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Rework blitter functions arguments #185

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tehKaiN opened this issue Mar 4, 2023 · 3 comments
Open

Rework blitter functions arguments #185

tehKaiN opened this issue Mar 4, 2023 · 3 comments

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@tehKaiN
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tehKaiN commented Mar 4, 2023

Currently, blitCopy() etc require something like 10 args, passing which is a bad idea performance-wise.

It could be replace by passing an arg struct. Instead of

blitCopy(s_pBgSub, 0, 0, s_pBfr->pBack, 0, 0, 320, 128, MINTERM_COPY);
blitCopy(s_pBgSub, 0, 128, s_pBfr->pBack, 0, 128, 320, 128, MINTERM_COPY);

It would be something like

tBlitCopyArgs sArgs = {s_pBgSub, 0, 0, s_pBfr->pBack, 0, 0, 320, 128, MINTERM_COPY};
blitCopyPredefined(&sArgs);
sArgs.uwSrcY = 128;
sArgs.uwDstY = 128;
blitCopyPredefined(&sArgs);

Pros:

  • less stdcall overhead
  • ability to cache repetitive blits

Cons:

  • a bit less readable syntax (completely optional if old functions stay as is)
  • no compile-time checks if all struct fields have been set - especially dangerous if additional field will be added in future. Could be resolved by
@Vairn
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Vairn commented Jun 6, 2023

seems like a good idea, you can do some easy batch rendereing with only changing two values, especially with my wall rendering calls blitcopymask 2000* odd times a frame.

might be an little exaggerated

@steamknight
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If we pass a structure, there will be a pointer dereference for each original parameter inside the blit call. I'm curious if that will still be faster than passing in 10 arguments to the function or if the compiler can optimize the extra dereference away.

@tehKaiN
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tehKaiN commented Jun 7, 2023

Definitely needs benchmarking!

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