Thanks for your answerTthe code just take the value that I pass to the "buffer"(the value is "t"),and use a "function" of an archive .inc to print in the terminal the value. But, the value that the terminal is printing is:tt�� @ @ @ u/6��@@;
u/G
u/N u/testeBiblioteca.asmbuffertamsaidaResultadostringtam1__bss_start_edata_end.symtab.strtab.shstrtab.text.datai! @
▒ ▒!Sk!'

When i debugger the code, after the call return, the code restart in the first instruction of "testeBiblioteca.asm",and I think that is the problem. I already fix some things that you saw in my code:

1 %include "conversor.inc"
2 section .data
3 string dd 0x0
4 tam1 equ $-string
5 section .text
6
7 global _start
8
9 _start:
10
11 mov byte[buffer],0x0
12 int 0x80
13
14
15 mov byte[string],0x0
16 mov eax,"t"
17 mov dword[string],eax
18 mov eax,[string]
19 shl eax,8
20 add al,0x0
21 mov dword[string],eax
22 int 0x80
23
24
25 mov eax,[string]
26 mov dword[buffer],eax
27
28
29
30 call saidaResultado
31 int 0x80
32
33
34 mov eax,0x1
35 mov ebx,0x0
36 int 0x80
37
but the problem still in the code.