Beginner here, I am missing a few lines to modify the code I already have to wor

Question

Beginner here, I am missing a few lines to modify the code I already have to work with an argument. What I need is very easy, but I'm new and confused -- would probably only take a few minutes of time from someone who is experienced (I think?!).

I only need a portion of NASM assembly code please (using I/O asm_io.asm routines). Nothing too complicated, just very simple, beginner code (like the Hello World stuff used in someone's first course). I already have my .asm, .inc, makefile, cdecl.h, driver.c etc etc. All I am missing is the few lines of code to modify it and make it do what is specifically described below.

For example: make argv, then argv banana. I need to go through the 2nd line argument banana in a loop and then print it out like this: b a n a n a. Then find the index of the last letter in a second loop and check if it is upper case, if so change it to lower case. (ie: change bananA and display b a n a n a, or banana is fine change nothing and display b a n a n a. What lines of code will make it do this? What makes it leave a space or locate the last letter?

Again, I do not need anything complicated, just a few basic lines using simple language to perform these loops using asm_io.asm routines (ie: mov ebx, dword [ebp+12] or call print_nl etc etc, this is the type of code I am missing in my .asm). I am new to this and appreciate help.

Can you please give a brief outline of each line so I understand and can write my own final code, thanks. (ie: mov [str1+1] ; means this and that will happen) Thank you!

Explanation / Answer

message: db 'hello world'

msglength: equ 12

buffersize: dw 1024

start

   mov eax 3

mov ebx,2

mov ecx ,hello

mov edx,hellolen

int 80th

mov eax,1

mov ebx,0

section .txt

pop ebx ;argc

pop ebx   argv[5];

pop ebx   banana;

int 80th ;

mov ecx,5

loop:

dec ecx

jne loop             

push ebp

mov ebp,esp

push ebx;

mov ebx,[ebp+12]; argv

mov eax ;argv[1]

call printf

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