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;carwar.c:1365: lenSq = x*x + y*y; // get squared length
    ld    l,4 (ix)
    ld    h,5 (ix)
    push    hl
    ld    l,4 (ix)
    ld    h,5 (ix)
    push    hl
    call    __mulint_rrx_s
    pop    af
    ex    (sp),hl
    ld    l,6 (ix)
    ld    h,7 (ix)
    push    hl
    ld    l,6 (ix)
    ld    h,7 (ix)
    push    hl
    call    __mulint_rrx_s
    pop    af
    pop    af
    ld    b,h
    ld    c,l
    pop    de
    ld    a,e
    add    a,c
    ld    c,a
    ld    a,d
    adc    a,b
    ld    b,a
 

 
__mulint_rrx_s::
        ld      hl,#2
        add     hl,sp
        ld      e,(hl)
        inc     hl
        ld      d,(hl)
        inc     hl
        ld      a,(hl)
        inc     hl
        ld      h,(hl)
        ld      l,a
        ;; Fall through
__muluchar_rrx_hds::
__mulint_rrx_hds::
    ;; Parameters:
    ;;    HL, DE (left, right irrelivent)
    ld    b,h
    ld    c,l
    ;; 16-bit multiplication
    ;;
    ;; Entry conditions
    ;;   BC = multiplicand
    ;;   DE = multiplier
    ;;
    ;; Exit conditions
    ;;   DE = less significant word of product
    ;;
    ;; Register used: AF,BC,DE,HL
.mul16:
        ld      hl,#0
        ld      a,b
        ; ld c,c
        ld      b,#16
        ;; Optimise for the case when this side has 8 bits of data or
        ;; less.  This is often the case with support address calls.
        or      a
        jp      NZ,1$
        ld      b,#8
        ld      a,c
1$:
        ;; Taken from z88dk, which originally borrowed from the
        ;; Spectrum rom.
        add     hl,hl
        rl      c
        rla                     ;DLE 27/11/98
        jr      NC,2$
        add     hl,de
2$:
        djnz    1$
        ret