Whoa, FixedDiv in PlayStation Doom is very different from vanilla Doom.
https://github.com/BodbDearg/PsyDoom/blob/master/game/Doom/Base/m_fixed.cpp
https://github.com/BodbDearg/PsyDoom/blob/master/game/Doom/Base/m_fixed.cpp
Comments
The PlayStation FixedDiv implementation doesn't use division and it doesn't use 64-bit math.