From 2ff5a1fdb1cbf57c6a8cd0c303ef5c327091d5ab Mon Sep 17 00:00:00 2001 From: Matthew Wang Date: Mon, 1 Jun 2020 17:10:13 -0700 Subject: [PATCH] Use lookup-table instead of macro for TX rate estimates Change INTERPOLATE_RATE() macro to a lookup-table instead for the sake of readability. Signed-off-by: Matthew Wang --- wpa_supplicant/scan.c | 122 ++++++++++++++++++++++++++---------------- 1 file changed, 75 insertions(+), 47 deletions(-) diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c index b47573094..1c62c2ecf 100644 --- a/wpa_supplicant/scan.c +++ b/wpa_supplicant/scan.c @@ -2187,6 +2187,60 @@ void scan_snr(struct wpa_scan_res *res) } +/* Minimum SNR required to achieve a certain bitrate. */ +struct minsnr_bitrate_entry { + int minsnr; + unsigned int bitrate; /* in Mbps */ +}; + +/* VHT needs to be enabled in order to achieve MCS8 and MCS9 rates. */ +static const int vht_mcs = 8; + +static const struct minsnr_bitrate_entry vht20_table[] = { + { 0, 0 }, + { 2, 6500 }, /* HT20 MCS0 */ + { 5, 13000 }, /* HT20 MCS1 */ + { 9, 19500 }, /* HT20 MCS2 */ + { 11, 26000 }, /* HT20 MCS3 */ + { 15, 39000 }, /* HT20 MCS4 */ + { 18, 52000 }, /* HT20 MCS5 */ + { 20, 58500 }, /* HT20 MCS6 */ + { 25, 65000 }, /* HT20 MCS7 */ + { 29, 78000 }, /* VHT20 MCS8 */ + { -1, 78000 } /* SNR > 29 */ +}; + +static const struct minsnr_bitrate_entry vht40_table[] = { + { 0, 0 }, + { 5, 13500 }, /* HT40 MCS0 */ + { 8, 27000 }, /* HT40 MCS1 */ + { 12, 40500 }, /* HT40 MCS2 */ + { 14, 54000 }, /* HT40 MCS3 */ + { 18, 81000 }, /* HT40 MCS4 */ + { 21, 108000 }, /* HT40 MCS5 */ + { 23, 121500 }, /* HT40 MCS6 */ + { 28, 135000 }, /* HT40 MCS7 */ + { 32, 162000 }, /* VHT40 MCS8 */ + { 34, 180000 }, /* VHT40 MCS9 */ + { -1, 180000 } /* SNR > 34 */ +}; + +static const struct minsnr_bitrate_entry vht80_table[] = { + { 0, 0 }, + { 8, 29300 }, /* VHT80 MCS0 */ + { 11, 58500 }, /* VHT80 MCS1 */ + { 15, 87800 }, /* VHT80 MCS2 */ + { 17, 117000 }, /* VHT80 MCS3 */ + { 21, 175500 }, /* VHT80 MCS4 */ + { 24, 234000 }, /* VHT80 MCS5 */ + { 26, 263300 }, /* VHT80 MCS6 */ + { 31, 292500 }, /* VHT80 MCS7 */ + { 35, 351000 }, /* VHT80 MCS8 */ + { 37, 390000 }, /* VHT80 MCS9 */ + { -1, 390000 } /* SNR > 37 */ +}; + + static unsigned int interpolate_rate(int snr, int snr0, int snr1, int rate0, int rate1) { @@ -2194,68 +2248,42 @@ static unsigned int interpolate_rate(int snr, int snr0, int snr1, } -#define INTERPOLATE_RATE(snr0, snr1, rate0, rate1) \ - if (snr < (snr1)) \ - return interpolate_rate(snr, (snr0), (snr1), (rate0), (rate1)) +static unsigned int max_rate(const struct minsnr_bitrate_entry table[], + int snr, int vht) +{ + const struct minsnr_bitrate_entry *prev, *entry = table; + + while ((entry->minsnr != -1) && + (snr >= entry->minsnr) && + (vht || entry - table <= vht_mcs)) + entry++; + if (entry == table) + return entry->bitrate; + prev = entry - 1; + if (entry->minsnr == -1 || (!vht && entry - table > vht_mcs)) + return prev->bitrate; + return interpolate_rate(snr, prev->minsnr, entry->minsnr, prev->bitrate, + entry->bitrate); +} + static unsigned int max_ht20_rate(int snr, int vht) { - if (snr < 0) - return 0; - INTERPOLATE_RATE(0, 2, 0, 6500); /* HT20 MCS0 */ - INTERPOLATE_RATE(2, 5, 6500, 13000); /* HT20 MCS1 */ - INTERPOLATE_RATE(5, 9, 13000, 19500); /* HT20 MCS2 */ - INTERPOLATE_RATE(9, 11, 19500, 26000); /* HT20 MCS3 */ - INTERPOLATE_RATE(11, 15, 26000, 39000); /* HT20 MCS4 */ - INTERPOLATE_RATE(15, 18, 39000, 52000); /* HT20 MCS5 */ - INTERPOLATE_RATE(18, 20, 52000, 58500); /* HT20 MCS6 */ - INTERPOLATE_RATE(20, 25, 58500, 65000); /* HT20 MCS7 */ - if (!vht) - return 65000; - INTERPOLATE_RATE(25, 29, 65000, 78000); /* VHT20 MCS8 */ - return 78000; + return max_rate(vht20_table, snr, vht); } static unsigned int max_ht40_rate(int snr, int vht) { - if (snr < 0) - return 0; - INTERPOLATE_RATE(0, 5, 0, 13500); /* HT40 MCS0 */ - INTERPOLATE_RATE(5, 8, 13500, 27000); /* HT40 MCS1 */ - INTERPOLATE_RATE(8, 12, 27000, 40500); /* HT40 MCS2 */ - INTERPOLATE_RATE(12, 14, 40500, 54000); /* HT40 MCS3 */ - INTERPOLATE_RATE(14, 18, 54000, 81000); /* HT40 MCS4 */ - INTERPOLATE_RATE(18, 21, 81000, 108000); /* HT40 MCS5 */ - INTERPOLATE_RATE(21, 23, 108000, 121500); /* HT40 MCS6 */ - INTERPOLATE_RATE(23, 28, 121500, 135000); /* HT40 MCS7 */ - if (!vht) - return 135000; - INTERPOLATE_RATE(28, 32, 135000, 162000); /* VHT40 MCS8 */ - INTERPOLATE_RATE(32, 34, 162000, 180000); /* VHT40 MCS9 */ - return 180000; + return max_rate(vht40_table, snr, vht); } static unsigned int max_vht80_rate(int snr) { - if (snr < 0) - return 0; - INTERPOLATE_RATE(0, 8, 0, 29300); /* VHT80 MCS0 */ - INTERPOLATE_RATE(8, 11, 29300, 58500); /* VHT80 MCS1 */ - INTERPOLATE_RATE(11, 15, 58500, 87800); /* VHT80 MCS2 */ - INTERPOLATE_RATE(15, 17, 87800, 117000); /* VHT80 MCS3 */ - INTERPOLATE_RATE(17, 21, 117000, 175500); /* VHT80 MCS4 */ - INTERPOLATE_RATE(21, 24, 175500, 234000); /* VHT80 MCS5 */ - INTERPOLATE_RATE(24, 26, 234000, 263300); /* VHT80 MCS6 */ - INTERPOLATE_RATE(26, 31, 263300, 292500); /* VHT80 MCS7 */ - INTERPOLATE_RATE(31, 35, 292500, 351000); /* VHT80 MCS8 */ - INTERPOLATE_RATE(35, 37, 351000, 390000); /* VHT80 MCS9 */ - return 390000; + return max_rate(vht80_table, snr, 1); } -#undef INTERPOLATE_RATE - unsigned int wpas_get_est_tpt(const struct wpa_supplicant *wpa_s, const u8 *ies, size_t ies_len, int rate,