Module Name:	src
Committed By:	dyoung
Date:		Wed Mar  8 00:24:06 UTC 2006

Modified Files:
	src/sys/arch/i386/pci: geode.c geodereg.h
	src/sys/dev/ic: atw.c atwreg.h atwvar.h max2820reg.h rtw.c rtwphy.c
	    rtwphyio.c rtwreg.h sa2400reg.h si4136reg.h
	src/sys/lib/libkern: libkern.h

Log Message:
Move my bit-twiddling macros to libkern.h from my drivers, where
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);


To generate a diff of this commit:
cvs rdiff -r1.4 -r1.5 src/sys/arch/i386/pci/geode.c \
    src/sys/arch/i386/pci/geodereg.h
cvs rdiff -r1.109 -r1.110 src/sys/dev/ic/atw.c
cvs rdiff -r1.12 -r1.13 src/sys/dev/ic/atwreg.h
cvs rdiff -r1.19 -r1.20 src/sys/dev/ic/atwvar.h
cvs rdiff -r1.3 -r1.4 src/sys/dev/ic/max2820reg.h
cvs rdiff -r1.67 -r1.68 src/sys/dev/ic/rtw.c
cvs rdiff -r1.8 -r1.9 src/sys/dev/ic/rtwphy.c
cvs rdiff -r1.10 -r1.11 src/sys/dev/ic/rtwphyio.c
cvs rdiff -r1.16 -r1.17 src/sys/dev/ic/rtwreg.h
cvs rdiff -r1.4 -r1.5 src/sys/dev/ic/sa2400reg.h
cvs rdiff -r1.2 -r1.3 src/sys/dev/ic/si4136reg.h
cvs rdiff -r1.55 -r1.56 src/sys/lib/libkern/libkern.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.