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diff --git a/libjava/java/util/zip/Adler32.java b/libjava/java/util/zip/Adler32.java
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+/* Copyright (C) 1999  Cygnus Solutions
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+
+package java.util.zip;
+
+/**
+ * @author Per Bothner
+ * @date April 6, 1999.
+ */
+
+/*
+ * Written using on-line Java Platform 1.2 API Specification, as well
+ * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
+ * The actual Adler32 algorithm is taken from RFC 1950.
+ * Status:  Believed complete and correct.
+ */
+
+public class Adler32 implements Checksum
+{
+  private static int BASE = 65521; /* largest prime smaller than 65536 */
+
+  int s1;
+  int s2;
+
+  public Adler32 ()
+  {
+    reset();
+  }
+
+  public void reset () { s1 = 1;  s2 = 0; }
+
+  public void update (int bval)
+  {
+    s1 = (s1 + (bval & 0xFF)) % BASE;
+    s2 = (s1 + s2) % BASE;
+  }
+
+  public void update (byte[] buffer)
+  {
+    update(buffer, 0, buffer.length);
+  }
+
+  public void update (byte[] buf, int off, int len)
+  {
+    int s1 = this.s1;
+    int s2 = this.s2;
+    while (len > 0)
+      {
+	// We can defer the modulo operation.
+	int n = 4000;
+	if (n > len)
+	  n = len;
+	len -= n;
+	while (--n >= 0)
+	  {
+	    s1 = s1 + (buf[off++] & 0xFF);
+	    s2 = s2 + s1;
+	  }
+	s1 %= BASE;
+	s2 %= BASE;
+      }
+    this.s1 = s1;
+    this.s2 = s2;
+  }
+
+  public long getValue()
+  {
+    return ((long) s2 << 16) + s1;
+  }
+}
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