//===--- Integers.swift.gyb -----------------------------------*- swift -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
//
//===----------------------------------------------------------------------===//
// RUN: rm -rf %t ; mkdir -p %t
// RUN: %gyb -DWORD_BITS=%target-ptrsize %s -o %t/Integers.swift
// RUN: %line-directive %t/Integers.swift -- %target-build-swift %t/Integers.swift -swift-version 4 -Onone -o %t/a.out
// RUN: %line-directive %t/Integers.swift -- %target-run %t/a.out
// REQUIRES: executable_test

// FIXME: this test runs forever on iOS arm64
// REQUIRES: OS=macosx
%{
word_bits = int(WORD_BITS) / 2
from SwiftIntTypes import all_integer_types
}%

/// Prints the message if the body is uncommented; used for
/// diagnostics.
@_transparent
public func _log(_ message: @autoclosure () -> String) {
  // print(message())
}

extension FixedWidthInteger {
  @discardableResult
  // @_transparent
  public mutating func replaceUWord(_ n: Int, with newBits: UInt) -> Bool {
    let flippedBits = _word(at: n) ^ newBits
    self ^= Self(_truncatingBits: flippedBits) << (${word_bits} * n)
    if _word(at: n) != newBits {
      _log("###### overflow replacing word \(n) with \(newBits.hex)")
    }
    return _word(at: n) == newBits
  }

  /// a hex representation of every bit in the number
  func hexBits(_ bitWidth: Int) -> String {
    let hexDigits: [Unicode.Scalar] = [
      "0", "1", "2", "3", "4", "5", "6", "7",
      "8", "9", "A", "B", "C", "D", "E", "F"]

    var result = "".unicodeScalars
    var x = self
    var nibbles: Int = 0
    repeat {
      if nibbles % 4 == 0 && nibbles != 0 {
        result.insert("_", at: result.startIndex)
      }
      let lowUWord = x._word(at: 0)
      result.insert(
        hexDigits[Int(lowUWord._value) & 0xF],
        at: result.startIndex
      )
      x.replaceUWord(0, with: lowUWord & ~0xF)
      x /= 16
      nibbles += 1
    }
    while (nibbles << 2 < bitWidth || (x != 0 && x + 1 != 0))
    return (self < 0 ? "[-]" : "[+]") + String(result)
  }

  var hex: String { return hexBits(0) }
}

typealias Word = Int${word_bits}
typealias UWord = UInt${word_bits}
typealias DWord = Int${word_bits*2}
typealias UDWord = UInt${word_bits*2}

import StdlibUnittest


func expectEqual<T : FixedWidthInteger>(
  _ expected: T, _ actual: T,
  _ message: @autoclosure () -> String = "",
  stackTrace: SourceLocStack = SourceLocStack(),
  showFrame: Bool = true,
  file: String = #file, line: UInt = #line
) {
  if expected != actual {
    expectationFailure(
      "expected: \(String(reflecting: expected))"
      + " (of type \(String(reflecting: type(of: expected))))\n"
      + "  = \(expected.hex)\n"
      + "actual: \(String(reflecting: actual))"
      + " (of type \(String(reflecting: type(of: actual))))\n"
      + "  = \(actual.hex)\n",
      trace: message(),
      stackTrace: stackTrace.pushIf(showFrame, file: file, line: line))
  }
}

func expectEqual<T : FixedWidthInteger>(
  _ expected: (T, ArithmeticOverflow), _ actual: (T, ArithmeticOverflow),
  _ message: @autoclosure () -> String = "",
  stackTrace: SourceLocStack = SourceLocStack(),
  showFrame: Bool = true,
  file: String = #file, line: UInt = #line
) {
% for i in 0, 1:
  expectEqual(
    expected.${i}, actual.${i}, message(),
    stackTrace: stackTrace.pushIf(showFrame, file: file, line: line),
    showFrame: false)
% end
}

var tests = TestSuite("Integers")

tests.test("Literals") {
  // Testing against the official Int types so as not to depend on
  // unimplemented stuff.
  let a: UInt8 = 0b1_0_11_0_111
  expectEqual(a, 0b1_0_11_0_111)

  let b: Int16 = 183
  expectEqual(b, 0b1_0_11_0_111)

  let c: Int16 = -183
  expectEqual(c, -183)

  let d: Int8 = 127
  expectEqual(d, 127)

  let e: UInt8 = 255
  expectEqual(e, 255)
}

tests.test("Equality") {
  expectEqual(183 as UInt8, 183)
  expectNotEqual(183 as UInt8, 184)

  expectEqual(49 as Int8, 49)
  expectNotEqual(-49 as Int8, 49)
}

func indexOrder<T: Comparable>(x: T, y: T)
  -> ExpectedComparisonResult {
  return x < y ? .lt : x > y ? .gt : .eq
}

tests.test("Ordering") {
  checkComparable([127, 183, 184, 255] as [UInt8], oracle: indexOrder)
  checkComparable([-128, -1, 83, 84, 127] as [Int8], oracle: indexOrder)
  checkComparable([127, 183, 184, 255, 65535] as [UInt16], oracle: indexOrder)
  checkComparable([-32768, -32767, 83, 84, 32767] as [Int16], oracle: indexOrder)
}

tests.test("Simple-Arithmetic") {
  expectEqual(1 as Int8 + 2, 3)
  expectEqual(1 as Int8 - 2, -1)
  expectEqual(-5 as Int8 + 11, 6)
  expectEqual(3 as Int8 * 4, 12)
  expectEqual(4 as Int8 * -7, -28)
  expectEqual(-4 as Int8 * -7, 28)
  expectEqual(5 as Int8 / 2, 2)
  expectEqual(6 as Int8 / 2, 3)
  expectEqual(7 as Int8 / 2, 3)
  expectEqual(5 as Int8 % 3, 2)
  expectEqual(6 as Int8 % 3, 0)
  expectEqual(7 as Int8 % 3, 1)
}

% for w in map(lambda x: x.bits, all_integer_types(word_bits)):
%   for prefix in ['U', '']:
%     Type = '{}Int{}'.format(prefix, w)
tests.test("${Type}/Add/Overflow") {
  func f(_ x: ${Type}) -> ${Type} {
    return x + 1
  }
  expectCrashLater()
  _ = f(${Type}.max)
}

tests.test("${Type}/Subtract/Underflow") {
  func f(_ x: ${Type}) -> ${Type} {
    return x - 1
  }
  expectCrashLater()
  _ = f(${Type}.min)
}

tests.test("${Type}/AddInPlace/Overflow") {
  func f(_ x: inout ${Type}) {
    x += 1
  }
  expectCrashLater()
  var x = ${Type}.max
  f(&x)
}

tests.test("${Type}/SubtractInPlace/Underflow") {
  func f(_ x: inout ${Type}) {
    x -= 1
  }
  expectCrashLater()
  var x = ${Type}.min
  f(&x)
}
%   end
% end

tests.test("Simple-Bitwise") {
  expectEqual(0b100_1001 as Int8 >> 1, 0b10_0100)
  expectEqual(-0b100_1001 as Int8 >> 1, -0b10_0101)
  expectEqual(0b1011_0111 as UInt8 >> 1, 0b0101_1011)

  expectEqual(0b100_1001 as Int8 >> 1, 0b10_0100)
  expectEqual(-0b100_1001 as Int8 >> 1, -0b10_0101)
  expectEqual(0b1011_0111 as UInt8 >> 1, 0b0101_1011)

  expectEqual((0b1011_0111 as UInt8) & 0b0110_1110, 0b0010_0110)
  expectEqual((0b1011_0111 as UInt8) | 0b0110_1110, 0xFF)
  expectEqual((0b1011_0111 as UInt8) ^ 0b0110_1110, 0b1101_1001)
}

tests.test("MinMax") {
  expectEqual(255, UInt8.max)
  expectEqual(0, UInt8.min)
  expectEqual(127, Int8.max)
  expectEqual(-128, Int8.min)
}

tests.test("CountLeadingZeros") {
  expectEqual(0, UInt8.max.leadingZeroBitCount)
  expectEqual(8, UInt8.min.leadingZeroBitCount)
  expectEqual(1, Int8.max.leadingZeroBitCount)
  expectEqual(0, Int8.min.leadingZeroBitCount)
}

tests.test("CountTrainlingZeros") {
  expectEqual(0, UInt8.max.trailingZeroBitCount)
  expectEqual(8, UInt8.min.trailingZeroBitCount)
  expectEqual(0, Int8.max.trailingZeroBitCount)
  expectEqual(7, Int8.min.trailingZeroBitCount)
}

tests.test("Conversion8to16") {
  expectEqual(255, UInt16(UInt8.max))
  expectEqual(255, Int16(UInt8.max))
  expectEqual(0, UInt16(UInt8.min))
  expectEqual(0, Int16(UInt8.min))
  expectEqual(127, Int16(Int8.max))
  let negativeValue = Int8.min
  expectCrashLater()
  _ = UInt16(negativeValue)
}


tests.test("Conversion16to8") {
  expectEqual(255, UInt8(255 as UInt16))
  expectEqual(255, UInt8(255 as Int16))

  expectEqual(0, UInt8(0 as UInt16))
  expectEqual(0, UInt8(0 as Int16))

  expectEqual(127, Int8(127 as UInt16))
  expectEqual(127, Int8(127 as Int16))

  expectEqual(-128, Int8(-128 as Int16))
  let tooLarge: UInt16 = 128
  expectCrashLater()
  _ = Int8(tooLarge)
}

tests.test("Conversion16to8a") {
  let tooLarge: Int16 = 128
  expectCrashLater()
  _ = Int8(tooLarge)
}

tests.test("Conversion16to8b") {
  let tooLarge: Int16 = 256
  expectCrashLater()
  _ = UInt8(tooLarge)
}

tests.test("Conversion16to8c") {
  let tooLarge: UInt16 = 256
  expectCrashLater()
  _ = UInt8(tooLarge)
}

tests.test("ConversionWordToDWord") {
  expectEqual(1 << ${word_bits} - 1, UDWord(UWord.max))
  expectEqual(1 << ${word_bits} - 1, DWord(UWord.max))
  expectEqual(0, UDWord(UWord.min))
  expectEqual(0, DWord(UWord.min))
  expectEqual(1 << ${word_bits-1} - 1, DWord(Word.max))
  let negativeValue = Word.min
  expectCrashLater()
  _ = UDWord(negativeValue)
}

tests.test("ConversionDWordToWord") {
  expectEqual(~0, UWord(1 << ${word_bits} - 1 as UDWord))
  expectEqual(~0, UWord(1 << ${word_bits} - 1 as DWord))

  expectEqual(0, UWord(0 as UDWord))
  expectEqual(0, UWord(0 as DWord))

  expectEqual(Word.max, Word(1 << ${word_bits-1} - 1 as UDWord))
  expectEqual(Word.max, Word(1 << ${word_bits-1} - 1 as DWord))

  expectEqual(Word.min, Word(-1 << ${word_bits-1} as DWord))
  let tooLarge: UDWord = 1 << ${word_bits-1}
  expectCrashLater()
  _ = Word(tooLarge)
}

tests.test("ConversionDWordToWordA") {
  let tooLarge: DWord = 1 << ${word_bits}
  expectCrashLater()
  _ = Word(tooLarge)
}

tests.test("ConversionDWordToWordB") {
  let tooLarge: DWord = 1 << ${word_bits}
  expectCrashLater()
  _ = UWord(tooLarge)
}

tests.test("ConversionDWordToWordC") {
  let tooLarge: UDWord = 1 << ${word_bits}
  expectCrashLater()
  _ = UWord(tooLarge)
}

tests.test("extendingOrTruncating") {

  expectEqual(-2, Int8(extendingOrTruncating: UInt8.max - 1))
  expectEqual(3, Int8(extendingOrTruncating: 3 as UInt8))
  expectEqual(UInt8.max - 1, UInt8(extendingOrTruncating: -2 as Int8))
  expectEqual(3, UInt8(extendingOrTruncating: 3 as Int8))

  expectEqual(-2, DWord(extendingOrTruncating: UDWord.max - 1))
  expectEqual(3, DWord(extendingOrTruncating: 3 as UDWord))
  expectEqual(UDWord.max - 1, UDWord(extendingOrTruncating: -2 as DWord))
  expectEqual(3, UDWord(extendingOrTruncating: 3 as DWord))

  expectEqual(-2, Int32(extendingOrTruncating: -2 as Int8))
  expectEqual(3, Int32(extendingOrTruncating: 3 as Int8))
  expectEqual(127, Int32(extendingOrTruncating: 127 as UInt8))
  expectEqual(129, Int32(extendingOrTruncating: 129 as UInt8))
  expectEqual((1 << 31 - 1) << 1, UInt32(extendingOrTruncating: -2 as Int8))
  expectEqual(3, UInt32(extendingOrTruncating: 3 as Int8))
  expectEqual(128, UInt32(extendingOrTruncating: 128 as UInt8))
  expectEqual(129, UInt32(extendingOrTruncating: 129 as UInt8))

  expectEqual(-2, DWord(extendingOrTruncating: -2 as Int8))
  expectEqual(3, DWord(extendingOrTruncating: 3 as Int8))
  expectEqual(127, DWord(extendingOrTruncating: 127 as UInt8))
  expectEqual(129, DWord(extendingOrTruncating: 129 as UInt8))
  expectEqual(
    (1 << ${word_bits*2-1} - 1) << 1,
    UDWord(extendingOrTruncating: -2 as Int8))
  expectEqual(3, UDWord(extendingOrTruncating: 3 as Int8))
  expectEqual(128, UDWord(extendingOrTruncating: 128 as UInt8))
  expectEqual(129, UDWord(extendingOrTruncating: 129 as UInt8))

  expectEqual(-2, Int8(extendingOrTruncating: -2 as DWord))
  expectEqual(-2, Int8(extendingOrTruncating: -1 << 67 - 2 as DWord))
  expectEqual(127, Int8(extendingOrTruncating: 127 as UDWord))
  expectEqual(-127, Int8(extendingOrTruncating: 129 as UDWord))
  expectEqual(0b1111_1100, UInt8(extendingOrTruncating: -4 as DWord))
  expectEqual(0b1111_1100, UInt8(extendingOrTruncating: -1 << 67 - 4 as DWord))
  expectEqual(128, UInt8(extendingOrTruncating: 128 + 1024 as UDWord))
  expectEqual(129, UInt8(extendingOrTruncating: 129 + 1024 as UDWord))
}

tests.test("HeterogeneousEquality") {
  expectTrue(-1 as DWord != UDWord.max)
  expectTrue(DWord.max == UDWord.max / 2)
  expectTrue((0 as DWord) == 0 as UDWord)

  expectTrue(-1 as Int8 == -1 as DWord)
  expectTrue(UInt8.max != -1 as DWord)
  expectTrue(UInt8.max == 255 as DWord)
  expectTrue((0 as UInt8) == 0 as DWord)

  expectTrue(UInt8.max == 255 as UDWord)
  expectTrue(UInt8.max != UDWord.max)
  expectTrue((0 as UInt8) == (0 as UDWord))
}

tests.test("HeterogeneousOrdering") {
  expectTrue((-1 as DWord) < UDWord.max)
  expectTrue(DWord.max <= UDWord.max / 2)
  expectTrue(DWord.max >= UDWord.max / 2)
  expectTrue((0 as DWord) <= (0 as UDWord))
  expectTrue((0 as DWord) >= (0 as UDWord))

  expectTrue((-1 as Int8) <= -1 as DWord)
  expectTrue((-1 as Int8) >= -1 as DWord)
  expectTrue(UInt8.max > -1 as DWord)
  expectTrue(UInt8.max <= 255 as DWord)
  expectTrue(UInt8.max >= 255 as DWord)
  expectTrue((0 as UInt8) <= (0 as DWord))
  expectTrue((0 as UInt8) >= (0 as DWord))

  expectTrue(UInt8.max <= 255 as UDWord)
  expectTrue(UInt8.max >= 255 as UDWord)
  expectTrue(UInt8.max < UDWord.max)
  expectTrue((0 as UInt8) <= (0 as UDWord))
  expectTrue((0 as UInt8) >= (0 as UDWord))
}

tests.test("SmartBitShift/Homogeneous/Left/Int16") {
  let all1s = ~0 as Int16
  expectEqual(all1s, all1s << (0 as Int16))
  expectEqual(-2, all1s << (1 as Int16))
  expectEqual(Int16.min, all1s << (15 as Int16))
  expectEqual(0, all1s << (16 as Int16))

  expectEqual(-1, all1s << (-1 as Int16))
  expectEqual(-1, all1s << (-15 as Int16))
  expectEqual(-1, all1s << (-16 as Int16))
}

tests.test("SmartBitShift/Unconstrained/Left/Int16") {
  let all1s = ~0 as Int16
  expectEqual(all1s, all1s << 0)
  expectEqual(-2, all1s << 1)
  expectEqual(Int16.min, all1s << 15)
  expectEqual(0, all1s << 16)

  expectEqual(-1, all1s << -1)
  expectEqual(-1, all1s << -15)
  expectEqual(-1, all1s << -16)
}

tests.test("SmartBitShift/Homogeneous/Left/UInt16") {
  let all1s = ~0 as UInt16
  expectEqual(all1s, all1s << 0)
  expectEqual(0b1111_1111_1111_1110, all1s << 1)
  expectEqual(UInt16.max / 2 + 1, all1s << 15)
  expectEqual(0, all1s << 16)
}

tests.test("SmartBitShift/Heterogeneous/Left/Int16") {
  let all1s = ~0 as Int16
  expectEqual(all1s, all1s << (0 as Int8))
  expectEqual(-2, all1s << (1 as Int32))
  expectEqual(Int16.min, all1s << (15 as UInt32))
  expectEqual(0, all1s << (16 as UInt8))

  expectEqual(-1, all1s << (-1 as DWord))
  expectEqual(-1, all1s << (-15 as Int))
  expectEqual(-1, all1s << (-16 as Int32))
}

tests.test("SmartBitShift/Heterogeneous/Left/UInt16") {
  let all1s = ~0 as UInt16
  expectEqual(all1s, all1s << (0 as Int8))
  expectEqual(0b1111_1111_1111_1110, all1s << (1 as Int32))
  expectEqual(UInt16.max / 2 + 1, all1s << (15 as UInt32))
  expectEqual(0, all1s << (16 as UInt8))

  expectEqual(UInt16.max / 2, all1s << (-1 as DWord))
  expectEqual(1, all1s << (-15 as Int))
  expectEqual(0, all1s << (-16 as Int32))
}

tests.test("SmartBitShift/Unconstrained/Left/UInt16") {
  let all1s = ~0 as UInt16
  expectEqual(all1s, all1s << 0)
  expectEqual(0b1111_1111_1111_1110, all1s << 1)
  expectEqual(UInt16.max / 2 + 1, all1s << 15)
  expectEqual(0, all1s << 16)

  expectEqual(UInt16.max / 2, all1s << -1)
  expectEqual(1, all1s << -15)
  expectEqual(0, all1s << -16)
}

tests.test("Basics") {
  typealias I8 = UInt8
  let b8: I8 = 0b1_0_11_0_111
  expectEqual(b8, 0b1_0_11_0_111)
  expectEqual(b8, 183)
  expectNotEqual(b8, I8())
  expectEqual(I8(), 0)
  expectEqual(8, I8.bitWidth)
  expectEqual(16, Int16.bitWidth)
  expectEqual(32, Int32.bitWidth)
}

tests.test("word") {
  let x = UDWord(Int.max)
  expectEqual(Int.max._lowUWord, x._word(at: 0))
  expectEqual(0, x._word(at: 1))

  let y = DWord(Int.min)
  expectEqual(Int.min._lowUWord, y._word(at: 0))
  expectEqual(~0, y._word(at: 1))

  let z = UInt(~Int.min) + 1
  expectEqual(Int.min._lowUWord, z._word(at: 0))
  expectEqual(0, z._word(at: 1))
}

tests.test("words") {
  expectEqualSequence([UInt.max], (-1 as Int).words)
  expectEqualSequence([UInt.max], (-1 as Int8).words)
  expectEqualSequence([UInt.max], (-1 as Int16).words)
  expectEqualSequence([UInt.max], (-1 as Int32).words)
  expectEqualSequence([UInt.max], (-1 as Int64).words)

  expectEqualSequence([1], 1.words)
  expectEqualSequence([0], 0.words)
}

tests.test("multipliedFullWidth/UInt8") {
  let a: UInt8 = 42
  let b: UInt8 = 42
  let res = a.multipliedFullWidth(by: b)
  expectEqual(0x06, res.high)
  expectEqual(0xe4, res.low)
}

tests.test("multipliedFullWidth/Int8") {
  let a: Int8 = 42
  let b: Int8 = -42
  let res = a.multipliedFullWidth(by: b)
  expectEqual(Int8(bitPattern: 0xf9), res.high)
  expectEqual(0x1c, res.low)
}

tests.test("multipliedFullWidth/Int8/BothNegative") {
  let a: Int8 = -42
  let b: Int8 = -42
  let res = a.multipliedFullWidth(by: b)
  expectEqual(0x06, res.high)
  expectEqual(0xe4, res.low)
}

tests.test("MultiplyAndDivideFullWidth/Int8") {
  let a: Int8 = 42
  let b: Int8 = 43
  let res = a.multipliedFullWidth(by: b)
  let (quotient, remainder) = b.dividingFullWidth(res)
  expectEqual(a, quotient)
  expectEqual(0, remainder)
}

tests.test("Remainder/DividingBy0") {
  func f(_ x: Int, _ y: Int) -> Int {
    return x % y
  }
  expectCrashLater()
  _ = f(42, 0)
}

tests.test("Division/By0") {
  func f(_ x: Int, _ y: Int) -> Int {
    return x / y
  }
  expectCrashLater()
  _ = f(42, 0)
}

tests.test("DivideMinByMinusOne") {
  func f(_ x: Int) -> Int {
    return x / -1
  }
  expectCrashLater()
  _ = f(Int.min)
}

tests.test("MultiplyMinByMinusOne") {
  func f(_ x: Int) -> Int {
    return x * -1
  }
  expectCrashLater()
  _ = f(Int.min)
}

tests.test("signum/generic") {
  func check<T : BinaryInteger>(_ expected: T, _ x: T) {
    expectEqual(expected, x.signum())
  }
% for suffix in ['8', '16', '32', '64', '']:
  check(-1, Int${suffix}.min)
  check(-1, (-42) as Int${suffix})
  check(-1, (-1) as Int${suffix})
%   for u in ['U', '']:
  check(0, 0 as ${u}Int${suffix})
  check(1, 1 as ${u}Int${suffix})
  check(1, 42 as ${u}Int${suffix})
  check(1, ${u}Int${suffix}.max)
%   end
% end
}

tests.test("signum/concrete") {
% for suffix in ['8', '16', '32', '64', '']:
  expectEqual(-1 as Int${suffix}, Int${suffix}.min.signum())
  expectEqual(-1 as Int${suffix}, (-42 as Int${suffix}).signum())
  expectEqual(-1 as Int${suffix}, (-1 as Int${suffix}).signum())
%   for u in ['U', '']:
  expectEqual(0 as ${u}Int${suffix}, (0 as ${u}Int${suffix}).signum())
  expectEqual(1 as ${u}Int${suffix}, (1 as ${u}Int${suffix}).signum())
  expectEqual(1 as ${u}Int${suffix}, (42 as ${u}Int${suffix}).signum())
  expectEqual(1 as ${u}Int${suffix}, ${u}Int${suffix}.max.signum())
%   end
% end
}

var dwTests = TestSuite("DoubleWidth")

dwTests.test("Literals") {
  let w: DoubleWidth<UInt8> = 100
  expectTrue(w == 100 as Int)

  let x: DoubleWidth<UInt8> = 1000
  expectTrue(x == 1000 as Int)

  let y: DoubleWidth<Int8> = 1000
  expectTrue(y == 1000 as Int)
  
  let z: DoubleWidth<Int8> = -1000
  expectTrue(z == -1000 as Int)
}

dwTests.test("Arithmetic/unsigned") {
  let x: DoubleWidth<UInt8> = 1000
  let y: DoubleWidth<UInt8> = 1111
  expectTrue(x + 1 == 1001)
  expectTrue(x + x == 2000)
  expectTrue(x - 1 == 999)
  expectTrue(x - x == 0)
  expectTrue(y - x == 111)
  
  expectTrue(x * 7 == 7000)
  expectTrue(y * 7 == 7777)
  
  expectTrue(x / 3 == 333)
  expectTrue(x / x == 1)
  expectTrue(x / y == 0)
  expectTrue(y / x == 1)

  expectTrue(x % 3 == 1)
  expectTrue(x % y == x)
}

dwTests.test("Arithmetic/signed") {
  let x: DoubleWidth<Int8> = 1000
  let y: DoubleWidth<Int8> = -1111
  expectTrue(x + 1 == 1001)
  expectTrue(x + x == 2000)
  expectTrue(x - 1 == 999)
  expectTrue(x - x == 0)
  expectTrue(0 - x == -1000)
  expectTrue(x + y == -111)
  expectTrue(x - y == 2111)
  
  expectTrue(x * 7 == 7000)
  expectTrue(y * 7 == -7777)
  expectTrue(x * -7 == -7000)
  expectTrue(y * -7 == 7777)

  expectTrue(x / 3 == 333)
  expectTrue(x / x == 1)
  expectTrue(x / y == 0)
  expectTrue(y / x == -1)
  
  expectTrue(x % 3 == 1)
  expectTrue(y % 3 == -1)
  
  expectTrue(-y == 1111)
  expectTrue(-x == -1000)
}

dwTests.test("Nested") {
  typealias UInt128 = DoubleWidth<UInt64>
  typealias UInt256 = DoubleWidth<UInt128>
  typealias UInt512 = DoubleWidth<UInt256>
  typealias UInt1024 = DoubleWidth<UInt512>

  do {
    let x = UInt1024.max
    let (y, o) = x.addingReportingOverflow(1)
    expectEqual(y, 0)
    expectTrue(y == (0 as Int))
    expectTrue(o == .overflow)
  }

  typealias Int128 = DoubleWidth<Int64>
  typealias Int256 = DoubleWidth<Int128>
  typealias Int512 = DoubleWidth<Int256>
  typealias Int1024 = DoubleWidth<Int512>

  do {
    let x = Int1024.max
    let (y, o) = x.addingReportingOverflow(1)
    expectEqual(y, Int1024.min)
    expectLT(y, 0)
    expectTrue(y < (0 as Int))
    expectTrue(o == .overflow)
  }

  expectFalse(UInt1024.isSigned)
  expectEqual(UInt1024.bitWidth, 1024)
  expectTrue(Int1024.isSigned)
  expectEqual(Int1024.bitWidth, 1024)
}

// FIXME: Need more tests of DoubleWidth

runAllTests()