golang
diff --git a/‎src/crypto/aes/gcm_ppc64x.go
Lines changed: 5 additions & 27 deletions b/‎src/crypto/aes/gcm_ppc64x.go
Lines changed: 5 additions & 27 deletions
@@ -51,6 +51,8 @@ type gcmAsm struct {
 	tagSize int
 }
 
+func counterCryptASM(nr int, out, in []byte, counter *[gcmBlockSize]byte, key *uint32)
+
 // NewGCM returns the AES cipher wrapped in Galois Counter Mode. This is only
 // called by crypto/cipher.NewGCM via the gcmAble interface.
 func (c *aesCipherAsm) NewGCM(nonceSize, tagSize int) (cipher.AEAD, error) {
@@ -114,34 +116,10 @@ func (g *gcmAsm) deriveCounter(counter *[gcmBlockSize]byte, nonce []byte) {
 // into out. counter is the initial count value and will be updated with the next
 // count value. The length of out must be greater than or equal to the length
 // of in.
+// counterCryptASM implements counterCrypt which then allows the loop to
+// be unrolled and optimized.
 func (g *gcmAsm) counterCrypt(out, in []byte, counter *[gcmBlockSize]byte) {
-	var mask [gcmBlockSize]byte
-
-	for len(in) >= gcmBlockSize {
-		// Hint to avoid bounds check
-		_, _ = in[15], out[15]
-		g.cipher.Encrypt(mask[:], counter[:])
-		gcmInc32(counter)
-
-		// XOR 16 bytes each loop iteration in 8 byte chunks
-		in0 := binary.LittleEndian.Uint64(in[0:])
-		in1 := binary.LittleEndian.Uint64(in[8:])
-		m0 := binary.LittleEndian.Uint64(mask[:8])
-		m1 := binary.LittleEndian.Uint64(mask[8:])
-		binary.LittleEndian.PutUint64(out[:8], in0^m0)
-		binary.LittleEndian.PutUint64(out[8:], in1^m1)
-		out = out[16:]
-		in = in[16:]
-	}
-
-	if len(in) > 0 {
-		g.cipher.Encrypt(mask[:], counter[:])
-		gcmInc32(counter)
-		// XOR leftover bytes
-		for i, inb := range in {
-			out[i] = inb ^ mask[i]
-		}
-	}
+	counterCryptASM(len(g.cipher.enc)/4-1, out, in, counter, &g.cipher.enc[0])
 }
 
 // increments the rightmost 32-bits of the count value by 1.