Initial data commit

Task/Variable-length-quantity/Java/variable-length-quantity.java

@@ -0,0 +1,59 @@
+public class VLQCode
+{
+  public static byte[] encode(long n)
+  {
+    int numRelevantBits = 64 - Long.numberOfLeadingZeros(n);
+    int numBytes = (numRelevantBits + 6) / 7;
+    if (numBytes == 0)
+      numBytes = 1;
+    byte[] output = new byte[numBytes];
+    for (int i = numBytes - 1; i >= 0; i--)
+    {
+      int curByte = (int)(n & 0x7F);
+      if (i != (numBytes - 1))
+        curByte |= 0x80;
+      output[i] = (byte)curByte;
+      n >>>= 7;
+    }
+    return output;
+  }
+
+  public static long decode(byte[] b)
+  {
+    long n = 0;
+    for (int i = 0; i < b.length; i++)
+    {
+      int curByte = b[i] & 0xFF;
+      n = (n << 7) | (curByte & 0x7F);
+      if ((curByte & 0x80) == 0)
+        break;
+    }
+    return n;
+  }
+
+  public static String byteArrayToString(byte[] b)
+  {
+    StringBuilder sb = new StringBuilder();
+    for (int i = 0; i < b.length; i++)
+    {
+      if (i > 0)
+        sb.append(", ");
+      String s = Integer.toHexString(b[i] & 0xFF);
+      if (s.length() < 2)
+        s = "0" + s;
+      sb.append(s);
+    }
+    return sb.toString();
+  }
+
+  public static void main(String[] args)
+  {
+    long[] testNumbers = { 2097152, 2097151, 1, 127, 128, 589723405834L };
+    for (long n : testNumbers)
+    {
+      byte[] encoded = encode(n);
+      long decoded = decode(encoded);
+      System.out.println("Original input=" + n + ", encoded = [" + byteArrayToString(encoded) + "], decoded=" + decoded + ", " + ((n == decoded) ? "OK" : "FAIL"));
+    }
+  }
+}