feature/int-extension (#57)

* moved function * updated
yeeth · Feb 22, 2019 · 954bcb6 · 954bcb6
1 parent 921fbd3
commit 954bcb6
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Showing 4 changed files with 20 additions and 10 deletions.
diff --git a/Sources/BeaconChain/BeaconChain.swift b/Sources/BeaconChain/BeaconChain.swift
@@ -135,7 +135,7 @@ extension BeaconChain {
             if registryChange {
                 seed = generateSeed(state: state, epoch: nextEpoch)
                 shufflingStartShard = (state.currentEpochStartShard + UInt64(currentCommitteesPerEpoch)) % SHARD_COUNT
-            } else if epochsSinceLastRegistryUpdate > 1 && isPowerOfTwo(Int(epochsSinceLastRegistryUpdate)) {
+            } else if epochsSinceLastRegistryUpdate > 1 && Int(epochsSinceLastRegistryUpdate).isPowerOfTwo() {
                 seed = generateSeed(state: state, epoch: nextEpoch)
                 shufflingStartShard = state.currentEpochStartShard
             } else {
@@ -234,14 +234,6 @@ extension BeaconChain {
         }
     }
 
-    static func isPowerOfTwo(_ value: Int) -> Bool {
-        if value == 0 {
-            return false
-        }
-
-        return 2 ** Int(log2(Double(value))) == value
-    }
-
     static func getEffectiveBalance(state: BeaconState, index: ValidatorIndex) -> Gwei {
         return min(state.validatorBalances[Int(index)], MAX_DEPOSIT_AMOUNT)
     }

diff --git a/Sources/BeaconChain/Extensions/Int.swift b/Sources/BeaconChain/Extensions/Int.swift
@@ -0,0 +1,8 @@
+import Foundation
+
+extension Int {
+
+    func isPowerOfTwo() -> Bool {
+        return (self > 0) && (self & (self - 1) == 0)
+    }
+}
diff --git a/Sources/BeaconChain/StateTransition.swift b/Sources/BeaconChain/StateTransition.swift
@@ -411,7 +411,7 @@ extension StateTransition {
             updateValidatorRegistry(state: &state)
         } else {
             let epochsSinceLastRegistryUpdate = currentEpoch - state.validatorRegistryUpdateEpoch
-            if epochsSinceLastRegistryUpdate > 1 && BeaconChain.isPowerOfTwo(Int(epochsSinceLastRegistryUpdate)) {
+            if epochsSinceLastRegistryUpdate > 1 && Int(epochsSinceLastRegistryUpdate).isPowerOfTwo() {
                 state.currentCalculationEpoch = nextEpoch
                 state.currentEpochSeed = BeaconChain.generateSeed(state: state, epoch: state.currentCalculationEpoch)
             }

diff --git a/Tests/BeaconChainTests/Extensions/IntTests.swift b/Tests/BeaconChainTests/Extensions/IntTests.swift
@@ -0,0 +1,10 @@
+import XCTest
+@testable import BeaconChain
+
+final class IntTests: XCTestCase {
+
+    func testIsPowerOfTwo() {
+        XCTAssertTrue(4.isPowerOfTwo())
+        XCTAssertFalse(3.isPowerOfTwo())
+    }
+}