.data
s:         .asciz  "%llu\n"
.text
.global mystrspn

mystrspn:
    pushl   %ebp
    movl    %esp, %ebp
    pushl   %ebx
    pushl   %edi
    pushl   %esi

    movl    8(%ebp), %eax
    movl    12(%ebp), %ebx

    movl    $0, %ecx
Loop1:
    movzbl  (%eax), %edx
    cmpl    $0, %edx
    jz      end

    movl    12(%ebp), %ebx
Loop2:
    movzbl    (%ebx), %esi
    cmpl    $0, %esi
    jz      end
    cmpl    %edx,   %esi
    jz      next_letter
    incl    %ebx
    jmp     Loop2
next_letter:
    incl    %ecx
    incl    %eax
    jmp     Loop1
end:
    movl    %ecx, %eax
    popl    %esi
    popl    %edi
    popl    %ebx
    popl    %ebp
    ret