From 2f16497bf84400b53d5527306895f70d6288ae20 Mon Sep 17 00:00:00 2001
From: DDoSolitary <DDoSolitary@gmail.com>
Date: Sun, 10 Mar 2019 11:48:56 +0800
Subject: [PATCH] Fix alignment padding calculation.

---
 src/utils/radiotap_writer.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/utils/radiotap_writer.cpp b/src/utils/radiotap_writer.cpp
index cd17f44..4bb3465 100644
--- a/src/utils/radiotap_writer.cpp
+++ b/src/utils/radiotap_writer.cpp
@@ -41,7 +41,8 @@ namespace Tins {
 namespace Utils {
 
 uint32_t calculate_padding(uint32_t alignment, uint32_t offset) {
-    return offset % alignment;
+    uint32_t extra = offset % alignment;
+    return extra == 0 ? 0 : alignment - extra;
 }
 
 uint32_t get_bit(uint32_t value) {