News: 11 March 2016 - Forum Rules
Current Moderators - DarkSol, KingMike, MathOnNapkins, Azkadellia, Danke

Author Topic: Hacking SMW  (Read 1497 times)

matalog

  • Jr. Member
  • **
  • Posts: 35
    • View Profile
Hacking SMW
« on: April 09, 2016, 09:57:15 am »
I have been trying to apply a hack to Super Mario World (U)!  This hack - http://www.romhacking.net/hacks/2242/

I have cleaned the ROM first and it adds the required header, but when I read the MD5 or CRC32 checksums when it is hacked, they don't equal the figures on the linked page.

SNES9x says the checksum is okay, but I would rather not have errors down the line.

Does any one know if there is a definite "Super Mario World (USA) (NOINTRO)"  ROM somewhere, that maybe I would have better luck with the checksums?

I have tried this on 2 different SMWU! roms and both checksum okay in SNES9x and none of the checksums are the same as the linked page.

Thanks for any help,

Matt.

Nightcrawler

  • Hero Member
  • *****
  • Posts: 5768
    • View Profile
    • Nightcrawler's Translation Corporation
Re: Hacking SMW
« Reply #1 on: April 09, 2016, 10:23:26 am »
The checksum being reported from SNES9x is the internal ROM checksum. This is an entirely DIFFERENT entity from the target ROM file hash (MD5/CRC32) reported on the hack's page. Secondly, the hashes being reported on the hacks page are for the ORIGINAL ROM that the patch is for (without the header). It is NOT the hash for the resulting patched ROM.

In summary, to match the ROM info, check the original ROM without a header and they should match.

The internal checksum reported from SNES9x is internal ROM data that hack authors may or may not choose to update. So, it is possible for it to be reported as bad, but you still have a correctly patched ROM. Because the internal checksum is an unreliable indication is why the community uses target file hashes instead.

In your case, the patch author did updated the internal checksum data from the original ROM for an extra layer of confidence (many do not bother) and it does report as good.  So, your ROM is likely patched correctly! :) This may seem a little confusing at first, but walk through it and you'll get it.
TransCorp - Over 20 years of community dedication.
Dual Orb 2, Wozz, Emerald Dragon, Tenshi No Uta, Glory of Heracles IV SFC/SNES Translations

matalog

  • Jr. Member
  • **
  • Posts: 35
    • View Profile
Re: Hacking SMW
« Reply #2 on: April 09, 2016, 10:56:59 am »
Nightcrawler, you put it so simply, it makes perfect sense first time!

And you're absolutely correct.  Thanks for taking the time to reply :-)

vortex

  • Jr. Member
  • **
  • Posts: 60
    • View Profile
Re: Hacking SMW
« Reply #3 on: April 10, 2016, 11:28:44 am »
This particular SMW hack needs a standard original Super Mario World ROM with the header. This rom is widely know as base for patching.

To cacluate the CRC-32 you will need this program (Hasher)
http://www.romhacking.net/utilities/1002/

Once you load your original rom in this program, it must say Header= Yes and the CRC number provided in the ROM/ISO info must match with this one. If you patch this original rom with the provided IPS, it will produce a correctly patched hacked rom.

The internal checksum is something else - just 2 bytes. These 2 bytes corespond to the hack, not original rom and if you edit the rom, these two bytes must be changed accordingly - the author of the hack even bothered to fix this redundant info - thus snes9x will give you checksum= ok. But even on checksum bad, the game would be ok.