common/bitutil, consensus/ethash: reusable bitutil package

2 files changed, 2 insertions, 86 deletions

diff --git a/consensus/ethash/algorithm.go b/consensus/ethash/algorithm.go
index 7e8fbfc37..365fe5520 100644
--- a/consensus/ethash/algorithm.go
+++ b/consensus/ethash/algorithm.go
@@ -27,6 +27,7 @@ import (
 	"unsafe"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/bitutil"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
 	"github.com/ethereum/go-ethereum/log"
@@ -142,7 +143,7 @@ func generateCache(dest []uint32, epoch uint64, seed []byte) {
 				dstOff = j * hashBytes
 				xorOff = (binary.LittleEndian.Uint32(cache[dstOff:]) % uint32(rows)) * hashBytes
 			)
-			xorBytes(temp, cache[srcOff:srcOff+hashBytes], cache[xorOff:xorOff+hashBytes])
+			bitutil.XORBytes(temp, cache[srcOff:srcOff+hashBytes], cache[xorOff:xorOff+hashBytes])
 			keccak512(cache[dstOff:], temp)
 
 			atomic.AddUint32(&progress, 1)
diff --git a/consensus/ethash/xor.go b/consensus/ethash/xor.go
deleted file mode 100644
index 90e232746..000000000
--- a/consensus/ethash/xor.go
+++ /dev/null
@@ -1,85 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Source: https://golang.org/src/crypto/cipher/xor.go
-
-package ethash
-
-import (
-	"runtime"
-	"unsafe"
-)
-
-const wordSize = int(unsafe.Sizeof(uintptr(0)))
-const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x"
-
-// fastXORBytes xors in bulk. It only works on architectures that
-// support unaligned read/writes.
-func fastXORBytes(dst, a, b []byte) int {
-	n := len(a)
-	if len(b) < n {
-		n = len(b)
-	}
-
-	w := n / wordSize
-	if w > 0 {
-		dw := *(*[]uintptr)(unsafe.Pointer(&dst))
-		aw := *(*[]uintptr)(unsafe.Pointer(&a))
-		bw := *(*[]uintptr)(unsafe.Pointer(&b))
-		for i := 0; i < w; i++ {
-			dw[i] = aw[i] ^ bw[i]
-		}
-	}
-
-	for i := (n - n%wordSize); i < n; i++ {
-		dst[i] = a[i] ^ b[i]
-	}
-
-	return n
-}
-
-func safeXORBytes(dst, a, b []byte) int {
-	n := len(a)
-	if len(b) < n {
-		n = len(b)
-	}
-	for i := 0; i < n; i++ {
-		dst[i] = a[i] ^ b[i]
-	}
-	return n
-}
-
-// xorBytes xors the bytes in a and b. The destination is assumed to have enough
-// space. Returns the number of bytes xor'd.
-func xorBytes(dst, a, b []byte) int {
-	if supportsUnaligned {
-		return fastXORBytes(dst, a, b)
-	}
-	// TODO(hanwen): if (dst, a, b) have common alignment
-	// we could still try fastXORBytes. It is not clear
-	// how often this happens, and it's only worth it if
-	// the block encryption itself is hardware
-	// accelerated.
-	return safeXORBytes(dst, a, b)
-}
-
-// fastXORWords XORs multiples of 4 or 8 bytes (depending on architecture.)
-// The arguments are assumed to be of equal length.
-func fastXORWords(dst, a, b []byte) {
-	dw := *(*[]uintptr)(unsafe.Pointer(&dst))
-	aw := *(*[]uintptr)(unsafe.Pointer(&a))
-	bw := *(*[]uintptr)(unsafe.Pointer(&b))
-	n := len(b) / wordSize
-	for i := 0; i < n; i++ {
-		dw[i] = aw[i] ^ bw[i]
-	}
-}
-
-func xorWords(dst, a, b []byte) {
-	if supportsUnaligned {
-		fastXORWords(dst, a, b)
-	} else {
-		safeXORBytes(dst, a, b)
-	}
-}