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input.c revision 1.24
      1 /*	$NetBSD: input.c,v 1.24 2009/08/12 04:48:03 dholland Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Ed James.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 /*
     36  * Copyright (c) 1987 by Ed James, UC Berkeley.  All rights reserved.
     37  *
     38  * Copy permission is hereby granted provided that this notice is
     39  * retained on all partial or complete copies.
     40  *
     41  * For more info on this and all of my stuff, mail edjames (at) berkeley.edu.
     42  */
     43 
     44 #include <sys/cdefs.h>
     45 #ifndef lint
     46 #if 0
     47 static char sccsid[] = "@(#)input.c	8.1 (Berkeley) 5/31/93";
     48 #else
     49 __RCSID("$NetBSD: input.c,v 1.24 2009/08/12 04:48:03 dholland Exp $");
     50 #endif
     51 #endif /* not lint */
     52 
     53 #include "include.h"
     54 #include "pathnames.h"
     55 
     56 static void rezero(void);
     57 static void noise(void);
     58 static int gettoken(void);
     59 static const char *setplane(int);
     60 static const char *turn(int);
     61 static const char *circle(int);
     62 static const char *left(int);
     63 static const char *right(int);
     64 static const char *Left(int);
     65 static const char *Right(int);
     66 static const char *delayb(int);
     67 static const char *beacon(int);
     68 static const char *ex_it(int);
     69 static const char *airport(int);
     70 static const char *climb(int);
     71 static const char *descend(int);
     72 static const char *setalt(int);
     73 static const char *setrelalt(int);
     74 static const char *benum(int);
     75 static const char *to_dir(int);
     76 static const char *rel_dir(int);
     77 static const char *mark(int);
     78 static const char *unmark(int);
     79 static const char *ignore(int);
     80 
     81 
     82 
     83 #define MAXRULES	6
     84 #define MAXDEPTH	15
     85 
     86 #define RETTOKEN	'\n'
     87 #define REDRAWTOKEN	'\014'	/* CTRL(L) */
     88 #define	SHELLTOKEN	'!'
     89 #define HELPTOKEN	'?'
     90 #define ALPHATOKEN	256
     91 #define NUMTOKEN	257
     92 
     93 typedef struct {
     94 	int	token;
     95 	int	to_state;
     96 	const char	*str;
     97 	const char	*(*func)(int);
     98 } RULE;
     99 
    100 typedef struct {
    101 	int	num_rules;
    102 	RULE	*rule;
    103 } STATE;
    104 
    105 typedef struct {
    106 	char	str[20];
    107 	int	state;
    108 	int	rule;
    109 	int	ch;
    110 	int	pos;
    111 } STACK;
    112 
    113 #define T_RULE		stack[level].rule
    114 #define T_STATE		stack[level].state
    115 #define T_STR		stack[level].str
    116 #define T_POS		stack[level].pos
    117 #define	T_CH		stack[level].ch
    118 
    119 #define NUMELS(a)	(sizeof (a) / sizeof (*(a)))
    120 
    121 #define NUMSTATES	NUMELS(st)
    122 
    123 static
    124 RULE	state0[] = {	{ ALPHATOKEN,	1,	"%c:",		setplane},
    125 			{ RETTOKEN,	-1,	"",		NULL	},
    126 			{ HELPTOKEN,	12,	" [a-z]<ret>",	NULL	}},
    127 	state1[] = {	{ 't',		2,	" turn",	turn	},
    128 			{ 'a',		3,	" altitude:",	NULL	},
    129 			{ 'c',		4,	" circle",	circle	},
    130 			{ 'm',		7,	" mark",	mark	},
    131 			{ 'u',		7,	" unmark",	unmark	},
    132 			{ 'i',		7,	" ignore",	ignore	},
    133 			{ HELPTOKEN,	12,	" tacmui",	NULL	}},
    134 	state2[] = {	{ 'l',		6,	" left",	left	},
    135 			{ 'r',		6,	" right",	right	},
    136 			{ 'L',		4,	" left 90",	Left	},
    137 			{ 'R',		4,	" right 90",	Right	},
    138 			{ 't',		11,	" towards",	NULL	},
    139 			{ 'w',		4,	" to 0",	to_dir	},
    140 			{ 'e',		4,	" to 45",	to_dir	},
    141 			{ 'd',		4,	" to 90",	to_dir	},
    142 			{ 'c',		4,	" to 135",	to_dir	},
    143 			{ 'x',		4,	" to 180",	to_dir	},
    144 			{ 'z',		4,	" to 225",	to_dir	},
    145 			{ 'a',		4,	" to 270",	to_dir	},
    146 			{ 'q',		4,	" to 315",	to_dir	},
    147 			{ HELPTOKEN,	12,	" lrLRt<dir>",	NULL	}},
    148 	state3[] = {	{ '+',		10,	" climb",	climb	},
    149 			{ 'c',		10,	" climb",	climb	},
    150 			{ '-',		10,	" descend",	descend	},
    151 			{ 'd',		10,	" descend",	descend	},
    152 			{ NUMTOKEN,	7,	" %c000 feet",	setalt	},
    153 			{ HELPTOKEN,	12,	" +-cd[0-9]",	NULL	}},
    154 	state4[] = {	{ '@',		9,	" at",		NULL	},
    155 			{ 'a',		9,	" at",		NULL	},
    156 			{ RETTOKEN,	-1,	"",		NULL	},
    157 			{ HELPTOKEN,	12,	" @a<ret>",	NULL	}},
    158 	state5[] = {	{ NUMTOKEN,	7,	"%c",		delayb	},
    159 			{ HELPTOKEN,	12,	" [0-9]",	NULL	}},
    160 	state6[] = {	{ '@',		9,	" at",		NULL	},
    161 			{ 'a',		9,	" at",		NULL	},
    162 			{ 'w',		4,	" 0",		rel_dir	},
    163 			{ 'e',		4,	" 45",		rel_dir	},
    164 			{ 'd',		4,	" 90",		rel_dir	},
    165 			{ 'c',		4,	" 135",		rel_dir	},
    166 			{ 'x',		4,	" 180",		rel_dir	},
    167 			{ 'z',		4,	" 225",		rel_dir	},
    168 			{ 'a',		4,	" 270",		rel_dir	},
    169 			{ 'q',		4,	" 315",		rel_dir	},
    170 			{ RETTOKEN,	-1,	"",		NULL	},
    171 			{ HELPTOKEN,	12,	" @a<dir><ret>",NULL	}},
    172 	state7[] = {	{ RETTOKEN,	-1,	"",		NULL	},
    173 			{ HELPTOKEN,	12,	" <ret>",	NULL	}},
    174 	state8[] = {	{ NUMTOKEN,	4,	"%c",		benum	},
    175 			{ HELPTOKEN,	12,	" [0-9]",	NULL	}},
    176 	state9[] = {	{ 'b',		5,	" beacon #",	NULL	},
    177 			{ '*',		5,	" beacon #",	NULL	},
    178 			{ HELPTOKEN,	12,	" b*",		NULL	}},
    179 	state10[] = {	{ NUMTOKEN,	7,	" %c000 ft",	setrelalt},
    180 			{ HELPTOKEN,	12,	" [0-9]",	NULL	}},
    181 	state11[] = {	{ 'b',		8,	" beacon #",	beacon	},
    182 			{ '*',		8,	" beacon #",	beacon	},
    183 			{ 'e',		8,	" exit #",	ex_it	},
    184 			{ 'a',		8,	" airport #",	airport	},
    185 			{ HELPTOKEN,	12,	" b*ea",	NULL	}},
    186 	state12[] = {	{ -1,		-1,	"",		NULL	}};
    187 
    188 #define DEF_STATE(s)	{ NUMELS(s),	(s)	}
    189 
    190 static STATE st[] = {
    191 	DEF_STATE(state0), DEF_STATE(state1), DEF_STATE(state2),
    192 	DEF_STATE(state3), DEF_STATE(state4), DEF_STATE(state5),
    193 	DEF_STATE(state6), DEF_STATE(state7), DEF_STATE(state8),
    194 	DEF_STATE(state9), DEF_STATE(state10), DEF_STATE(state11),
    195 	DEF_STATE(state12)
    196 };
    197 
    198 static PLANE p;
    199 static STACK stack[MAXDEPTH];
    200 static int level;
    201 static int tval;
    202 static int dest_type, dest_no, dir;
    203 
    204 static int
    205 pop(void)
    206 {
    207 	if (level == 0)
    208 		return (-1);
    209 	level--;
    210 
    211 	ioclrtoeol(T_POS);
    212 
    213 	(void)strcpy(T_STR, "");
    214 	T_RULE = -1;
    215 	T_CH = -1;
    216 	return (0);
    217 }
    218 
    219 static void
    220 rezero(void)
    221 {
    222 	iomove(0);
    223 
    224 	level = 0;
    225 	T_STATE = 0;
    226 	T_RULE = -1;
    227 	T_CH = -1;
    228 	T_POS = 0;
    229 	(void)strcpy(T_STR, "");
    230 }
    231 
    232 static void
    233 push(int ruleno, int ch)
    234 {
    235 	int	newstate, newpos;
    236 
    237 	assert(level < (MAXDEPTH - 1));
    238 	(void)snprintf(T_STR, sizeof(T_STR),
    239 		st[T_STATE].rule[ruleno].str, tval);
    240 	T_RULE = ruleno;
    241 	T_CH = ch;
    242 	newstate = st[T_STATE].rule[ruleno].to_state;
    243 	newpos = T_POS + strlen(T_STR);
    244 
    245 	ioaddstr(T_POS, T_STR);
    246 
    247 	if (level == 0)
    248 		ioclrtobot();
    249 	level++;
    250 	T_STATE = newstate;
    251 	T_POS = newpos;
    252 	T_RULE = -1;
    253 	(void)strcpy(T_STR, "");
    254 }
    255 
    256 int
    257 getcommand(void)
    258 {
    259 	int	c, i, done;
    260 	const char	*s, *(*func)(int);
    261 	PLANE	*pp;
    262 
    263 	rezero();
    264 
    265 	do {
    266 		c = gettoken();
    267 		if (c == tty_new.c_cc[VERASE]) {
    268 			if (pop() < 0)
    269 				noise();
    270 		} else if (c == tty_new.c_cc[VKILL]) {
    271 			while (pop() >= 0)
    272 				;
    273 		} else {
    274 			done = 0;
    275 			for (i = 0; i < st[T_STATE].num_rules; i++) {
    276 				if (st[T_STATE].rule[i].token == c ||
    277 				    st[T_STATE].rule[i].token == tval) {
    278 					push(i, (c >= ALPHATOKEN) ? tval : c);
    279 					done = 1;
    280 					break;
    281 				}
    282 			}
    283 			if (!done)
    284 				noise();
    285 		}
    286 	} while (T_STATE != -1);
    287 
    288 	if (level == 1)
    289 		return (1);	/* forced update */
    290 
    291 	dest_type = T_NODEST;
    292 
    293 	for (i = 0; i < level; i++) {
    294 		func = st[stack[i].state].rule[stack[i].rule].func;
    295 		if (func != NULL)
    296 			if ((s = (*func)(stack[i].ch)) != NULL) {
    297 				ioerror(stack[i].pos,
    298 				    (int)strlen(stack[i].str), s);
    299 				return (-1);
    300 			}
    301 	}
    302 
    303 	pp = findplane(p.plane_no);
    304 	if (pp->new_altitude != p.new_altitude)
    305 		pp->new_altitude = p.new_altitude;
    306 	else if (pp->status != p.status)
    307 		pp->status = p.status;
    308 	else {
    309 		pp->new_dir = p.new_dir;
    310 		pp->delayd = p.delayd;
    311 		pp->delayd_no = p.delayd_no;
    312 	}
    313 	return (0);
    314 }
    315 
    316 static void
    317 noise(void)
    318 {
    319 	(void)putchar('\07');
    320 	(void)fflush(stdout);
    321 }
    322 
    323 static int
    324 gettoken(void)
    325 {
    326 	while ((tval = getAChar()) == REDRAWTOKEN || tval == SHELLTOKEN)
    327 	{
    328 		if (tval == SHELLTOKEN)
    329 		{
    330 #ifdef BSD
    331 			struct itimerval	itv;
    332 			itv.it_value.tv_sec = 0;
    333 			itv.it_value.tv_usec = 0;
    334 			(void)setitimer(ITIMER_REAL, &itv, NULL);
    335 #endif
    336 #ifdef SYSV
    337 			int aval;
    338 			aval = alarm(0);
    339 #endif
    340 			if (fork() == 0)	/* child */
    341 			{
    342 				char *shell, *base;
    343 
    344 				done_screen();
    345 
    346 						 /* run user's favorite shell */
    347 				if ((shell = getenv("SHELL")) != NULL)
    348 				{
    349 					base = strrchr(shell, '/');
    350 					if (base == NULL)
    351 						base = shell;
    352 					else
    353 						base++;
    354 					(void)execl(shell, base, (char *) 0);
    355 				}
    356 				else
    357 					(void)execl(_PATH_BSHELL, "sh",
    358 					    (char *) 0);
    359 
    360 				exit(0);	/* oops */
    361 			}
    362 
    363 			(void)wait(0);
    364 			(void)tcsetattr(fileno(stdin), TCSADRAIN, &tty_new);
    365 #ifdef BSD
    366 			itv.it_value.tv_sec = 0;
    367 			itv.it_value.tv_usec = 1;
    368 			itv.it_interval.tv_sec = sp->update_secs;
    369 			itv.it_interval.tv_usec = 0;
    370 			(void)setitimer(ITIMER_REAL, &itv, NULL);
    371 #endif
    372 #ifdef SYSV
    373 			alarm(aval);
    374 #endif
    375 		}
    376 		(void)redraw();
    377 	}
    378 
    379 	if (isdigit(tval))
    380 		return (NUMTOKEN);
    381 	else if (isalpha(tval))
    382 		return (ALPHATOKEN);
    383 	else
    384 		return (tval);
    385 }
    386 
    387 static const char *
    388 setplane(int c)
    389 {
    390 	PLANE	*pp;
    391 
    392 	pp = findplane(number(c));
    393 	if (pp == NULL)
    394 		return ("Unknown Plane");
    395 	(void)memcpy(&p, pp, sizeof (p));
    396 	p.delayd = 0;
    397 	return (NULL);
    398 }
    399 
    400 /* ARGSUSED */
    401 static const char *
    402 turn(int c __unused)
    403 {
    404 	if (p.altitude == 0)
    405 		return ("Planes at airports may not change direction");
    406 	return (NULL);
    407 }
    408 
    409 /* ARGSUSED */
    410 static const char *
    411 circle(int c __unused)
    412 {
    413 	if (p.altitude == 0)
    414 		return ("Planes cannot circle on the ground");
    415 	p.new_dir = MAXDIR;
    416 	return (NULL);
    417 }
    418 
    419 /* ARGSUSED */
    420 static const char *
    421 left(int c __unused)
    422 {
    423 	dir = D_LEFT;
    424 	p.new_dir = p.dir - 1;
    425 	if (p.new_dir < 0)
    426 		p.new_dir += MAXDIR;
    427 	return (NULL);
    428 }
    429 
    430 /* ARGSUSED */
    431 static const char *
    432 right(int c __unused)
    433 {
    434 	dir = D_RIGHT;
    435 	p.new_dir = p.dir + 1;
    436 	if (p.new_dir >= MAXDIR)
    437 		p.new_dir -= MAXDIR;
    438 	return (NULL);
    439 }
    440 
    441 /* ARGSUSED */
    442 static const char *
    443 Left(int c __unused)
    444 {
    445 	p.new_dir = p.dir - 2;
    446 	if (p.new_dir < 0)
    447 		p.new_dir += MAXDIR;
    448 	return (NULL);
    449 }
    450 
    451 /* ARGSUSED */
    452 static const char *
    453 Right(int c __unused)
    454 {
    455 	p.new_dir = p.dir + 2;
    456 	if (p.new_dir >= MAXDIR)
    457 		p.new_dir -= MAXDIR;
    458 	return (NULL);
    459 }
    460 
    461 static const char *
    462 delayb(int c)
    463 {
    464 	int	xdiff, ydiff;
    465 
    466 	c -= '0';
    467 
    468 	if (c >= sp->num_beacons)
    469 		return ("Unknown beacon");
    470 	xdiff = sp->beacon[(int)c].x - p.xpos;
    471 	xdiff = SGN(xdiff);
    472 	ydiff = sp->beacon[(int)c].y - p.ypos;
    473 	ydiff = SGN(ydiff);
    474 	if (xdiff != displacement[p.dir].dx || ydiff != displacement[p.dir].dy)
    475 		return ("Beacon is not in flight path");
    476 	p.delayd = 1;
    477 	p.delayd_no = c;
    478 
    479 	if (dest_type != T_NODEST) {
    480 		switch (dest_type) {
    481 		case T_BEACON:
    482 			xdiff = sp->beacon[dest_no].x - sp->beacon[(int)c].x;
    483 			ydiff = sp->beacon[dest_no].y - sp->beacon[(int)c].y;
    484 			break;
    485 		case T_EXIT:
    486 			xdiff = sp->exit[dest_no].x - sp->beacon[(int)c].x;
    487 			ydiff = sp->exit[dest_no].y - sp->beacon[(int)c].y;
    488 			break;
    489 		case T_AIRPORT:
    490 			xdiff = sp->airport[dest_no].x - sp->beacon[(int)c].x;
    491 			ydiff = sp->airport[dest_no].y - sp->beacon[(int)c].y;
    492 			break;
    493 		default:
    494 			return ("Bad case in delayb!  Get help!");
    495 		}
    496 		if (xdiff == 0 && ydiff == 0)
    497 			return ("Would already be there");
    498 		p.new_dir = DIR_FROM_DXDY(xdiff, ydiff);
    499 		if (p.new_dir == p.dir)
    500 			return ("Already going in that direction");
    501 	}
    502 	return (NULL);
    503 }
    504 
    505 /* ARGSUSED */
    506 static const char *
    507 beacon(int c __unused)
    508 {
    509 	dest_type = T_BEACON;
    510 	return (NULL);
    511 }
    512 
    513 /* ARGSUSED */
    514 static const char *
    515 ex_it(int c __unused)
    516 {
    517 	dest_type = T_EXIT;
    518 	return (NULL);
    519 }
    520 
    521 /* ARGSUSED */
    522 static const char *
    523 airport(int c __unused)
    524 {
    525 	dest_type = T_AIRPORT;
    526 	return (NULL);
    527 }
    528 
    529 /* ARGSUSED */
    530 static const char *
    531 climb(int c __unused)
    532 {
    533 	dir = D_UP;
    534 	return (NULL);
    535 }
    536 
    537 /* ARGSUSED */
    538 static const char *
    539 descend(int c __unused)
    540 {
    541 	dir = D_DOWN;
    542 	return (NULL);
    543 }
    544 
    545 static const char *
    546 setalt(int c)
    547 {
    548 	int newalt = c - '0';
    549 	if ((p.altitude == newalt) && (p.new_altitude == p.altitude))
    550 		return ("Already at that altitude");
    551 	if (p.new_altitude == newalt) {
    552 		return ("Already going to that altitude");
    553 	}
    554 	p.new_altitude = newalt;
    555 	return (NULL);
    556 }
    557 
    558 static const char *
    559 setrelalt(int c)
    560 {
    561 	int newalt;
    562 
    563 	if (c == 0)
    564 		return ("altitude not changed");
    565 
    566 	switch (dir) {
    567 	case D_UP:
    568 		newalt = p.altitude + c - '0';
    569 		break;
    570 	case D_DOWN:
    571 		newalt = p.altitude - (c - '0');
    572 		break;
    573 	default:
    574 		return ("Unknown case in setrelalt!  Get help!");
    575 	}
    576 
    577 	if (p.new_altitude == newalt)
    578 		return ("Already going to that altitude");
    579 
    580 	p.new_altitude = newalt;
    581 
    582 	if (p.new_altitude < 0)
    583 		return ("Altitude would be too low");
    584 	else if (p.new_altitude > 9)
    585 		return ("Altitude would be too high");
    586 	return (NULL);
    587 }
    588 
    589 static const char *
    590 benum(int c)
    591 {
    592 	dest_no = c -= '0';
    593 
    594 	switch (dest_type) {
    595 	case T_BEACON:
    596 		if (c >= sp->num_beacons)
    597 			return ("Unknown beacon");
    598 		p.new_dir = DIR_FROM_DXDY(sp->beacon[(int)c].x - p.xpos,
    599 			sp->beacon[(int)c].y - p.ypos);
    600 		break;
    601 	case T_EXIT:
    602 		if (c >= sp->num_exits)
    603 			return ("Unknown exit");
    604 		p.new_dir = DIR_FROM_DXDY(sp->exit[(int)c].x - p.xpos,
    605 			sp->exit[(int)c].y - p.ypos);
    606 		break;
    607 	case T_AIRPORT:
    608 		if (c >= sp->num_airports)
    609 			return ("Unknown airport");
    610 		p.new_dir = DIR_FROM_DXDY(sp->airport[(int)c].x - p.xpos,
    611 			sp->airport[(int)c].y - p.ypos);
    612 		break;
    613 	default:
    614 		return ("Unknown case in benum!  Get help!");
    615 	}
    616 	return (NULL);
    617 }
    618 
    619 static const char *
    620 to_dir(int c)
    621 {
    622 	p.new_dir = dir_no(c);
    623 	return (NULL);
    624 }
    625 
    626 static const char *
    627 rel_dir(int c)
    628 {
    629 	int	angle;
    630 
    631 	angle = dir_no(c);
    632 	switch (dir) {
    633 	case D_LEFT:
    634 		p.new_dir = p.dir - angle;
    635 		if (p.new_dir < 0)
    636 			p.new_dir += MAXDIR;
    637 		break;
    638 	case D_RIGHT:
    639 		p.new_dir = p.dir + angle;
    640 		if (p.new_dir >= MAXDIR)
    641 			p.new_dir -= MAXDIR;
    642 		break;
    643 	default:
    644 		return ("Bizarre direction in rel_dir!  Get help!");
    645 	}
    646 	return (NULL);
    647 }
    648 
    649 /* ARGSUSED */
    650 static const char *
    651 mark(int c __unused)
    652 {
    653 	if (p.altitude == 0)
    654 		return ("Cannot mark planes on the ground");
    655 	if (p.status == S_MARKED)
    656 		return ("Already marked");
    657 	p.status = S_MARKED;
    658 	return (NULL);
    659 }
    660 
    661 /* ARGSUSED */
    662 static const char *
    663 unmark(int c __unused)
    664 {
    665 	if (p.altitude == 0)
    666 		return ("Cannot unmark planes on the ground");
    667 	if (p.status == S_UNMARKED)
    668 		return ("Already unmarked");
    669 	p.status = S_UNMARKED;
    670 	return (NULL);
    671 }
    672 
    673 /* ARGSUSED */
    674 static const char *
    675 ignore(int c __unused)
    676 {
    677 	if (p.altitude == 0)
    678 		return ("Cannot ignore planes on the ground");
    679 	if (p.status == S_IGNORED)
    680 		return ("Already ignored");
    681 	p.status = S_IGNORED;
    682 	return (NULL);
    683 }
    684 
    685 int
    686 dir_no(int ch)
    687 {
    688 	int	dirno;
    689 
    690 	dirno = -1;
    691 	switch (ch) {
    692 	case 'w':	dirno = 0;	break;
    693 	case 'e':	dirno = 1;	break;
    694 	case 'd':	dirno = 2;	break;
    695 	case 'c':	dirno = 3;	break;
    696 	case 'x':	dirno = 4;	break;
    697 	case 'z':	dirno = 5;	break;
    698 	case 'a':	dirno = 6;	break;
    699 	case 'q':	dirno = 7;	break;
    700 	default:
    701 		(void)fprintf(stderr, "bad character in dir_no\n");
    702 		break;
    703 	}
    704 	return (dirno);
    705 }
    706