[#170] checksum: Drop Empty method

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

object/fmt.go

@@ -1,6 +1,7 @@
 package object
 
 import (
+	"bytes"
 	"crypto/ecdsa"
 	"crypto/sha256"
 	"errors"
@@ -20,10 +21,10 @@ var errIncorrectID = errors.New("incorrect object identifier")
 // CalculatePayloadChecksum calculates and returns checksum of
 // object payload bytes.
 func CalculatePayloadChecksum(payload []byte) *checksum.Checksum {
-	res := checksum.New()
-	res.SetSHA256(sha256.Sum256(payload))
+	var res checksum.Checksum
+	checksum.Calculate(&res, checksum.SHA256, payload)
 
-	return res
+	return &res
 }
 
 // CalculateAndSetPayloadChecksum calculates checksum of current
@@ -38,7 +39,7 @@ func CalculateAndSetPayloadChecksum(obj *Object) {
 // corresponds to its payload.
 func VerifyPayloadChecksum(obj *Object) error {
 	actual := CalculatePayloadChecksum(obj.Payload())
-	if !checksum.Equal(obj.PayloadChecksum(), actual) {
+	if !bytes.Equal(obj.PayloadChecksum().Value(), actual.Value()) {
 		return errCheckSumMismatch
 	}
 

object/object.go

@@ -201,33 +201,45 @@ func (o *Object) SetCreationEpoch(v uint64) {
 
 // PayloadChecksum returns checksum of the object payload.
 func (o *Object) PayloadChecksum() *checksum.Checksum {
-	return checksum.NewFromV2(
-		(*object.Object)(o).
+	var v checksum.Checksum
+	v.ReadFromV2(
+		*(*object.Object)(o).
 			GetHeader().
 			GetPayloadHash(),
 	)
+
+	return &v
 }
 
 // SetPayloadChecksum sets checksum of the object payload.
 func (o *Object) SetPayloadChecksum(v *checksum.Checksum) {
+	var v2 refs.Checksum
+	v.WriteToV2(&v2)
+
 	o.setHeaderField(func(h *object.Header) {
-		h.SetPayloadHash(v.ToV2())
+		h.SetPayloadHash(&v2)
 	})
 }
 
 // PayloadHomomorphicHash returns homomorphic hash of the object payload.
 func (o *Object) PayloadHomomorphicHash() *checksum.Checksum {
-	return checksum.NewFromV2(
-		(*object.Object)(o).
+	var v checksum.Checksum
+	v.ReadFromV2(
+		*(*object.Object)(o).
 			GetHeader().
 			GetHomomorphicHash(),
 	)
+
+	return &v
 }
 
 // SetPayloadHomomorphicHash sets homomorphic hash of the object payload.
 func (o *Object) SetPayloadHomomorphicHash(v *checksum.Checksum) {
+	var v2 refs.Checksum
+	v.WriteToV2(&v2)
+
 	o.setHeaderField(func(h *object.Header) {
-		h.SetHomomorphicHash(v.ToV2())
+		h.SetHomomorphicHash(&v2)
 	})
 }
 

object/raw_test.go

@@ -122,23 +122,23 @@ func TestObject_SetCreationEpoch(t *testing.T) {
 
 func TestObject_SetPayloadChecksum(t *testing.T) {
 	obj := New()
-	cs := checksum.New()
+	var cs checksum.Checksum
 	cs.SetSHA256(randSHA256Checksum(t))
 
-	obj.SetPayloadChecksum(cs)
+	obj.SetPayloadChecksum(&cs)
 
-	require.Equal(t, cs, obj.PayloadChecksum())
+	require.Equal(t, &cs, obj.PayloadChecksum())
 }
 
 func TestObject_SetPayloadHomomorphicHash(t *testing.T) {
 	obj := New()
 
-	cs := checksum.New()
+	var cs checksum.Checksum
 	cs.SetTillichZemor(randTZChecksum(t))
 
-	obj.SetPayloadHomomorphicHash(cs)
+	obj.SetPayloadHomomorphicHash(&cs)
 
-	require.Equal(t, cs, obj.PayloadHomomorphicHash())
+	require.Equal(t, &cs, obj.PayloadHomomorphicHash())
 }
 
 func TestObject_SetAttributes(t *testing.T) {