100111 AND 1001 = 0
Shift-right 1
010011 AND 1001 = 0
Shift-right 1
001001 AND 1001 = 1 // Pattern FOUND!

100111 AND 001001 = 000001

x = 100111
if (x AND 1001 == 1001)
  print "found"

if ((TestPattern & SearchPattern) == SearchPattern)
{
   // then match
}

if ((InputPattern AND SearchMask) == SearchPattern)
{
    // then match
}