## Linux and UNIX Man Pages

Test Your Knowledge in Computers #592
Difficulty: Medium
Suppose we want to sort a huge collection of 1 trillion, 10^12, elements. Doing so with Selection Sort or Insertion Sort would require about n^2 = (10^12)^2 = 10^24 or 1 sextillion comparisons.
True or False?

# ieee80211_generic_frame_duration(9) [centos man page]

```IEEE80211_GENERIC_FR(9) 				  The basic mac80211 driver inte				   IEEE80211_GENERIC_FR(9)

NAME
ieee80211_generic_frame_duration - Calculate the duration field for a frame

SYNOPSIS
__le16 ieee80211_generic_frame_duration(struct ieee80211_hw * hw, struct ieee80211_vif * vif, enum ieee80211_band band, size_t frame_len,
struct ieee80211_rate * rate);

ARGUMENTS
hw
pointer obtained from ieee80211_alloc_hw.

vif
struct ieee80211_vif pointer from the add_interface callback.

band
the band to calculate the frame duration on

frame_len
the length of the frame.

rate
the rate at which the frame is going to be transmitted.

DESCRIPTION
Calculate the duration field of some generic frame, given its length and transmission rate (in 100kbps).

RETURN
The duration.

AUTHOR
Johannes Berg <johannes@sipsolutions.net>
Author.

Kernel Hackers Manual 3.10					     June 2014						   IEEE80211_GENERIC_FR(9)```

## Check Out this Related Man Page

```ENUM MAC80211_RATE_C(9) 				  The basic mac80211 driver inte				   ENUM MAC80211_RATE_C(9)

NAME
enum_mac80211_rate_control_flags - per-rate flags set by the Rate Control algorithm.

SYNOPSIS
enum mac80211_rate_control_flags {
IEEE80211_TX_RC_USE_RTS_CTS,
IEEE80211_TX_RC_USE_CTS_PROTECT,
IEEE80211_TX_RC_USE_SHORT_PREAMBLE,
IEEE80211_TX_RC_MCS,
IEEE80211_TX_RC_GREEN_FIELD,
IEEE80211_TX_RC_40_MHZ_WIDTH,
IEEE80211_TX_RC_DUP_DATA,
IEEE80211_TX_RC_SHORT_GI,
IEEE80211_TX_RC_VHT_MCS,
IEEE80211_TX_RC_80_MHZ_WIDTH,
IEEE80211_TX_RC_160_MHZ_WIDTH
};

CONSTANTS
IEEE80211_TX_RC_USE_RTS_CTS
Use RTS/CTS exchange for this rate.

IEEE80211_TX_RC_USE_CTS_PROTECT
CTS-to-self protection is required. This is set if the current BSS requires ERP protection.

IEEE80211_TX_RC_USE_SHORT_PREAMBLE
Use short preamble.

IEEE80211_TX_RC_MCS
HT rate.

IEEE80211_TX_RC_GREEN_FIELD
Indicates whether this rate should be used in Greenfield mode.

IEEE80211_TX_RC_40_MHZ_WIDTH
Indicates if the Channel Width should be 40 MHz.

IEEE80211_TX_RC_DUP_DATA
The frame should be transmitted on both of the adjacent 20 MHz channels, if the current channel type is NL80211_CHAN_HT40MINUS or
NL80211_CHAN_HT40PLUS.

IEEE80211_TX_RC_SHORT_GI
Short Guard interval should be used for this rate.

IEEE80211_TX_RC_VHT_MCS
VHT MCS rate, in this case the idx field is split into a higher 4 bits (Nss) and lower 4 bits (MCS number)

IEEE80211_TX_RC_80_MHZ_WIDTH
Indicates 80 MHz transmission

IEEE80211_TX_RC_160_MHZ_WIDTH
Indicates 160 MHz transmission (80+80 isn't supported yet)

DESCRIPTION
These flags are set by the Rate control algorithm for each rate during tx, in the flags member of struct ieee80211_tx_rate.

AUTHOR
Johannes Berg <johannes@sipsolutions.net>
Author.

Kernel Hackers Manual 3.10					     June 2014						   ENUM MAC80211_RATE_C(9)```

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