42 lines
2.1 KiB
Nim
42 lines
2.1 KiB
Nim
# beacon_chain
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# Copyright (c) 2018 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import
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./datatypes, ./digest, ./helpers, ./validator
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func get_shards_and_committees_for_slot*(state: BeaconState,
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slot: uint64
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): seq[ShardAndCommittee] =
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let earliest_slot_in_array = state.last_state_recalculation_slot - CYCLE_LENGTH
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assert earliest_slot_in_array <= slot
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assert slot < earliest_slot_in_array + CYCLE_LENGTH * 2
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return state.shard_and_committee_for_slots[int slot - earliest_slot_in_array]
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# TODO, slot is a uint64; will be an issue on int32 arch.
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# Clarify with EF if light clients will need the beacon chain
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func get_block_hash*(state: BeaconState, current_block: BeaconBlock, slot: int): Eth2Digest =
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let earliest_slot_in_array = current_block.slot.int - state.recent_block_hashes.len
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assert earliest_slot_in_array <= slot
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assert slot < current_block.slot.int
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return state.recent_block_hashes[slot - earliest_slot_in_array]
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func get_beacon_proposer*(state: BeaconState, slot: uint64): ValidatorRecord =
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## From Casper RPJ mini-spec:
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## When slot i begins, validator Vidx is expected
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## to create ("propose") a block, which contains a pointer to some parent block
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## that they perceive as the "head of the chain",
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## and includes all of the **attestations** that they know about
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## that have not yet been included into that chain.
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##
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## idx in Vidx == p(i mod N), pi being a random permutation of validators indices (i.e. a committee)
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let
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first_committee = get_shards_and_committees_for_slot(state, slot)[0].committee
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index = first_committee[(slot mod len(first_committee).uint64).int]
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state.validators[index]
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