1package kzg
  2
  3import (
  4	"bytes"
  5	"crypto/rand"
  6	"math/big"
  7	"testing"
  8
  9	cryptoConstants "github.com/iden3/go-iden3-crypto/constants"
 10	"github.com/stretchr/testify/assert"
 11)
 12
 13func randBI() *big.Int {
 14	maxbits := 256
 15	b := make([]byte, (maxbits/8)-1)
 16	_, err := rand.Read(b)
 17	if err != nil {
 18		panic(err)
 19	}
 20	r := new(big.Int).SetBytes(b)
 21	return new(big.Int).Mod(r, cryptoConstants.Q)
 22}
 23
 24func neg(a *big.Int) *big.Int {
 25	return new(big.Int).Neg(a)
 26}
 27
 28func TestPolynomial(t *testing.T) {
 29	b0 := big.NewInt(int64(0))
 30	b1 := big.NewInt(int64(1))
 31	b2 := big.NewInt(int64(2))
 32	b3 := big.NewInt(int64(3))
 33	b4 := big.NewInt(int64(4))
 34	b5 := big.NewInt(int64(5))
 35	b6 := big.NewInt(int64(6))
 36	b16 := big.NewInt(int64(16))
 37
 38	a := []*big.Int{b1, b0, b5}
 39	b := []*big.Int{b3, b0, b1}
 40
 41	// new Finite Field
 42	r, ok := new(big.Int).SetString("21888242871839275222246405745257275088548364400416034343698204186575808495617", 10) //nolint:lll
 43	assert.True(nil, ok)
 44
 45	// polynomial multiplication
 46	o := polynomialMul(a, b)
 47	assert.Equal(t, o, []*big.Int{b3, b0, b16, b0, b5})
 48
 49	// polynomial division
 50	quo, rem := polynomialDiv(a, b)
 51	assert.Equal(t, quo[0].Int64(), int64(5))
 52	// check the rem result without modulo
 53	assert.Equal(t, new(big.Int).Sub(rem[0], r).Int64(), int64(-14))
 54
 55	c := []*big.Int{neg(b4), b0, neg(b2), b1}
 56	d := []*big.Int{neg(b3), b1}
 57	quo2, rem2 := polynomialDiv(c, d)
 58	assert.Equal(t, quo2, []*big.Int{b3, b1, b1})
 59	assert.Equal(t, rem2[0].Int64(), int64(5))
 60
 61	// polynomial addition
 62	o = polynomialAdd(a, b)
 63	assert.Equal(t, o, []*big.Int{b4, b0, b6})
 64
 65	// polynomial subtraction
 66	o1 := polynomialSub(a, b)
 67	o2 := polynomialSub(b, a)
 68	o = polynomialAdd(o1, o2)
 69	assert.True(t, bytes.Equal(b0.Bytes(), o[0].Bytes()))
 70	assert.True(t, bytes.Equal(b0.Bytes(), o[1].Bytes()))
 71	assert.True(t, bytes.Equal(b0.Bytes(), o[2].Bytes()))
 72
 73	c = []*big.Int{b5, b6, b1}
 74	d = []*big.Int{b1, b3}
 75	o = polynomialSub(c, d)
 76	assert.Equal(t, o, []*big.Int{b4, b3, b1})
 77
 78	// NewPolZeroAt
 79	o = newPolZeroAt(3, 4, b4)
 80	assert.Equal(t, polynomialEval(o, big.NewInt(3)), b4)
 81	o = newPolZeroAt(2, 4, b3)
 82	assert.Equal(t, polynomialEval(o, big.NewInt(2)), b3)
 83}
 84
 85func BenchmarkArithmetic(b *testing.B) {
 86	// generate arrays with bigint
 87	var p, q []*big.Int
 88	for i := 0; i < 1000; i++ {
 89		pi := randBI()
 90		p = append(p, pi)
 91	}
 92	for i := 1000 - 1; i >= 0; i-- {
 93		q = append(q, p[i])
 94	}
 95
 96	b.Run("polynomialSub", func(b *testing.B) {
 97		for i := 0; i < b.N; i++ {
 98			polynomialSub(p, q)
 99		}
100	})
101	b.Run("polynomialMul", func(b *testing.B) {
102		for i := 0; i < b.N; i++ {
103			polynomialMul(p, q)
104		}
105	})
106	b.Run("polynomialDiv", func(b *testing.B) {
107		for i := 0; i < b.N; i++ {
108			polynomialDiv(p, q)
109		}
110	})
111}