#!/bin/bash
 # Aumenta y disminuye el contraste (range 0-255) by 16
 #
 #get current brightness in hex and convert to decimal
 var1=`setpci -s 00:02.1 F4.B`
 var1d=$((0x$var1))
 case "$1" in
       up)
               #calculate new brightness
               var2=`echo "ibase=10; obase=16; a=($var1d+16);if (a<255) print a else print 255" | bc`
               echo "$0: increasing brightness from 0x$var1 to 0x$var2"
               setpci -s 00:02.1 F4.B=$var2
               ;;
       down)
               #calculate new brightness
               var2=`echo "ibase=10; obase=16; a=($var1d-16);if (a>15) print a else print 15" | bc`
               echo "$0: decreasing brightness from 0x$var1 to 0x$var2"
               setpci -s 00:02.1 F4.B=$var2
               ;;
       set)
               #n.b. this does allow "set 0" i.e. backlight off
               echo "$0: setting brightness to 0x$2"
               setpci -s 00:02.1 F4.B=$2
               ;;
       get)
               echo "$0: current brightness is 0x$var1"
               ;;
       toggle)
               if [ $var1d -eq 0 ] ; then
                       echo "toggling up"
                       setpci -s 00:02.1 F4.B=FF
               else
                       echo "toggling down"
                       setpci -s 00:02.1 F4.B=0
               fi
               ;;
       *)
               echo "uso: $0 {up|down|set <val>|get|toggle}"
               ;;
 esac
 exit 0