;; this macro will save the stack base pointer on the stack so we can safely
  ;; use call again without breaking "retn" instruction
  ;; we restore it with instruction "leave" ("pop rbp" works too)
  ;; we also set rbp to the current stack (which is set to rbp+parameters size)
  %macro enter 0
  push rbp
  mov rbp, rsp
  %endmacro

  ;; --- RO STATIC SEGMENT
  section .data
title:                DB "Exercice.S", 0
title_eol:            DB `Exercice.S\n`, 0
debug_return:         DB "Debug: %s = %d", 0
str_glfwInit:         DB "glfwInit", 0
str_exiting_properly: DB `Properly closing the process now\n`

  ;; --- RW STATIC 0 FILLED SEGMENT
  section .bss
window: RESQ 1
width:  RESD 1
height: RESD 1

  ;; --- executable code segment ---
  section .text
  extern exit, printf, sleep
  extern glfwInit, glfwTerminate, glfwCreateWindow, glfwMakeContextCurrent, glfwWindowShouldClose
  extern glClearColor, glClear, glfwSwapBuffers, glfwPollEvents, glBegin, glEnd, glFlush, glViewport
  extern glColor3f, glVertex2f, glfwGetFramebufferSize
  global _start
  default rel

_start:
  call initialize_windows
  mov rdi, 0
  call exit

initialize_windows:
  enter

  mov rdi, title_eol
  call printf

  ;; glfwinit()
  call glfwInit wrt ..plt

  ;; glfwcreatewindow()
  mov rdi, 800
  mov rsi, 600
  mov rdx, title
  mov rcx, 0
  mov r8, 0
  call glfwCreateWindow wrt ..plt
  mov [window], rax

  ;; glfwmakecontextcurrent()
  mov rdi, [window]
  call glfwMakeContextCurrent

  mov rdi, __float32__(0.1) ; red
  mov rsi, __float32__(0.1) ; green
  mov rdx, __float32__(0.1) ; blue
  mov rcx, __float32__(0.0) ; alpha
  call glClearColor

main_loop:
  mov rdi, [window]
  lea rsi, [width]
  lea rdx, [height]
  call glfwGetFramebufferSize

  mov rdi, 0
  mov rsi, 0
  mov rdx, [width]
  mov rcx, [height]
  call glViewport

  mov rdi, 0x00004000 ; GL_COLOR_BUFFER_BIT
  call glClear

  mov rdi, 0x0004 ; GL_TRIANGLES
  call glBegin

  mov rdi, __float32__(0.0)
  mov rdi, __float32__(0.0)
  mov rdx, __float32__(0.0)
  call glColor3f

  mov rdi, __float32__(0.0)
  mov rsi, __float32__(-1.0)
  call glVertex2f

  mov rdi, __float32__(-1.0)
  mov rsi, __float32__(1.0)
  call glVertex2f

  mov rdi, __float32__(1.0)
  mov rsi, __float32__(1.0)
  call glVertex2f

  call glEnd
  call glFlush

  mov rdi, [window]
  call glfwSwapBuffers

  call glfwPollEvents

  mov rdi, [window]
  call glfwWindowShouldClose

  ;; "infinite loop" until event
  cmp rax, 0
  je main_loop

  call glfwTerminate

  mov rdi, 1
  call sleep

  mov rdi, str_exiting_properly
  call printf wrt ..plt

  leave
  retn