CHIP8 thread

[Chrono Archangel]

Originally Posted by runawayprisoner

Looking good. Do Super Chip games work?

Nope, too lazy
I hadn't touched my chip8 emu in like 6 months... and decided to fix these last week. Probably gonna be like that with SChip8 too XD

I have no way of doing proper input emulation with the platform im using... (at least so far i cant, theres no specific ways of catching keydowns and keyups seperatly)

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[runawayprisoner]

Ah... there's a problem. Maybe you can try an on-screen keypad that works with a mouse... or make a toggle down/toggle up keypad instead of a down then up keypad. Well, just to test if the games work right or not.

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[Chrono Archangel]

Originally Posted by runawayprisoner

Ah... there's a problem. Maybe you can try an on-screen keypad that works with a mouse... or make a toggle down/toggle up keypad instead of a down then up keypad. Well, just to test if the games work right or not.

Yeah, for testing purposes i did so that when a key is pressed it just stays "pressed"... so i can toggle up/down constantly for the paddle in pong for example. I might be able to use WinAPI instead... ill take a look eventually.

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[runawayprisoner]

*chant Java 1000 times* It's nice when you have everything built-in and uniform across platforms, ei?

That reminds me. I wonder if I should move my arse to complete that Chip-8/Super Chip documentation I'd been working on. Thing is... I don't think it offers more than what other documents do. If anything, maybe I'll go more into the technique and the actual implementation of the pseudo ideas rather than providing a table.

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[Dax]

Quick update: I've got 13 instructions so far: JP, CALL, RET, and the 10 LD functions. HUGE thanks to Hatori for guiding me quite a bit through this process. Also thanks to Shendo, RunawayPrisoner, and anyone else who I missed.

Edit: I have everything except DRW now, as well as correct input[no input in a DOS window]. Just gotta hook it up to a SDL/OGL window to see if it works.

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Last edited by Dax; March 19th, 2009 at 03:29..

[Dax]

I need some help with fetching opcodes. For some reason, my emulator reads the first 4 opcodes of Pong fine, but the fifth is seen as FFEA, when it should be A2EA.

Here's how I fetch opcodes:

regs.OP = (unsigned short)( (RAM[regs.PC] << 8) | RAM[regs.PC + 1] );

Here's how I do the classic case/switch statement:

switch( ((regs.OP & 0xF000) >> 12) )

The emu loads the ROM fine, and in RAM, the contents are correct. So it's not a loading issue.

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[Dax]

Well I figured out the opcode bug. I had to switch to unsigned chars, from regular chars. Now my emu has graphics(I also had to check for != 0 in the DRW function)!!! Glitched, but I don't care at the moment!!

First pic: Pong
Second: Blitz

Compatibility list:
Pong: "Title", never crashes. No input yet, so can't play.
Blitz: "Title", crashes a few seconds after emulation begins.

Attached Images

	WOOOOOOOT.png (40.7 KB, 14 views)
	blitz.png (35.7 KB, 12 views)

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Last edited by Dax; March 26th, 2009 at 09:39..

[Chrono Archangel]

w00t w00t. first bits of graphics are always fun to see

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[Phil]

I bet when the first Sony sign showed up on PCSX2, CK and Ref, Saquib, Zerofrog and the rest all held hands together and cried lol

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[Dax]

Originally Posted by Chrono Archangel

w00t w00t. first bits of graphics are always fun to see

Indeed. You had no idea how happy I was. I've been working on this like a week straight, at the least.

Originally Posted by Phil

I bet when the first Sony sign showed up on PCSX2, CK and Ref, Saquib, Zerofrog and the rest all held hands together and cried lol

Probably.

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[strike105x]

Keep it up
GL with the rest of the project

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[Dax]

Thanks. I hope to finish it maybe this weekend, assuming there are no huge problems left in the code..

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[Dax]

Updated the first post with useful docs/sites/forum threads. Hopefully that'll help anyone else who decides to start their own emu.

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[cottonvibes]

Originally Posted by Dax

Well I figured out the opcode bug. I had to switch to unsigned chars, from regular chars. Now my emu has graphics(I also had to check for != 0 in the DRW function)!!! Glitched, but I don't care at the moment!!

on my nes emu I have this code in a header called 'types.h':

#pragma once

typedef unsigned char  u8,	byte;
typedef unsigned short u16,	ushort;
typedef unsigned int   u32,	uint, uptr;

typedef signed char  s8;
typedef signed short s16;
typedef signed int   s32, sptr;

typedef void*	HANDLE;

its alot nicer doing something like

a = (u8)(b - c);

instead of

a = (unsigned char)(b - c);

Originally Posted by Phil

I bet when the first Sony sign showed up on PCSX2, CK and Ref, Saqib, Zerofrog and the rest all held hands together and cried lol

i think they all joined the team after that (except for Saqib)
i think ref and zerofrog joined sometime in 2005~2006, and pcsx2 was started like in ~2002 or something.
most-likely they got 'something' to show up in those 3 years, it was probably just really slow xD

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[Dax]

I did something similar in my c8 header by defining bytes and words as unsigned chars and unsigned shorts, but thanks. :3

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[Dax]

Blitz now shows B, and never crashes, and pong occasionally shows a zero[in addition to the balls and the paddle, drawn in the wrong spots], which then disappears quickly. I'm still trying to figure out why.

Attached Images

blitz2.png (47.1 KB, 14 views)

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[runawayprisoner]

Originally Posted by Dax

Blitz now shows B, and never crashes, and pong occasionally shows a zero[in addition to the balls and the paddle, drawn in the wrong spots], which then disappears quickly. I'm still trying to figure out why.

Amen... if you trace out the right coordinates for those, then you should start choppin' the draw opcode. It's the culprit for 110% of any kind of weird output.

Oh, and more important than that: check your flag!

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[Dax]

I've been taking a short break, as I was burnt out on debugging pong line by line for hours.

Today I think I'll audit the code to make sure each opcode matches the docs.

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Last edited by Dax; March 31st, 2009 at 13:18.. Reason: Stupid double post, even though I only hit it ONCE.

[jaskt7]

Okay, since I finished my chip8 emulator in flash I got a little bored and curious. So I decided to make a program that will decompile chip8 games (not all) and convert it into pure action script. So, if you have adobe flash, you can test this if you like.

The link is http://babbage.cs.missouri.edu/~jask...p8/convert.php

There is instructions on the page on how to use it, it should be self-explanatory.

Tell me what you think of it.

~justin

[Dax]

Pong now has perfect ingame graphics[chip8 flickers, so the right paddle was gone at the time of the screen]:

Attached Images

omfg.png (50.1 KB, 9 views)

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