!/bin/bash
# increase/decrease/set/get the backlight brightness (range 0-255) by 16
#
#get current brightness in hex and convert to decimal
var1=`setpci -s 00:02.0 F4.B`
var1=`echo $var1 | tr '[a-z]' '[A-Z]'`
var1d=$var1
case "$1" in
up)
#calculate new brightness
var2=`echo "ibase=16; obase=10; a=($var1d+F);if (a<FF) print a else print FF" | bc`
echo "$0: increasing brightness from 0x$var1 to 0x$var2"
setpci -s 00:02.0 F4.B=$var2
;;
down)
#calculate new brightness
var2=`echo "ibase=16; obase=10; a=($var1d-F);if (a>01) print a else print 01" | bc`
echo "$0: decreasing brightness from 0x$var1 to 0x$var2"
setpci -s 00:02.0 F4.B=$var2
;;
set)
#n.b. this does allow "set 0" i.e. backlight off
echo "$0: setting brightness to 0x$2"
setpci -s 00:02.0 F4.B=$2
;;
get)
echo "$0: current brightness is 0x$var1"
;;
toggle)
if [ $var1d -eq 0 ] ; then
echo "toggling up"
setpci -s 00:02.0 F4.B=FF
else
echo "toggling down"
setpci -s 00:02.0 F4.B=0
fi
;;
*)
echo "usage: $0 {up|down|set <val>|get|toggle}"
;;
esac
exit 0