section .bss
        c:      resb  1
section .text
        global  _start

_start:

_loop:
        mov     eax, 3  ; read() syscall
        mov     ebx, 0  ; read from stdin
        mov     ecx, c
        mov     edx, 1  ; read one byte at a time
        int     0x80

        cmp     eax, 1  ; check number of bytes read
        jne     _exit

        mov     eax, 341 ; rot 13 stuff
        mov     ebx, [c]
        int     0x80
        mov     [c], al ; store rot13'd char in c

        mov     eax, 4  ; write() syscall
        mov     ebx, 1  ; wrie to stdout
        mov     ecx, c
        mov     edx, 1  ; write one byte at a time
        int     80h

        cmp     eax, 1  ; check number of bytes written
        jne     _exit

        jmp     _loop

_exit:
        mov eax,1
        int 80h
; vim: set ft=nasm: