1. Introduction

This report provides an in-depth technical analysis of the "Guess the Number" program written in x86_64 Assembly language for Linux systems. The program serves as an educational model demonstrating fundamental low-level programming concepts, system call interactions, and efficient memory management.

2. Structural Analysis

Memory Sections Architecture:

section .data    ; Initialized data section (46 bytes messages + 12 bytes variables)
section .bss     ; Uninitialized data section (5 bytes input buffer)  
section .text    ; Code section (147 bytes instructions)
global _start    ; Entry point

Memory Layout Model:

0x00400000: _start (Program Code)
0x00401000: .data (Messages and Variables)
0x00402000: .bss (Temporary Input Buffer)
0x7ffffff0: Stack (Function Management)

3. Random Number Generation - Mathematical Analysis

; Theory: System time as random seed
mov eax, 13       ; sys_time - NR 13 in syscall table
mov ebx, 0        ; NULL pointer
mov ecx, num      ; Storage address (0x00401050)
mov edx, 4        ; int size (4 bytes)
int 0x80          ; Transition to kernel mode

; Mathematical transformation: f(x) = (x mod 100) + 1
mov eax, [num]    ; Load value (64-bit timestamp)
xor edx, edx      ; EDX = 0 (for DIV operation)
mov ecx, 100      ; Divisor
div ecx           ; EAX = quotient, EDX = remainder
inc edx           ; EDX = EDX + 1 (Range 1-100)
mov [num], edx    ; Store final result

Statistical Analysis:

• Distribution: Uniform
• Range: 1 ≤ x ≤ 100
• Cycle: 2³² unique values

4. Input Processing Engine - Algorithm

String Processing Stages:

; Phase 1: Read from STDIN
mov eax, 3        ; sys_read
mov ebx, 0        ; file descriptor 0 (STDIN)
mov ecx, input    ; buffer address (0x00402000)
mov edx, 5        ; buffer size (4 digits + newline)
int 0x80          ; System call

; Phase 2: ASCII to Integer Conversion
mov ecx, eax      ; Bytes read count
dec ecx           ; Exclude newline (0xA)
mov esi, input    ; Data source
mov edi, 0        ; Index
xor eax, eax      ; Clear EAX (result = 0)

convert_loop:
    mov bl, byte [esi]    ; Load character
    cmp bl, 0xA           ; Check end of line
    je convert_done       ; Jump if end
    sub bl, '0'           ; ASCII to binary: '5' → 5
    imul eax, 10          ; Result = Result × 10
    add eax, ebx          ; Result = Result + Digit
    inc esi               ; Next pointer
    loop convert_loop     ; ECX--, if ECX≠0 jump

Mathematical Formula: