; Simple Text-Based Snake Game in x86 Assembly

section .data
    snake_body db 'O'  ; Snake body character
    food db '*'         ; Food character
    empty_space db '.'  ; Empty space character
    board_size equ 10   ; Size of the game board

section .bss
    snake_x resb 100    ; X positions of snake segments
    snake_y resb 100    ; Y positions of snake segments
    snake_length resb 1 ; Length of the snake
    food_x resb 1       ; X position of food
    food_y resb 1       ; Y position of food
    direction resb 1    ; Direction of movement (0: up, 1: right, 2: down, 3: left)
    game_over resb 1    ; Flag indicating game over

section .text
    global _start

_start:
    ; Initialize game state
    call init_game

    ; Main game loop
game_loop:
    ; Render game board
    call render_board

    ; Move snake
    call move_snake

    ; Check for collisions
    call check_collisions

    ; Check for food eaten
    call check_food

    ; Check for game over
    cmp byte [game_over], 1
    je game_over

    ; Pause for a moment
    call sleep

    ; Repeat game loop
    jmp game_loop

game_over:
    ; Game over message
    mov eax, 4          ; syscall number for sys_write
    mov ebx, 1          ; file descriptor 1 (stdout)
    mov ecx, game_over_msg
    call print_string

    ; Exit program
    mov eax, 1          ; syscall number for sys_exit
    xor ebx, ebx        ; exit code 0
    int 0x80            ; call kernel

init_game:
    ; Initialize snake position and direction
    mov byte [snake_length], 3
    mov byte [snake_x], 5
    mov byte [snake_y], 5
    mov byte [direction], 1

    ; Generate initial food position
    call generate_food

    ret

render_board:
    ; Clear screen
    mov eax, 0x2       ; syscall number for sys_ioctl
    mov ebx, 1         ; file descriptor 1 (stdout)
    mov ecx, 0x5412   ; ioctl code for clear screen
    int 0x80          ; call kernel

    ; Render snake
    mov eax, 4         ; syscall number for sys_write
    mov ebx, 1         ; file descriptor 1 (stdout)
    mov ecx, snake_body
    mov edx, 1         ; message length
    call print_char

    ; Render food
    mov eax, 4         ; syscall number for sys_write
    mov ebx, 1         ; file descriptor 1 (stdout)
    mov ecx, food
    mov edx, 1         ; message length
    call print_char

    ; Render empty spaces
    mov eax, 4         ; syscall number for sys_write
    mov ebx, 1         ; file descriptor 1 (stdout)
    mov ecx, empty_space
    mov edx, 1         ; message length
    call print_char

    ; Move cursor to next line
    mov eax, 4         ; syscall number for sys_write
    mov ebx, 1         ; file descriptor 1 (stdout)
    mov ecx, newline
    mov edx, 1         ; message length
    call print_char

    ret

move_snake:
    ; Update snake position based on direction
    cmp byte [direction], 0
    je move_up
    cmp byte [direction], 1
    je move_right
    cmp byte [direction], 2
    je move_down
    cmp byte [direction], 3
    je move_left

    ; Move up
move_up:
    dec byte [snake_y]
    ret

    ; Move right
move_right:
    inc byte [snake_x]
    ret

    ; Move down
move_down:
    inc byte [snake_y]
    ret

    ; Move left
move_left:
    dec byte [snake_x]
    ret

check_collisions:
    ; Check if snake collided with walls or itself
    ; (not implemented in this example)
    ret

check_food:
    ; Check if snake ate the food
    ; (not implemented in this example)
    ret

generate_food:
    ; Generate random food position
    ; (not implemented in this example)
    ret

sleep:
    ; Sleep for a moment to control game speed
    ; (not implemented in this example)
    ret

print_string:
    ; Print a null-terminated string to stdout
    ; (not implemented in this example)
    ret

print_char:
    ; Print a single character to stdout
    ; (not implemented in this example)
    ret

; Define game over message
game_over_msg db 'Game over!', 0

; Define newline character
newline db 10, 0