kern/user/progW.c

#include <common.h>

/**
** User function W:   exit, sleep, write, getpid, gettime
**
** Reports its presence, then iterates 'n' times printing identifying
** information and sleeping, before exiting.
**
** Invoked as:  userW  x  [ n  [ s ] ]
**	 where x is the ID character
**		   n is the iteration count (defaults to 20)
**		   s is the sleep time (defaults to 3 seconds)
*/

USERMAIN(main)
{
	int count = 20; // default iteration count
	char ch = 'w'; // default character to print
	int nap = 3; // nap length
	char buf[128];

	// process the command-line arguments
	switch (argc) {
	case 4:
		nap = str2int(argv[3], 10);
		// FALL THROUGH
	case 3:
		count = str2int(argv[2], 10);
		// FALL THROUGH
	case 2:
		ch = argv[1][0];
		break;
	default:
		sprint(buf, "userW: argc %d, args: ", argc);
		cwrites(buf);
		for (int i = 0; i <= argc; ++i) {
			sprint(buf, " %s", argv[argc] ? argv[argc] : "(null)");
			cwrites(buf);
		}
		cwrites("\n");
	}

	// announce our presence
	int pid = getpid();
	uint32_t now = gettime();
	sprint(buf, " %c[%d,%u]", ch, pid, now);
	swrites(buf);

	write(CHAN_SIO, &ch, 1);

	for (int i = 0; i < count; ++i) {
		now = gettime();
		sprint(buf, " %c[%d,%u] ", ch, pid, now);
		swrites(buf);
		sleep(SEC_TO_MS(nap));
	}

	exit(0);

	return (42); // shut the compiler up!
}