CHIP8 thread - Page 23

omegadox · July 8th, 2011, 23:20

I want to make a test unit some day:

- Test Math results / Binary Coded Decimal
- Test 0xF Flag on AND, OR, XOR, ADD, SUB, Collision
- Test syscalls
- Test Save/Load RPL flags
- Test Call / Jump
- Test for Vertical Wrap hack (Blitz was created on machines that didn't support vertical wrap)
- Test for normal wrapping
- Test fonts
- Super Chip8 tests
- maybe mega chip tests?

Note about hybrid games: They are special chip8 programs containing native runtime code. Some are really whole native programs that doesn't use the chip8 interpreter at all (I wouldn't call them chip8 programs or hybrid :P). The normal [real] hybrids just use syscalls to call native CDP1802 code inside the rom itself which help chip8 games access any part of memory such as the video buffer, chip8 registers, stack memory, chip8 interpreter work memory. Also can read the cdp1802 register for some info such as pointers, PCs, and interrupt info. I also think its illegal in chip8 programming to have programs call code outside the rom such as interpreter code or the HW rom.

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BestCoder · July 16th, 2011, 22:47

The link to my testrom has been changed. The readme file is more complete now.
http://forums.ngemu.com/attachment.p...5&d=1309812602

I'll post my Chip8/SuperChip8 emu later.

Last edited by BestCoder; July 26th, 2011 at 18:52..

xampf · September 10th, 2011, 18:40

thanks for that great testroom helped me quite a lot

Merci beacoup keep your good work up !

Edit: finished my Chip-8 Emulator now, its entierly written in Java.
Could upload it if someones is interested

Last edited by xampf; September 11th, 2011 at 00:18..

BestCoder · September 11th, 2011, 16:53

You're welcome.

nondescript · May 23rd, 2012, 23:58

hi guys,

I am following cowgod's chip 8 documentation to code up my emulator in java and i am having problem understanding the following instruction

8xy6 - SHR Vx {, Vy}
Set Vx = Vx SHR 1.

If the least-significant bit of Vx is 1, then VF is set to 1, otherwise 0. Then Vx is divided by 2.

It says to shift by 1, if so, what is the use of y in the instruction 8xy6. Can anyone clarify that for me? Appreciate your help!

**refraction** · May 25th, 2012, 16:10

there is no use for the Y, just ignore it

It's probably just in there for opcode format purposes.

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Dont PM me for help, use the forums, thats what its for!

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nondescript · May 25th, 2012, 19:06

Thanks! refraction,

I have another question. I am implementing the draw function. According to the specs, when writing new pixels the pixels are xored. That would mean if in a position there is a pixel written and if i write 0 then the pixel wont get cleared. Is that correct? I was assuming the sprite bits in the memory is what will be written in the screen.

tykel · May 26th, 2012, 12:06

Yeah: (old ^ new = ...)
0 ^ 0 = 0
1 ^ 1 = 0
1 ^ 0 = 1
0 ^ 1 = 1

So basically, two set pixels cancel each other out.

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mash16 (chip16 emulator) img16 (chip16 sprite converter)
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Stefonzo · June 14th, 2012, 23:14

Hello I'm new here and have been recently working on programming a chip-8 emulator in c++. I have split the code into three parts, chip8.h, chip8.cpp, and main.cpp. I have finished chip8.h and am working on chip8.cpp however have one question:
What memory location is 'NN' or 'NNN' referring to? Sorry if this is in the wrong section.

Thanks
Stefonzo

**refraction** · June 15th, 2012, 00:10

Quote:

Originally Posted by Stefonzo

Hello I'm new here and have been recently working on programming a chip-8 emulator in c++. I have split the code into three parts, chip8.h, chip8.cpp, and main.cpp. I have finished chip8.h and am working on chip8.cpp however have one question:
What memory location is 'NN' or 'NNN' referring to? Sorry if this is in the wrong section.

Thanks
Stefonzo

NN literally refers to 2 numbers and 3 for NNN. So NN can be any number from 0x00 up to 0xFF and NNN can be anything from 0x000 up to 0xFFF

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Dont PM me for help, use the forums, thats what its for!

My Chip16 Emulator RefChip16 http://code.google.com/p/refchip16/

Prads · June 19th, 2012, 04:32

Just wanted post my dynarec chip8 emulator that I wrote in the past. Thought it might be helpful for people who wants to learn how write a dynarec cpu. I created this just for learning purpose, to teach myself about dynarec so the code isn't perfect.

And no input and sound emulation, so it just shows the first screen. :P
Link: http://www.pradsprojects.com/downloa...8%20dynarec.7z

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xampf · June 19th, 2012, 12:34

I didnt look into it yet, but does it handle self-modifying code? And how did you assign the registers?
And it would be great if you would post it also over at emutalk, it looks very promising!

Prads · June 19th, 2012, 14:59

Quote:

Originally Posted by xampf

I didnt look into it yet, but does it handle self-modifying code? And how did you assign the registers?
And it would be great if you would post it also over at emutalk, it looks very promising!

Nah it doesn't handle self modifying codes. I didn't want to make the code too complicated that it would scare people away. lol :P

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Last edited by Prads; June 19th, 2012 at 15:06..

**refraction** · June 19th, 2012, 23:31

Quote:

Originally Posted by Prads

Nah it doesn't handle self modifying codes. I didn't want to make the code too complicated that it would scare people away. lol :P

It doesn't make it too much more complicated. In the recompiling code area, keep an array of memory and when you "read" a bit of memory for the opcode, write to this second array the block start address of that recompiled code, then when you do a write to memory, you can check that array to see if it has a value (you can even have a .isRecd bool on it if you want just incase 0 is the address written to :P) and if it has an address, clear that address in the recompiler cache so it needs to be recompiled.

its more complicated to explain than implement >.< lol. This is what i did on my chip16 emu anyways

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Dont PM me for help, use the forums, thats what its for!

My Chip16 Emulator RefChip16 http://code.google.com/p/refchip16/

Prads · June 20th, 2012, 01:06

Quote:

Originally Posted by refraction

It doesn't make it too much more complicated. In the recompiling code area, keep an array of memory and when you "read" a bit of memory for the opcode, write to this second array the block start address of that recompiled code, then when you do a write to memory, you can check that array to see if it has a value (you can even have a .isRecd bool on it if you want just incase 0 is the address written to :P) and if it has an address, clear that address in the recompiler cache so it needs to be recompiled.

its more complicated to explain than implement >.< lol. This is what i did on my chip16 emu anyways

Yeah that makes sense. I can use that in my current emu project. Thanks!

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KrossX · September 18th, 2012, 23:35

Because I had to give it a try too mostly to learn about video and sound output...
After quite some work, then after a ton of more work to actually get some pictures I got this!

Just to see I was reading the sprite bytes wrong and how it hangs right there...

Now that looks more decent.
Also, it requires a D3D11 GPU.

#EDIT: Ooops, forgot... timers.

#EDIT2: Yay! With a thousand FPS points!

#EDIT3: Superrrr!

__________________

Last edited by KrossX; September 26th, 2012 at 08:41..

KrossX · September 28th, 2012, 21:59

Question! I gotta go, so I'll post this before that. I still haven't read the entire thread though, sorry if this has been answered.

I was checking this demo/test...

I previously simply scaled whether super8 stuff was enabled or not. If enabled, display works like at 128x64 otherwise 64x32. Buuuut! This demo calls 0x00FE on startup and at the end scrolls down 1. But, the scrolling function works at 128x64 even with Super8 disabled. It also let me know that n=0 with Super8 disabled is still a big sprite (8x16).

So ma'question is, in the MegaChip, when this super/scroll functions are used, do they work at SuperChip resolution or MegaChip resolution?

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Hatorijr · September 29th, 2012, 14:24

been a while since i looked into megachip, last i looked there really was not nearly enough information available to emulate it, has that since changed?

**ShendoXT** · September 30th, 2012, 09:24

Um? What is Super8? You mean Super Chip?
And for MegaChip do you mean new extension (2007) or SuperChip?

There are three different virtual machines:
Chip8 (Original)
SuperChip (Extension)
MegaChip (Extension, but the author did not bother to release official emulator for 5 years, ignore it).

KrossX · September 30th, 2012, 10:20

My apologies for the terms used. When I used "super8" and "Super8" though I thought to refer to the SuperChip from the first post, I actually just refer to 0x00FE and 0x00FF of said SuperChip. When I mentioned MegaChip, I meant as the MEGAChip mentioned in the first post.

I'll refrain from making such confusing and silly questions, my apologies again.

__________________

May 23rd, 2012, 23:58	#445
nondescript Registered User Join Date: Dec 2011 Posts: 11	confusion over SHR instruction hi guys, I am following cowgod's chip 8 documentation to code up my emulator in java and i am having problem understanding the following instruction 8xy6 - SHR Vx {, Vy} Set Vx = Vx SHR 1. If the least-significant bit of Vx is 1, then VF is set to 1, otherwise 0. Then Vx is divided by 2. It says to shift by 1, if so, what is the use of y in the instruction 8xy6. Can anyone clarify that for me? Appreciate your help!

May 25th, 2012, 16:10	#446
refraction PCSX2 Coder $refraction's Avatar$ Join Date: Jan 2004 Location: Plymouth, UK Posts: 10,037	there is no use for the Y, just ignore it It's probably just in there for opcode format purposes. __________________ http://www.pcsx2.net Intel i7 920 @ 3.4Ghz, POV GTX 570 1.3Gb, 1.8Tb HD space, 6Gb OCZ Reaper PC3-14400 Triple Channel Dont PM me for help, use the forums, thats what its for! My Chip16 Emulator RefChip16 http://code.google.com/p/refchip16/
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July 8th, 2011, 23:20	#441
omegadox Code it the hard way :P Join Date: Jul 2008 Posts: 1,267	I want to make a test unit some day: - Test Math results / Binary Coded Decimal - Test 0xF Flag on AND, OR, XOR, ADD, SUB, Collision - Test syscalls - Test Save/Load RPL flags - Test Call / Jump - Test for Vertical Wrap hack (Blitz was created on machines that didn't support vertical wrap) - Test for normal wrapping - Test fonts - Super Chip8 tests - maybe mega chip tests? Note about hybrid games: They are special chip8 programs containing native runtime code. Some are really whole native programs that doesn't use the chip8 interpreter at all (I wouldn't call them chip8 programs or hybrid :P). The normal [real] hybrids just use syscalls to call native CDP1802 code inside the rom itself which help chip8 games access any part of memory such as the video buffer, chip8 registers, stack memory, chip8 interpreter work memory. Also can read the cdp1802 register for some info such as pointers, PCs, and interrupt info. I also think its illegal in chip8 programming to have programs call code outside the rom such as interpreter code or the HW rom. __________________ Current Projects Eimu - Chip8X Emulator Super64 - N64 Emulator Emulators are for learning, fun and success and not for demanding gamers and freeloaders. :: I love my Monarch girl ::

July 16th, 2011, 22:47	#442
BestCoder Registered User Join Date: Feb 2011 Posts: 40	The link to my testrom has been changed. The readme file is more complete now. http://forums.ngemu.com/attachment.p...5&d=1309812602 I'll post my Chip8/SuperChip8 emu later. Last edited by BestCoder; July 26th, 2011 at 18:52..

September 10th, 2011, 18:40	#443
xampf Registered User Join Date: Sep 2011 Location: swiss Posts: 4	thanks for that great testroom helped me quite a lot Merci beacoup keep your good work up ! Edit: finished my Chip-8 Emulator now, its entierly written in Java. Could upload it if someones is interested Last edited by xampf; September 11th, 2011 at 00:18..

September 11th, 2011, 16:53	#444
BestCoder Registered User Join Date: Feb 2011 Posts: 40	You're welcome.

May 25th, 2012, 19:06	#447
nondescript Registered User Join Date: Dec 2011 Posts: 11	Thanks! refraction, I have another question. I am implementing the draw function. According to the specs, when writing new pixels the pixels are xored. That would mean if in a position there is a pixel written and if i write 0 then the pixel wont get cleared. Is that correct? I was assuming the sprite bits in the memory is what will be written in the screen.

May 26th, 2012, 12:06	#448
tykel Sober coder Join Date: Aug 2010 Location: London, UK Posts: 433	Yeah: (old ^ new = ...) 0 ^ 0 = 0 1 ^ 1 = 0 1 ^ 0 = 1 0 ^ 1 = 1 So basically, two set pixels cancel each other out. __________________ tchip16 (chip16 assembler) Js16 (browser chip16 emulator) mash16 (chip16 emulator) img16 (chip16 sprite converter) ______________________________________ Desktop: i5 750 @ 3.6 Ghz, 4GB ram, GTX 570 OC \| Windows 7 Pro 64 Laptop: (Thinkpad) i5 430M, 4GB ram, Intel IGP \| Arch Linux, Windows 7 Pro 64

June 14th, 2012, 23:14	#449
Stefonzo Registered User Join Date: Jun 2012 Location: United States Posts: 2	Hello I'm new here and have been recently working on programming a chip-8 emulator in c++. I have split the code into three parts, chip8.h, chip8.cpp, and main.cpp. I have finished chip8.h and am working on chip8.cpp however have one question: What memory location is 'NN' or 'NNN' referring to? Sorry if this is in the wrong section. Thanks Stefonzo

June 19th, 2012, 04:32	#451
Prads Registered User Join Date: Sep 2011 Location: Australia Posts: 89	Just wanted post my dynarec chip8 emulator that I wrote in the past. Thought it might be helpful for people who wants to learn how write a dynarec cpu. I created this just for learning purpose, to teach myself about dynarec so the code isn't perfect. And no input and sound emulation, so it just shows the first screen. :P Link: http://www.pradsprojects.com/downloa...8%20dynarec.7z __________________ My Programming Projects: www.pradsprojects.com

June 19th, 2012, 12:34	#452
xampf Registered User Join Date: Sep 2011 Location: swiss Posts: 4	I didnt look into it yet, but does it handle self-modifying code? And how did you assign the registers? And it would be great if you would post it also over at emutalk, it looks very promising!

September 18th, 2012, 23:35	#456
KrossX クロッスエクス Join Date: Mar 2006 Location: Argentina Posts: 3,649	Because I had to give it a try too mostly to learn about video and sound output... After quite some work, then after a ton of more work to actually get some pictures I got this! Just to see I was reading the sprite bytes wrong and how it hangs right there... Now that looks more decent. Also, it requires a D3D11 GPU. #EDIT: Ooops, forgot... timers. #EDIT2: Yay! With a thousand FPS points! #EDIT3: Superrrr! __________________ Last edited by KrossX; September 26th, 2012 at 08:41..

September 28th, 2012, 21:59	#457
KrossX クロッスエクス Join Date: Mar 2006 Location: Argentina Posts: 3,649	Question! I gotta go, so I'll post this before that. I still haven't read the entire thread though, sorry if this has been answered. I was checking this demo/test... I previously simply scaled whether super8 stuff was enabled or not. If enabled, display works like at 128x64 otherwise 64x32. Buuuut! This demo calls 0x00FE on startup and at the end scrolls down 1. But, the scrolling function works at 128x64 even with Super8 disabled. It also let me know that n=0 with Super8 disabled is still a big sprite (8x16). So ma'question is, in the MegaChip, when this super/scroll functions are used, do they work at SuperChip resolution or MegaChip resolution? __________________

September 29th, 2012, 14:24	#458
Hatorijr Emu Author Join Date: Dec 2004 Location: North Carolina Posts: 599	been a while since i looked into megachip, last i looked there really was not nearly enough information available to emulate it, has that since changed?

September 30th, 2012, 09:24	#459
ShendoXT Moderator Join Date: Feb 2006 Location: Croatia Posts: 4,550	Um? What is Super8? You mean Super Chip? And for MegaChip do you mean new extension (2007) or SuperChip? There are three different virtual machines: Chip8 (Original) SuperChip (Extension) MegaChip (Extension, but the author did not bother to release official emulator for 5 years, ignore it). __________________ Shendo's software blog Core i5 2400 3.1 Ghz \| ASRock H67M \| GTX460 768Mb \| 8GB DDR3 1333 \| 1500 Gb HDD Grundig VLC 7121 C (1080p) 32" \| Razer DeathAdder \| Logitech G110 \| Windows 7 x64 Don't PM or ask me about VMP-MCR conversions. I will ignore you if you do.

September 30th, 2012, 10:20	#460
KrossX クロッスエクス Join Date: Mar 2006 Location: Argentina Posts: 3,649	My apologies for the terms used. When I used "super8" and "Super8" though I thought to refer to the SuperChip from the first post, I actually just refer to 0x00FE and 0x00FF of said SuperChip. When I mentioned MegaChip, I meant as the MEGAChip mentioned in the first post. I'll refrain from making such confusing and silly questions, my apologies again. __________________