Search found 968 matches

by nymus
Wed Dec 20, 2023 9:42 am
Forum: Programming Discussion
Topic: Timer precision
Replies: 13
Views: 1495

Re: Timer precision

Is it not OK/faster to use the FPU for division and convert back to integer? I guess the #define method works if there are just a few common values being used.
by nymus
Mon Mar 13, 2023 9:35 am
Forum: Programming Discussion
Topic: How to define a variable at a specific memory location, and whether it's cached or not
Replies: 9
Views: 916

Re: How to define a variable at a specific memory location, and whether it's cached or not

With careful management, you could theoretically access 4 banks of memory simultaneously with minimal performance penalty as each independent ram chip has a single sense amplifier that covers two 2048kb banks each. Would you mind clarifying this? I thought that regardless of the physical ram arrang...
by nymus
Sat Nov 27, 2021 3:13 pm
Forum: Gaming Forum
Topic: The Dreamcast turns 21 today!
Replies: 8
Views: 2389

Re: The Dreamcast turns 21 today!

Japanese launch date remembered! Still thinking...
by nymus
Thu Sep 09, 2021 8:09 pm
Forum: Gaming Forum
Topic: The Dreamcast turns 21 today!
Replies: 8
Views: 2389

Re: The Dreamcast turns 21 today!

Still Dreaming. Best wishes to all.
by nymus
Thu Sep 02, 2021 5:34 pm
Forum: Programming Discussion
Topic: GCC changing signdess whole expression
Replies: 2
Views: 685

Re: GCC changing signdess whole expression

I can confirm that gcc will only warn when it suspects overflow will occur, depending on optimization and warning levels. Using char as follows, gcc doesn't warn for '255' but does for '400' #include <stdio.h> unsigned char m_font_timer = 255; char Getsum(char p_top_left_x) { char l_sum = (((p_top_l...
by nymus
Wed Aug 25, 2021 8:25 am
Forum: Programming Discussion
Topic: GCC changing signdess whole expression
Replies: 2
Views: 685

Re: GCC changing signdess whole expression

Sorry this is a guess, but ill confirm later. It could be that: - you are not performing any comparisons, so even -wsign-compare won't warn, which exposes the potential reason as... - unsigned has a higher range of (positive) values than signed, so the intermediate ops based on a signed type would p...
by nymus
Fri Feb 12, 2021 9:49 am
Forum: Programming Discussion
Topic: Some questions about SH4 asm instruction
Replies: 7
Views: 1296

Re: Some questions about SH4 asm instruction

It is interesting to note that GNU as (gas) expects you to provide aligned/pre-calculated displacements, which is apparently different from the official assembler. I haven't used it but the examples in the SH4 programming manual show that the displacement in both source and binary is an index just l...
by nymus
Wed Sep 09, 2020 8:23 pm
Forum: Gaming Forum
Topic: The Dreamcast turns 21 today!
Replies: 8
Views: 2389

Re: The Dreamcast turns 21 today!

Happy Birthday Dreamcast! I have a lot fond memories and I will be playing it more frequently from now on. I really enjoyed watching video reviews and then seeing the games match what was shown. I've oiled my gd-rom so it's much quieter, but I still love hearing the drive squeak when it accepts a di...
by nymus
Sun Feb 23, 2020 3:06 pm
Forum: Programming Discussion
Topic: High Resolution Dreamcast Video Modes!
Replies: 14
Views: 29258

Re: High Resolution Dreamcast Video Modes!

I just wanted to post a better picture. The 1152x864 and 800x600 rendered correctly whereas the others I tried were just garbled like before. I gave up on trying to figure out the stretching/squishing algorithm because just writing pixels to the screen is a huge task for me. Not bad looking for a 40...
by nymus
Thu Feb 20, 2020 8:14 am
Forum: Programming Discussion
Topic: High Resolution Dreamcast Video Modes!
Replies: 14
Views: 29258

Re: High Resolution Dreamcast Video Modes!

That definitely doesn’t look right, though. It should look right if you multiply the horizontal axis of the image by the horizontal scale in the file (STARTUP_video_params.video_scale_multiplier holds that float), and then copy the image directly from RAM to the framebuffer. That’s the first test; ...
by nymus
Wed Feb 19, 2020 4:54 pm
Forum: Programming Discussion
Topic: High Resolution Dreamcast Video Modes!
Replies: 14
Views: 29258

Re: High Resolution Dreamcast Video Modes!

Exciting stuff! I went back and read the readme which was definitely easier to integrate than the way I had hacked it. The modes output correctly (I tried 800x600, 1024x768 and 720p) but I've been having trouble rendering using the pvr 3d pipeline because I'm not informed on the detailed workings of...
by nymus
Tue Feb 18, 2020 3:48 am
Forum: Programming Discussion
Topic: High Resolution Dreamcast Video Modes!
Replies: 14
Views: 29258

Re: High Resolution Dreamcast Video Modes!

BRILLIANT! Thanks. It always wondered why we couldn't output higher resolutions even though the GPU was based on a pc chip. So, you're saying that the 3D and 2D pipeline would be working optimally with a lower resolution but the ramdac would upscale the image? Maybe a photograph would help demonstra...
by nymus
Tue Jul 30, 2019 12:08 pm
Forum: Programming Discussion
Topic: Anybody available to help with dc-load-ip testing?
Replies: 21
Views: 4693

Re: Anybody available to help with dc-load-ip testing?

It's great that you are excited to get this working. Personally, I don't think re-dialing would be a big issue since the videos show it taking less than 5 seconds... I'd love to read your guides on Dreamcast gdb-over-bba though, just to get the hang of cross-platform debugging. I suppose I've never ...
by nymus
Wed Jun 12, 2019 2:41 am
Forum: Programming Discussion
Topic: unable to find a register to spill in class 'FP0_REGS'
Replies: 12
Views: 1004

Re: unable to find a register to spill in class 'FP0_REGS'

Please correct me if I'm wrong regarding gcc's SuperH status... I think some of these have been discussed in these forums before...

- SuperH support was dropped some time ago?
- SuperH's lack of atomic operations limits the extent to which C++11 and above can be supported?
by nymus
Sun Mar 17, 2019 10:53 am
Forum: Off-Topic Forum
Topic: A sincere apology from Ian Micheal
Replies: 13
Views: 3461

Re: A sincere apology from Ian Micheal

Hah! I just saw your name in the programming forums and it made me smile to see you back after all this time. I've also taken a walk down my own memory lane and know there are things I wish I could have done differently. Don't feel bad. We've somehow made it this far and if there's anything I specif...
by nymus
Tue Sep 11, 2018 8:01 am
Forum: Programming Discussion
Topic: KOS - static initialisation failure: __gnu_cxx::__concurrence_lock_error
Replies: 17
Views: 2753

Re: KOS - static initialisation failure: __gnu_cxx::__concurrence_lock_error

That looks like an optimization by the compiler. The data is const and initialized so it can simply use the addressed value at compile time.

I think one would use extern or volatile to let the compiler know that the data is persistent.
by nymus
Sun Sep 09, 2018 2:33 pm
Forum: Games and Software Hacking, Prototypes, and Devkits Discussion
Topic: Happy Birthday Dreamcast!
Replies: 0
Views: 2534

Happy Birthday Dreamcast!

It's still thinking... I'm happy to say that my nieces enjoy playing our beloved console.

Next year will be 9/9/19...

All the best to everyone.