F function code moved to compression package

This will let us to import only F code from projects that require only F
compression function and use govendor to manage dependencies (hello,
go-ethereum!)

f.go → compression/f.go

@@ -4,13 +4,18 @@
 //
 // Modified by KEEP SEZC to expose F compression function.
 //
-
-package blake2b
+package compression
 
 import (
 	"math/bits"
 )
 
+// IV is an initialization vector for BLAKE2b
+var IV = [8]uint64{
+	0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
+	0x510e527fade682d1, 0x9b05688c2b3e6c1f, 0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
+}
+
 // the precomputed values for BLAKE2b
 // there are 10 16-byte arrays - one for each round
 // the entries are calculated from the sigma constants.
@@ -35,7 +40,7 @@ func F(h *[8]uint64, m [16]uint64, c [2]uint64, f bool, rounds uint32) {
 	c0, c1 := c[0], c[1]
 
 	v0, v1, v2, v3, v4, v5, v6, v7 := h[0], h[1], h[2], h[3], h[4], h[5], h[6], h[7]
-	v8, v9, v10, v11, v12, v13, v14, v15 := iv[0], iv[1], iv[2], iv[3], iv[4], iv[5], iv[6], iv[7]
+	v8, v9, v10, v11, v12, v13, v14, v15 := IV[0], IV[1], IV[2], IV[3], IV[4], IV[5], IV[6], IV[7]
 	v12 ^= c0
 	v13 ^= c1
 

f_test.go → compression/f_test.go

@@ -1,4 +1,4 @@
-package blake2b
+package compression
 
 import (
 	"encoding/binary"

go.mod

@@ -1,3 +1,3 @@
-module github.com/keep-network/blake2
+module github.com/keep-network/blake2b
 
 go 1.12

hash.go

@@ -20,6 +20,8 @@ import (
 	"encoding/binary"
 	"errors"
 	"hash"
+
+	"github.com/keep-network/blake2b/compression"
 )
 
 const (
@@ -35,22 +37,11 @@ const (
 	Rounds = 12
 )
 
-var (
-	useAVX2 bool
-	useAVX  bool
-	useSSE4 bool
-)
-
 var (
 	errKeySize  = errors.New("blake2b: invalid key size")
 	errHashSize = errors.New("blake2b: invalid hash size")
 )
 
-var iv = [8]uint64{
-	0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
-	0x510e527fade682d1, 0x9b05688c2b3e6c1f, 0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
-}
-
 // Sum512 returns the BLAKE2b-512 checksum of the data.
 func Sum512(data []byte) [Size]byte {
 	var sum [Size]byte
@@ -115,7 +106,7 @@ func newDigest(hashSize int, key []byte) (*digest, error) {
 }
 
 func checkSum(sum *[Size]byte, hashSize int, data []byte) {
-	h := iv
+	h := compression.IV
 	h[0] ^= uint64(hashSize) | (1 << 16) | (1 << 24)
 	var c [2]uint64
 
@@ -203,7 +194,7 @@ func (d *digest) BlockSize() int { return BlockSize }
 func (d *digest) Size() int { return d.size }
 
 func (d *digest) Reset() {
-	d.h = iv
+	d.h = compression.IV
 	d.h[0] ^= uint64(d.size) | (uint64(d.keyLen) << 8) | (1 << 16) | (1 << 24)
 	d.offset, d.c[0], d.c[1] = 0, 0, 0
 	if d.keyLen > 0 {
@@ -283,7 +274,7 @@ func hashBlocks(h *[8]uint64, blocks []byte, c *[2]uint64, f bool) {
 			i += 8
 		}
 
-		F(h, m, [2]uint64{c0, c1}, f, Rounds)
+		compression.F(h, m, [2]uint64{c0, c1}, f, Rounds)
 	}
 	c[0], c[1] = c0, c1
 }

xof.go

@@ -8,6 +8,8 @@ import (
 	"encoding/binary"
 	"errors"
 	"io"
+
+	"github.com/keep-network/blake2b/compression"
 )
 
 // XOF defines the interface to hash functions that
@@ -172,6 +174,6 @@ func (x *xof) Read(p []byte) (n int, err error) {
 func (d *digest) initConfig(cfg *[Size]byte) {
 	d.offset, d.c[0], d.c[1] = 0, 0, 0
 	for i := range d.h {
-		d.h[i] = iv[i] ^ binary.LittleEndian.Uint64(cfg[i*8:])
+		d.h[i] = compression.IV[i] ^ binary.LittleEndian.Uint64(cfg[i*8:])
 	}
 }