Small toOpenArray optim + notes on in-place hashing

status-im · May 9, 2019 · ef24e63 · ef24e63
1 parent 144b972
commit ef24e63
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Showing 2 changed files with 4 additions and 1 deletion.
diff --git a/beacon_chain/spec/digest.nim b/beacon_chain/spec/digest.nim
@@ -34,6 +34,9 @@ func shortLog*(x: Eth2Digest): string =
   # result = is needed to fix https://github.com/status-im/nim-beacon-chain/issues/209
   result = ($x)[0..7]
 
+# TODO: expose an in-place digest function
+#       when hashing in loop or into a buffer
+#       See: https://github.com/cheatfate/nimcrypto/blob/b90ba3abd/nimcrypto/sha2.nim#L570
 func eth2hash*(v: openArray[byte]): Eth2Digest {.inline.} =
   result = sha256.digest(v)
 

diff --git a/beacon_chain/spec/validator.nim b/beacon_chain/spec/validator.nim
@@ -48,7 +48,7 @@ func get_shuffled_seq*(seed: Eth2Digest,
     source_buffer[32] = round_bytes1
 
     # Only one pivot per round.
-    let pivot = bytes_to_int(eth2hash(pivot_buffer).data[0..7]) mod list_size
+    let pivot = bytes_to_int(eth2hash(pivot_buffer).data.toOpenArray(0, 7)) mod list_size
 
     ## Only need to run, per round, position div 256 hashes, so precalculate
     ## them. This consumes memory, but for low-memory devices, it's possible