finit                ; Initialize the FPU.
  fldpi                ; Load pi into st(0).
  pushd 180
  fild DWORD PTR [esp] ; Load 180 into st(0).  Pi is now st(1).
  fdiv                 ; Divide pi by 180, store result in st(0).
  fld oldFovValue      ; Load the old FOV into st(0).  Move the divided result into st(1).
  fmul                 ; Multiply the old FOV value by st(1) and store it in st(0).
  pushd 2
  fild DWORD PTR [esp]
  fdiv
  fptan
  fstp st
  fild aspect1
  fild aspect2
  fdiv
  fmul
  fld1
  fpatan
  pushd 2
  fild DWORD PTR [esp]
  fmul
  pushd 180
  fild DWORD PTR [esp]
  fldpi
  fdiv
  fmul
  fstp newFovValue
  add esp,16