HOW TO: Fix Hot/Cold Bonus Bug [SNES]

[McMarkis]

 

Problem:
There is a bug in the SNES code responsible for calculating the Hot/Cold Bonus for every player attribute (Speed, Agility, etc.).
As a result, no attribute receives a negative bonus; instead, the attribute is consistently given the maximum boost (15) if the bonus was negative.
An unsigned division error caused the bug, the details can be found here.

Solution:
Fix the division error if the Boost is negative, preventing the Max Boost from being applied. This limits the Boost from (-3 to +3) per attribute as intended.

Technical Details:
We convert the negative number to positive for the division, then revert it to negative and apply the bonus. If the number was already positive, no changes are required.

New Code:


Special thanks to @chaos for helping with the assembly and providing GENS documentation on player attributes, bonuses etc.

Patch:

Download the patch tool to create your own ROM or patch an existing ROM.

Hex Version:

1) Replace old hex value with new hex value.

===========================
Headerless ROM (.SFC)
===========================
  ROM Offsets: (hex) FD224
  Old: B9 12 1A 4A 4A
  New: 20 32 FB EA EA

  ROM Offsets: (hex) FFB32
  Old: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
  New: B9 12 1A 10 09 49 FF 1A 4A 4A 49 FF 1A 60 4A 4A 60

===========================
Headered ROM (.SMC)
===========================
  ROM Offsets: (hex) FD434
  Old: B9 12 1A 4A 4A
  New: 20 32 FB EA EA

  ROM Offsets: (hex) FFD32
  Old: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
  New: B9 12 1A 10 09 49 FF 1A 4A 4A 49 FF 1A 60 4A 4A 60

NHL '94 (USA)_Hot_Cold_Patched.zip

Edited August 30, 2024 by McMarkis

[kidswasted]

I’ve only played one game so far but definitely notice Bure breaking away from the rest on a breakaway. This is amazing work!