.text
.global main

// r5 - capasity
// r6 - ptr
// r7 - size
main:
    push {r5, r6, r7, lr}
    mov r5, #1
    mov r7, #0
    mov r6, #0
    b reallocation

input:
    ldr r0, stdin_ptr
    ldr r0, [r0]
    bl fgetc
    cmp r0, #-1
    beq output

    strb r0, [r6, r7]
    add r7, #1

    cmp r7, r5
    blt input

    add r5, r5
    b reallocation

reallocation:
    mov r0, r6
    mov r1, r5
    bl realloc
    mov r6, r0
    b input

output:
    sub r7, #1

    ldrb r0, [r6, r7]
    ldr r1, stdout_ptr
    ldr r1, [r1]
    bl fputc

    cmp r7, #0
    bgt output

    b end_main

end_main:
    mov r0, r6
    bl free
    pop {r5, r6, r7, lr}
    bx lr

stdin_ptr:
    .word stdin

stdout_ptr:
    .word stdout