/*- * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); /* * IEEE 802.11 PHY-related support. */ #include "opt_inet.h" #include #include #include #include #include #include #include #include #include #include #include #ifdef notyet struct ieee80211_ds_plcp_hdr { uint8_t i_signal; uint8_t i_service; uint16_t i_length; uint16_t i_crc; } __packed; #endif /* notyet */ /* shorthands to compact tables for readability */ #define OFDM IEEE80211_T_OFDM #define CCK IEEE80211_T_CCK #define TURBO IEEE80211_T_TURBO #define HALF IEEE80211_T_OFDM_HALF #define QUART IEEE80211_T_OFDM_QUARTER #define HT IEEE80211_T_HT /* XXX the 11n and the basic rate flag are unfortunately overlapping. Grr. */ #define N(r) (IEEE80211_RATE_MCS | r) #define PBCC (IEEE80211_T_OFDM_QUARTER+1) /* XXX */ #define B(r) (IEEE80211_RATE_BASIC | r) #define Mb(x) (x*1000) static struct ieee80211_rate_table ieee80211_11b_table = { .rateCount = 4, /* XXX no PBCC */ .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = CCK, 1000, 0x00, B(2), 0 },/* 1 Mb */ [1] = { .phy = CCK, 2000, 0x04, B(4), 1 },/* 2 Mb */ [2] = { .phy = CCK, 5500, 0x04, B(11), 1 },/* 5.5 Mb */ [3] = { .phy = CCK, 11000, 0x04, B(22), 1 },/* 11 Mb */ [4] = { .phy = PBCC, 22000, 0x04, 44, 3 } /* 22 Mb */ }, }; static struct ieee80211_rate_table ieee80211_11g_table = { .rateCount = 12, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = CCK, 1000, 0x00, B(2), 0 }, [1] = { .phy = CCK, 2000, 0x04, B(4), 1 }, [2] = { .phy = CCK, 5500, 0x04, B(11), 2 }, [3] = { .phy = CCK, 11000, 0x04, B(22), 3 }, [4] = { .phy = OFDM, 6000, 0x00, 12, 4 }, [5] = { .phy = OFDM, 9000, 0x00, 18, 4 }, [6] = { .phy = OFDM, 12000, 0x00, 24, 6 }, [7] = { .phy = OFDM, 18000, 0x00, 36, 6 }, [8] = { .phy = OFDM, 24000, 0x00, 48, 8 }, [9] = { .phy = OFDM, 36000, 0x00, 72, 8 }, [10] = { .phy = OFDM, 48000, 0x00, 96, 8 }, [11] = { .phy = OFDM, 54000, 0x00, 108, 8 } }, }; static struct ieee80211_rate_table ieee80211_11a_table = { .rateCount = 8, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = OFDM, 6000, 0x00, B(12), 0 }, [1] = { .phy = OFDM, 9000, 0x00, 18, 0 }, [2] = { .phy = OFDM, 12000, 0x00, B(24), 2 }, [3] = { .phy = OFDM, 18000, 0x00, 36, 2 }, [4] = { .phy = OFDM, 24000, 0x00, B(48), 4 }, [5] = { .phy = OFDM, 36000, 0x00, 72, 4 }, [6] = { .phy = OFDM, 48000, 0x00, 96, 4 }, [7] = { .phy = OFDM, 54000, 0x00, 108, 4 } }, }; static struct ieee80211_rate_table ieee80211_half_table = { .rateCount = 8, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = HALF, 3000, 0x00, B(6), 0 }, [1] = { .phy = HALF, 4500, 0x00, 9, 0 }, [2] = { .phy = HALF, 6000, 0x00, B(12), 2 }, [3] = { .phy = HALF, 9000, 0x00, 18, 2 }, [4] = { .phy = HALF, 12000, 0x00, B(24), 4 }, [5] = { .phy = HALF, 18000, 0x00, 36, 4 }, [6] = { .phy = HALF, 24000, 0x00, 48, 4 }, [7] = { .phy = HALF, 27000, 0x00, 54, 4 } }, }; static struct ieee80211_rate_table ieee80211_quarter_table = { .rateCount = 8, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = QUART, 1500, 0x00, B(3), 0 }, [1] = { .phy = QUART, 2250, 0x00, 4, 0 }, [2] = { .phy = QUART, 3000, 0x00, B(9), 2 }, [3] = { .phy = QUART, 4500, 0x00, 9, 2 }, [4] = { .phy = QUART, 6000, 0x00, B(12), 4 }, [5] = { .phy = QUART, 9000, 0x00, 18, 4 }, [6] = { .phy = QUART, 12000, 0x00, 24, 4 }, [7] = { .phy = QUART, 13500, 0x00, 27, 4 } }, }; static struct ieee80211_rate_table ieee80211_turbog_table = { .rateCount = 7, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = TURBO, 12000, 0x00, B(12), 0 }, [1] = { .phy = TURBO, 24000, 0x00, B(24), 1 }, [2] = { .phy = TURBO, 36000, 0x00, 36, 1 }, [3] = { .phy = TURBO, 48000, 0x00, B(48), 3 }, [4] = { .phy = TURBO, 72000, 0x00, 72, 3 }, [5] = { .phy = TURBO, 96000, 0x00, 96, 3 }, [6] = { .phy = TURBO, 108000, 0x00, 108, 3 } }, }; static struct ieee80211_rate_table ieee80211_turboa_table = { .rateCount = 8, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = TURBO, 12000, 0x00, B(12), 0 }, [1] = { .phy = TURBO, 18000, 0x00, 18, 0 }, [2] = { .phy = TURBO, 24000, 0x00, B(24), 2 }, [3] = { .phy = TURBO, 36000, 0x00, 36, 2 }, [4] = { .phy = TURBO, 48000, 0x00, B(48), 4 }, [5] = { .phy = TURBO, 72000, 0x00, 72, 4 }, [6] = { .phy = TURBO, 96000, 0x00, 96, 4 }, [7] = { .phy = TURBO, 108000, 0x00, 108, 4 } }, }; static struct ieee80211_rate_table ieee80211_11ng_table = { .rateCount = 36, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = CCK, 1000, 0x00, B(2), 0 }, [1] = { .phy = CCK, 2000, 0x04, B(4), 1 }, [2] = { .phy = CCK, 5500, 0x04, B(11), 2 }, [3] = { .phy = CCK, 11000, 0x04, B(22), 3 }, [4] = { .phy = OFDM, 6000, 0x00, 12, 4 }, [5] = { .phy = OFDM, 9000, 0x00, 18, 4 }, [6] = { .phy = OFDM, 12000, 0x00, 24, 6 }, [7] = { .phy = OFDM, 18000, 0x00, 36, 6 }, [8] = { .phy = OFDM, 24000, 0x00, 48, 8 }, [9] = { .phy = OFDM, 36000, 0x00, 72, 8 }, [10] = { .phy = OFDM, 48000, 0x00, 96, 8 }, [11] = { .phy = OFDM, 54000, 0x00, 108, 8 }, [12] = { .phy = HT, 6500, 0x00, N(0), 4 }, [13] = { .phy = HT, 13000, 0x00, N(1), 6 }, [14] = { .phy = HT, 19500, 0x00, N(2), 6 }, [15] = { .phy = HT, 26000, 0x00, N(3), 8 }, [16] = { .phy = HT, 39000, 0x00, N(4), 8 }, [17] = { .phy = HT, 52000, 0x00, N(5), 8 }, [18] = { .phy = HT, 58500, 0x00, N(6), 8 }, [19] = { .phy = HT, 65000, 0x00, N(7), 8 }, [20] = { .phy = HT, 13000, 0x00, N(8), 4 }, [21] = { .phy = HT, 26000, 0x00, N(9), 6 }, [22] = { .phy = HT, 39000, 0x00, N(10), 6 }, [23] = { .phy = HT, 52000, 0x00, N(11), 8 }, [24] = { .phy = HT, 78000, 0x00, N(12), 8 }, [25] = { .phy = HT, 104000, 0x00, N(13), 8 }, [26] = { .phy = HT, 117000, 0x00, N(14), 8 }, [27] = { .phy = HT, 130000, 0x00, N(15), 8 }, [28] = { .phy = HT, 19500, 0x00, N(16), 4 }, [29] = { .phy = HT, 39000, 0x00, N(17), 6 }, [30] = { .phy = HT, 58500, 0x00, N(18), 6 }, [31] = { .phy = HT, 78000, 0x00, N(19), 8 }, [32] = { .phy = HT, 117000, 0x00, N(20), 8 }, [33] = { .phy = HT, 156000, 0x00, N(21), 8 }, [34] = { .phy = HT, 175500, 0x00, N(22), 8 }, [35] = { .phy = HT, 195000, 0x00, N(23), 8 }, }, }; static struct ieee80211_rate_table ieee80211_11na_table = { .rateCount = 32, .info = { /* short ctrl */ /* Preamble dot11Rate Rate */ [0] = { .phy = OFDM, 6000, 0x00, B(12), 0 }, [1] = { .phy = OFDM, 9000, 0x00, 18, 0 }, [2] = { .phy = OFDM, 12000, 0x00, B(24), 2 }, [3] = { .phy = OFDM, 18000, 0x00, 36, 2 }, [4] = { .phy = OFDM, 24000, 0x00, B(48), 4 }, [5] = { .phy = OFDM, 36000, 0x00, 72, 4 }, [6] = { .phy = OFDM, 48000, 0x00, 96, 4 }, [7] = { .phy = OFDM, 54000, 0x00, 108, 4 }, [8] = { .phy = HT, 6500, 0x00, N(0), 0 }, [9] = { .phy = HT, 13000, 0x00, N(1), 2 }, [10] = { .phy = HT, 19500, 0x00, N(2), 2 }, [11] = { .phy = HT, 26000, 0x00, N(3), 4 }, [12] = { .phy = HT, 39000, 0x00, N(4), 4 }, [13] = { .phy = HT, 52000, 0x00, N(5), 4 }, [14] = { .phy = HT, 58500, 0x00, N(6), 4 }, [15] = { .phy = HT, 65000, 0x00, N(7), 4 }, [16] = { .phy = HT, 13000, 0x00, N(8), 0 }, [17] = { .phy = HT, 26000, 0x00, N(9), 2 }, [18] = { .phy = HT, 39000, 0x00, N(10), 2 }, [19] = { .phy = HT, 52000, 0x00, N(11), 4 }, [20] = { .phy = HT, 78000, 0x00, N(12), 4 }, [21] = { .phy = HT, 104000, 0x00, N(13), 4 }, [22] = { .phy = HT, 117000, 0x00, N(14), 4 }, [23] = { .phy = HT, 130000, 0x00, N(15), 4 }, [24] = { .phy = HT, 19500, 0x00, N(16), 0 }, [25] = { .phy = HT, 39000, 0x00, N(17), 2 }, [26] = { .phy = HT, 58500, 0x00, N(18), 2 }, [27] = { .phy = HT, 78000, 0x00, N(19), 4 }, [28] = { .phy = HT, 117000, 0x00, N(20), 4 }, [29] = { .phy = HT, 156000, 0x00, N(21), 4 }, [30] = { .phy = HT, 175500, 0x00, N(22), 4 }, [31] = { .phy = HT, 195000, 0x00, N(23), 4 }, }, }; #undef Mb #undef B #undef OFDM #undef HALF #undef QUART #undef CCK #undef TURBO #undef XR #undef HT #undef N /* * Setup a rate table's reverse lookup table and fill in * ack durations. The reverse lookup tables are assumed * to be initialized to zero (or at least the first entry). * We use this as a key that indicates whether or not * we've previously setup the reverse lookup table. * * XXX not reentrant, but shouldn't matter */ static void ieee80211_setup_ratetable(struct ieee80211_rate_table *rt) { #define WLAN_CTRL_FRAME_SIZE \ (sizeof(struct ieee80211_frame_ack) + IEEE80211_CRC_LEN) int i; for (i = 0; i < nitems(rt->rateCodeToIndex); i++) rt->rateCodeToIndex[i] = (uint8_t) -1; for (i = 0; i < rt->rateCount; i++) { uint8_t code = rt->info[i].dot11Rate; uint8_t cix = rt->info[i].ctlRateIndex; uint8_t ctl_rate = rt->info[cix].dot11Rate; /* * Map without the basic rate bit. * * It's up to the caller to ensure that the basic * rate bit is stripped here. * * For HT, use the MCS rate bit. */ code &= IEEE80211_RATE_VAL; if (rt->info[i].phy == IEEE80211_T_HT) { code |= IEEE80211_RATE_MCS; } /* XXX assume the control rate is non-MCS? */ ctl_rate &= IEEE80211_RATE_VAL; rt->rateCodeToIndex[code] = i; /* * XXX for 11g the control rate to use for 5.5 and 11 Mb/s * depends on whether they are marked as basic rates; * the static tables are setup with an 11b-compatible * 2Mb/s rate which will work but is suboptimal * * NB: Control rate is always less than or equal to the * current rate, so control rate's reverse lookup entry * has been installed and following call is safe. */ rt->info[i].lpAckDuration = ieee80211_compute_duration(rt, WLAN_CTRL_FRAME_SIZE, ctl_rate, 0); rt->info[i].spAckDuration = ieee80211_compute_duration(rt, WLAN_CTRL_FRAME_SIZE, ctl_rate, IEEE80211_F_SHPREAMBLE); } #undef WLAN_CTRL_FRAME_SIZE } /* Setup all rate tables */ static void ieee80211_phy_init(void) { static struct ieee80211_rate_table * const ratetables[] = { &ieee80211_half_table, &ieee80211_quarter_table, &ieee80211_11na_table, &ieee80211_11ng_table, &ieee80211_turbog_table, &ieee80211_turboa_table, &ieee80211_11a_table, &ieee80211_11g_table, &ieee80211_11b_table }; int i; for (i = 0; i < nitems(ratetables); ++i) ieee80211_setup_ratetable(ratetables[i]); } SYSINIT(wlan_phy, SI_SUB_DRIVERS, SI_ORDER_FIRST, ieee80211_phy_init, NULL); const struct ieee80211_rate_table * ieee80211_get_ratetable(struct ieee80211_channel *c) { const struct ieee80211_rate_table *rt; /* XXX HT */ if (IEEE80211_IS_CHAN_HALF(c)) rt = &ieee80211_half_table; else if (IEEE80211_IS_CHAN_QUARTER(c)) rt = &ieee80211_quarter_table; else if (IEEE80211_IS_CHAN_HTA(c)) rt = &ieee80211_11na_table; else if (IEEE80211_IS_CHAN_HTG(c)) rt = &ieee80211_11ng_table; else if (IEEE80211_IS_CHAN_108G(c)) rt = &ieee80211_turbog_table; else if (IEEE80211_IS_CHAN_ST(c)) rt = &ieee80211_turboa_table; else if (IEEE80211_IS_CHAN_TURBO(c)) rt = &ieee80211_turboa_table; else if (IEEE80211_IS_CHAN_A(c)) rt = &ieee80211_11a_table; else if (IEEE80211_IS_CHAN_ANYG(c)) rt = &ieee80211_11g_table; else if (IEEE80211_IS_CHAN_B(c)) rt = &ieee80211_11b_table; else { /* NB: should not get here */ panic("%s: no rate table for channel; freq %u flags 0x%x\n", __func__, c->ic_freq, c->ic_flags); } return rt; } /* * Convert PLCP signal/rate field to 802.11 rate (.5Mbits/s) * * Note we do no parameter checking; this routine is mainly * used to derive an 802.11 rate for constructing radiotap * header data for rx frames. * * XXX might be a candidate for inline */ uint8_t ieee80211_plcp2rate(uint8_t plcp, enum ieee80211_phytype type) { if (type == IEEE80211_T_OFDM) { static const uint8_t ofdm_plcp2rate[16] = { [0xb] = 12, [0xf] = 18, [0xa] = 24, [0xe] = 36, [0x9] = 48, [0xd] = 72, [0x8] = 96, [0xc] = 108 }; return ofdm_plcp2rate[plcp & 0xf]; } if (type == IEEE80211_T_CCK) { static const uint8_t cck_plcp2rate[16] = { [0xa] = 2, /* 0x0a */ [0x4] = 4, /* 0x14 */ [0x7] = 11, /* 0x37 */ [0xe] = 22, /* 0x6e */ [0xc] = 44, /* 0xdc , actually PBCC */ }; return cck_plcp2rate[plcp & 0xf]; } return 0; } /* * Covert 802.11 rate to PLCP signal. */ uint8_t ieee80211_rate2plcp(int rate, enum ieee80211_phytype type) { /* XXX ignore type for now since rates are unique */ switch (rate) { /* OFDM rates (cf IEEE Std 802.11a-1999, pp. 14 Table 80) */ case 12: return 0xb; case 18: return 0xf; case 24: return 0xa; case 36: return 0xe; case 48: return 0x9; case 72: return 0xd; case 96: return 0x8; case 108: return 0xc; /* CCK rates (IEEE Std 802.11b-1999 page 15, subclause 18.2.3.3) */ case 2: return 10; case 4: return 20; case 11: return 55; case 22: return 110; /* IEEE Std 802.11g-2003 page 19, subclause 19.3.2.1 */ case 44: return 220; } return 0; /* XXX unsupported/unknown rate */ } #define CCK_SIFS_TIME 10 #define CCK_PREAMBLE_BITS 144 #define CCK_PLCP_BITS 48 #define OFDM_SIFS_TIME 16 #define OFDM_PREAMBLE_TIME 20 #define OFDM_PLCP_BITS 22 #define OFDM_SYMBOL_TIME 4 #define OFDM_HALF_SIFS_TIME 32 #define OFDM_HALF_PREAMBLE_TIME 40 #define OFDM_HALF_PLCP_BITS 22 #define OFDM_HALF_SYMBOL_TIME 8 #define OFDM_QUARTER_SIFS_TIME 64 #define OFDM_QUARTER_PREAMBLE_TIME 80 #define OFDM_QUARTER_PLCP_BITS 22 #define OFDM_QUARTER_SYMBOL_TIME 16 #define TURBO_SIFS_TIME 8 #define TURBO_PREAMBLE_TIME 14 #define TURBO_PLCP_BITS 22 #define TURBO_SYMBOL_TIME 4 /* * Compute the time to transmit a frame of length frameLen bytes * using the specified rate, phy, and short preamble setting. * SIFS is included. */ uint16_t ieee80211_compute_duration(const struct ieee80211_rate_table *rt, uint32_t frameLen, uint16_t rate, int isShortPreamble) { uint8_t rix = rt->rateCodeToIndex[rate]; uint32_t bitsPerSymbol, numBits, numSymbols, phyTime, txTime; uint32_t kbps; KASSERT(rix != (uint8_t)-1, ("rate %d has no info", rate)); kbps = rt->info[rix].rateKbps; if (kbps == 0) /* XXX bandaid for channel changes */ return 0; switch (rt->info[rix].phy) { case IEEE80211_T_CCK: phyTime = CCK_PREAMBLE_BITS + CCK_PLCP_BITS; if (isShortPreamble && rt->info[rix].shortPreamble) phyTime >>= 1; numBits = frameLen << 3; txTime = CCK_SIFS_TIME + phyTime + ((numBits * 1000)/kbps); break; case IEEE80211_T_OFDM: bitsPerSymbol = (kbps * OFDM_SYMBOL_TIME) / 1000; KASSERT(bitsPerSymbol != 0, ("full rate bps")); numBits = OFDM_PLCP_BITS + (frameLen << 3); numSymbols = howmany(numBits, bitsPerSymbol); txTime = OFDM_SIFS_TIME + OFDM_PREAMBLE_TIME + (numSymbols * OFDM_SYMBOL_TIME); break; case IEEE80211_T_OFDM_HALF: bitsPerSymbol = (kbps * OFDM_HALF_SYMBOL_TIME) / 1000; KASSERT(bitsPerSymbol != 0, ("1/4 rate bps")); numBits = OFDM_PLCP_BITS + (frameLen << 3); numSymbols = howmany(numBits, bitsPerSymbol); txTime = OFDM_HALF_SIFS_TIME + OFDM_HALF_PREAMBLE_TIME + (numSymbols * OFDM_HALF_SYMBOL_TIME); break; case IEEE80211_T_OFDM_QUARTER: bitsPerSymbol = (kbps * OFDM_QUARTER_SYMBOL_TIME) / 1000; KASSERT(bitsPerSymbol != 0, ("1/2 rate bps")); numBits = OFDM_PLCP_BITS + (frameLen << 3); numSymbols = howmany(numBits, bitsPerSymbol); txTime = OFDM_QUARTER_SIFS_TIME + OFDM_QUARTER_PREAMBLE_TIME + (numSymbols * OFDM_QUARTER_SYMBOL_TIME); break; case IEEE80211_T_TURBO: /* we still save OFDM rates in kbps - so double them */ bitsPerSymbol = ((kbps << 1) * TURBO_SYMBOL_TIME) / 1000; KASSERT(bitsPerSymbol != 0, ("turbo bps")); numBits = TURBO_PLCP_BITS + (frameLen << 3); numSymbols = howmany(numBits, bitsPerSymbol); txTime = TURBO_SIFS_TIME + TURBO_PREAMBLE_TIME + (numSymbols * TURBO_SYMBOL_TIME); break; default: panic("%s: unknown phy %u (rate %u)\n", __func__, rt->info[rix].phy, rate); break; } return txTime; } static const uint16_t ht20_bps[32] = { 26, 52, 78, 104, 156, 208, 234, 260, 52, 104, 156, 208, 312, 416, 468, 520, 78, 156, 234, 312, 468, 624, 702, 780, 104, 208, 312, 416, 624, 832, 936, 1040 }; static const uint16_t ht40_bps[32] = { 54, 108, 162, 216, 324, 432, 486, 540, 108, 216, 324, 432, 648, 864, 972, 1080, 162, 324, 486, 648, 972, 1296, 1458, 1620, 216, 432, 648, 864, 1296, 1728, 1944, 2160 }; #define OFDM_PLCP_BITS 22 #define HT_L_STF 8 #define HT_L_LTF 8 #define HT_L_SIG 4 #define HT_SIG 8 #define HT_STF 4 #define HT_LTF(n) ((n) * 4) /* * Calculate the transmit duration of an 11n frame. */ uint32_t ieee80211_compute_duration_ht(uint32_t frameLen, uint16_t rate, int streams, int isht40, int isShortGI) { uint32_t bitsPerSymbol, numBits, numSymbols, txTime; KASSERT(rate & IEEE80211_RATE_MCS, ("not mcs %d", rate)); KASSERT((rate &~ IEEE80211_RATE_MCS) < 31, ("bad mcs 0x%x", rate)); if (isht40) bitsPerSymbol = ht40_bps[rate & 0x1f]; else bitsPerSymbol = ht20_bps[rate & 0x1f]; numBits = OFDM_PLCP_BITS + (frameLen << 3); numSymbols = howmany(numBits, bitsPerSymbol); if (isShortGI) txTime = ((numSymbols * 18) + 4) / 5; /* 3.6us */ else txTime = numSymbols * 4; /* 4us */ return txTime + HT_L_STF + HT_L_LTF + HT_L_SIG + HT_SIG + HT_STF + HT_LTF(streams); } #undef HT_LTF #undef HT_STF #undef HT_SIG #undef HT_L_SIG #undef HT_L_LTF #undef HT_L_STF #undef OFDM_PLCP_BITS