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author | adrian <adrian@FreeBSD.org> | 2011-01-28 08:35:55 +0000 |
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committer | adrian <adrian@FreeBSD.org> | 2011-01-28 08:35:55 +0000 |
commit | 2dc68374964e0ce1ac3ef355d0b1ffffdfaafd0e (patch) | |
tree | f4a1dfbf8c19384fa0d8aacd88c0e41c562a5837 | |
parent | 4d002160ce841251c6eae54ef713c0b159b250ea (diff) | |
download | FreeBSD-src-2dc68374964e0ce1ac3ef355d0b1ffffdfaafd0e.zip FreeBSD-src-2dc68374964e0ce1ac3ef355d0b1ffffdfaafd0e.tar.gz |
Bring in some 802.11n packet duration calculation functions from a mix of Sam/Rui and linux ath9k .
This will eventually be used by rate control modules and by the TX
code for calculating packet duration when handling rts/cts protection.
Obtained from: sam@, rpaulo@, linux ath9k
-rw-r--r-- | sys/dev/ath/ath_hal/ah.c | 72 | ||||
-rw-r--r-- | sys/dev/ath/ath_hal/ah.h | 15 |
2 files changed, 86 insertions, 1 deletions
diff --git a/sys/dev/ath/ath_hal/ah.c b/sys/dev/ath/ath_hal/ah.c index f208d48..031caa2 100644 --- a/sys/dev/ath/ath_hal/ah.c +++ b/sys/dev/ath/ath_hal/ah.c @@ -234,6 +234,78 @@ ath_hal_reverseBits(uint32_t val, uint32_t n) return retval; } +/* 802.11n related timing definitions */ + +#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) + +#define HT_RC_2_MCS(_rc) ((_rc) & 0xf) +#define HT_RC_2_STREAMS(_rc) ((((_rc) & 0x78) >> 3) + 1) +#define IS_HT_RATE(_rc) ( (_rc) & IEEE80211_RATE_MCS) + +/* + * Calculate the duration of a packet whether it is 11n or legacy. + */ +uint32_t +ath_hal_pkt_txtime(struct ath_hal *ah, const HAL_RATE_TABLE *rates, uint32_t frameLen, + uint16_t rateix, HAL_BOOL isht40, HAL_BOOL shortPreamble) +{ + uint8_t rc; + int numStreams; + + rc = rates->info[rateix].rateCode; + + /* Legacy rate? Return the old way */ + if (! IS_HT_RATE(rc)) + return ath_hal_computetxtime(ah, rates, frameLen, rateix, shortPreamble); + + /* 11n frame - extract out the number of spatial streams */ + numStreams = HT_RC_2_STREAMS(rc); + KASSERT(numStreams == 1 || numStreams == 2, ("number of spatial streams needs to be 1 or 2: MCS rate 0x%x!", rateix)); + + return ath_computedur_ht(frameLen, rc, numStreams, isht40, shortPreamble); +} + +/* + * Calculate the transmit duration of an 11n frame. + * This only works for MCS0->MCS15. + */ +uint32_t +ath_computedur_ht(uint32_t frameLen, uint16_t rate, int streams, HAL_BOOL isht40, + HAL_BOOL isShortGI) +{ + static const uint16_t ht20_bps[16] = { + 26, 52, 78, 104, 156, 208, 234, 260, + 52, 104, 156, 208, 312, 416, 468, 520 + }; + static const uint16_t ht40_bps[16] = { + 54, 108, 162, 216, 324, 432, 486, 540, + 108, 216, 324, 432, 648, 864, 972, 1080, + }; + uint32_t bitsPerSymbol, numBits, numSymbols, txTime; + + KASSERT(rate & IEEE80211_RATE_MCS, ("not mcs %d", rate)); + KASSERT((rate &~ IEEE80211_RATE_MCS) < 16, ("bad mcs 0x%x", rate)); + + if (isht40) + bitsPerSymbol = ht40_bps[rate & 0xf]; + else + bitsPerSymbol = ht20_bps[rate & 0xf]; + 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); +} + /* * Compute the time to transmit a frame of length frameLen bytes * using the specified rate, phy, and short preamble setting. diff --git a/sys/dev/ath/ath_hal/ah.h b/sys/dev/ath/ath_hal/ah.h index c9bdfbb..3a8ad6b 100644 --- a/sys/dev/ath/ath_hal/ah.h +++ b/sys/dev/ath/ath_hal/ah.h @@ -882,7 +882,20 @@ extern void __ahdecl ath_hal_process_noisefloor(struct ath_hal *ah); extern u_int __ahdecl ath_hal_getwirelessmodes(struct ath_hal*); /* - * Calculate the transmit duration of a frame. + * Calculate the packet TX time for a legacy or 11n frame + */ +extern uint32_t __ahdecl ath_hal_pkt_txtime(struct ath_hal *ah, + const HAL_RATE_TABLE *rates, uint32_t frameLen, + uint16_t rateix, HAL_BOOL isht40, HAL_BOOL shortPreamble); + +/* + * Calculate the duration of an 11n frame. + */ +extern uint32_t __ahdecl ath_computedur_ht(uint32_t frameLen, uint16_t rate, + int streams, HAL_BOOL isht40, HAL_BOOL isShortGI); + +/* + * Calculate the transmit duration of a legacy frame. */ extern uint16_t __ahdecl ath_hal_computetxtime(struct ath_hal *, const HAL_RATE_TABLE *rates, uint32_t frameLen, |