Strange results with dividing in assembler on intel 80368 32 bit

Question

It gets stuck in an infinite loop in function "prebroj". It should count how many digits there are in my result number so i can return it as a string later and exit when %eax becomes 0. When I run it in the debugger when i divide my number (%eax) by the required base (%ecx) so as to get how many digits there is, at one point after the division it returns a very strange number to %eax, but the remainder of the division in %edx keeps returning perfectly normal, even though the resulting number in %eax makes no sense whatsoever. Here is the code, it's rather long but I figured it might be helpful to provide the whole thing. The problem loop is at line 152, near the end. I put a bunch of comments next to it so it's easier to find (the only problem is the loop, I just put the whole program in case it might be relevant, short program description in top comments):

#unsigned saberi2 (char *num1, unsigned base1, char *num2, unsigned, base2, char *sum, unsigned *sum_length, unsigned sum_base);
#           8       12      16      20  24      28      32
#the subprogram is called from a c program and takes the first 2 numbers from args 1 and 3 as strings (to be converted), their respective bases from args 2 and 4, and returns the sum as a string at the address from arg 5
.text
.globl saberi2

saberi2:
pushl %ebp
movl %esp, %ebp
pushl %ebx
pushl %esi
subl $16, %esp          # -4(%ebp) i -8(%ebp) su prvi i drugi broj
movl $1, -8(%ebp)
movl $0, -12(%ebp)

prov_prvi:
movl 8(%ebp), %esi
movb (%esi), %bl
cmpb $'-', %bl
jne nm1
movl $-1, -8(%ebp)
incl %esi
jmp np1
nm1:
cmpb $'+', %bl
jne np1
incl %esi
np1:
movl $0, %eax
movl 12(%ebp), %ecx
cmpl $10, %ecx
ja preko10_1

ispod10_1:
movb (%esi), %bl
cmpb $0, %bl
je kraj1
subb $'0', %bl
cmpb $0, %bl
jl greska1
cmpb 12(%ebp), %bl
jg greska1
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp ispod10_1

preko10_1:
movb (%esi), %bl
cmpb $0, %bl
je kraj1
subb $'0', %bl
cmpb $0, %bl
jl greska1
cmpb $9, %bl
jg slovo1
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp preko10_1
slovo1:
subb $7, %bl            #17 je razmak od 0 do A
cmpb $10, %bl
jl greska1
cmpb 12(%ebp), %bl
jg greska1
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp preko10_1

kraj1:
movl -8(%ebp), %ecx
mull %ecx
movl %eax, -4(%ebp)

prov_drugi:
movl 16(%ebp), %esi
movb (%esi), %bl
movl $1, -8(%ebp)
cmpb $'-', %bl
jne nm2
movl $-1, -8(%ebp)
incl %esi
jmp np2
nm2:
cmpb $'+', %bl
jne np2
incl %esi
np2:
movl $0, %eax
movl 20(%ebp), %ecx
cmpl $10, %ecx
ja preko10_2

ispod10_2:
movb (%esi), %bl
cmpb $0, %bl
je kraj2
subb $'0', %bl
cmpb $0, %bl
jb greska2
cmpb 20(%ebp), %bl
ja greska2
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp ispod10_2

preko10_2:
movb (%esi), %bl
cmpb $0, %bl
je kraj2
subb $'0', %bl
cmpb $0, %bl
jl greska2
cmpb $9, %bl
jg slovo2
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp preko10_2
slovo2:
subb $7, %bl            #17 je razmak od 0 do A
cmpb $10, %bl
jl greska2
cmpb 20(%ebp), %bl
jg greska2
mull %ecx
movb %bl, -12(%ebp)
addl -12(%ebp), %eax
incl %esi
jmp preko10_2

kraj2:
movl -8(%ebp), %ecx
mull %ecx
addl -4(%ebp), %eax
jo greska3

ispis:
movl 24(%ebp), %ebx     #ebx je adresa zbira
movl %eax, -4(%ebp)     #eax je zbir
movl $0, %esi           #esi je broj cifara zbira
movl 32(%ebp), %ecx     #ecx je baza zbira

prebroj:
cmpl $0, %eax           #brojanje cifara zbira
je unesi            #-----------------------------------------------
divl %ecx           #THIS IS THE LOOP-------------------------------
incl %esi           #-----------------------------------------------
movl %eax, -12(%ebp)
jmp prebroj

unesi:                  #unos cifara na adresu iz arg
movl %esi, 28(%ebp)
movl -4(%ebp), %eax
cmpl $0, %eax
jg nmi
movb $'-', (%ebx)
incl %esi
nmi:
movb $0, (%ebx, %esi, 1)
decl %esi
cmpl $10, %ecx
ja preko10_i

ispod10_i:
cmpl $0, %eax
je preende
divl %ecx
addb $'0', %dl
movb %dl, (%ebx, %esi, 1)
decl %esi
jmp ispod10_i

preko10_i:
cmpl $0, %eax
je preende
divl %ecx
cmpb $9, %dl
ja slovoi
addb $'0', %dl
movb %dl, (%ebx, %esi, 1)
decl %esi
jmp preko10_i
slovoi:
addb $55, %dl
movb %dl, (%ebx, %esi, 1)
decl %esi
jmp preko10_i

greska1:
movl $1, %eax
jmp ende

greska2:
movl $2, %eax
jmp ende

greska3:
movl $3, %eax
jmp ende

preende:
movl $0, %eax
ende:
popl %esi
popl %ebx
movl %ebp, %esp
popl %ebp
ret