Pierwiastek 3 stopnia w assemblerze

Witam, mam problem z kodem pierwiastka 3 stopnia w assemblerze (z podanej liczny, z podana dokładnością). Czy ktoś mógłby pomóc znaleźć mi błąd?
(wykorzystuje wzór bodajże newtona-raphson, program do kompilacji to nasm oraz gcc, interfejs w c)

;uzywane wzory: przyblizenie = 2/3*poprzednie + x/3 *(1/poprzednie^2) - ze wzoru newtona-raphsona
;|
section .text use32

global	_pier3

_pier3:

	%idefine xx          [ebp+8]
	%idefine epsilon     [ebp+12]


	;ramka stosu
	push	ebp
	mov	ebp, esp

	finit               ; Initialize FPU
    fld  qword epsilon         ; st(0)=epsilon
    fld  qword [root]          ; st(0)=prevroot (Copy of root), st(1)=epsilon
    fld  qword [TwoThirds]       ; st(0)=(2/3), st(1)=prevroot, st(2)=epsilon 
    fld  qword xx              ; st(0)=x, st(1)=(2/3), st(2)=prevroot, st(3)=epsilon
    fdiv qword [Three]          ; st(0)=(x/3), st(1)=(2/3), st(2)=prevroot, st(3)=epsilon
    fld st2           ; st(0)=root, st(1)=(x/3), st(2)=(2/3), st(3)=prevroot, st(4)=epsilon

repeatAgain:
    fld st0           ; st(0)=root, st(1)=root, st(2)=(x/3), st(3)=(2/3), st(4)=prevroot, st(5)=epsilon
    fmul st0, st3  ; st(0)=(2/3*root), st(1)=root, st(2)=(x/3), st(3)=(2/3), st(4)=prevroot, st(5)=epsilon           
    fxch                ; st(0)=root, st(1)=(2/3*root), st(2)=(x/3), st(3)=(2/3), st(4)=prevroot, st(5)=epsilon
    fmul st0, st0  ; st(0)=(root*root), st(1)=(2/3*root), st(2)=(x/3), st(3)=(2/3), st(4)=prevroot, st(5)=epsilon
    fdivr st0, st2  ; st(0)=((x/3)/(root*root)), st(1)=(2/3*root), st(2)=(x/3), st(3)=(2/3), st(4)=prevroot, st(5)=epsilon
    faddp               ; st(0)=((2/3*root)+(x/3)/(root*root)), st(1)=(x/3), st(2)=(2/3), st(3)=prevroot, st(4)=epsilon
    fxch st3          ; st(0)=prevroot, st(1)=(x/3), st(2)=(2/3), newroot=st(3)=((2/3*root)+(x/3)/(root*root)), st(4)=epsilon 
    fsub st0, st3   ; st(0)=(prevroot-newroot), st(1)=(x/3), st(2)=(2/3), st(3)=newroot, st(4)=epsilon
    fabs                ; st(0)=(|prevroot-newroot|), st(1)=(x/3), st(2)=(2/3), st(3)=newroot, st(4)=epsilon
    fld st4         ; st(0)=0.001, st(1)=(|prevroot-newroot|), st(2)=(x/3), st(3)=(2/3), st(4)=newroot, st(5)=epsilon

    fcompp              ; Do compare&set x87 flags pop top two values off stack
                        ;     st(0)=(x/3), st(1)=(2/3), st(2)=newroot, st(3)=epsilon    
    fstsw ax            ; Copy x87 Status Word containing the result to AX
    fwait               ; Insure previous instruction completed
    sahf                ; Transfer condition codes to the CPU's flags register

    fld st2           ; st(0)=newroot, st(1)=(x/3), st(2)=(2/3), st(3)=newroot, st(4)=epsilon
    jbe repeatAgain     ; If 0.001 <= (|oldroot-newroot|) repeat
	; Remove temporary values on stack, cubed root in st(0)
    ffree st4       ; st(0)=newroot, st(1)=(x/3), st(2)=(2/3), st(3)=epsilon
    ffree st3       ; st(0)=newroot, st(1)=(x/3), st(2)=(2/3)
    ffree st2       ; st(0)=newroot, st(1)=(x/3)
    ffree st1       ; st(0)=newroot

	leave
	ret
	
	section .data
	root    db    1.0
    Three   db    3.0
	TwoThirds dq  0.6666666666666666