// "Task macros" from discussion at https://forum.arduino.cc/t/is-there-a-non-blocking-delay-thats-as-easy-to-use-as-the-built-in-delay-function/1195423/17?u=davex
// and the https://github.com/DrDiettrich/ALib0 library that that snippet was drawn from
// Also see https://forum.arduino.cc/t/hook-for-rtos-in-timer0-on-avr/1132394/4
// wokwi https://wokwi.com/projects/382926594591467521
// These macros build state machines with millis() and switch-case infrastructure.

// WAIT::  The output is suspicious per
// https://forum.arduino.cc/t/is-there-a-non-blocking-delay-thats-as-easy-to-use-as-the-built-in-delay-function/1195423/22

# define millis_t uint32_t
# define taskBegin() static int _mark = 0; static millis_t __attribute__((unused)) time_Stamp = 0; switch(_mark){ case 0:
# define taskSwitch() { _mark = __LINE__; return; case __LINE__: ; }
# define taskDelay(interval) time_Stamp = millis(); taskSwitch(); if ((millis() - time_Stamp) < (interval)) return;
# define taskWaitFor(condition) taskSwitch(); if (!(condition)) return;
# define taskRestart() { _mark = 0; return; }
# define taskEnd() _mark=0; }

void setup() {
  Serial.begin(115200);
}

void loop() {
  {
    taskBegin();
    Serial.println("Hello world!");
    taskDelay(500);
    taskEnd();
  }
  {
    taskBegin();
    Serial.println("        Hello mars!");
    taskDelay(700);
    taskEnd();
  }
}

// alternately:

void he (void) {
  taskBegin();
  Serial.print(millis());
  Serial.println(" Hello world!");
  taskDelay(500);
  taskEnd();
}

void hm (void) {
  taskBegin();
  Serial.print(millis());
  Serial.println("         Hello mars!");

  taskDelay(700);
  taskEnd();

}