add is_power_of_2 implementation

beacon_chain/spec/helpers.nim

@@ -134,4 +134,4 @@ func get_domain*(fork_data: ForkData, slot: uint64, domain_type: uint64): uint64
   # TODO Slot overflow? Or is slot 32 bits for all intents and purposes?
   (get_fork_version(fork_data, slot) shl 32) + domain_type
 
-func is_power_of_2*(v: uint64): bool = discard # TODO
+func is_power_of_2*(v: uint64): bool = (v and (v-1)) == 0

tests/all_tests.nim

@@ -8,5 +8,6 @@
 import
   ./test_beaconstate,
   ./test_block_processing,
+  ./test_helpers,
   ./test_ssz,
   ./test_validator

tests/test_beaconstate.nim

@@ -7,7 +7,7 @@
 
 import
   sequtils, unittest,
-  ./testhelpers,
+  ./testutil,
   ../beacon_chain/extras,
   ../beacon_chain/spec/[beaconstate, datatypes, digest]
 

tests/test_block_processing.nim

@@ -7,7 +7,7 @@
 
 import
   options, sequtils, unittest,
-  ./testhelpers,
+  ./testutil,
   ../beacon_chain/spec/[beaconstate, datatypes, digest],
   ../beacon_chain/[extras, state_transition]
 

tests/test_helpers.nim

@@ -0,0 +1,19 @@
+# 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
+  sequtils, unittest,
+  ../beacon_chain/spec/[helpers]
+
+suite "Spec helpers":
+  test "is_power_of_2 should do its job":
+    check:
+      is_power_of_2(1) == true
+      is_power_of_2(2) == true
+      is_power_of_2(3) == false
+      is_power_of_2(4) == true
+      is_power_of_2(not 0'u64) == false