1 files changed, 46 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/compress/IntegerCompressor.java b/vespajlib/src/main/java/com/yahoo/compress/IntegerCompressor.java
new file mode 100644
index 00000000000..cbf12bd3d94
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/compress/IntegerCompressor.java
@@ -0,0 +1,46 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.compress;
+
+import java.nio.ByteBuffer;
+
+/**
+ * TODO: balder
+ */
+public class IntegerCompressor {
+
+    public static void putCompressedNumber(int n, ByteBuffer buf) {
+        int negative = n < 0 ? 0x80 : 0x0;
+        if (negative != 0) {
+            n = -n;
+        }
+        if (n < (0x1 << 5)) {
+            byte b = (byte)(n | negative);
+            buf.put(b);
+        } else if (n < (0x1 << 13)) {
+            n = n | 0x4000 | (negative << 8);
+            buf.putShort((short)n);
+        } else if ( n < (0x1 << 29)) {
+            n = n | 0x60000000 | (negative << 24);
+            buf.putInt(n);
+        } else {
+            throw new IllegalArgumentException("Number '" + ((negative != 0) ? -n : n) + "' too big, must extend encoding");
+        }
+    }
+
+    public static void putCompressedPositiveNumber(int n, ByteBuffer buf) {
+        if (n < 0) {
+            throw new IllegalArgumentException("Number '" + n + "' must be positive");
+        }
+        if (n < (0x1 << 6)) {
+            buf.put((byte)n);
+        } else if (n < (0x1 << 14)) {
+            n = n | 0x8000;
+            buf.putShort((short)n);
+        } else if ( n < (0x1 << 30)) {
+            n = n | 0xc0000000;
+            buf.putInt(n);
+        } else {
+            throw new IllegalArgumentException("Number '" + n + "' too big, must extend encoding");
+        }
+    }
+}