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stephentyronestephentyrone
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Initial setup of IntegerUtilities module.
Seeded with rotate(right:) and rotate(left:) on FixedWidthInteger. These implementations are basically sane, but need documentation written for users who are not already familiar with bitwise rotation.
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‎Package.swift

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@@ -22,6 +22,7 @@ let package = Package(
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targets: [
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// User-facing modules
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.target(name: "ComplexModule", dependencies: ["RealModule"]),
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.target(name: "IntegerUtilities", dependencies: []),
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.target(name: "Numerics", dependencies: ["ComplexModule", "RealModule"]),
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.target(name: "RealModule", dependencies: ["_NumericsShims"]),
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@@ -31,6 +32,7 @@ let package = Package(
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// Unit test bundles
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.testTarget(name: "ComplexTests", dependencies: ["_TestSupport"]),
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.testTarget(name: "IntegerUtilitiesTests", dependencies: ["IntegerUtilities"]),
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.testTarget(name: "RealTests", dependencies: ["_TestSupport"]),
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// Test executables

‎Sources/IntegerUtilities/Rotate.swift

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//===--- Rotate.swift -----------------------------------------*- swift -*-===//
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//
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// This source file is part of the Swift Numerics open source project
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//
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// Copyright (c) 2021 Apple Inc. and the Swift Numerics 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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//
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//===----------------------------------------------------------------------===//
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extension FixedWidthInteger {
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@_transparent @usableFromInline
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internal func rotateImplementation(right count: Int) -> Self {
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// We don't have an unsigned right shift operation for signed values, so
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// we need to convert to an unsigned type. The only unsigned type that's
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// guaranteed to be able to represent the bit pattern of any Self value
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// is Magnitude. It would be possible to have Magnitude be _wider_ than
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// Self, but that's OK as long as we're careful to complement the shift
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// count using Self.bitWidth and not Magnitude.bitWidth or zero.
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let bitPattern = Magnitude(truncatingIfNeeded: self)
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let countComplement = Self.bitWidth &- count
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return Self(truncatingIfNeeded:
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bitPattern &>> count | bitPattern &<< countComplement
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)
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}
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/// `self` rotated bitwise right by `count` bits.
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///
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/// Equivalent to `rotated(left: 0 &- count)`.
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@inlinable
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public func rotated<Count: BinaryInteger>(right count: Count) -> Self {
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rotateImplementation(right: Int(truncatingIfNeeded: count))
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}
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/// `self` rotated bitwise left by `count` bits.
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///
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/// Equivalent to `rotated(right: 0 &- count)`.
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@inlinable
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public func rotated<Count: BinaryInteger>(left count: Count) -> Self {
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rotateImplementation(right: 0 &- Int(truncatingIfNeeded: count))
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}
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}

‎Tests/IntegerUtilitiesTests/RotateTests.swift

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//===--- RotateTests.swift ------------------------------------*- 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) 2021 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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import IntegerUtilities
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import XCTest
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final class IntegerUtilitiesTests: XCTestCase {
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func testRotateUInt8() {
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let x: UInt8 = 0b10011100
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XCTAssertEqual(0b01001110, x.rotated(right:-7))
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XCTAssertEqual(0b00100111, x.rotated(right:-6))
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XCTAssertEqual(0b10010011, x.rotated(right:-5))
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XCTAssertEqual(0b11001001, x.rotated(right:-4))
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XCTAssertEqual(0b11100100, x.rotated(right:-3))
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XCTAssertEqual(0b01110010, x.rotated(right:-2))
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XCTAssertEqual(0b00111001, x.rotated(right:-1))
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XCTAssertEqual(0b10011100, x.rotated(right: 0))
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XCTAssertEqual(0b01001110, x.rotated(right: 1))
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XCTAssertEqual(0b00100111, x.rotated(right: 2))
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XCTAssertEqual(0b10010011, x.rotated(right: 3))
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XCTAssertEqual(0b11001001, x.rotated(right: 4))
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XCTAssertEqual(0b11100100, x.rotated(right: 5))
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XCTAssertEqual(0b01110010, x.rotated(right: 6))
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XCTAssertEqual(0b00111001, x.rotated(right: 7))
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XCTAssertEqual(0b10011100, x.rotated(right: 8))
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}
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func testRotateInt16() {
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let x = Int16(bitPattern: 0b1001110000111110)
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XCTAssertEqual(Int16(bitPattern: 0b1001110000111110), x.rotated(left:-16))
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XCTAssertEqual(Int16(bitPattern: 0b0011100001111101), x.rotated(left:-15))
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XCTAssertEqual(Int16(bitPattern: 0b0111000011111010), x.rotated(left:-14))
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XCTAssertEqual(Int16(bitPattern: 0b1110000111110100), x.rotated(left:-13))
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XCTAssertEqual(Int16(bitPattern: 0b1100001111101001), x.rotated(left:-12))
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XCTAssertEqual(Int16(bitPattern: 0b1000011111010011), x.rotated(left:-11))
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XCTAssertEqual(Int16(bitPattern: 0b0000111110100111), x.rotated(left:-10))
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XCTAssertEqual(Int16(bitPattern: 0b0001111101001110), x.rotated(left:-9))
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XCTAssertEqual(Int16(bitPattern: 0b0011111010011100), x.rotated(left:-8))
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XCTAssertEqual(Int16(bitPattern: 0b0111110100111000), x.rotated(left:-7))
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XCTAssertEqual(Int16(bitPattern: 0b1111101001110000), x.rotated(left:-6))
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XCTAssertEqual(Int16(bitPattern: 0b1111010011100001), x.rotated(left:-5))
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XCTAssertEqual(Int16(bitPattern: 0b1110100111000011), x.rotated(left:-4))
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XCTAssertEqual(Int16(bitPattern: 0b1101001110000111), x.rotated(left:-3))
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XCTAssertEqual(Int16(bitPattern: 0b1010011100001111), x.rotated(left:-2))
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XCTAssertEqual(Int16(bitPattern: 0b0100111000011111), x.rotated(left:-1))
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XCTAssertEqual(Int16(bitPattern: 0b1001110000111110), x.rotated(left: 0))
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XCTAssertEqual(Int16(bitPattern: 0b0011100001111101), x.rotated(left: 1))
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XCTAssertEqual(Int16(bitPattern: 0b0111000011111010), x.rotated(left: 2))
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XCTAssertEqual(Int16(bitPattern: 0b1110000111110100), x.rotated(left: 3))
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XCTAssertEqual(Int16(bitPattern: 0b1100001111101001), x.rotated(left: 4))
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XCTAssertEqual(Int16(bitPattern: 0b1000011111010011), x.rotated(left: 5))
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XCTAssertEqual(Int16(bitPattern: 0b0000111110100111), x.rotated(left: 6))
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XCTAssertEqual(Int16(bitPattern: 0b0001111101001110), x.rotated(left: 7))
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XCTAssertEqual(Int16(bitPattern: 0b0011111010011100), x.rotated(left: 8))
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XCTAssertEqual(Int16(bitPattern: 0b0111110100111000), x.rotated(left: 9))
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XCTAssertEqual(Int16(bitPattern: 0b1111101001110000), x.rotated(left: 10))
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XCTAssertEqual(Int16(bitPattern: 0b1111010011100001), x.rotated(left: 11))
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XCTAssertEqual(Int16(bitPattern: 0b1110100111000011), x.rotated(left: 12))
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XCTAssertEqual(Int16(bitPattern: 0b1101001110000111), x.rotated(left: 13))
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XCTAssertEqual(Int16(bitPattern: 0b1010011100001111), x.rotated(left: 14))
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XCTAssertEqual(Int16(bitPattern: 0b0100111000011111), x.rotated(left: 15))
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XCTAssertEqual(Int16(bitPattern: 0b1001110000111110), x.rotated(left: 16))
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}
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}
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