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//===--- ByteSwap.swift ---------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2021 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
//
//===----------------------------------------------------------------------===//
// This test checks performance of Swift byte swap.
// rdar://problem/22151907
import TestsUtils
public let benchmarks =
BenchmarkInfo(
name: "ByteSwap",
runFunction: run_ByteSwap,
tags: [.validation, .algorithm])
// a naive O(n) implementation of byteswap.
@inline(never)
func byteswap_n(_ a: UInt64) -> UInt64 {
return ((a & 0x00000000000000FF) &<< 56) |
((a & 0x000000000000FF00) &<< 40) |
((a & 0x0000000000FF0000) &<< 24) |
((a & 0x00000000FF000000) &<< 8) |
((a & 0x000000FF00000000) &>> 8) |
((a & 0x0000FF0000000000) &>> 24) |
((a & 0x00FF000000000000) &>> 40) |
((a & 0xFF00000000000000) &>> 56)
}
// a O(logn) implementation of byteswap.
@inline(never)
func byteswap_logn(_ a: UInt64) -> UInt64 {
var a = a
a = (a & 0x00000000FFFFFFFF) << 32 | (a & 0xFFFFFFFF00000000) >> 32
a = (a & 0x0000FFFF0000FFFF) << 16 | (a & 0xFFFF0000FFFF0000) >> 16
a = (a & 0x00FF00FF00FF00FF) << 8 | (a & 0xFF00FF00FF00FF00) >> 8
return a
}
@inline(never)
public func run_ByteSwap(_ n: Int) {
var s: UInt64 = 0
for _ in 1...10000*n {
// Check some results.
let x : UInt64 = UInt64(getInt(0))
s = s &+ byteswap_logn(byteswap_n(x &+ 2457))
&+ byteswap_logn(byteswap_n(x &+ 9129))
&+ byteswap_logn(byteswap_n(x &+ 3333))
}
check(s == (2457 &+ 9129 &+ 3333) &* 10000 &* n)
}
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