kern/user/progFG.c

#include <common.h>

/**
** User function main #3:  exit, sleep, write
**
** Prints its ID, then loops N times sleeping and printing, then exits.
**
** Invoked as:  main3  x  n  s
**	 where x is the ID character
**		   n is the iteration count
**		   s is the sleep time in seconds
*/

USERMAIN(main)
{
	char ch = '3'; // default character to print
	int nap = 10; // default sleep time
	int count = 30; // iteration count
	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, "main3: 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 n = swritech(ch);
	if (n != 1) {
		sprint(buf, "=== %c, write #1 returned %d\n", ch, n);
		cwrites(buf);
	}

	write(CHAN_SIO, &ch, 1);

	for (int i = 0; i < count; ++i) {
		sleep(SEC_TO_MS(nap));
		write(CHAN_SIO, &ch, 1);
	}

	exit(0);

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