.data
        SYSEXIT = 60
        EXIT_SUCCESS = 0
        STDIN = 0
        STDOUT = 1
        SYSWRITE = 1
        SYSREAD = 0
        BUFLEN = 100

.bss
        .comm input, 100
        .comm output, 100

.text
.global main
main:

        movq $SYSREAD, %rax
        movq $STDIN, %rdi
        movq $input, %rsi
        movq $BUFLEN, %rdx
        syscall


        movq %rax, %rdx
        dec %rdx
        movq %rdx, %r8
        dec %r8

        movq $0, %rdi

petla:
        movq $0, %rbx
        movb input(,%rdi,1), %bl
        movb %bl, output(, %r8, 1)
        inc %rdi
        dec %r8
        cmp %rdx, %rdi
        jl petla
        movb $'\n', output(,%rdi,1)

        movq $SYSWRITE, %rax
        movq $STDOUT, %rdi
        movq $output, %rsi
        movq $BUFLEN, %rdx
        syscall

        movq $SYSEXIT, %rax
        movq $EXIT_SUCCESS, %rdi
        syscall