I had duplicated them. Improve the macros' names. Simplify their
implementation.
A brief description of each macro is below.
BIT(n): Return a bitmask with bit m set, where the least
significant bit is bit 0.
BITS(m, n): Return a bitmask with bits m through n, inclusive,
set. It does not matter whether m>n or m<=n.
The least significant bit is bit 0.
A "bitfield" is a span of consecutive bits defined by a
bitmask, where 1s select the bits in the bitfield. SHIFTIN,
SHIFTOUT, and SHIFTOUT_MASK help read and write bitfields
from device registers.
SHIFTIN(v, mask): Left-shift bits `v' into the bitfield
defined by `mask', and return them. No
side-effects.
SHIFTOUT(v, mask): Extract and return the bitfield selected
by `mask' from `v', right-shifting the
bits so that the rightmost selected bit
is at bit 0. No side-effects.
SHIFTOUT_MASK(mask): Right-shift the bits in `mask' so that
the rightmost non-zero bit is at bit
0. This is useful for finding the
greatest unsigned value that a bitfield
can hold. No side-effects. Note that
SHIFTOUT_MASK(m) = SHIFTOUT(m, m).
Examples:
/*
* Register definitions taken from the RFMD RF3000 manual.
*/
#define RF3000_GAINCTL 0x11 /* TX variable gain control */
#define RF3000_GAINCTL_TXVGC_MASK BITS(7, 2)
#define RF3000_GAINCTL_SCRAMBLER BIT(1)
/*
* Shift the transmit power into the transmit-power field of the
* gain-control register and write it to the baseband processor.
*/
atw_rf3000_write(sc, RF3000_GAINCTL,
SHIFTIN(txpower, RF3000_GAINCTL_TXVGC_MASK));
/*
* Register definitions taken from the ADMtek ADM8211 manual.
*
*/
#define ATW_RXSTAT_OWN BIT(31) /* 1: NIC may fill descriptor */
/* ... */
#define ATW_RXSTAT_DA1 BIT(17) /* DA bit 1, admin'd address */
#define ATW_RXSTAT_DA0 BIT(16) /* DA bit 0, group address */
#define ATW_RXSTAT_RXDR_MASK BITS(15,12) /* RX data rate */
#define ATW_RXSTAT_FL_MASK BITS(11,0) /* RX frame length, last
* descriptor only
*/
/* Extract the frame length from the Rx descriptor's
* status field.
*/
len = SHIFTOUT(rxstat, ATW_RXSTAT_FL_MASK);
Duration and PLCP Length fields, and delete the abominable
atw_frame_setdurs() subroutine.
Make rtw(4) use the new ieee80211_compute_duration() calling
convention.
Add an ieee80211_key argument to ieee80211_compute_duration() and
lightly constify arguments. Get the crypto header length from the
key argument instead of blithely assuming a WEP header. Add some
inline documentation. Account for data padding (IEEE80211_F_DATAPAD).
will eventually share it.
In the IBSS merge logic, check conditions in a different order so
that they run faster in the common case---no merge. Fix the
rate-limiting on the debug outputs (enabled by IFF_LINK0).
Begin conditioning device configuration on revision number. Four
revisions are known:
1.1/1.5 -> ADM8211A,
2.0 -> ADM8211B,
3.0 -> ADM8211C.
The B and C parts, which are not supported yet, have AP capability.
denote a signed dBm Rx power, so rename them to _DBM_ and change
the signedness. Add new _DB_ flags for unsigned Rx power measured
from an arbitrary reference.
Try to synchronize net80211/ieee80211_radiotap.h with my tcpdump
sources (which public tcpdump has not seen, yet) and with FreeBSD.
dyoung