calcBlockReward(height):
  if height == 0:
    return 0
  reward = 50 * 1e18
  halvings = height / 210000
  if halvings > 63:
    return 0  // reward effectively zero
  divisor = 2 ** halvings
  return reward / divisor

Finalize(block):
  height = block.number
  reward = calcBlockReward(height)
  unlock = height + CoinbaseMaturityBlocks

  if reward > 0:
    lockbox[unlock].addr = coinbase
    lockbox[unlock].amt  = reward

  // Pay matured rewards for current height
  if lockbox[height].amt > 0:
    AddBalance(lockbox[height].addr, lockbox[height].amt)
    Clear(lockbox[height])

totalIssued(upToHeight):
  sum = 0
  for h in 1..upToHeight:
    sum += calcBlockReward(h)
  return sum
// approaches 21e6 * 1e18 wei

schedKeyAddr(height):
  return keccak256("maturity:addr:" || height)

schedKeyAmt(height):
  return keccak256("maturity:amt:" || height)