Files
swift-mirror/validation-test/stdlib/HashingAvalanche.swift
2016-02-24 15:10:25 -08:00

63 lines
1.9 KiB
Swift

// RUN: %target-build-swift -Xfrontend -disable-access-control -module-name a %s -o %t.out -O
// RUN: %target-run %t.out
// REQUIRES: executable_test
import SwiftPrivate
import StdlibUnittest
// Also import modules which are used by StdlibUnittest internally. This
// workaround is needed to link all required libraries in case we compile
// StdlibUnittest with -sil-serialize-all.
import SwiftPrivate
#if _runtime(_ObjC)
import ObjectiveC
#endif
var HashingTestSuite = TestSuite("Hashing")
func avalancheTest(bits: Int, _ hashUnderTest: (UInt64) -> UInt64, _ pValue: Double) {
let testsInBatch = 100000
let testData = randArray64(testsInBatch)
let testDataHashed = Array(testData.lazy.map { hashUnderTest($0) })
for inputBit in 0..<bits {
// Using an array here makes the test too slow.
var bitFlips = UnsafeMutablePointer<Int>(allocatingCapacity: bits)
for i in 0..<bits {
bitFlips[i] = 0
}
for i in testData.indices {
let inputA = testData[i]
let outputA = testDataHashed[i]
let inputB = inputA ^ (1 << UInt64(inputBit))
let outputB = hashUnderTest(inputB)
var delta = outputA ^ outputB
for outputBit in 0..<bits {
if delta & 1 == 1 {
bitFlips[outputBit] += 1
}
delta = delta >> 1
}
}
for outputBit in 0..<bits {
expectTrue(
chiSquaredUniform2(testsInBatch, bitFlips[outputBit], pValue),
"inputBit: \(inputBit), outputBit: \(outputBit)")
}
bitFlips.deallocateCapacity(bits)
}
}
// White-box testing: assume that the other N-bit to N-bit mixing functions
// just dispatch to these. (Avalanche test is relatively expensive.)
HashingTestSuite.test("_mixUInt64/avalanche") {
avalancheTest(64, _mixUInt64, 0.02)
}
HashingTestSuite.test("_mixUInt32/avalanche") {
avalancheTest(32, { UInt64(_mixUInt32(UInt32($0 & 0xffff_ffff))) }, 0.02)
}
runAllTests()