kern/user/progZ.c

#include <common.h>

/**
** User function Z:	 exit, sleep, write, getpid
**
** Prints its ID, then records PID and PPID, loops printing its ID,
** and finally re-gets PPID for comparison.  Yields after every second
** ID print in the loop.
**
** This code is used as a handy "spawn me" test routine; it is spawned
** by several of the standard test processes.
**
** Invoked as:	userZ  x  [ n ]
**	 where x is the ID character
**		   n is the iteration count (defaults to 10)
*/

USERMAIN(main)
{
	int count = 10; // default iteration count
	char ch = 'z'; // default character to print
	char buf[128];

	// process the command-line arguments
	switch (argc) {
	case 3:
		count = str2int(argv[2], 10);
		// FALL THROUGH
	case 2:
		ch = argv[1][0];
		break;
	default:
		sprint(buf, "?: 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();
	sprint(buf, " %c[%d]", ch, pid);
	swrites(buf);

	// iterate for a while; occasionally yield the CPU
	for (int i = 0; i < count; ++i) {
		sprint(buf, " %c[%d]", ch, i);
		swrites(buf);
		DELAY(STD);
		if (i & 1) {
			sleep(0);
		}
	}

	exit(0);

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