diff -r 000000000000 -r 0d277415ed02 emul/mini/src/main/java/org/apidesign/bck2brwsr/emul/zip/CRC32.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/emul/mini/src/main/java/org/apidesign/bck2brwsr/emul/zip/CRC32.java	Thu Feb 07 12:58:12 2013 +0100
@@ -0,0 +1,181 @@
+/* -*-mode:java; c-basic-offset:2; -*- */
+/*
+Copyright (c) 2011 ymnk, JCraft,Inc. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  1. Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+
+  2. Redistributions in binary form must reproduce the above copyright 
+     notice, this list of conditions and the following disclaimer in 
+     the documentation and/or other materials provided with the distribution.
+
+  3. The names of the authors may not be used to endorse or promote products
+     derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
+INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * This program is based on zlib-1.1.3, so all credit should go authors
+ * Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
+ * and contributors of zlib.
+ */
+
+package org.apidesign.bck2brwsr.emul.zip;
+
+import org.apidesign.bck2brwsr.emul.lang.System;
+
+final class CRC32 implements Checksum {
+
+  /*
+   *  The following logic has come from RFC1952.
+   */
+  private int v = 0;
+  private static int[] crc_table = null;
+  static {
+    crc_table = new int[256];
+    for (int n = 0; n < 256; n++) {
+      int c = n;
+      for (int k = 8;  --k >= 0; ) {
+        if ((c & 1) != 0)
+	  c = 0xedb88320 ^ (c >>> 1);
+        else
+          c = c >>> 1;
+      }
+      crc_table[n] = c;
+    }
+  }
+
+  public void update (byte[] buf, int index, int len) {
+    int c = ~v;
+    while (--len >= 0)
+      c = crc_table[(c^buf[index++])&0xff]^(c >>> 8);
+    v = ~c;
+  }
+
+  public void reset(){
+    v = 0;
+  }
+
+  public void reset(long vv){
+    v = (int)(vv&0xffffffffL);
+  }
+
+  public long getValue(){
+    return (long)(v&0xffffffffL);
+  }
+
+  // The following logic has come from zlib.1.2.
+  private static final int GF2_DIM = 32;
+  static long combine(long crc1, long crc2, long len2){
+    long row;
+    long[] even = new long[GF2_DIM];
+    long[] odd = new long[GF2_DIM];
+
+    // degenerate case (also disallow negative lengths)
+    if (len2 <= 0)
+      return crc1;
+
+    // put operator for one zero bit in odd
+    odd[0] = 0xedb88320L;          // CRC-32 polynomial
+    row = 1;
+    for (int n = 1; n < GF2_DIM; n++) {
+        odd[n] = row;
+        row <<= 1;
+    }
+
+    // put operator for two zero bits in even
+    gf2_matrix_square(even, odd);
+
+    // put operator for four zero bits in odd
+    gf2_matrix_square(odd, even);
+
+    // apply len2 zeros to crc1 (first square will put the operator for one
+    // zero byte, eight zero bits, in even)
+    do {
+      // apply zeros operator for this bit of len2
+      gf2_matrix_square(even, odd);
+      if ((len2 & 1)!=0)
+        crc1 = gf2_matrix_times(even, crc1);
+      len2 >>= 1;
+
+      // if no more bits set, then done
+      if (len2 == 0)
+        break;
+
+      // another iteration of the loop with odd and even swapped
+      gf2_matrix_square(odd, even);
+      if ((len2 & 1)!=0)
+        crc1 = gf2_matrix_times(odd, crc1);
+      len2 >>= 1;
+
+      // if no more bits set, then done
+    } while (len2 != 0);
+
+    /* return combined crc */
+    crc1 ^= crc2;
+    return crc1;
+  }
+
+  private static long gf2_matrix_times(long[] mat, long vec){
+    long sum = 0;
+    int index = 0;
+    while (vec!=0) {
+      if ((vec & 1)!=0)
+        sum ^= mat[index];
+      vec >>= 1;
+      index++;
+    }
+    return sum;
+  }
+
+  static final void gf2_matrix_square(long[] square, long[] mat) {
+    for (int n = 0; n < GF2_DIM; n++)
+      square[n] = gf2_matrix_times(mat, mat[n]);
+  }
+
+  /*
+  private java.util.zip.CRC32 crc32 = new java.util.zip.CRC32();
+
+  public void update(byte[] buf, int index, int len){
+    if(buf==null) {crc32.reset();}
+    else{crc32.update(buf, index, len);}
+  }
+  public void reset(){
+    crc32.reset();
+  }
+  public void reset(long init){
+    if(init==0L){
+      crc32.reset();
+    }
+    else{
+      System.err.println("unsupported operation");
+    }
+  }
+  public long getValue(){
+    return crc32.getValue();
+  }
+*/
+  public CRC32 copy(){
+    CRC32 foo = new CRC32();
+    foo.v = this.v;
+    return foo;
+  }
+
+  public static int[] getCRC32Table(){
+    int[] tmp = new int[crc_table.length];
+    System.arraycopy(crc_table, 0, tmp, 0, tmp.length);
+    return tmp;
+  }
+}