janwichelmann / aoeagepatchstandalone Goto Github PK

When playing the 'Defend the Wonder' game mode with the AgePatch installed and properly set-up, the game starts at the Dark Age, instead of post-renaissance.

While looking into this issue with scripter, we found out that this happens because, at the offsets 0x00429A3C, 0x00429C10 and 0x00429AC5, where the game is supposed to force post-renaissance start due to the fact that the 'Defend the Wonder' game mode is being played, the Post-Renaissance Age ID is pushed as a single byte, even though its value is greater than 127, which causes it to be stored as a signed negative 4-byte value in the stack. Thus, the code, when reading that argument from the stack at line 591 in AgePatch.cpp doesn't the positive value it expects.

A good way to solve that bug that doesn't require creating new codecaves just because of 3 extra bytes would be inserting this line:

movzx eax, al

Right after line 591 in AgePatch.cpp. This way, only the last byte of the argument in the stack will be read every time when this function is called.