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Source file src/pkg/big/int_test.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package big

import (
    "bytes"
    "encoding/hex"
    "fmt"
    "testing"
    "testing/quick"
)


func isNormalized(x *Int) bool {
    if len(x.abs) == 0 {
        return !x.neg
    }
    // len(x.abs) > 0
    return x.abs[len(x.abs)-1] != 0
}


type funZZ func(z, x, y *Int) *Int
type argZZ struct {
    z, x, y *Int
}


var sumZZ = []argZZ{
    argZZ{NewInt(0), NewInt(0), NewInt(0)},
    argZZ{NewInt(1), NewInt(1), NewInt(0)},
    argZZ{NewInt(1111111110), NewInt(123456789), NewInt(987654321)},
    argZZ{NewInt(-1), NewInt(-1), NewInt(0)},
    argZZ{NewInt(864197532), NewInt(-123456789), NewInt(987654321)},
    argZZ{NewInt(-1111111110), NewInt(-123456789), NewInt(-987654321)},
}


var prodZZ = []argZZ{
    argZZ{NewInt(0), NewInt(0), NewInt(0)},
    argZZ{NewInt(0), NewInt(1), NewInt(0)},
    argZZ{NewInt(1), NewInt(1), NewInt(1)},
    argZZ{NewInt(-991 * 991), NewInt(991), NewInt(-991)},
    // TODO(gri) add larger products
}


func TestSignZ(t *testing.T) {
    var zero Int
    for _, a := range sumZZ {
        s := a.z.Sign()
        e := a.z.Cmp(&zero)
        if s != e {
            t.Errorf("got %d; want %d for z = %v", s, e, a.z)
        }
    }
}


func TestSetZ(t *testing.T) {
    for _, a := range sumZZ {
        var z Int
        z.Set(a.z)
        if !isNormalized(&z) {
            t.Errorf("%v is not normalized", z)
        }
        if (&z).Cmp(a.z) != 0 {
            t.Errorf("got z = %v; want %v", z, a.z)
        }
    }
}


func TestAbsZ(t *testing.T) {
    var zero Int
    for _, a := range sumZZ {
        var z Int
        z.Abs(a.z)
        var e Int
        e.Set(a.z)
        if e.Cmp(&zero) < 0 {
            e.Sub(&zero, &e)
        }
        if z.Cmp(&e) != 0 {
            t.Errorf("got z = %v; want %v", z, e)
        }
    }
}


func testFunZZ(t *testing.T, msg string, f funZZ, a argZZ) {
    var z Int
    f(&z, a.x, a.y)
    if !isNormalized(&z) {
        t.Errorf("msg: %v is not normalized", z, msg)
    }
    if (&z).Cmp(a.z) != 0 {
        t.Errorf("%s%+v\n\tgot z = %v; want %v", msg, a, &z, a.z)
    }
}


func TestSumZZ(t *testing.T) {
    AddZZ := func(z, x, y *Int) *Int { return z.Add(x, y) }
    SubZZ := func(z, x, y *Int) *Int { return z.Sub(x, y) }
    for _, a := range sumZZ {
        arg := a
        testFunZZ(t, "AddZZ", AddZZ, arg)

        arg = argZZ{a.z, a.y, a.x}
        testFunZZ(t, "AddZZ symmetric", AddZZ, arg)

        arg = argZZ{a.x, a.z, a.y}
        testFunZZ(t, "SubZZ", SubZZ, arg)

        arg = argZZ{a.y, a.z, a.x}
        testFunZZ(t, "SubZZ symmetric", SubZZ, arg)
    }
}


func TestProdZZ(t *testing.T) {
    MulZZ := func(z, x, y *Int) *Int { return z.Mul(x, y) }
    for _, a := range prodZZ {
        arg := a
        testFunZZ(t, "MulZZ", MulZZ, arg)

        arg = argZZ{a.z, a.y, a.x}
        testFunZZ(t, "MulZZ symmetric", MulZZ, arg)
    }
}


// mulBytes returns x*y via grade school multiplication. Both inputs
// and the result are assumed to be in big-endian representation (to
// match the semantics of Int.Bytes and Int.SetBytes).
func mulBytes(x, y []byte) []byte {
    z := make([]byte, len(x)+len(y))

    // multiply
    k0 := len(z) - 1
    for j := len(y) - 1; j >= 0; j-- {
        d := int(y[j])
        if d != 0 {
            k := k0
            carry := 0
            for i := len(x) - 1; i >= 0; i-- {
                t := int(z[k]) + int(x[i])*d + carry
                z[k], carry = byte(t), t>>8
                k--
            }
            z[k] = byte(carry)
        }
        k0--
    }

    // normalize (remove leading 0's)
    i := 0
    for i < len(z) && z[i] == 0 {
        i++
    }

    return z[i:]
}


func checkMul(a, b []byte) bool {
    var x, y, z1 Int
    x.SetBytes(a)
    y.SetBytes(b)
    z1.Mul(&x, &y)

    var z2 Int
    z2.SetBytes(mulBytes(a, b))

    return z1.Cmp(&z2) == 0
}


func TestMul(t *testing.T) {
    if err := quick.Check(checkMul, nil); err != nil {
        t.Error(err)
    }
}


type mulRangeZ struct {
    a, b int64
    prod string
}


var mulRangesZ = []mulRangeZ{
    // entirely positive ranges are covered by mulRangesN
    mulRangeZ{-1, 1, "0"},
    mulRangeZ{-2, -1, "2"},
    mulRangeZ{-3, -2, "6"},
    mulRangeZ{-3, -1, "-6"},
    mulRangeZ{1, 3, "6"},
    mulRangeZ{-10, -10, "-10"},
    mulRangeZ{0, -1, "1"},                      // empty range
    mulRangeZ{-1, -100, "1"},                   // empty range
    mulRangeZ{-1, 1, "0"},                      // range includes 0
    mulRangeZ{-1e9, 0, "0"},                    // range includes 0
    mulRangeZ{-1e9, 1e9, "0"},                  // range includes 0
    mulRangeZ{-10, -1, "3628800"},              // 10!
    mulRangeZ{-20, -2, "-2432902008176640000"}, // -20!
    mulRangeZ{-99, -1,
        "-933262154439441526816992388562667004907159682643816214685929" +
            "638952175999932299156089414639761565182862536979208272237582" +
            "511852109168640000000000000000000000", // -99!
    },
}


func TestMulRangeZ(t *testing.T) {
    var tmp Int
    // test entirely positive ranges
    for i, r := range mulRangesN {
        prod := tmp.MulRange(int64(r.a), int64(r.b)).String()
        if prod != r.prod {
            t.Errorf("#%da: got %s; want %s", i, prod, r.prod)
        }
    }
    // test other ranges
    for i, r := range mulRangesZ {
        prod := tmp.MulRange(r.a, r.b).String()
        if prod != r.prod {
            t.Errorf("#%db: got %s; want %s", i, prod, r.prod)
        }
    }
}


type stringTest struct {
    in   string
    out  string
    base int
    val  int64
    ok   bool
}


var stringTests = []stringTest{
    stringTest{in: "", ok: false},
    stringTest{in: "a", ok: false},
    stringTest{in: "z", ok: false},
    stringTest{in: "+", ok: false},
    stringTest{in: "-", ok: false},
    stringTest{in: "0b", ok: false},
    stringTest{in: "0x", ok: false},
    stringTest{in: "2", base: 2, ok: false},
    stringTest{in: "0b2", base: 0, ok: false},
    stringTest{in: "08", ok: false},
    stringTest{in: "8", base: 8, ok: false},
    stringTest{in: "0xg", base: 0, ok: false},
    stringTest{in: "g", base: 16, ok: false},
    stringTest{"0", "0", 0, 0, true},
    stringTest{"0", "0", 10, 0, true},
    stringTest{"0", "0", 16, 0, true},
    stringTest{"+0", "0", 0, 0, true},
    stringTest{"-0", "0", 0, 0, true},
    stringTest{"10", "10", 0, 10, true},
    stringTest{"10", "10", 10, 10, true},
    stringTest{"10", "10", 16, 16, true},
    stringTest{"-10", "-10", 16, -16, true},
    stringTest{"+10", "10", 16, 16, true},
    stringTest{"0x10", "16", 0, 16, true},
    stringTest{in: "0x10", base: 16, ok: false},
    stringTest{"-0x10", "-16", 0, -16, true},
    stringTest{"+0x10", "16", 0, 16, true},
    stringTest{"00", "0", 0, 0, true},
    stringTest{"0", "0", 8, 0, true},
    stringTest{"07", "7", 0, 7, true},
    stringTest{"7", "7", 8, 7, true},
    stringTest{"023", "19", 0, 19, true},
    stringTest{"23", "23", 8, 19, true},
    stringTest{"cafebabe", "cafebabe", 16, 0xcafebabe, true},
    stringTest{"0b0", "0", 0, 0, true},
    stringTest{"-111", "-111", 2, -7, true},
    stringTest{"-0b111", "-7", 0, -7, true},
    stringTest{"0b1001010111", "599", 0, 0x257, true},
    stringTest{"1001010111", "1001010111", 2, 0x257, true},
}


func format(base int) string {
    switch base {
    case 2:
        return "%b"
    case 8:
        return "%o"
    case 16:
        return "%x"
    }
    return "%d"
}


func TestGetString(t *testing.T) {
    z := new(Int)
    for i, test := range stringTests {
        if !test.ok {
            continue
        }
        z.SetInt64(test.val)

        if test.base == 10 {
            s := z.String()
            if s != test.out {
                t.Errorf("#%da got %s; want %s\n", i, s, test.out)
            }
        }

        s := fmt.Sprintf(format(test.base), z)
        if s != test.out {
            t.Errorf("#%db got %s; want %s\n", i, s, test.out)
        }
    }
}


func TestSetString(t *testing.T) {
    tmp := new(Int)
    for i, test := range stringTests {
        n1, ok1 := new(Int).SetString(test.in, test.base)
        n2, ok2 := tmp.SetString(test.in, test.base)
        expected := NewInt(test.val)
        if ok1 != test.ok || ok2 != test.ok {
            t.Errorf("#%d (input '%s') ok incorrect (should be %t)", i, test.in, test.ok)
            continue
        }
        if !ok1 || !ok2 {
            continue
        }

        if ok1 && !isNormalized(n1) {
            t.Errorf("#%d (input '%s'): %v is not normalized", i, test.in, *n1)
        }
        if ok2 && !isNormalized(n2) {
            t.Errorf("#%d (input '%s'): %v is not normalized", i, test.in, *n2)
        }

        if n1.Cmp(expected) != 0 {
            t.Errorf("#%d (input '%s') got: %s want: %d\n", i, test.in, n1, test.val)
        }
        if n2.Cmp(expected) != 0 {
            t.Errorf("#%d (input '%s') got: %s want: %d\n", i, test.in, n2, test.val)
        }
    }
}


type divisionSignsTest struct {
    x, y int64
    q, r int64 // T-division
    d, m int64 // Euclidian division
}


// Examples from the Go Language Spec, section "Arithmetic operators"
var divisionSignsTests = []divisionSignsTest{
    divisionSignsTest{5, 3, 1, 2, 1, 2},
    divisionSignsTest{-5, 3, -1, -2, -2, 1},
    divisionSignsTest{5, -3, -1, 2, -1, 2},
    divisionSignsTest{-5, -3, 1, -2, 2, 1},
    divisionSignsTest{1, 2, 0, 1, 0, 1},
    divisionSignsTest{8, 4, 2, 0, 2, 0},
}


func TestDivisionSigns(t *testing.T) {
    for i, test := range divisionSignsTests {
        x := NewInt(test.x)
        y := NewInt(test.y)
        q := NewInt(test.q)
        r := NewInt(test.r)
        d := NewInt(test.d)
        m := NewInt(test.m)

        q1 := new(Int).Quo(x, y)
        r1 := new(Int).Rem(x, y)
        if !isNormalized(q1) {
            t.Errorf("#%d Quo: %v is not normalized", i, *q1)
        }
        if !isNormalized(r1) {
            t.Errorf("#%d Rem: %v is not normalized", i, *r1)
        }
        if q1.Cmp(q) != 0 || r1.Cmp(r) != 0 {
            t.Errorf("#%d QuoRem: got (%s, %s), want (%s, %s)", i, q1, r1, q, r)
        }

        q2, r2 := new(Int).QuoRem(x, y, new(Int))
        if !isNormalized(q2) {
            t.Errorf("#%d Quo: %v is not normalized", i, *q2)
        }
        if !isNormalized(r2) {
            t.Errorf("#%d Rem: %v is not normalized", i, *r2)
        }
        if q2.Cmp(q) != 0 || r2.Cmp(r) != 0 {
            t.Errorf("#%d QuoRem: got (%s, %s), want (%s, %s)", i, q2, r2, q, r)
        }

        d1 := new(Int).Div(x, y)
        m1 := new(Int).Mod(x, y)
        if !isNormalized(d1) {
            t.Errorf("#%d Div: %v is not normalized", i, *d1)
        }
        if !isNormalized(m1) {
            t.Errorf("#%d Mod: %v is not normalized", i, *m1)
        }
        if d1.Cmp(d) != 0 || m1.Cmp(m) != 0 {
            t.Errorf("#%d DivMod: got (%s, %s), want (%s, %s)", i, d1, m1, d, m)
        }

        d2, m2 := new(Int).DivMod(x, y, new(Int))
        if !isNormalized(d2) {
            t.Errorf("#%d Div: %v is not normalized", i, *d2)
        }
        if !isNormalized(m2) {
            t.Errorf("#%d Mod: %v is not normalized", i, *m2)
        }
        if d2.Cmp(d) != 0 || m2.Cmp(m) != 0 {
            t.Errorf("#%d DivMod: got (%s, %s), want (%s, %s)", i, d2, m2, d, m)
        }
    }
}


func checkSetBytes(b []byte) bool {
    hex1 := hex.EncodeToString(new(Int).SetBytes(b).Bytes())
    hex2 := hex.EncodeToString(b)

    for len(hex1) < len(hex2) {
        hex1 = "0" + hex1
    }

    for len(hex1) > len(hex2) {
        hex2 = "0" + hex2
    }

    return hex1 == hex2
}


func TestSetBytes(t *testing.T) {
    if err := quick.Check(checkSetBytes, nil); err != nil {
        t.Error(err)
    }
}


func checkBytes(b []byte) bool {
    b2 := new(Int).SetBytes(b).Bytes()
    return bytes.Compare(b, b2) == 0
}


func TestBytes(t *testing.T) {
    if err := quick.Check(checkSetBytes, nil); err != nil {
        t.Error(err)
    }
}


func checkQuo(x, y []byte) bool {
    u := new(Int).SetBytes(x)
    v := new(Int).SetBytes(y)

    if len(v.abs) == 0 {
        return true
    }

    r := new(Int)
    q, r := new(Int).QuoRem(u, v, r)

    if r.Cmp(v) >= 0 {
        return false
    }

    uprime := new(Int).Set(q)
    uprime.Mul(uprime, v)
    uprime.Add(uprime, r)

    return uprime.Cmp(u) == 0
}


type quoTest struct {
    x, y string
    q, r string
}


var quoTests = []quoTest{
    quoTest{
        "476217953993950760840509444250624797097991362735329973741718102894495832294430498335824897858659711275234906400899559094370964723884706254265559534144986498357",
        "9353930466774385905609975137998169297361893554149986716853295022578535724979483772383667534691121982974895531435241089241440253066816724367338287092081996",
        "50911",
        "1",
    },
    quoTest{
        "11510768301994997771168",
        "1328165573307167369775",
        "8",
        "885443715537658812968",
    },
}


func TestQuo(t *testing.T) {
    if err := quick.Check(checkQuo, nil); err != nil {
        t.Error(err)
    }

    for i, test := range quoTests {
        x, _ := new(Int).SetString(test.x, 10)
        y, _ := new(Int).SetString(test.y, 10)
        expectedQ, _ := new(Int).SetString(test.q, 10)
        expectedR, _ := new(Int).SetString(test.r, 10)

        r := new(Int)
        q, r := new(Int).QuoRem(x, y, r)

        if q.Cmp(expectedQ) != 0 || r.Cmp(expectedR) != 0 {
            t.Errorf("#%d got (%s, %s) want (%s, %s)", i, q, r, expectedQ, expectedR)
        }
    }
}


func TestQuoStepD6(t *testing.T) {
    // See Knuth, Volume 2, section 4.3.1, exercise 21. This code exercises
    // a code path which only triggers 1 in 10^{-19} cases.

    u := &Int{false, nat{0, 0, 1 + 1<<(_W-1), _M ^ (1 << (_W - 1))}}
    v := &Int{false, nat{5, 2 + 1<<(_W-1), 1 << (_W - 1)}}

    r := new(Int)
    q, r := new(Int).QuoRem(u, v, r)
    const expectedQ64 = "18446744073709551613"
    const expectedR64 = "3138550867693340382088035895064302439801311770021610913807"
    const expectedQ32 = "4294967293"
    const expectedR32 = "39614081266355540837921718287"
    if q.String() != expectedQ64 && q.String() != expectedQ32 ||
        r.String() != expectedR64 && r.String() != expectedR32 {
        t.Errorf("got (%s, %s) want (%s, %s) or (%s, %s)", q, r, expectedQ64, expectedR64, expectedQ32, expectedR32)
    }
}


type bitLenTest struct {
    in  string
    out int
}


var bitLenTests = []bitLenTest{
    bitLenTest{"-1", 1},
    bitLenTest{"0", 0},
    bitLenTest{"1", 1},
    bitLenTest{"2", 2},
    bitLenTest{"4", 3},
    bitLenTest{"0xabc", 12},
    bitLenTest{"0x8000", 16},
    bitLenTest{"0x80000000", 32},
    bitLenTest{"0x800000000000", 48},
    bitLenTest{"0x8000000000000000", 64},
    bitLenTest{"0x80000000000000000000", 80},
    bitLenTest{"-0x4000000000000000000000", 87},
}


func TestBitLen(t *testing.T) {
    for i, test := range bitLenTests {
        x, ok := new(Int).SetString(test.in, 0)
        if !ok {
            t.Errorf("#%d test input invalid: %s", i, test.in)
            continue
        }

        if n := x.BitLen(); n != test.out {
            t.Errorf("#%d got %d want %d\n", i, n, test.out)
        }
    }
}


type expTest struct {
    x, y, m string
    out     string
}


var expTests = []expTest{
    expTest{"5", "0", "", "1"},
    expTest{"-5", "0", "", "-1"},
    expTest{"5", "1", "", "5"},
    expTest{"-5", "1", "", "-5"},
    expTest{"-2", "3", "2", "0"},
    expTest{"5", "2", "", "25"},
    expTest{"1", "65537", "2", "1"},
    expTest{"0x8000000000000000", "2", "", "0x40000000000000000000000000000000"},
    expTest{"0x8000000000000000", "2", "6719", "4944"},
    expTest{"0x8000000000000000", "3", "6719", "5447"},
    expTest{"0x8000000000000000", "1000", "6719", "1603"},
    expTest{"0x8000000000000000", "1000000", "6719", "3199"},
    expTest{
        "2938462938472983472983659726349017249287491026512746239764525612965293865296239471239874193284792387498274256129746192347",
        "298472983472983471903246121093472394872319615612417471234712061",
        "29834729834729834729347290846729561262544958723956495615629569234729836259263598127342374289365912465901365498236492183464",
        "23537740700184054162508175125554701713153216681790245129157191391322321508055833908509185839069455749219131480588829346291",
    },
}


func TestExp(t *testing.T) {
    for i, test := range expTests {
        x, ok1 := new(Int).SetString(test.x, 0)
        y, ok2 := new(Int).SetString(test.y, 0)
        out, ok3 := new(Int).SetString(test.out, 0)

        var ok4 bool
        var m *Int

        if len(test.m) == 0 {
            m, ok4 = nil, true
        } else {
            m, ok4 = new(Int).SetString(test.m, 0)
        }

        if !ok1 || !ok2 || !ok3 || !ok4 {
            t.Errorf("#%d: error in input", i)
            continue
        }

        z := y.Exp(x, y, m)
        if !isNormalized(z) {
            t.Errorf("#%d: %v is not normalized", i, *z)
        }
        if z.Cmp(out) != 0 {
            t.Errorf("#%d: got %s want %s", i, z, out)
        }
    }
}


func checkGcd(aBytes, bBytes []byte) bool {
    a := new(Int).SetBytes(aBytes)
    b := new(Int).SetBytes(bBytes)

    x := new(Int)
    y := new(Int)
    d := new(Int)

    GcdInt(d, x, y, a, b)
    x.Mul(x, a)
    y.Mul(y, b)
    x.Add(x, y)

    return x.Cmp(d) == 0
}


type gcdTest struct {
    a, b    int64
    d, x, y int64
}


var gcdTests = []gcdTest{
    gcdTest{120, 23, 1, -9, 47},
}


func TestGcd(t *testing.T) {
    for i, test := range gcdTests {
        a := NewInt(test.a)
        b := NewInt(test.b)

        x := new(Int)
        y := new(Int)
        d := new(Int)

        expectedX := NewInt(test.x)
        expectedY := NewInt(test.y)
        expectedD := NewInt(test.d)

        GcdInt(d, x, y, a, b)

        if expectedX.Cmp(x) != 0 ||
            expectedY.Cmp(y) != 0 ||
            expectedD.Cmp(d) != 0 {
            t.Errorf("#%d got (%s %s %s) want (%s %s %s)", i, x, y, d, expectedX, expectedY, expectedD)
        }
    }

    quick.Check(checkGcd, nil)
}


var primes = []string{
    "2",
    "3",
    "5",
    "7",
    "11",

    "13756265695458089029",
    "13496181268022124907",
    "10953742525620032441",
    "17908251027575790097",

    // http://code.google.com/p/go/issues/detail?id=638
    "18699199384836356663",

    "98920366548084643601728869055592650835572950932266967461790948584315647051443",
    "94560208308847015747498523884063394671606671904944666360068158221458669711639",

    // http://primes.utm.edu/lists/small/small3.html
    "449417999055441493994709297093108513015373787049558499205492347871729927573118262811508386655998299074566974373711472560655026288668094291699357843464363003144674940345912431129144354948751003607115263071543163",
    "230975859993204150666423538988557839555560243929065415434980904258310530753006723857139742334640122533598517597674807096648905501653461687601339782814316124971547968912893214002992086353183070342498989426570593",
    "5521712099665906221540423207019333379125265462121169655563495403888449493493629943498064604536961775110765377745550377067893607246020694972959780839151452457728855382113555867743022746090187341871655890805971735385789993",
    "203956878356401977405765866929034577280193993314348263094772646453283062722701277632936616063144088173312372882677123879538709400158306567338328279154499698366071906766440037074217117805690872792848149112022286332144876183376326512083574821647933992961249917319836219304274280243803104015000563790123",
}


var composites = []string{
    "21284175091214687912771199898307297748211672914763848041968395774954376176754",
    "6084766654921918907427900243509372380954290099172559290432744450051395395951",
    "84594350493221918389213352992032324280367711247940675652888030554255915464401",
    "82793403787388584738507275144194252681",
}


func TestProbablyPrime(t *testing.T) {
    for i, s := range primes {
        p, _ := new(Int).SetString(s, 10)
        if !ProbablyPrime(p, 20) {
            t.Errorf("#%d prime found to be non-prime (%s)", i, s)
        }
    }

    for i, s := range composites {
        c, _ := new(Int).SetString(s, 10)
        if ProbablyPrime(c, 20) {
            t.Errorf("#%d composite found to be prime (%s)", i, s)
        }
    }
}


type intShiftTest struct {
    in    string
    shift uint
    out   string
}


var rshTests = []intShiftTest{
    intShiftTest{"0", 0, "0"},
    intShiftTest{"-0", 0, "0"},
    intShiftTest{"0", 1, "0"},
    intShiftTest{"0", 2, "0"},
    intShiftTest{"1", 0, "1"},
    intShiftTest{"1", 1, "0"},
    intShiftTest{"1", 2, "0"},
    intShiftTest{"2", 0, "2"},
    intShiftTest{"2", 1, "1"},
    intShiftTest{"-1", 0, "-1"},
    intShiftTest{"-1", 1, "-1"},
    intShiftTest{"-1", 10, "-1"},
    intShiftTest{"-100", 2, "-25"},
    intShiftTest{"-100", 3, "-13"},
    intShiftTest{"-100", 100, "-1"},
    intShiftTest{"4294967296", 0, "4294967296"},
    intShiftTest{"4294967296", 1, "2147483648"},
    intShiftTest{"4294967296", 2, "1073741824"},
    intShiftTest{"18446744073709551616", 0, "18446744073709551616"},
    intShiftTest{"18446744073709551616", 1, "9223372036854775808"},
    intShiftTest{"18446744073709551616", 2, "4611686018427387904"},
    intShiftTest{"18446744073709551616", 64, "1"},
    intShiftTest{"340282366920938463463374607431768211456", 64, "18446744073709551616"},
    intShiftTest{"340282366920938463463374607431768211456", 128, "1"},
}


func TestRsh(t *testing.T) {
    for i, test := range rshTests {
        in, _ := new(Int).SetString(test.in, 10)
        expected, _ := new(Int).SetString(test.out, 10)
        out := new(Int).Rsh(in, test.shift)

        if !isNormalized(out) {
            t.Errorf("#%d: %v is not normalized", i, *out)
        }
        if out.Cmp(expected) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, expected)
        }
    }
}


func TestRshSelf(t *testing.T) {
    for i, test := range rshTests {
        z, _ := new(Int).SetString(test.in, 10)
        expected, _ := new(Int).SetString(test.out, 10)
        z.Rsh(z, test.shift)

        if !isNormalized(z) {
            t.Errorf("#%d: %v is not normalized", i, *z)
        }
        if z.Cmp(expected) != 0 {
            t.Errorf("#%d: got %s want %s", i, z, expected)
        }
    }
}


var lshTests = []intShiftTest{
    intShiftTest{"0", 0, "0"},
    intShiftTest{"0", 1, "0"},
    intShiftTest{"0", 2, "0"},
    intShiftTest{"1", 0, "1"},
    intShiftTest{"1", 1, "2"},
    intShiftTest{"1", 2, "4"},
    intShiftTest{"2", 0, "2"},
    intShiftTest{"2", 1, "4"},
    intShiftTest{"2", 2, "8"},
    intShiftTest{"-87", 1, "-174"},
    intShiftTest{"4294967296", 0, "4294967296"},
    intShiftTest{"4294967296", 1, "8589934592"},
    intShiftTest{"4294967296", 2, "17179869184"},
    intShiftTest{"18446744073709551616", 0, "18446744073709551616"},
    intShiftTest{"9223372036854775808", 1, "18446744073709551616"},
    intShiftTest{"4611686018427387904", 2, "18446744073709551616"},
    intShiftTest{"1", 64, "18446744073709551616"},
    intShiftTest{"18446744073709551616", 64, "340282366920938463463374607431768211456"},
    intShiftTest{"1", 128, "340282366920938463463374607431768211456"},
}


func TestLsh(t *testing.T) {
    for i, test := range lshTests {
        in, _ := new(Int).SetString(test.in, 10)
        expected, _ := new(Int).SetString(test.out, 10)
        out := new(Int).Lsh(in, test.shift)

        if !isNormalized(out) {
            t.Errorf("#%d: %v is not normalized", i, *out)
        }
        if out.Cmp(expected) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, expected)
        }
    }
}


func TestLshSelf(t *testing.T) {
    for i, test := range lshTests {
        z, _ := new(Int).SetString(test.in, 10)
        expected, _ := new(Int).SetString(test.out, 10)
        z.Lsh(z, test.shift)

        if !isNormalized(z) {
            t.Errorf("#%d: %v is not normalized", i, *z)
        }
        if z.Cmp(expected) != 0 {
            t.Errorf("#%d: got %s want %s", i, z, expected)
        }
    }
}


func TestLshRsh(t *testing.T) {
    for i, test := range rshTests {
        in, _ := new(Int).SetString(test.in, 10)
        out := new(Int).Lsh(in, test.shift)
        out = out.Rsh(out, test.shift)

        if !isNormalized(out) {
            t.Errorf("#%d: %v is not normalized", i, *out)
        }
        if in.Cmp(out) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, in)
        }
    }
    for i, test := range lshTests {
        in, _ := new(Int).SetString(test.in, 10)
        out := new(Int).Lsh(in, test.shift)
        out.Rsh(out, test.shift)

        if !isNormalized(out) {
            t.Errorf("#%d: %v is not normalized", i, *out)
        }
        if in.Cmp(out) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, in)
        }
    }
}


var int64Tests = []int64{
    0,
    1,
    -1,
    4294967295,
    -4294967295,
    4294967296,
    -4294967296,
    9223372036854775807,
    -9223372036854775807,
    -9223372036854775808,
}


func TestInt64(t *testing.T) {
    for i, testVal := range int64Tests {
        in := NewInt(testVal)
        out := in.Int64()

        if out != testVal {
            t.Errorf("#%d got %d want %d", i, out, testVal)
        }
    }
}


type bitwiseTest struct {
    x, y                 string
    and, or, xor, andNot string
}

var bitwiseTests = []bitwiseTest{
    bitwiseTest{"0x00", "0x00", "0x00", "0x00", "0x00", "0x00"},
    bitwiseTest{"0x00", "0x01", "0x00", "0x01", "0x01", "0x00"},
    bitwiseTest{"0x01", "0x00", "0x00", "0x01", "0x01", "0x01"},
    bitwiseTest{"-0x01", "0x00", "0x00", "-0x01", "-0x01", "-0x01"},
    bitwiseTest{"-0xaf", "-0x50", "-0xf0", "-0x0f", "0xe1", "0x41"},
    bitwiseTest{"0x00", "-0x01", "0x00", "-0x01", "-0x01", "0x00"},
    bitwiseTest{"0x01", "0x01", "0x01", "0x01", "0x00", "0x00"},
    bitwiseTest{"-0x01", "-0x01", "-0x01", "-0x01", "0x00", "0x00"},
    bitwiseTest{"0x07", "0x08", "0x00", "0x0f", "0x0f", "0x07"},
    bitwiseTest{"0x05", "0x0f", "0x05", "0x0f", "0x0a", "0x00"},
    bitwiseTest{"0x013ff6", "0x9a4e", "0x1a46", "0x01bffe", "0x01a5b8", "0x0125b0"},
    bitwiseTest{"-0x013ff6", "0x9a4e", "0x800a", "-0x0125b2", "-0x01a5bc", "-0x01c000"},
    bitwiseTest{"-0x013ff6", "-0x9a4e", "-0x01bffe", "-0x1a46", "0x01a5b8", "0x8008"},
    bitwiseTest{
        "0x1000009dc6e3d9822cba04129bcbe3401",
        "0xb9bd7d543685789d57cb918e833af352559021483cdb05cc21fd",
        "0x1000001186210100001000009048c2001",
        "0xb9bd7d543685789d57cb918e8bfeff7fddb2ebe87dfbbdfe35fd",
        "0xb9bd7d543685789d57ca918e8ae69d6fcdb2eae87df2b97215fc",
        "0x8c40c2d8822caa04120b8321400",
    },
    bitwiseTest{
        "0x1000009dc6e3d9822cba04129bcbe3401",
        "-0xb9bd7d543685789d57cb918e833af352559021483cdb05cc21fd",
        "0x8c40c2d8822caa04120b8321401",
        "-0xb9bd7d543685789d57ca918e82229142459020483cd2014001fd",
        "-0xb9bd7d543685789d57ca918e8ae69d6fcdb2eae87df2b97215fe",
        "0x1000001186210100001000009048c2000",
    },
    bitwiseTest{
        "-0x1000009dc6e3d9822cba04129bcbe3401",
        "-0xb9bd7d543685789d57cb918e833af352559021483cdb05cc21fd",
        "-0xb9bd7d543685789d57cb918e8bfeff7fddb2ebe87dfbbdfe35fd",
        "-0x1000001186210100001000009048c2001",
        "0xb9bd7d543685789d57ca918e8ae69d6fcdb2eae87df2b97215fc",
        "0xb9bd7d543685789d57ca918e82229142459020483cd2014001fc",
    },
}


type bitFun func(z, x, y *Int) *Int

func testBitFun(t *testing.T, msg string, f bitFun, x, y *Int, exp string) {
    expected := new(Int)
    expected.SetString(exp, 0)

    out := f(new(Int), x, y)
    if out.Cmp(expected) != 0 {
        t.Errorf("%s: got %s want %s", msg, out, expected)
    }
}


func testBitFunSelf(t *testing.T, msg string, f bitFun, x, y *Int, exp string) {
    self := new(Int)
    self.Set(x)
    expected := new(Int)
    expected.SetString(exp, 0)

    self = f(self, self, y)
    if self.Cmp(expected) != 0 {
        t.Errorf("%s: got %s want %s", msg, self, expected)
    }
}


func TestBitwise(t *testing.T) {
    x := new(Int)
    y := new(Int)
    for _, test := range bitwiseTests {
        x.SetString(test.x, 0)
        y.SetString(test.y, 0)

        testBitFun(t, "and", (*Int).And, x, y, test.and)
        testBitFunSelf(t, "and", (*Int).And, x, y, test.and)
        testBitFun(t, "andNot", (*Int).AndNot, x, y, test.andNot)
        testBitFunSelf(t, "andNot", (*Int).AndNot, x, y, test.andNot)
        testBitFun(t, "or", (*Int).Or, x, y, test.or)
        testBitFunSelf(t, "or", (*Int).Or, x, y, test.or)
        testBitFun(t, "xor", (*Int).Xor, x, y, test.xor)
        testBitFunSelf(t, "xor", (*Int).Xor, x, y, test.xor)
    }
}


type notTest struct {
    in  string
    out string
}

var notTests = []notTest{
    notTest{"0", "-1"},
    notTest{"1", "-2"},
    notTest{"7", "-8"},
    notTest{"0", "-1"},
    notTest{"-81910", "81909"},
    notTest{
        "298472983472983471903246121093472394872319615612417471234712061",
        "-298472983472983471903246121093472394872319615612417471234712062",
    },
}

func TestNot(t *testing.T) {
    in := new(Int)
    out := new(Int)
    expected := new(Int)
    for i, test := range notTests {
        in.SetString(test.in, 10)
        expected.SetString(test.out, 10)
        out = out.Not(in)
        if out.Cmp(expected) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, expected)
        }
        out = out.Not(out)
        if out.Cmp(in) != 0 {
            t.Errorf("#%d: got %s want %s", i, out, in)
        }
    }
}


type modInverseTest struct {
    element string
    prime   string
}

var modInverseTests = []modInverseTest{
    modInverseTest{"1", "7"},
    modInverseTest{"1", "13"},
    modInverseTest{"239487239847", "2410312426921032588552076022197566074856950548502459942654116941958108831682612228890093858261341614673227141477904012196503648957050582631942730706805009223062734745341073406696246014589361659774041027169249453200378729434170325843778659198143763193776859869524088940195577346119843545301547043747207749969763750084308926339295559968882457872412993810129130294592999947926365264059284647209730384947211681434464714438488520940127459844288859336526896320919633919"},
}

func TestModInverse(t *testing.T) {
    var element, prime Int
    one := NewInt(1)
    for i, test := range modInverseTests {
        (&element).SetString(test.element, 10)
        (&prime).SetString(test.prime, 10)
        inverse := new(Int).ModInverse(&element, &prime)
        inverse.Mul(inverse, &element)
        inverse.Mod(inverse, &prime)
        if inverse.Cmp(one) != 0 {
            t.Errorf("#%d: failed (e·e^(-1)=%s)", i, inverse)
        }
    }
}