1 files changed, 33 insertions, 16 deletions

diff --git a/src/org/tukaani/xz/check/CRC64.java b/src/org/tukaani/xz/check/CRC64.java
index 02b15b7..a590a25 100644
--- a/src/org/tukaani/xz/check/CRC64.java
+++ b/src/org/tukaani/xz/check/CRC64.java
@@ -1,7 +1,8 @@
 /*
  * CRC64
  *
- * Author: Lasse Collin <lasse.collin@tukaani.org>
+ * Authors: Brett Okken <brett.okken.os@gmail.com>
+ *          Lasse Collin <lasse.collin@tukaani.org>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -10,37 +11,53 @@
 package org.tukaani.xz.check;
 
 public class CRC64 extends Check {
-    private static final long poly = 0xC96C5795D7870F42L;
-    private static final long[] crcTable = new long[256];
-
-    private long crc = -1;
+    private static final long[][] TABLE = new long[4][256];
 
     static {
-        for (int b = 0; b < crcTable.length; ++b) {
-                long r = b;
+        final long poly64 = 0xC96C5795D7870F42L;
+
+        for (int s = 0; s < 4; ++s) {
+            for (int b = 0; b < 256; ++b) {
+                long r = s == 0 ? b : TABLE[s - 1][b];
                 for (int i = 0; i < 8; ++i) {
-                        if ((r & 1) == 1)
-                                r = (r >>> 1) ^ poly;
-                        else
-                                r >>>= 1;
+                    if ((r & 1) == 1) {
+                        r = (r >>> 1) ^ poly64;
+                    } else {
+                        r >>>= 1;
+                    }
                 }
-
-                crcTable[b] = r;
+                TABLE[s][b] = r;
+            }
         }
     }
 
+    private long crc = -1;
+
     public CRC64() {
         size = 8;
         name = "CRC64";
     }
 
+    @Override
     public void update(byte[] buf, int off, int len) {
-        int end = off + len;
+        final int end = off + len;
+        int i = off;
+
+        for (int end4 = end - 3; i < end4; i += 4) {
+            final int tmp = (int)crc;
+            crc = TABLE[3][(tmp & 0xFF) ^ (buf[i] & 0xFF)] ^
+                  TABLE[2][((tmp >>> 8) & 0xFF) ^ (buf[i + 1] & 0xFF)] ^
+                  (crc >>> 32) ^
+                  TABLE[1][((tmp >>> 16) & 0xFF) ^ (buf[i + 2] & 0xFF)] ^
+                  TABLE[0][((tmp >>> 24) & 0xFF) ^ (buf[i + 3] & 0xFF)];
+        }
 
-        while (off < end)
-            crc = crcTable[(buf[off++] ^ (int)crc) & 0xFF] ^ (crc >>> 8);
+        while (i < end)
+            crc = TABLE[0][(buf[i++] & 0xFF) ^ ((int)crc & 0xFF)] ^
+                  (crc >>> 8);
     }
 
+    @Override
     public byte[] finish() {
         long value = ~crc;
         crc = -1;