SpritesMind.Net

Hi, I've been looking at the documents suggested in the "Best practices for writing C on 68000?" thread and one thing that the docs don't talk about much is global variables. Are there any performance penalties with using them? Lots of my functions will be using them and I'm not sure that having glo...

Thanks Shiru, those suggestions helped a lot!

Scrolling is much, much smoother now, as you can see from my latest update:

http://www.youtube.com/watch?v=RWLPk1tap8M

*********** EDIT: January 4th, 2013 *************** A bit of unfortunate news. I'm stopping all development for this project. Art and videos will also be taken down. I wish and hope to revisit this project again, but won't be happening any time soon. Thanks for watching, DJCC. *********** Hi, The f...

Hi,

Just wanted to let you guys know I tried out your suggestions and it's definitely helped. The benchmark numbers for that routine has dropped to 13045, a pretty dramatic improvement!.

Thanks again for your help!
DJCC

Isn't GCC optimizer is smart enough to detect that the value is never used so it does not even try to calculate it, i.e. your u16 tileNumber ... line does not execute at all when you comment out its use? Yeah. I realized that the compiler was stripping that out right after posting. Should've though...

I played around some more with the code, following the pseudocode I wrote earlier. It definitely helps with performance. Again, running 1000 times, the benchmark number drops to around 42240 ticks. But by accident I discovered something weird. So I'm caching the tile flag like this: u16 tileAttr = T...

Stef wrote: By the way, can't you use the following method ?

Code: Select all

void VDP_setTileMapRect(u16 plan, const u16 *data, u16 index, u16 flags, u16 x, u16 y, u16 w, u16 h);

I probably could. I didn't think of it at the time. I'll try it out later today.

auto increment register does wonders How would I use that, like this? // pseudocode-ish code ahead. // pre-loop setup plctrl = (u32 *) GFX_CTRL_PORT; pwdata = (u16 *) GFX_DATA_PORT; addr = <some location in the plane I want to write to> *plctrl = GFX_WRITE_VRAM_ADDR(addr); // only calling this once...

In the last SGDK i replaced the GFX_WRITE_VRAM_ADDR macro : #define GFX_WRITE_VRAM_ADDR(adr) vramwrite_tab[adr] Yes, that's the version I have. It is noticeably faster than the version Shiru mentioned. Anyway as Shiru said, i think there is something wrong in your code... If thoe methods slow down ...

Hi, I've been using getTick()/getSubTick() as suggested in the Code Benchmarking techniques thread, running a thousand iterations and measuring the time it takes. For example, I've been benchmarking a loop that sets a column of tiles at the edge of the screen when the screen scrolls. One surprising ...

Maybe I spoke too soon. To get general idea of what my main loop performs like, I call getTick() at the beginning (starttime) and the end (endtime). But if I do a endtime - starttime I get zero. I also get zero if I use getSubTick(). But if I call getSubTick before and after some calls to VDP_setTil...

I'm calling getSubTick() before and after the code I'm trying to benchmark and I'm getting numbers! And when I optimize the code the numbers get smaller!

So it seems to be working for me. Thanks!

One idea I've got is to find the code I want to benchmark and set it to run a thousand or ten thousand times, and have something visible happen when it's done. Because it's looping many, many times, the amount of time it takes should be measurable with a stopwatch. Not the most friendly way, but it ...

Hi,

Are there any general discussion forums for the 68000 CPU? Somewhere I can post general CPU questions. I was hoping to find something similar to www.6502.org, which has a pretty active community.

Thanks!
DJCC

Let's say I want to benchmark a while loop in my main game loop. How would your suggested technique work? If I understand it, the color would change only for a fraction of a second, which would be hard to time manually.