5 bitplane 64x64 rectangle with the cookie cut function (4 active DMA channels) probably isn't going to be very fast.

How fast is it ?

I added a feature to imagecon to generate a greyscale version of the palette.

Then in the main loop I now:

wait for the vertical blank
set the greyscale palette
do 4 blits
set the color palette

.mainLoop: bsr waitVerticalBlank bsr installGreyscalePalette move.l #4,d0 ; blit the object 4 times each frame .blitLoop: bsr moveBlitterObject dbra d0,.blitLoop bsr.s installColorPalette bra.s .mainLoop


So when the screen changes to color, that's how many scan lines we have used blitting stuff.

The `NUM_COLORS` variable in the [Makefile](Makefile) sets the number of colors. This automatically creates the correct bitplane and palette data as well as reconfiguring the example code. So now we can see what impact the number of bitplanes has on blit speed:

5 bitplanes
-----------
![5 bitplanes](5bitplanes-screenshot.png?raw=true)

At 5 bitplanes we don't have enough time to do 5 blits.

4 bitplanes
-----------
![4 bitplanes](4bitplanes-screenshot.png?raw=true)

3 bitplanes
-----------
![3 bitplanes](3bitplanes-screenshot.png?raw=true)

2 bitplanes
-----------
![5 bitplanes](2bitplanes-screenshot.png?raw=true)

1 bitplanes
-----------
![5 bitplanes](1bitplanes-screenshot.png?raw=true)

Lots of time left over with 1 bitplane :-D

[Download disk image](bin/blit_speed.adf?raw=true)

1.5 KiB Raw Blame History

how fast are my blits?

1.5 KiB

Raw Blame History