convert decimal to binary and contrary !

[admin]

Use this function, it returns a number that is stored in bits starring from offset to offset + length (not inclusive). offset is the lowest bit number that you want to get. length is number of bits to get.

Code:

function getbits(value, offset, length)
  local mask = bit.lshift(1, length) - 1
  return bit.band(bit.rshift(value, offset), mask)
end

value = 5000
result = getbits(value, 9, 3)
log(result)

Note that bits are counted from right to left starting from 0. So bits 9..11 are this: 0001 0011 1000 1000