section .data
    hello:     db 'heLlo FeliCia',10    ; 'Hello, World!' plus a linefeed character
    helloLen:  equ $-hello             ; Length of the 'Hello world!' string

section .bss
    str1 resb helloLen

section .text
    global _start

_start:
    mov eax,4            ; The system call for write (sys_write)
    mov ebx,1            ; File descriptor 1 - standard output
    mov ecx,hello        ; Put the offset of hello in ecx
    mov edx,helloLen     ; helloLen is a constant, so we don't need to say
                         ;  mov edx,[helloLen] to get its actual value
    int 80h              ; Call the kernel

    mov esi, hello
    mov edi, str1
    mov ecx, helloLen

convertLoop:
    cmp ecx, 0          ; Check if we've reached the end of the string
    jz printToggle      ; If yes, jump to printToggle
    mov al, byte [esi]  ; Load the byte from hello into al
    cmp al, 'A'         ; Compare with 'A'
    jl notUppercase     ; If less than 'A', it's not uppercase
    cmp al, 'Z'         ; Compare with 'Z'
    jg notUppercase     ; If greater than 'Z', it's not uppercase
    add al, 32          ; Convert uppercase to lowercase
    jmp contToggle      ; Continue toggling
notUppercase:
    cmp al, 'a'         ; Compare with 'a'
    jl notLowercase     ; If less than 'a', it's not lowercase
    cmp al, 'z'         ; Compare with 'z'
    jg notLowercase     ; If greater than 'z', it's not lowercase
    sub al, 32          ; Convert lowercase to uppercase
contToggle:
    mov [edi], al       ; Store the character into str1
    inc esi             ; Move to the next character in hello
    inc edi             ; Move to the next character in str1
    dec ecx             ; Decrement the counter
    jmp convertLoop     ; Repeat the loop

printToggle:
    mov eax,4           ; The system call for write (sys_write)
    mov ebx,1           ; File descriptor 1 - standard output
    mov ecx,str1        ; Pointer to the converted string
    mov edx,helloLen    ; Length of the converted string
    int 80h             ; Call the kernel

exit:
    mov eax,1           ; The system call for exit (sys_exit)
    mov ebx,0           ; Exit with return "code" of 0 (no error)
    int 80h             ; Call the kernel

notLowercase:           ; Define label notLowercase
    jmp contToggle      ; Jump to contToggle

notToggle:              ; Define label notToggle
    jmp contToggle      ; Jump to contToggle