Search found 495 matches

by Miquel
Wed Jul 08, 2020 1:51 pm
Forum: Mega/SegaCD
Topic: mcd-verificator (CD core accuracy tests)
Replies: 6
Views: 269

Re: mcd-verificator (CD core accuracy tests)

Hi KRIKzz, curiosity just spike up a lot with you messages, what is your project about? Perhaps a MegaCD/SegaCD in a FPGA? Just curious...
by Miquel
Thu May 14, 2020 1:32 pm
Forum: Megadrive/Genesis
Topic: VDP 8x16 Interlace Mode
Replies: 7
Views: 853

Re: VDP 8x16 Interlace Mode

Also:
Working on 1:2 resolution is weird for graphical artist, or anyone else, I have never seen do it. Pixels are not square any more.
Doubled resolution is done by interlacing images (on different lines), not sure of the result quality on 90’s phosphor tv’s.
by Miquel
Tue May 12, 2020 10:35 am
Forum: Megadrive/Genesis
Topic: VDP 8x16 Interlace Mode
Replies: 7
Views: 853

Re: VDP 8x16 Interlace Mode

You need twice the memory for tiles, backgrounds and sprites alike, and there is no much to start with if you use all the others planes. So it’s a case between resolutions vs diversity, where variety is already somewhat scarce. On lots of design questions memory is the underlying factor, today as ev...
by Miquel
Thu Apr 30, 2020 9:21 pm
Forum: Megadrive/Genesis
Topic: Alternative to Vasm assembler?
Replies: 27
Views: 2651

Re: Alternative to Vasm assembler?

As far as I know that can’t be done: the problem is that symbols '/' and '-' are interpreted as division and minus.
by Miquel
Sat Apr 25, 2020 6:35 pm
Forum: Megadrive/Genesis
Topic: Alternative to Vasm assembler?
Replies: 27
Views: 2651

Re: Alternative to Vasm assembler?

Very true - the C preprocessor can be run on gas files (use .S instead of .s for automatically doing so). Pragmas and defines and stuff can be used. This does make a gas assembler specific file very flexible compared to more traditional assemblers. I didn't know! investigation about to lunch. Defin...
by Miquel
Thu Apr 23, 2020 4:25 pm
Forum: Megadrive/Genesis
Topic: Alternative to Vasm assembler?
Replies: 27
Views: 2651

Re: Alternative to Vasm assembler?

After doing asm on several platforms I have to recommend gcc/gas. Why? Because macros are quite powerful, not perfect, but good enough to make extend programing simpler than others. (I know I touched a sensitive point, waiting for massive angry replies… ;) ) And to be honest GAS is probably the wors...
by Miquel
Tue Mar 31, 2020 1:41 am
Forum: SGDK
Topic: Brainstorming a way to hscan colors in SGDK
Replies: 10
Views: 1080

Re: Brainstorming a way to hscan colors in SGDK

Set the exception to jump to ram, there jump again to the desired h-int routine, you can use an absolute word jump, then wrote your routine in asm. It’s important to only push/pop the registers you’re going to use if you are cpu constrained; also there is the user stack pointer (usp) so you can swap...
by Miquel
Fri Mar 27, 2020 11:12 pm
Forum: SGDK
Topic: A challenge with tiles..
Replies: 1
Views: 420

Re: A challenge with tiles..

Let’s first agree on what’s the situation: as I understand you have a map, a 2D matrix, where each element is a metatile of 5x5 tiles. Is that correct? Something like this: struct Tile { int indexOfTileOnVRAM; int colisionResponseIndex; }; struct Metatile { Tile tiles[ 5 ][ 5 ]; }; const Metatile me...
by Miquel
Tue Mar 24, 2020 11:53 pm
Forum: SGDK
Topic: The small-questions-not-worth-dedicated-topics topic
Replies: 5
Views: 1243

Re: The small-questions-not-worth-dedicated-topics topic

Here is my first one. I understand we use const to save data to the rom. But if I need to have a writable version of it in runtime, is there a proper way of doing things or do I just create a new variable and copy the values from a to b? Don't do that, you're making it worst. Use "const" for data t...
by Miquel
Wed Mar 04, 2020 6:15 pm
Forum: Hardware
Topic: Proper USB power mod for the Megadrive 2
Replies: 5
Views: 3068

Re: Proper USB power mod for the Megadrive 2

Usb requires to a least to power 500 mA, but there is no upper limit. But the point of this project, I think, is to reuse old usb chargers; I don’t see the scenario were data cables will be useful.
by Miquel
Mon Jan 06, 2020 3:22 pm
Forum: Megadrive/Genesis
Topic: General Gunstar Heroes rambling
Replies: 5
Views: 3266

Re: General Gunstar Heroes rambling

By dynamically loading I mean that, when the sprite changes, its tiles are loaded from rom to ram the previous frame, the space of vram that occupies the sprite is always the same. The idea is to have large animations for the main character, which is the most repetitive one, so can lead to visual sa...
by Miquel
Sat Jan 04, 2020 10:53 pm
Forum: Megadrive/Genesis
Topic: General Gunstar Heroes rambling
Replies: 5
Views: 3266

Re: General Gunstar Heroes rambling

The 'SEGA' animation at the start generates multiple scaled copes of the logo on the CPU on start-up and animates between them. The original unscaled SEGA logo appears to be the only uncompressed graphics in the rom. For some reason I just thought of it, the sprites of the two main characters/heroe...
by Miquel
Sat Jan 04, 2020 12:56 pm
Forum: Megadrive/Genesis
Topic: 68000 programming optimization tips? (for speed)
Replies: 28
Views: 12806

Re: 68000 programming optimization tips? (for speed)

The most stupid optimization, but useful since can be done in lot of occasions: move.b 0xA10001, d0 and.b #0xF , d0 Optimized: moveq.l #0xF, d0 and.b 0xA10001, d0 If you are going for bit operations probably can be done. Also clears the register which perhaps is what you need.
by Miquel
Wed Jan 01, 2020 12:50 pm
Forum: Megadrive/Genesis
Topic: General Gunstar Heroes rambling
Replies: 5
Views: 3266

Re: General Gunstar Heroes rambling

Palettes are defined independently as 16 uncompressed colours, then referenced in palette sets which are just pointers to 4 palettes to load at once. Makes sense that way, palettes can be loaded anytime. You can compress them do, there are unused bits, but bit manipulation is not cheap at cpu level...
by Miquel
Wed Dec 25, 2019 2:39 pm
Forum: Megadrive/Genesis
Topic: Shinobi arcade port
Replies: 3
Views: 2483

Re: Shinobi arcade port

Congratulations! Good job.