p_ArcTan:
    .db __ArcTanEnd-1-$
    ex  de,hl       ;de = y
    pop hl
    ex  (sp),hl     ;hl = x
    push    hl
    ld  a,h     ;Get pairity
    xor d
    jp  m,__ArcTanSS-p_ArcTan-1
    add hl,de       ; |
    jr  __ArcTanDS  ; |
__ArcTanSS:         ; |hl = x +- y
    sbc hl,de       ; |
__ArcTanDS:         ;/
    ex  de,hl       ;de = x +- y
    ld  b,6     ;\
__ArcTan64:         ; |
    add hl,hl       ; |hl = 64y
    djnz    __ArcTan64  ;/
    call    $3F00+sub_SDiv  ;hl = 64y/(x +- y)
x_ArcTanEntry2:
    pop af      ;\
    rla         ; |Right side, fine
    ret nc      ;/
    sbc a,a     ;\
    sub h       ; |Reverse sign extend
    ld  h,a     ;/
    ld  a,l     ;\
    add a,128       ; |Add or sub 128
    ld  l,a     ;/
    ret
__ArcTanEnd: