1. Objective To modify the game code of Pokémon Fire Red (USA, Rev 1) so that any experience points (EXP) earned after a battle are automatically doubled before being added to a Pokémon’s total EXP.
Original bytes: 00 00 47 70 Patch to: 40 00 47 70 pokemon fire red exp multiplier x2
Go to ROM offset 0x023C1E (2 bytes before the return). Change: before the function returns
At the end of the EXP calculation, before the function returns, we insert a left-shift (multiplication by 2) of the value in r0 . doubling stays within 32-bit).
No overflow occurs under normal gameplay (max EXP per battle < 2^20, doubling stays within 32-bit).