kern/user/idle.c

#include <common.h>

/**
** Idle process:  write, getpid, gettime, exit
**
** Reports itself, then loops forever delaying and printing a character.
** MUST NOT SLEEP, as it must always be available in the ready queue
** when there is no other process to dispatch.
**
** Invoked as:	idle
*/

USERMAIN(main)
{
	// this is the character we will repeatedly print
	char ch = '.';

	// ignore the command-line arguments
	(void)argc;
	(void)argv;

	// get some current information
	uint_t pid = getpid();
	uint32_t now = gettime();
	enum priority_e prio = getprio();

	char buf[128];
	sprint(buf, "Idle [%d], started @ %u\n", pid, prio, now);
	cwrites(buf);

	// report our presence on the console
	cwrites("Idle started\n");

	write(CHAN_SIO, &ch, 1);

	// idle() should never block - it must always be available
	// for dispatching when we need to pick a new current process

	for (;;) {
		DELAY(LONG);
		write(CHAN_SIO, &ch, 1);
	}

	// we should never reach this point!
	now = gettime();
	sprint(buf, "Idle [%d] EXITING @ %u!?!?!\n", pid, now);
	cwrites(buf);

	exit(1);

	return (42);
}