#include "schedos-app.h"

#include "x86sync.h"

/*****************************************************************************

* schedos-1

*

* This tiny application prints red "1"s to the console.

* It yields the CPU to the kernel after each "1" using the sys_yield()

* system call. This lets the kernel (schedos-kern.c) pick another

* application to run, if it wants.

*

* The other schedos-* processes simply #include this file after defining

* PRINTCHAR appropriately.

*

*****************************************************************************/

#ifndef PRINTCHAR

#define PRINTCHAR ('1' | 0x0C00)

#endif

// UNCOMMENT THE NEXT LINE TO USE EXERCISE 8 CODE INSTEAD OF EXERCISE 6

// #define __EXERCISE_8__

void

start(void)

{

int i;

for (i = 0; i < RUNCOUNT; i++) {

#ifndef __EXERCISE_8__

/* EXERCISE 6: use a system call to print characters *****************/

sys_print(PRINTCHAR);

#endif

#ifdef __EXERCISE_8__

/* EXERCISE 8: use a lock to prevent race conditions *****************/

// spinlock until we obtain write lock

while (atomic_swap(&spinlock, 1) != 0)

continue;

// write

*cursorpos++ = PRINTCHAR;

// release write lock

atomic_swap(&spinlock, 0);

#endif

sys_yield();

}

// Yield forever.

while (1)

sys_exit(0);

}