//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

/// A linear congruential generator with user-specified seed value. Useful for generating a predictable "random" number sequence.
public struct SimpleLCG: RandomNumberGenerator {

  var state: UInt64

  public init(seed: UInt64) {
    state = seed
  }

  public mutating func next() -> UInt64 {
    state = state &* 6364136223846793005 &+ 1442695040888963407
    return state
  }
}