From 5724d286d0a2612364bf18d6c57caf3a7c6e750e Mon Sep 17 00:00:00 2001
From: Lars Toenning <dev@ltoenning.de>
Date: Sun, 5 Feb 2023 11:26:15 +0100
Subject: [PATCH] Add 8.33 kHz spacing helper methods

Related to #186
---
 src/blackmisc/aviation/comsystem.cpp | 13 +++++++++++++
 src/blackmisc/aviation/comsystem.h   |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/src/blackmisc/aviation/comsystem.cpp b/src/blackmisc/aviation/comsystem.cpp
index c056ca5f6..5c5d78613 100644
--- a/src/blackmisc/aviation/comsystem.cpp
+++ b/src/blackmisc/aviation/comsystem.cpp
@@ -181,6 +181,19 @@ namespace BlackMisc::Aviation
         }
     }
 
+    bool CComSystem::isExclusiveWithin8_33kHzChannel(const PhysicalQuantities::CFrequency &freq)
+    {
+        const int freqKHz = freq.value(CFrequencyUnit::kHz());
+        if (freqKHz < 118000 || freqKHz >= 137000 || !isValid8_33kHzChannel(freqKHz)) { return false; }
+        return !isWithin25kHzChannel(freq);
+    }
+
+    bool CComSystem::isWithin25kHzChannel(const PhysicalQuantities::CFrequency &freq)
+    {
+        const int end = static_cast<int>(freq.value(CFrequencyUnit::kHz())) % 100;
+        return end == 0 || end == 25 || end == 50 || end == 75;
+    }
+
     bool CComSystem::isWithinChannelSpacing(const CFrequency &setFrequency, const CFrequency &compareFrequency, CComSystem::ChannelSpacing channelSpacing)
     {
         if (setFrequency.isNull() || compareFrequency.isNull()) { return false; }
diff --git a/src/blackmisc/aviation/comsystem.h b/src/blackmisc/aviation/comsystem.h
index e10542ba0..586c8f7ef 100644
--- a/src/blackmisc/aviation/comsystem.h
+++ b/src/blackmisc/aviation/comsystem.h
@@ -148,6 +148,13 @@ namespace BlackMisc::Aviation
         //! Round passed frequency in kHz to 8.33 frequency spacing
         static int round8_33kHzChannel(int fKHz);
 
+        //! Is frequency a "new" 8.33 kHz frequency and not within 25 kHz spacing
+        //! E.g. returns false for 122.825 but true for 118.305
+        static bool isExclusiveWithin8_33kHzChannel(const PhysicalQuantities::CFrequency &freq);
+
+        //! Is frequency within 25 kHz frequency spacing
+        static bool isWithin25kHzChannel(const PhysicalQuantities::CFrequency &freq);
+
         //! Parses almost any shitty string to a valid COM frequency
         static PhysicalQuantities::CFrequency parseComFrequency(const QString &input, PhysicalQuantities::CPqString::SeparatorMode sep);