From 2f68cc45ebacf6d228b76e1de78e429de443a308 Mon Sep 17 00:00:00 2001
From: "Tristan B. Velloza Kildaire" <deavmi@redxen.eu>
Date: Fri, 29 Sep 2023 10:02:50 +0200
Subject: [PATCH] CoapPacket

- Implemented `determineLenType(size_t)`
---
 source/doap/protocol/packet.d | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/source/doap/protocol/packet.d b/source/doap/protocol/packet.d
index 05a653e..e168a6b 100644
--- a/source/doap/protocol/packet.d
+++ b/source/doap/protocol/packet.d
@@ -116,6 +116,39 @@ public class CoapPacket
         return this.options;
     }
 
+    /** 
+     * Given a payload size this determins
+     * the required type of option length
+     * encoding to be used.
+     *
+     * If the size is unsupported then
+     * `OptionLenType.UPPER_PAYLOAD_MARKER`
+     * is returned.
+     *
+     * Params:
+     *   dataSize = the payload's size
+     * Returns: the `OptionLenType`
+     */
+    private static OptionLenType determineLenType(size_t dataSize)
+    {
+        if(dataSize >= 0 && dataSize <= 12)
+        {
+            return OptionLenType.ZERO_TO_TWELVE;
+        }
+        else if(dataSize >= 13 && dataSize <= 268)
+        {
+            return OptionLenType._8BIT_EXTENDED;
+        }
+        else if(dataSize >= 269 && dataSize <= 65804)
+        {
+            return OptionLenType._12_BIT_EXTENDED;
+        }
+        else
+        {
+            return OptionLenType.UPPER_PAYLOAD_MARKER;
+        }
+    }
+
 
     public void setType(MessageType type)
     {