kern/user/progABC.c

#include <common.h>

/**
** User function main #1:  exit, write
**
** Prints its ID, then loops N times delaying and printing, then exits.
** Verifies the return byte count from each call to write().
**
** Invoked as:  main1  x  n
**	 where x is the ID character
**		   n is the iteration count
*/

USERMAIN(main)
{
	int count = 30; // default iteration count
	char ch = '1'; // default character to print
	char buf[128]; // local char buffer

	// 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, "%s: argc %d, args: ", argv[0], 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);
	}

	// iterate and print the required number of other characters
	for (int i = 0; i < count; ++i) {
		DELAY(STD);
		n = swritech(ch);
		if (n != 1) {
			sprint(buf, "== %c, write #2 returned %d\n", ch, n);
			cwrites(buf);
		}
	}

	// all done!
	exit(0);

	// should never reach this code; if we do, something is
	// wrong with exit(), so we'll report it

	char msg[] = "*1*";
	msg[1] = ch;
	n = write(CHAN_SIO, msg, 3); /* shouldn't happen! */
	if (n != 3) {
		sprint(buf, "User %c, write #3 returned %d\n", ch, n);
		cwrites(buf);
	}

	// this should really get us out of here
	return (42);
}