Add Float40 methods

This commit adds Float40 related methods, and keeps the Float16 version
which will be deleted in a near future once the Float40 migration is
ready.

common/float40_test.go

@@ -0,0 +1,95 @@
+package common
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConversionsFloat40(t *testing.T) {
+	testVector := map[Float40]string{
+		6*0x800000000 + 123:    "123000000",
+		2*0x800000000 + 4545:   "454500",
+		30*0x800000000 + 10235: "10235000000000000000000000000000000",
+		0x000000000:            "0",
+		0x800000000:            "0",
+		0x0001:                 "1",
+		0x0401:                 "1025",
+		0x800000000 + 1:        "10",
+		0xFFFFFFFFFF:           "343597383670000000000000000000000000000000",
+	}
+
+	for test := range testVector {
+		fix, err := test.BigInt()
+		require.NoError(t, err)
+		assert.Equal(t, fix.String(), testVector[test])
+
+		bi, ok := new(big.Int).SetString(testVector[test], 10)
+		require.True(t, ok)
+
+		fl, err := NewFloat40(bi)
+		assert.NoError(t, err)
+
+		fx2, err := fl.BigInt()
+		require.NoError(t, err)
+		assert.Equal(t, fx2.String(), testVector[test])
+	}
+}
+
+func TestExpectError(t *testing.T) {
+	testVector := map[string]error{
+		"9922334455000000000000000000000000000000":   nil,
+		"9922334455000000000000000000000000000001":   ErrFloat40NotEnoughPrecission,
+		"9922334454999999999999999999999999999999":   ErrFloat40NotEnoughPrecission,
+		"42949672950000000000000000000000000000000":  nil,
+		"99223344556573838487575":                    ErrFloat40NotEnoughPrecission,
+		"992233445500000000000000000000000000000000": ErrFloat40E31,
+		"343597383670000000000000000000000000000000": nil,
+		"343597383680000000000000000000000000000000": ErrFloat40NotEnoughPrecission,
+		"343597383690000000000000000000000000000000": ErrFloat40NotEnoughPrecission,
+		"343597383700000000000000000000000000000000": ErrFloat40E31,
+	}
+	for test := range testVector {
+		bi, ok := new(big.Int).SetString(test, 10)
+		require.True(t, ok)
+		_, err := NewFloat40(bi)
+		assert.Equal(t, testVector[test], err)
+	}
+}
+
+func BenchmarkFloat40(b *testing.B) {
+	newBigInt := func(s string) *big.Int {
+		bigInt, ok := new(big.Int).SetString(s, 10)
+		if !ok {
+			panic("Can not convert string to *big.Int")
+		}
+		return bigInt
+	}
+	type pair struct {
+		Float40 Float40
+		BigInt  *big.Int
+	}
+	testVector := []pair{
+		{6*0x800000000 + 123, newBigInt("123000000")},
+		{2*0x800000000 + 4545, newBigInt("454500")},
+		{30*0x800000000 + 10235, newBigInt("10235000000000000000000000000000000")},
+		{0x000000000, newBigInt("0")},
+		{0x800000000, newBigInt("0")},
+		{0x0001, newBigInt("1")},
+		{0x0401, newBigInt("1025")},
+		{0x800000000 + 1, newBigInt("10")},
+		{0xFFFFFFFFFF, newBigInt("343597383670000000000000000000000000000000")},
+	}
+	b.Run("NewFloat40()", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_, _ = NewFloat40(testVector[i%len(testVector)].BigInt)
+		}
+	})
+	b.Run("Float40.BigInt()", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_, _ = testVector[i%len(testVector)].Float40.BigInt()
+		}
+	})
+}