1 files changed, 36 insertions, 0 deletions
diff --git a/src/main/kotlin/SizedInteger.kt b/src/main/kotlin/SizedInteger.kt
new file mode 100644
index 0000000..48e4e25
--- /dev/null
+++ b/src/main/kotlin/SizedInteger.kt
@@ -0,0 +1,36 @@
+import java.math.BigInteger
+
+/**
+ * [SizedInteger] represents an unsigned integer number of arbitrary yet fixed length. It's useful for storing integers
+ * got from a connection as message fields.
+ *
+ * @param size The size of the field, measured in bytes.
+ * @param value The value of the field.
+ *
+ * @throws IllegalArgumentException if the size required to store the provided value is bigger than the provided size.
+ */
+class SizedInteger(val size: ULong, value: BigInteger) {
+    init {
+        if (!this.sizeOk(size, value)) {
+            throw IllegalArgumentException()
+        }
+    }
+
+    constructor(size: ULong) : this(size, 0.toBigInteger())
+
+    /**
+     * @throws IllegalStateException on set if the declared size is not enough for the new value.
+     */
+    var value = value
+        set(value) {
+            if (!this.sizeOk(value)) {
+                throw IllegalStateException()
+            }
+        }
+
+    private fun sizeOk(size: ULong, value: BigInteger): Boolean {
+        val requiredSize = value.toByteArray().size.toUInt()
+        return requiredSize <= size
+    }
+    private fun sizeOk(value: BigInteger): Boolean = sizeOk(this.size, value)
+}
+\ No newline at end of file