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e9d4687e31
* De-underscore @frozen for enums * Add @frozen for structs, deprecate @_fixed_layout for them * Switch usage from _fixed_layout to frozen
114 lines
3.2 KiB
Swift
114 lines
3.2 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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/// This file implements SipHash-2-4 and SipHash-1-3
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/// (https://131002.net/siphash/).
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///
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/// This file is based on the reference C implementation, which was released
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/// to public domain by:
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///
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/// * Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
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/// * Daniel J. Bernstein <djb@cr.yp.to>
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//===----------------------------------------------------------------------===//
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extension Hasher {
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// FIXME: Remove @usableFromInline and @frozen once Hasher is resilient.
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// rdar://problem/38549901
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@usableFromInline @frozen
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internal struct _State {
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// "somepseudorandomlygeneratedbytes"
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private var v0: UInt64 = 0x736f6d6570736575
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private var v1: UInt64 = 0x646f72616e646f6d
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private var v2: UInt64 = 0x6c7967656e657261
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private var v3: UInt64 = 0x7465646279746573
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// The fields below are reserved for future use. They aren't currently used.
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private var v4: UInt64 = 0
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private var v5: UInt64 = 0
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private var v6: UInt64 = 0
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private var v7: UInt64 = 0
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@inline(__always)
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internal init(rawSeed: (UInt64, UInt64)) {
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v3 ^= rawSeed.1
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v2 ^= rawSeed.0
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v1 ^= rawSeed.1
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v0 ^= rawSeed.0
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}
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}
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}
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extension Hasher._State {
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@inline(__always)
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private static func _rotateLeft(_ x: UInt64, by amount: UInt64) -> UInt64 {
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return (x &<< amount) | (x &>> (64 - amount))
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}
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@inline(__always)
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private mutating func _round() {
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v0 = v0 &+ v1
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v1 = Hasher._State._rotateLeft(v1, by: 13)
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v1 ^= v0
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v0 = Hasher._State._rotateLeft(v0, by: 32)
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v2 = v2 &+ v3
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v3 = Hasher._State._rotateLeft(v3, by: 16)
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v3 ^= v2
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v0 = v0 &+ v3
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v3 = Hasher._State._rotateLeft(v3, by: 21)
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v3 ^= v0
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v2 = v2 &+ v1
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v1 = Hasher._State._rotateLeft(v1, by: 17)
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v1 ^= v2
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v2 = Hasher._State._rotateLeft(v2, by: 32)
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}
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@inline(__always)
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private func _extract() -> UInt64 {
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return v0 ^ v1 ^ v2 ^ v3
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}
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}
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extension Hasher._State {
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@inline(__always)
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internal mutating func compress(_ m: UInt64) {
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v3 ^= m
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_round()
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v0 ^= m
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}
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@inline(__always)
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internal mutating func finalize(tailAndByteCount: UInt64) -> UInt64 {
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compress(tailAndByteCount)
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v2 ^= 0xff
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for _ in 0..<3 {
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_round()
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}
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return _extract()
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}
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}
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extension Hasher._State {
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@inline(__always)
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internal init() {
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self.init(rawSeed: Hasher._executionSeed)
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}
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@inline(__always)
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internal init(seed: Int) {
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let executionSeed = Hasher._executionSeed
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// Prevent sign-extending the supplied seed; this makes testing slightly
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// easier.
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let seed = UInt(bitPattern: seed)
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self.init(rawSeed: (
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executionSeed.0 ^ UInt64(truncatingIfNeeded: seed),
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executionSeed.1))
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}
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}
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