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Old 02 June 2019, 16:23   #1
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Join Date: Jun 2017
Location: Paris
Posts: 51
Puzzling: Blitter line drawing faster on second execution

Hi guys,

A most puzzling problem to me, that you surely will solve in a blink.

Here is the code of a little program that just draws 20 times the same line with the Blitter in a loop.

But first, run WinUAE. Use a standard A500 1.3 512Kb Chip / 512Kb Fast configuration and boot the ADF. By standard, I mean a perfect emulation. When the prompt appears, type "desireONE" and press Enter. Watch the red part and the number in the bottom left : 139. Press the mouse button to exit the program, and type "desireONE" and press Enter again. The red part is smaller and the number reads 116.

So the problem is: why does the program run faster the second time (and times forward)?

The ZIP includes the code.

Notice that the problem won't occur if you assemble in ASM-One. You have to run the program from the disk to notice it.

Thanks for your help!
Attached Files
File Type: zip (318.5 KB, 20 views)
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