From 0db2ff0dad55689bd672188c336c011e77b05bc1 Mon Sep 17 00:00:00 2001
From: redcode <manuel@zxe.io>
Date: Thu, 1 Nov 2018 02:47:48 +0100
Subject: [PATCH] README.md

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index 46d4837..6c212a8 100644
--- a/README.md
+++ b/README.md
@@ -159,6 +159,8 @@ void (* halt)(void *context, zboolean state);
 ```
 **Description**  
 Callback: Called when the CPU enters or exits the halt state.  
+**Note**
+This callback is **optional**, it must be set to `NULL` if not used.
 **Parameters**  
 `context` → The value of the member `context`.  
 `state` → `TRUE` if halted; `FALSE` otherwise.