diff --git a/core/src/com/riiablo/io/BitUtils.java b/core/src/com/riiablo/io/BitUtils.java
new file mode 100644
index 00000000..d22f4b48
--- /dev/null
+++ b/core/src/com/riiablo/io/BitUtils.java
@@ -0,0 +1,27 @@
+package com.riiablo.io;
+
+public class BitUtils {
+  private BitUtils() {}
+
+  public static boolean isUnsigned(long value, int bits) {
+    assert 0 < bits : "bits(" + bits + ") < " + 0;
+    assert bits <= Long.SIZE : "bits(" + bits + ") > " + Long.SIZE;
+    return (value & (1 << (bits - 1))) == 0;
+  }
+
+  public static boolean isUnsigned(byte value) {
+    return isUnsigned(value, Byte.SIZE);
+  }
+
+  public static boolean isUnsigned(short value) {
+    return isUnsigned(value, Short.SIZE);
+  }
+
+  public static boolean isUnsigned(int value) {
+    return isUnsigned(value, Integer.SIZE);
+  }
+
+  public static boolean isUnsigned(long value) {
+    return isUnsigned(value, Long.SIZE);
+  }
+}
diff --git a/core/src/com/riiablo/io/SafeUnsigned.java b/core/src/com/riiablo/io/SafeUnsigned.java
new file mode 100644
index 00000000..9333003a
--- /dev/null
+++ b/core/src/com/riiablo/io/SafeUnsigned.java
@@ -0,0 +1,22 @@
+package com.riiablo.io;
+
+public class SafeUnsigned extends RuntimeException {
+  public final long value;
+
+  SafeUnsigned(long value) {
+    super("value(" + value + ") is not unsigned!");
+    this.value = value;
+  }
+
+  public short u8() {
+    return (short) value;
+  }
+
+  public int u16() {
+    return (int) value;
+  }
+
+  public long u32() {
+    return (long) value;
+  }
+}