#include "SDL_interface.S"

#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600

// integer-params:  RDI, RSI, RDX, RCX, R8, R9
// caller-saved:    RAX, RCX, RDX, RSI, RDI, R8-R11
// callee-saved:    RBX, RSP, RBP, R12-R15

.section .rodata
  failed_to_create_window:  .string "Window could not be created\nSDL_error: %s\n"
  failed_to_initialize_sdl: .string "SDL could not be initialized\nSDL_error: %s\n"
  greeting:                 .string "Hello, SDL!\n"
  window_title:             .string "snake.s"

.section .text
  .global main

  // void _print_sdl_error(char const * format)
  .type _print_sdl_error, @function
  _print_sdl_error:
    push %rbp
    mov %rsp, %rbp

    push %rdi
    sub $8, %rsp
 
    call SDL_GetError@PLT
    mov %rax, %rsi
 
    add $8, %rsp
    pop %rdi

    call printf@PLT
    jmp .Lexit

    leave
    ret

  .type main, @function
  main: 
    push %rbp
    mov %rsp, %rbp

    // initialize SDL
    mov $SDL_INIT_VIDEO, %rdi
    call SDL_Init@PLT

    // check if initialization was successful
    cmp $0, %rax
    jae 1f
      lea failed_to_initialize_sdl(%rip), %rdi
      call _print_sdl_error@PLT
      mov $1, %rax
      jmp .Lexit
  1:

    // create a window
    lea window_title(%rip), %rdi
    mov $SDL_WINDOWPOS_UNDEFINED, %rsi
    mov $SDL_WINDOWPOS_UNDEFINED, %rdx
    mov $SCREEN_WIDTH, %rcx
    mov $SCREEN_HEIGHT, %r8
    mov $SDL_WINDOW_SHOWN, %r9
    call SDL_CreateWindow@PLT

    cmp $0, %rax
    jne 1f
      lea failed_to_create_window(%rip), %rdi
      call _print_sdl_error@PLT
      mov $1, %rax
      jmp .Lexit
  1:

  mov %rax, %rdi
  call SDL_DestroyWindow@PLT
  call SDL_Quit@PLT

  .Lsuccess:
    lea greeting(%rip), %rdi
    xor %rax, %rax
    call printf@PLT

    xor %rax, %rax

  .Lexit:
    leave
    ret