Add the types used in the beacon chain

beacon_chain/datatypes.nim

@@ -0,0 +1,75 @@
+# beacon_chain
+# Copyright (c) 2018 Status Research & Development GmbH
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import intsets, stint, eth_common
+
+type
+  AttestationVote* = object
+    # Implementation pending https://ethresear.ch/t/implementations-of-proof-of-concept-beacon-chains/2509/5?u=mratsim
+
+  Keccak256_Digest* = distinct Hash256
+  Blake2_256_Digest* = distinct Hash256
+
+  BeaconBlock* = object
+    parentHash*: Keccak256_Digest             # Hash of the parent block
+    slotNumber*: int64                        # Slot number (for the PoS mechanism)
+    randaoReveal*: Keccak256_Digest           # Randao commitment reveal
+    attestationVotes*: seq[AttestationVote]   # Attestation votes
+    mainChainRef*: Keccak256_Digest           # Reference to main chain block
+    activeStatehash*: Blake2_256_Digest       # Hash of the active state
+    crystallizedStateHash*: Blake2_256_Digest # Hash of the crystallized state
+
+  ActiveState* = IntSet
+    # ## Spec
+    # attestation_count: int64
+    # attester_bitfields: seq[byte]
+
+    # Note:
+    # We use IntSet from Nim Standard library which are efficient sparse bitsets.
+    # See: https://nim-lang.org/docs/intsets.html
+    #
+    # Future:
+    #   IntSets stores the first 34 elements in an array[34, int] instead of a bitfield
+    #   to avoid heap allocation in profiled common cases.
+    #
+    #   In Ethereum we probably always have over 34 attesters given the goal of decentralization.
+    #   Allocating 8 * 34 = 272 bytes on the stack is wasteful, when this can be packed in just 8 bytes
+    #   with room to spare.
+    #
+    #   Also, IntSets uses machine int size while we require int64 even on 32-bit platform.
+
+  CrystallizedState* = object
+    activeValidators: seq[ValidatorRecord] # List of active validators
+    queuedValidators: seq[ValidatorRecord] # List of joined but not yet inducted validators
+    exitedValidators: seq[ValidatorRecord] # List of removed validators pending withdrawal
+    curEpochShuffling: seq[int32] #int24   # The permutation of validators used to determine who cross-links what shard in this epoch
+    currentEpoch: int64                    # The current epoch
+    lastJustifiedEpoch: int64              # The last justified epoch
+    lastFinalizedEpoch: int64              # The last finalized epoch
+    dynasty: int64                         # The current dynasty
+    next_shard: int16                      # The next shard that cross-linking assignment will start from
+    currentCheckpoint: Keccak256_Digest    # The current FFG checkpoint
+    crosslinkRecords: seq[CrosslinkRecord] # Records about the most recent crosslink `for each shard
+    totalDeposits: Int256                  # Total balance of deposits
+    crosslinkSeed: Keccak256_Digest        # Used to select the committees for each shard
+    crosslinkSeedLastReset: int64          # Last epoch the crosslink seed was reset
+
+  BLSPublicKey = object
+    # Stub for BLS signature
+    data: array[32, byte]
+
+  ValidatorRecord* = object
+    pubkey: BLSPublicKey                   # The validator's public key
+    withdrawalShard: int16                 # What shard the validator's balance will be sent to after withdrawal
+    withdrawalAddress: EthAddress          # And what address
+    randaoCommitment: Keccak256_Digest     # The validator's current RANDAO beacon commitment
+    balance: int64                         # Current balance
+    switchDynasty: int64                   # Dynasty where the validator can (be inducted | be removed | withdraw their balance)
+
+  CrosslinkRecord* = object
+    epoch: int64                           # What epoch the crosslink was submitted in
+    hash: Keccak256_Digest                 # The block hash