解析Linux笔记本基于“敲打”的命令

require 'sys/syscall.ph';  # for subsecond timing 

my $option = $ARGV[0] || ""; # simple option handling 

# filename for hdaps sensor reads 
my $hdapsFN = "/sys/devices/platform/hdaps/position"; 


my $UPDATE_THRESHOLD =   4;      # threshold of force that indicates a knock 
my $INTERVAL_THRESHOLD = 100000; # microseconds of time required between knock 
                                 # events 
my $SLEEP_INTERVAL =     0.01;   # time to pause between hdaps reads 

my $MAX_TIMEOUT_LENGTH = 4;      # maximum length in seconds of knock pattern 
                                 # length 
my $MAX_KNOCK_DEV =      100000; # maximum acceptable deviation between recorded 
                                 # pattern values and knocking values 

my $LISTEN_TIMEOUT =     2;      # timeout value in seconds between knock 
                                 # events when in listening mode 

my @baseKnocks = ();             # contains knock intervals currently entered 
my %knockHash = ();              # contains knock patterns, associated commands 

my $prevInterval =       0;      # previous interval of time 
my $knockCount =         0;      # current number of knocks detected 

my $restX = 0; # `resting' positiong of X axis accelerometer 
my $restY = 0; # `resting' positiong of Y axis accelerometer 
my $currX = 0; # current position of X axis accelerometer 
my $currY = 0; # current position of Y axis accelerometer 
my $lastX = 0; # most recent position of X axis accelerometer 
my $lastY = 0; # most recent position of Y axis accelerometer 


my $startTime = 0;  # to manage timeout intervals 
my $currTime  = 0;  # to manage timeout intervals 
my $timeOut   = 0;  # perpetual loop variable 
my $knockAge  = 0;  # count of knocks to cycle time interval 

sub checkAccelerometer() { 

  my $ret; 
  $ret = readPosition (); 
  if( $ret ){ 
    print "no accelerometer data available - tis bork ed\n"; 
    exit(1); 
  } 

}#checkAccelerometer