From ae292619788bf7cdc33b669d1d3771294a60ccf1 Mon Sep 17 00:00:00 2001
From: Bill Somerville <g4wjs@classdesign.com>
Date: Sat, 11 Apr 2015 15:29:37 +0000
Subject: [PATCH] Remove compiler warning and avoid a potential issue with IB

Subtracting unsigned types  is tricky, made sure result  does not wrap
to avoid potentially implementation defined behaviour.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5211 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 mainwindow.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mainwindow.cpp b/mainwindow.cpp
index 4beabefe5..b8508b949 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -3,7 +3,6 @@
 #include "mainwindow.h"
 
 #include <cinttypes>
-#include <cstdlib>
 #include <limits>
 
 #include <QThread>
@@ -953,8 +952,12 @@ void MainWindow::displayDialFrequency ()
   bool valid {false};
   for (int row = 0; row < frequencies->rowCount (); ++row)
     {
+      // we need to do specific checks for above and below here to
+      // ensure that we can use unsigned Radio::Frequency since we
+      // potentially use the full 64-bit unsigned range.
       auto working_frequency = frequencies->data (frequencies->index (row, 0)).value<Frequency> ();
-      if (std::llabs (working_frequency - m_dialFreq) < 10000)
+      auto offset = m_dialFreq > working_frequency ? m_dialFreq - working_frequency : working_frequency - m_dialFreq;
+      if (offset < 10000u)
         {
           valid = true;
         }