From f7fc4f932f5663ee95fe14d90f2816ba2981bcd6 Mon Sep 17 00:00:00 2001
From: Fabio Scotto di Santolo <fabio.scottodisantolo@gmail.com>
Date: Thu, 3 Jul 2025 11:13:40 +0200
Subject: [PATCH] Added modified max program with stdin input

---
 asmc32.sh |   2 +-
 imax.asm  | 129 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 130 insertions(+), 1 deletion(-)
 create mode 100644 imax.asm

diff --git a/asmc32.sh b/asmc32.sh
index fe43f81..87a0353 100755
--- a/asmc32.sh
+++ b/asmc32.sh
@@ -4,7 +4,7 @@ compile() {
     local filename="$(basename "$1")"
     local basename="${filename%.*}"
 
-    nasm -f elf32 -o "$basename.o" "$filename"
+    nasm -f elf32 -g -F dwarf -o "$basename.o" "$filename"
     ld -m elf_i386 -o "$basename" "$basename.o"
     rm "$basename.o"
 }
diff --git a/imax.asm b/imax.asm
new file mode 100644
index 0000000..4f04e05
--- /dev/null
+++ b/imax.asm
@@ -0,0 +1,129 @@
+; A simple program that prints the max between two numbers from stdin
+; 
+; Author: Fabio Scotto di Santolo
+; Date:   02/07/2025
+
+global _start
+
+section .text
+_start:
+    ; Prompt for first number:
+    mov eax, 0x04               ; write syscall 
+    mov ebx, 1                  ; STDOUT file descriptor
+    mov ecx, prompt
+    mov edx, len0
+    int 0x80                    ; trigger syscall
+
+    ; Read first number
+    mov eax, 0x03               ; read syscall
+    mov ebx, 0                  ; STDIN file descriptor
+    mov ecx, buffer1
+    mov edx, 32 
+    int 0x80                    ; trigger syscall
+
+    mov edi, buffer1            ; save buffer address
+    mov esi, eax                ; save length 
+
+    ; Prompt for second number:
+    mov eax, 0x04               ; write syscall 
+    mov ebx, 1                  ; STDOUT file descriptor
+    mov ecx, prompt
+    mov edx, len0
+    int 0x80                    ; trigger syscall
+
+    ; Read second number
+    mov eax, 0x03               ; read syscall
+    mov ebx, 0                  ; STDIN file descriptor
+    mov ecx, buffer2
+    mov edx, 32 
+    int 0x80                    ; trigger syscall
+
+    ; Convert second number
+    mov ecx, buffer2            ; save buffer address
+    mov ebx, eax                ; save length
+    call ascii_to_int
+    push eax                    ; save converted second number in the stack
+
+    ; Convert first number
+    mov ecx, edi                ; ECX = address
+    mov ebx, esi                ; EBX = length
+    call ascii_to_int           ; EAX = first number
+
+    ; compare numbers
+    pop ebx                     ; restore converted second number from stack
+    cmp eax, ebx                ; compare a and b values
+    jg  greater
+    jle less_or_equal
+
+less_or_equal:                  ; print b is greater or equal than b
+    mov eax, 0x04               ; write syscall
+    mov ebx, 1                  ; STDOUT file descriptor
+    mov ecx, msg1
+    mov edx, len1
+    int 0x80                    ; trigger syscall
+    jmp end
+
+greater:                        ; print a is greater than b
+    mov eax, 0x04               ; write syscall
+    mov ebx, 1                  ; STDOUT file descriptor
+    mov ecx, msg2
+    mov edx, len2
+    int 0x80                    ; trigger syscall
+    jmp end
+
+end:
+    ; call syscall exit
+    mov eax, 0x1
+    xor ebx, ebx                ; reset register to 0
+    int 0x80                    ; trigger syscall
+
+; --- ASCII to Integer Conversion Routine ---
+ascii_to_int:
+    push ebx
+    push ecx
+    push edx
+    push esi
+
+    xor eax, eax
+    xor edx, edx
+    mov esi, ecx
+    mov ecx, ebx
+
+convert_loop:
+    cmp byte [esi], 0xA         ; newline?
+    je convert_done
+    cmp byte [esi], 0xD         ; carriage return?
+    je convert_done
+
+    mov ebx, 10
+    mul ebx                     ; EAX *= 10
+
+    movzx ebx, byte [esi]
+    sub ebx, '0'
+    add eax, ebx                ; EAX += digit
+
+    inc esi
+    loop convert_loop
+
+convert_done:
+    pop esi
+    pop edx
+    pop ecx
+    pop ebx
+    ret
+
+section .data
+    prompt: db "Insert a number: "
+    len0: equ $ - prompt
+
+    msg1: db "A is less or equal than B", 0xA
+    len1: equ $ - msg1
+
+    msg2: db "A is greater than B", 0xA
+    len2: equ $ - msg2
+
+section .bss
+    buffer1: resb 32            ; a buffer of 32 bytes
+    buffer2: resb 32            ; a buffer of 32 bytes
+
+