Get rid of unsafe usage and add tests

tz/hash.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"hash"
 	"math"
-	"unsafe"
 
 	"github.com/nspcc-dev/tzhash/gf127"
 )
@@ -17,19 +16,12 @@ const (
 	hashBlockSize = 128
 )
 
-type (
+type digest struct {
-	digest struct {
+	x [4]gf127.GF127
-		x [4]gf127.GF127
+}
-	}
 
-	digest2 digest
+// type assertion
-)
+var _ hash.Hash = new(digest)
-
-// type assertions
-var (
-	_ hash.Hash = new(digest)
-	_ hash.Hash = new(digest2)
-)
 
 var (
 	minmax  = [2]gf127.GF127{{0, 0}, {math.MaxUint64, math.MaxUint64}}
@@ -93,46 +85,11 @@ func (d *digest) BlockSize() int {
 	return hashBlockSize
 }
 
-func (d *digest2) Write(data []byte) (n int, err error) {
-	n = len(data)
-
-	// We need to transpose matrix, because
-	// mulBitRightx2 accepts matrix by columns, not rows
-	a := d.x[1]
-	d.x[1] = d.x[2]
-	d.x[2] = a
-
-	h1 := (*gf127.GF127x2)(unsafe.Pointer(&d.x[0]))
-	h2 := (*gf127.GF127x2)(unsafe.Pointer(&d.x[2]))
-	for _, b := range data {
-		mulBitRightx2(h1, h2, &minmax[(b>>7)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>6)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>5)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>4)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>3)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>2)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>1)&1])
-		mulBitRightx2(h1, h2, &minmax[(b>>0)&1])
-	}
-
-	// transpose matrix back
-	a = d.x[1]
-	d.x[1] = d.x[2]
-	d.x[2] = a
-
-	return
-}
-func (d *digest2) Sum(b []byte) []byte      { return (*digest)(d).Sum(b) }
-func (d *digest2) Reset()                   { (*digest)(d).Reset() }
-func (d *digest2) Size() int                { return (*digest)(d).Size() }
-func (d *digest2) BlockSize() int           { return (*digest)(d).BlockSize() }
-func (d *digest2) checkSum() [hashSize]byte { return (*digest)(d).checkSum() }
-
 // Sum returnz Tillich-Zémor checksum of data
 func Sum(data []byte) [hashSize]byte {
-	d := new(digest2)
+	d := new(digest)
 	d.Reset()
-	d.Write(data)
+	_, _ = d.Write(data) // no errors
 	return d.checkSum()
 }
 
@@ -215,4 +172,3 @@ func SubtractL(c, a []byte) (b []byte, err error) {
 }
 
 func mulBitRight(c00, c01, c10, c11, e *gf127.GF127)
-func mulBitRightx2(c00c01 *gf127.GF127x2, c10c11 *gf127.GF127x2, e *gf127.GF127)

tz/hash_avx2.go

@@ -0,0 +1,55 @@
+package tz
+
+import (
+	"hash"
+
+	"github.com/nspcc-dev/tzhash/gf127"
+)
+
+type digest2 struct {
+	x [2]gf127.GF127x2
+}
+
+var _ hash.Hash = new(digest2)
+
+func (d *digest2) Write(data []byte) (n int, err error) {
+	n = len(data)
+	for _, b := range data {
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>7)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>6)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>5)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>4)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>3)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>2)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>1)&1])
+		mulBitRightx2(&d.x[0], &d.x[1], &minmax[(b>>0)&1])
+	}
+	return
+}
+
+func (d *digest2) Sum(in []byte) []byte {
+	// Make a copy of d so that caller can keep writing and summing.
+	d0 := *d
+	h := d0.checkSum()
+	return append(in, h[:]...)
+}
+func (d *digest2) Reset() {
+	d.x[0] = gf127.GF127x2{1, 0, 0, 0}
+	d.x[1] = gf127.GF127x2{0, 0, 0, 1}
+}
+func (d *digest2) Size() int      { return hashSize }
+func (d *digest2) BlockSize() int { return hashBlockSize }
+func (d *digest2) checkSum() (b [hashSize]byte) {
+	// Matrix is stored transposed,
+	// but we need to use order consistent with digest.
+	h := d.x[0].ByteArray()
+	copy(b[:], h[:8])
+	copy(b[16:], h[8:])
+
+	h = d.x[1].ByteArray()
+	copy(b[8:], h[:8])
+	copy(b[24:], h[8:])
+	return
+}
+
+func mulBitRightx2(c00c10 *gf127.GF127x2, c01c11 *gf127.GF127x2, e *gf127.GF127)

tz/hash_test.go

@@ -8,7 +8,49 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+var testCases = []struct {
+	input []byte
+	hash  string
+}{
+	{
+		[]byte{0, 1, 2, 3, 4, 5, 6, 7, 8},
+		"00000000000001e4a545e5b90fb6882b00000000000000c849cd88f79307f67100000000000000cd0c898cb68356e624000000000000007cbcdc7c5e89b16e4b",
+	},
+	{
+		[]byte{4, 8, 15, 16, 23, 42, 255, 0, 127, 65, 32, 123, 42, 45, 201, 210, 213, 244},
+		"4db8a8e253903c70ab0efb65fe6de05a36d1dc9f567a147152d0148a86817b2062908d9b026a506007c1118e86901b672a39317c55ee3c10ac8efafa79efe8ee",
+	},
+}
+
 func TestHash(t *testing.T) {
+	t.Run("test AVX digest", func(t *testing.T) {
+		d := new(digest)
+		for _, tc := range testCases {
+			d.Reset()
+			_, _ = d.Write(tc.input)
+			sum := d.checkSum()
+			hash := hex.EncodeToString(sum[:])
+			if hash != tc.hash {
+				t.Errorf("expected (%s), got (%s)", tc.hash, hash)
+			}
+		}
+	})
+
+	t.Run("test AVX2 digest", func(t *testing.T) {
+		d := new(digest)
+		for _, tc := range testCases {
+			d.Reset()
+			_, _ = d.Write(tc.input)
+			sum := d.checkSum()
+			hash := hex.EncodeToString(sum[:])
+			if hash != tc.hash {
+				t.Errorf("expected (%s), got (%s)", tc.hash, hash)
+			}
+		}
+	})
+}
+
+func TestHomomorphism(t *testing.T) {
 	var (
 		c1, c2    sl2
 		n         int
@@ -36,7 +78,7 @@ func TestHash(t *testing.T) {
 	require.Equal(t, h, c1.ByteArray())
 }
 
-var testCases = []struct {
+var testCasesConcat = []struct {
 	Hash  string
 	Parts []string
 }{{
@@ -62,7 +104,7 @@ func TestConcat(t *testing.T) {
 		err            error
 	)
 
-	for _, tc := range testCases {
+	for _, tc := range testCasesConcat {
 		expect, err = hex.DecodeString(tc.Hash)
 		require.NoError(t, err)
 
@@ -86,7 +128,7 @@ func TestValidate(t *testing.T) {
 		err  error
 	)
 
-	for _, tc := range testCases {
+	for _, tc := range testCasesConcat {
 		hash, _ = hex.DecodeString(tc.Hash)
 		require.NoError(t, err)