function bit(p)
  return 2 ^ (p - 1)
-- 1-based indexing
end

-- Typical call: if hasbit(x, bit(3)) then ...
function hasbit(x, p)
  return x % (p + p) >= p
end

function setbit(x, p)
  return hasbit(x, p) and x or x + p
end

function clearbit(x, p)
  return hasbit(x, p) and x - p or x
end

function toBin(i, b)
  local sBin = ""
  for n=1,b do
    if hasbit(i,bit(n)) then
      sBin = "1" .. sBin
    else
      sBin = "0" .. sBin
    end
  end
  return sBin
end

aHex = {
  [0] = "0",
  [1] = "1",
  [2] = "2",
  [3] = "3",
  [4] = "4",
  [5] = "5",
  [6] = "6",
  [7] = "7",
  [8] = "8",
  [9] = "9",
  [10] = "A",
  [11] = "B",
  [12] = "C",
  [13] = "D",
  [14] = "E",
  [15] = "F",
}
local tArgs = { ... }
if not tArgs[1] then
  print("Usage: hash <TEXT_TO_HASH>")
  return
end
sTestPhrase = "KyoHash31415926535897" .. tArgs[1]

nPos = 1;
nStep = 0;
nBits = 32*4
nLoops = 3

aBits = {}

for n=1,nBits do
  table.insert( aBits, "0" )
end

for l=1,nLoops do
  for n=1,string.len(sTestPhrase) do
    local x = toBin(string.byte(string.sub(sTestPhrase,n,n)), 7)
    for n2=1,7 do
      if string.sub(x,n2,n2) == "1" then
        if nStep > 3 then
          nStep = nStep - 2
        end
        if aBits[nPos] == "1" then
          aBits[nPos] = "0"
        else
          aBits[nPos] = "1"
        end
      else
        nStep = nStep + nStep + 1
        nPos = nPos + nStep
        if nStep > nBits then
          nStep = nStep - nBits
        end
      end
      nPos = nPos + 4
      if nPos > nBits then
        local nTemp = aBits[1]
        for n3=2,nBits do
          aBits[n3 - 1] = aBits[n3]
        end
        aBits[nBits] = nTemp
        nPos = nPos - nBits
      end
    end
  end
  term.clear()
  term.setCursorPos(1,1)
  for n=1,nBits do
    io.write(aBits[n])
  end
  io.write("\n\n" .. nStep .. " " .. nPos .. "\n\n")
  sleep(0.01)
end


print("")
nCount = 0
sHash = ""
for n=1,nBits/4 do
  sTemp = ""
  for n2=1,4 do
    nCount = nCount + 1
    sTemp = sTemp .. aBits[nCount]
  end
  sHash = sHash .. aHex[tonumber(sTemp,2)]
end
print("")
print(sHash)