1/*-
2 * Copyright (c) 2007-2009 Sam Leffler, Errno Consulting
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD$");
28
29/*
30 * IEEE 802.11 PHY-related support.
31 */
32
33#include <sys/param.h>
34#include <sys/types.h>
35
36#include <net/if_llc.h>
37
38#include <net80211/_ieee80211.h>
39#include <net80211/ieee80211.h>
40
41#define	IEEE80211_F_SHPREAMBLE	0x00040000	/* STATUS: use short preamble */
42
43#include <err.h>
44#include <stdio.h>
45#include <stdarg.h>
46#include <stdlib.h>
47#include <strings.h>
48#include <unistd.h>
49
50struct ieee80211_rate_table {
51	int		rateCount;		/* NB: for proper padding */
52	uint8_t		rateCodeToIndex[256];	/* back mapping */
53	struct {
54		uint8_t		phy;		/* CCK/OFDM/TURBO */
55		uint32_t	rateKbps;	/* transfer rate in kbs */
56		uint8_t		shortPreamble;	/* mask for enabling short
57						 * preamble in CCK rate code */
58		uint8_t		dot11Rate;	/* value for supported rates
59						 * info element of MLME */
60		uint8_t		ctlRateIndex;	/* index of next lower basic
61						 * rate; used for dur. calcs */
62		uint16_t	lpAckDuration;	/* long preamble ACK dur. */
63		uint16_t	spAckDuration;	/* short preamble ACK dur. */
64	} info[32];
65};
66
67uint16_t
68ieee80211_compute_duration(const struct ieee80211_rate_table *rt,
69	uint32_t frameLen, uint16_t rate, int isShortPreamble);
70
71#define	KASSERT(c, msg) do {			\
72	if (!(c)) {				\
73		printf msg;			\
74		putchar('\n');			\
75		exit(-1);			\
76	}					\
77} while (0)
78
79static void
80panic(const char *fmt, ...)
81{
82	va_list ap;
83
84	va_start(ap, fmt);
85	vprintf(fmt, ap);
86	va_end(ap);
87	exit(-1);
88}
89
90/* shorthands to compact tables for readability */
91#define	OFDM	IEEE80211_T_OFDM
92#define	CCK	IEEE80211_T_CCK
93#define	TURBO	IEEE80211_T_TURBO
94#define	HALF	IEEE80211_T_OFDM_HALF
95#define	QUART	IEEE80211_T_OFDM_QUARTER
96#define	PBCC	(IEEE80211_T_OFDM_QUARTER+1)		/* XXX */
97#define	B(r)	(0x80 | r)
98#define	Mb(x)	(x*1000)
99
100static struct ieee80211_rate_table ieee80211_11b_table = {
101    .rateCount = 4,		/* XXX no PBCC */
102    .info = {
103/*                                   short            ctrl  */
104/*                                Preamble  dot11Rate Rate */
105     [0] = { .phy = CCK,     1000,    0x00,      B(2),   0 },/*   1 Mb */
106     [1] = { .phy = CCK,     2000,    0x04,      B(4),   1 },/*   2 Mb */
107     [2] = { .phy = CCK,     5500,    0x04,     B(11),   1 },/* 5.5 Mb */
108     [3] = { .phy = CCK,    11000,    0x04,     B(22),   1 },/*  11 Mb */
109     [4] = { .phy = PBCC,   22000,    0x04,        44,   3 } /*  22 Mb */
110    },
111};
112
113static struct ieee80211_rate_table ieee80211_11g_table = {
114    .rateCount = 12,
115    .info = {
116/*                                   short            ctrl  */
117/*                                Preamble  dot11Rate Rate */
118     [0] = { .phy = CCK,     1000,    0x00,      B(2),   0 },
119     [1] = { .phy = CCK,     2000,    0x04,      B(4),   1 },
120     [2] = { .phy = CCK,     5500,    0x04,     B(11),   2 },
121     [3] = { .phy = CCK,    11000,    0x04,     B(22),   3 },
122     [4] = { .phy = OFDM,    6000,    0x00,        12,   4 },
123     [5] = { .phy = OFDM,    9000,    0x00,        18,   4 },
124     [6] = { .phy = OFDM,   12000,    0x00,        24,   6 },
125     [7] = { .phy = OFDM,   18000,    0x00,        36,   6 },
126     [8] = { .phy = OFDM,   24000,    0x00,        48,   8 },
127     [9] = { .phy = OFDM,   36000,    0x00,        72,   8 },
128    [10] = { .phy = OFDM,   48000,    0x00,        96,   8 },
129    [11] = { .phy = OFDM,   54000,    0x00,       108,   8 }
130    },
131};
132
133static struct ieee80211_rate_table ieee80211_11a_table = {
134    .rateCount = 8,
135    .info = {
136/*                                   short            ctrl  */
137/*                                Preamble  dot11Rate Rate */
138     [0] = { .phy = OFDM,    6000,    0x00,     B(12),   0 },
139     [1] = { .phy = OFDM,    9000,    0x00,        18,   0 },
140     [2] = { .phy = OFDM,   12000,    0x00,     B(24),   2 },
141     [3] = { .phy = OFDM,   18000,    0x00,        36,   2 },
142     [4] = { .phy = OFDM,   24000,    0x00,     B(48),   4 },
143     [5] = { .phy = OFDM,   36000,    0x00,        72,   4 },
144     [6] = { .phy = OFDM,   48000,    0x00,        96,   4 },
145     [7] = { .phy = OFDM,   54000,    0x00,       108,   4 }
146    },
147};
148
149static struct ieee80211_rate_table ieee80211_half_table = {
150    .rateCount = 8,
151    .info = {
152/*                                   short            ctrl  */
153/*                                Preamble  dot11Rate Rate */
154     [0] = { .phy = HALF,    3000,    0x00,      B(6),   0 },
155     [1] = { .phy = HALF,    4500,    0x00,         9,   0 },
156     [2] = { .phy = HALF,    6000,    0x00,     B(12),   2 },
157     [3] = { .phy = HALF,    9000,    0x00,        18,   2 },
158     [4] = { .phy = HALF,   12000,    0x00,     B(24),   4 },
159     [5] = { .phy = HALF,   18000,    0x00,        36,   4 },
160     [6] = { .phy = HALF,   24000,    0x00,        48,   4 },
161     [7] = { .phy = HALF,   27000,    0x00,        54,   4 }
162    },
163};
164
165static struct ieee80211_rate_table ieee80211_quarter_table = {
166    .rateCount = 8,
167    .info = {
168/*                                   short            ctrl  */
169/*                                Preamble  dot11Rate Rate */
170     [0] = { .phy = QUART,   1500,    0x00,      B(3),   0 },
171     [1] = { .phy = QUART,   2250,    0x00,         4,   0 },
172     [2] = { .phy = QUART,   3000,    0x00,      B(9),   2 },
173     [3] = { .phy = QUART,   4500,    0x00,         9,   2 },
174     [4] = { .phy = QUART,   6000,    0x00,     B(12),   4 },
175     [5] = { .phy = QUART,   9000,    0x00,        18,   4 },
176     [6] = { .phy = QUART,  12000,    0x00,        24,   4 },
177     [7] = { .phy = QUART,  13500,    0x00,        27,   4 }
178    },
179};
180
181static struct ieee80211_rate_table ieee80211_turbog_table = {
182    .rateCount = 7,
183    .info = {
184/*                                   short            ctrl  */
185/*                                Preamble  dot11Rate Rate */
186     [0] = { .phy = TURBO,   12000,   0x00,     B(12),   0 },
187     [1] = { .phy = TURBO,   24000,   0x00,     B(24),   1 },
188     [2] = { .phy = TURBO,   36000,   0x00,        36,   1 },
189     [3] = { .phy = TURBO,   48000,   0x00,     B(48),   3 },
190     [4] = { .phy = TURBO,   72000,   0x00,        72,   3 },
191     [5] = { .phy = TURBO,   96000,   0x00,        96,   3 },
192     [6] = { .phy = TURBO,  108000,   0x00,       108,   3 }
193    },
194};
195
196static struct ieee80211_rate_table ieee80211_turboa_table = {
197    .rateCount = 8,
198    .info = {
199/*                                   short            ctrl  */
200/*                                Preamble  dot11Rate Rate */
201     [0] = { .phy = TURBO,   12000,   0x00,     B(12),   0 },
202     [1] = { .phy = TURBO,   18000,   0x00,        18,   0 },
203     [2] = { .phy = TURBO,   24000,   0x00,     B(24),   2 },
204     [3] = { .phy = TURBO,   36000,   0x00,        36,   2 },
205     [4] = { .phy = TURBO,   48000,   0x00,     B(48),   4 },
206     [5] = { .phy = TURBO,   72000,   0x00,        72,   4 },
207     [6] = { .phy = TURBO,   96000,   0x00,        96,   4 },
208     [7] = { .phy = TURBO,  108000,   0x00,       108,   4 }
209    },
210};
211
212#undef	Mb
213#undef	B
214#undef	OFDM
215#undef	CCK
216#undef	TURBO
217#undef	XR
218
219/*
220 * Setup a rate table's reverse lookup table and fill in
221 * ack durations.  The reverse lookup tables are assumed
222 * to be initialized to zero (or at least the first entry).
223 * We use this as a key that indicates whether or not
224 * we've previously setup the reverse lookup table.
225 *
226 * XXX not reentrant, but shouldn't matter
227 */
228static void
229ieee80211_setup_ratetable(struct ieee80211_rate_table *rt)
230{
231#define	N(a)	(sizeof(a)/sizeof(a[0]))
232#define	WLAN_CTRL_FRAME_SIZE \
233	(sizeof(struct ieee80211_frame_ack) + IEEE80211_CRC_LEN)
234
235	int i;
236
237	for (i = 0; i < N(rt->rateCodeToIndex); i++)
238		rt->rateCodeToIndex[i] = (uint8_t) -1;
239	for (i = 0; i < rt->rateCount; i++) {
240		uint8_t code = rt->info[i].dot11Rate;
241		uint8_t cix = rt->info[i].ctlRateIndex;
242		uint8_t ctl_rate = rt->info[cix].dot11Rate;
243
244		rt->rateCodeToIndex[code] = i;
245		if (code & IEEE80211_RATE_BASIC) {
246			/*
247			 * Map w/o basic rate bit too.
248			 */
249			code &= IEEE80211_RATE_VAL;
250			rt->rateCodeToIndex[code] = i;
251		}
252
253		/*
254		 * XXX for 11g the control rate to use for 5.5 and 11 Mb/s
255		 *     depends on whether they are marked as basic rates;
256		 *     the static tables are setup with an 11b-compatible
257		 *     2Mb/s rate which will work but is suboptimal
258		 *
259		 * NB: Control rate is always less than or equal to the
260		 *     current rate, so control rate's reverse lookup entry
261		 *     has been installed and following call is safe.
262		 */
263		rt->info[i].lpAckDuration = ieee80211_compute_duration(rt,
264			WLAN_CTRL_FRAME_SIZE, ctl_rate, 0);
265		rt->info[i].spAckDuration = ieee80211_compute_duration(rt,
266			WLAN_CTRL_FRAME_SIZE, ctl_rate, IEEE80211_F_SHPREAMBLE);
267	}
268
269#undef WLAN_CTRL_FRAME_SIZE
270#undef N
271}
272
273/* Setup all rate tables */
274static void
275ieee80211_phy_init(void)
276{
277#define N(arr)	(int)(sizeof(arr) / sizeof(arr[0]))
278	static struct ieee80211_rate_table * const ratetables[] = {
279		&ieee80211_half_table,
280		&ieee80211_quarter_table,
281		&ieee80211_11a_table,
282		&ieee80211_11g_table,
283		&ieee80211_turbog_table,
284		&ieee80211_turboa_table,
285		&ieee80211_turboa_table,
286		&ieee80211_11a_table,
287		&ieee80211_11g_table,
288		&ieee80211_11b_table
289	};
290	int i;
291
292	for (i = 0; i < N(ratetables); ++i)
293		ieee80211_setup_ratetable(ratetables[i]);
294
295#undef N
296}
297#define CCK_SIFS_TIME		10
298#define CCK_PREAMBLE_BITS	144
299#define CCK_PLCP_BITS		48
300
301#define OFDM_SIFS_TIME		16
302#define OFDM_PREAMBLE_TIME	20
303#define OFDM_PLCP_BITS		22
304#define OFDM_SYMBOL_TIME	4
305
306#define OFDM_HALF_SIFS_TIME	32
307#define OFDM_HALF_PREAMBLE_TIME	40
308#define OFDM_HALF_PLCP_BITS	22
309#define OFDM_HALF_SYMBOL_TIME	8
310
311#define OFDM_QUARTER_SIFS_TIME 		64
312#define OFDM_QUARTER_PREAMBLE_TIME	80
313#define OFDM_QUARTER_PLCP_BITS		22
314#define OFDM_QUARTER_SYMBOL_TIME	16
315
316#define TURBO_SIFS_TIME		8
317#define TURBO_PREAMBLE_TIME	14
318#define TURBO_PLCP_BITS		22
319#define TURBO_SYMBOL_TIME	4
320
321#define	HT_L_STF	8
322#define	HT_L_LTF	8
323#define	HT_L_SIG	4
324#define	HT_SIG		8
325#define	HT_STF		4
326#define	HT_LTF(n)	((n) * 4)
327
328/*
329 * Compute the time to transmit a frame of length frameLen bytes
330 * using the specified rate, phy, and short preamble setting.
331 * SIFS is included.
332 */
333uint16_t
334ieee80211_compute_duration(const struct ieee80211_rate_table *rt,
335	uint32_t frameLen, uint16_t rate, int isShortPreamble)
336{
337	uint8_t rix = rt->rateCodeToIndex[rate];
338	uint32_t bitsPerSymbol, numBits, numSymbols, phyTime, txTime;
339	uint32_t kbps;
340
341	KASSERT(rix != (uint8_t)-1, ("rate %d has no info", rate));
342	kbps = rt->info[rix].rateKbps;
343	if (kbps == 0)			/* XXX bandaid for channel changes */
344		return 0;
345
346	switch (rt->info[rix].phy) {
347	case IEEE80211_T_CCK:
348		phyTime		= CCK_PREAMBLE_BITS + CCK_PLCP_BITS;
349		if (isShortPreamble && rt->info[rix].shortPreamble)
350			phyTime >>= 1;
351		numBits		= frameLen << 3;
352		txTime		= CCK_SIFS_TIME + phyTime
353				+ ((numBits * 1000)/kbps);
354		break;
355	case IEEE80211_T_OFDM:
356		bitsPerSymbol	= (kbps * OFDM_SYMBOL_TIME) / 1000;
357		KASSERT(bitsPerSymbol != 0, ("full rate bps"));
358
359		numBits		= OFDM_PLCP_BITS + (frameLen << 3);
360		numSymbols	= howmany(numBits, bitsPerSymbol);
361		txTime		= OFDM_SIFS_TIME
362				+ OFDM_PREAMBLE_TIME
363				+ (numSymbols * OFDM_SYMBOL_TIME);
364		break;
365	case IEEE80211_T_OFDM_HALF:
366		bitsPerSymbol	= (kbps * OFDM_HALF_SYMBOL_TIME) / 1000;
367		KASSERT(bitsPerSymbol != 0, ("1/4 rate bps"));
368
369		numBits		= OFDM_PLCP_BITS + (frameLen << 3);
370		numSymbols	= howmany(numBits, bitsPerSymbol);
371		txTime		= OFDM_HALF_SIFS_TIME
372				+ OFDM_HALF_PREAMBLE_TIME
373				+ (numSymbols * OFDM_HALF_SYMBOL_TIME);
374		break;
375	case IEEE80211_T_OFDM_QUARTER:
376		bitsPerSymbol	= (kbps * OFDM_QUARTER_SYMBOL_TIME) / 1000;
377		KASSERT(bitsPerSymbol != 0, ("1/2 rate bps"));
378
379		numBits		= OFDM_PLCP_BITS + (frameLen << 3);
380		numSymbols	= howmany(numBits, bitsPerSymbol);
381		txTime		= OFDM_QUARTER_SIFS_TIME
382				+ OFDM_QUARTER_PREAMBLE_TIME
383				+ (numSymbols * OFDM_QUARTER_SYMBOL_TIME);
384		break;
385	case IEEE80211_T_TURBO:
386		/* we still save OFDM rates in kbps - so double them */
387		bitsPerSymbol = ((kbps << 1) * TURBO_SYMBOL_TIME) / 1000;
388		KASSERT(bitsPerSymbol != 0, ("turbo bps"));
389
390		numBits       = TURBO_PLCP_BITS + (frameLen << 3);
391		numSymbols    = howmany(numBits, bitsPerSymbol);
392		txTime        = TURBO_SIFS_TIME + TURBO_PREAMBLE_TIME
393			      + (numSymbols * TURBO_SYMBOL_TIME);
394		break;
395	default:
396		panic("%s: unknown phy %u (rate %u)\n", __func__,
397		      rt->info[rix].phy, rate);
398		break;
399	}
400	return txTime;
401}
402
403uint32_t
404ieee80211_compute_duration_ht(const struct ieee80211_rate_table *rt,
405	uint32_t frameLen, uint16_t rate,
406	int streams, int isht40, int isShortGI)
407{
408	static const uint16_t ht20_bps[16] = {
409	    26, 52, 78, 104, 156, 208, 234, 260,
410	    52, 104, 156, 208, 312, 416, 468, 520
411	};
412	static const uint16_t ht40_bps[16] = {
413	    54, 108, 162, 216, 324, 432, 486, 540,
414	    108, 216, 324, 432, 648, 864, 972, 1080,
415	};
416	uint32_t bitsPerSymbol, numBits, numSymbols, txTime;
417
418	KASSERT(rate & IEEE80211_RATE_MCS, ("not mcs %d", rate));
419	KASSERT((rate &~ IEEE80211_RATE_MCS) < 16, ("bad mcs 0x%x", rate));
420
421	if (isht40)
422		bitsPerSymbol = ht40_bps[rate & 0xf];
423	else
424		bitsPerSymbol = ht20_bps[rate & 0xf];
425	numBits = OFDM_PLCP_BITS + (frameLen << 3);
426	numSymbols = howmany(numBits, bitsPerSymbol);
427	if (isShortGI)
428		txTime = ((numSymbols * 18) + 4) / 5;	/* 3.6us */
429	else
430		txTime = numSymbols * 4;		/* 4us */
431	return txTime + HT_L_STF + HT_L_LTF +
432	    HT_L_SIG + HT_SIG + HT_STF + HT_LTF(streams);
433}
434
435static const struct ieee80211_rate_table *
436mode2table(const char *mode)
437{
438	if (strcasecmp(mode, "half") == 0)
439		return &ieee80211_half_table;
440	else if (strcasecmp(mode, "quarter") == 0)
441		return &ieee80211_quarter_table;
442	else if (strcasecmp(mode, "hta") == 0)
443		return &ieee80211_11a_table;	/* XXX */
444	else if (strcasecmp(mode, "htg") == 0)
445		return &ieee80211_11g_table;	/* XXX */
446	else if (strcasecmp(mode, "108g") == 0)
447		return &ieee80211_turbog_table;
448	else if (strcasecmp(mode, "sturbo") == 0)
449		return &ieee80211_turboa_table;
450	else if (strcasecmp(mode, "turbo") == 0)
451		return &ieee80211_turboa_table;
452	else if (strcasecmp(mode, "11a") == 0)
453		return &ieee80211_11a_table;
454	else if (strcasecmp(mode, "11g") == 0)
455		return &ieee80211_11g_table;
456	else if (strcasecmp(mode, "11b") == 0)
457		return &ieee80211_11b_table;
458	else
459		return NULL;
460}
461
462const char *
463srate(int rate)
464{
465	static char buf[32];
466	if (rate & 1)
467		snprintf(buf, sizeof(buf), "%u.5", rate/2);
468	else
469		snprintf(buf, sizeof(buf), "%u", rate/2);
470	return buf;
471}
472
473static int
474checkpreamble(const struct ieee80211_rate_table *rt, uint8_t rix,
475	int isShortPreamble, int verbose)
476{
477	if (isShortPreamble) {
478		if (rt->info[rix].phy != IEEE80211_T_CCK) {
479			if (verbose)
480				warnx("short preamble not meaningful, ignored");
481			isShortPreamble = 0;
482		} else if (!rt->info[rix].shortPreamble) {
483			if (verbose)
484				warnx("short preamble not meaningful with "
485				    "rate %s, ignored",
486				    srate(rt->info[rix].dot11Rate &~ IEEE80211_RATE_BASIC));
487			isShortPreamble = 0;
488		}
489	}
490	return isShortPreamble;
491}
492
493static void
494usage(const char *progname)
495{
496	fprintf(stderr, "usage: %s [-a] [-l framelen] [-m mode] [-r rate] [-s]\n",
497	    progname);
498	fprintf(stderr, "-a             display calculations for all possible rates\n");
499	fprintf(stderr, "-l framelen    length in bytes of 802.11 payload (default 1536)\n");
500	fprintf(stderr, "-m 11a         calculate for 11a channel\n");
501	fprintf(stderr, "-m 11b         calculate for 11b channel\n");
502	fprintf(stderr, "-m 11g         calculate for 11g channel (default)\n");
503	fprintf(stderr, "-m half        calculate for 1/2 width channel\n");
504	fprintf(stderr, "-m quarter     calculate for 1/4 width channel\n");
505	fprintf(stderr, "-m 108g        calculate for dynamic turbo 11g channel\n");
506	fprintf(stderr, "-m sturbo      calculate for static turbo channel\n");
507	fprintf(stderr, "-m turbo       calculate for dynamic turbo 11a channel\n");
508	fprintf(stderr, "-r rate        IEEE rate code (default 54)\n");
509	fprintf(stderr, "-s             short preamble (default long)\n");
510	exit(0);
511}
512
513int
514main(int argc, char *argv[])
515{
516	const struct ieee80211_rate_table *rt;
517	const char *mode;
518	uint32_t frameLen;
519	uint16_t rate;
520	uint16_t time;
521	uint8_t rix;
522	int ch, allrates, isShortPreamble, isShort;
523	float frate;
524
525	ieee80211_phy_init();
526
527	mode = "11g";
528	isShortPreamble = 0;
529	frameLen = 1500
530		 + sizeof(struct ieee80211_frame)
531		 + LLC_SNAPFRAMELEN
532		 + IEEE80211_CRC_LEN
533		 ;
534	rate = 2*54;
535	allrates = 0;
536	while ((ch = getopt(argc, argv, "al:m:r:s")) != -1) {
537		switch (ch) {
538		case 'a':
539			allrates = 1;
540			break;
541		case 'l':
542			frameLen = strtoul(optarg, NULL, 0);
543			break;
544		case 'm':
545			mode = optarg;
546			break;
547		case 'r':
548			frate = atof(optarg);
549			rate = (int) 2*frate;
550			break;
551		case 's':
552			isShortPreamble = 1;
553			break;
554		default:
555			usage(argv[0]);
556			break;
557		}
558	}
559	rt = mode2table(mode);
560	if (rt == NULL)
561		errx(-1, "unknown mode %s", mode);
562	if (!allrates) {
563		rix = rt->rateCodeToIndex[rate];
564		if (rix == (uint8_t) -1)
565			errx(-1, "rate %s not valid for mode %s", srate(rate), mode);
566		isShort = checkpreamble(rt, rix, isShortPreamble, 1);
567
568		time = ieee80211_compute_duration(rt, frameLen, rate, isShort);
569		printf("%u usec to send %u bytes @ %s Mb/s, %s preamble\n",
570		    time, frameLen, srate(rate),
571		    isShort ? "short" : "long");
572	} else {
573		for (rix = 0; rix < rt->rateCount; rix++) {
574			rate = rt->info[rix].dot11Rate &~ IEEE80211_RATE_BASIC;
575			isShort = checkpreamble(rt, rix, isShortPreamble, 0);
576			time = ieee80211_compute_duration(rt, frameLen, rate,
577			    isShort);
578			printf("%u usec to send %u bytes @ %s Mb/s, %s preamble\n",
579			    time, frameLen, srate(rate),
580			    isShort ? "short" : "long");
581		}
582	}
583	return 0;
584}
585