a function that transforms a vector of bits ( c(0,1,1,0,0) ) to an unsigned integer (6). Includes a test as an example at the bottom.

bit.to.uint.R

bits.to.uint <- function(bits) {
  s=0
  for (i in 1:length(bits)) {
    s = s + 2^(i-1) * bits[i]
  }
  return(s)
}

cat(bits.to.uint( c(0,1,1,0,0) ) == 6)
cat(bits.to.uint( c(0,1,0,0,1) ) == 18 )
cat(bits.to.uint( c(1,0,0,0,0,0,0,0,1) ) == 257 )

Vectorisation is your friend:

bits.to.uint <- function(bits) {
  sum(2 ^ (seq_along(bits) - 1) * bits)
}