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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2022 - 2024 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
//
//===----------------------------------------------------------------------===//
extension BitArray {
/// Create and return a new bit array consisting of `count` random bits,
/// using the system random number generator.
///
/// - Parameter count: The number of random bits to generate.
public static func randomBits(count: Int) -> BitArray {
var rng = SystemRandomNumberGenerator()
return randomBits(count: count, using: &rng)
}
/// Create and return a new bit array consisting of `count` random bits,
/// using the given random number generator.
///
/// - Parameter count: The number of random bits to generate.
/// - Parameter rng: The random number generator to use.
public static func randomBits(
count: Int,
using rng: inout some RandomNumberGenerator
) -> BitArray {
precondition(count >= 0, "Invalid count")
guard count > 0 else { return BitArray() }
let (w, b) = _BitPosition(count).endSplit
var words = (0 ... w).map { _ in _Word(rng.next() as UInt) }
words[w].formIntersection(_Word(upTo: b))
return BitArray(_storage: words, count: count)
}
}
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