From 4f43ba2a7a15006cb40a26701f2173f82a34f0ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deronne?= <sebastien.deronne@gmail.com>
Date: Sun, 28 May 2023 19:03:22 +0200
Subject: [PATCH] wifi: Support retrieval of default 80+80MHz channel numbers

---
 src/wifi/model/wifi-phy-operating-channel.cc | 36 +++++++++++++++++---
 src/wifi/model/wifi-phy-operating-channel.h  | 16 ++++++---
 src/wifi/model/wifi-phy.cc                   |  5 ++-
 3 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/src/wifi/model/wifi-phy-operating-channel.cc b/src/wifi/model/wifi-phy-operating-channel.cc
index d39acbd18..c6ba69112 100644
--- a/src/wifi/model/wifi-phy-operating-channel.cc
+++ b/src/wifi/model/wifi-phy-operating-channel.cc
@@ -399,12 +399,38 @@ WifiPhyOperatingChannel::SetDefault(ChannelWidthMhz width, WifiStandard standard
 }
 
 uint8_t
-WifiPhyOperatingChannel::GetDefaultChannelNumber(ChannelWidthMhz width,
-                                                 WifiStandard standard,
-                                                 WifiPhyBand band)
+WifiPhyOperatingChannel::GetDefaultChannelNumber(
+    ChannelWidthMhz width,
+    WifiStandard standard,
+    WifiPhyBand band,
+    std::optional<uint8_t> previousChannelNumber /* = std::nullopt */)
 {
-    auto channelIt = FindFirst(0, 0, width, standard, band);
-
+    auto start = m_frequencyChannels.begin();
+    auto prevSegmentChannelIt = m_frequencyChannels.end();
+    if (previousChannelNumber)
+    {
+        prevSegmentChannelIt = FindFirst(*previousChannelNumber, 0, width, standard, band, start);
+        if (prevSegmentChannelIt != m_frequencyChannels.end())
+        {
+            start = std::next(prevSegmentChannelIt);
+        }
+    }
+    auto channelIt = FindFirst(0, 0, width, standard, band, start);
+    if (prevSegmentChannelIt != m_frequencyChannels.end() && channelIt != m_frequencyChannels.end())
+    {
+        const auto prevFreq = prevSegmentChannelIt->frequency;
+        const auto prevWidth = prevSegmentChannelIt->width;
+        const auto prevMaxFreq = prevFreq + (prevWidth / 2);
+        const auto nextFreq = channelIt->frequency;
+        const auto nextWidth = channelIt->width;
+        const auto nextMinFreq = nextFreq - (nextWidth / 2);
+        if (prevMaxFreq <= nextMinFreq)
+        {
+            // segments are contiguous to each others, find next segment to make sure they are
+            // not contiguous
+            channelIt = FindFirst(0, 0, width, standard, band, std::next(channelIt));
+        }
+    }
     if (channelIt != m_frequencyChannels.end())
     {
         // a channel matches the specified criteria
diff --git a/src/wifi/model/wifi-phy-operating-channel.h b/src/wifi/model/wifi-phy-operating-channel.h
index ca9dd02fb..58843807d 100644
--- a/src/wifi/model/wifi-phy-operating-channel.h
+++ b/src/wifi/model/wifi-phy-operating-channel.h
@@ -26,6 +26,7 @@
 
 #include "ns3/he-ru.h"
 
+#include <optional>
 #include <set>
 #include <tuple>
 #include <vector>
@@ -167,17 +168,22 @@ class WifiPhyOperatingChannel
     void SetDefault(ChannelWidthMhz width, WifiStandard standard, WifiPhyBand band);
 
     /**
-     * Get the default channel number of the given width and for the given standard
-     * and band.
+     * Get the default channel number for a given segment of the given width and for the given
+     * standard and band.
      *
      * \param width the channel width in MHz
      * \param standard the standard
      * \param band the PHY band
+     * \param previousChannelNumber the channel number of the previous (in frequency) segment (if
+     * non-contiguous operating channel is used). If there is no place for another segment that is
+     * not contiguous to that previous one (at a higher frequency), an error is thrown
      * \return the default channel number
      */
-    static uint8_t GetDefaultChannelNumber(ChannelWidthMhz width,
-                                           WifiStandard standard,
-                                           WifiPhyBand band);
+    static uint8_t GetDefaultChannelNumber(
+        ChannelWidthMhz width,
+        WifiStandard standard,
+        WifiPhyBand band,
+        std::optional<uint8_t> previousChannelNumber = std::nullopt);
 
     /**
      * Return the channel number for a given frequency segment.
diff --git a/src/wifi/model/wifi-phy.cc b/src/wifi/model/wifi-phy.cc
index d67f7bea1..cf2977db8 100644
--- a/src/wifi/model/wifi-phy.cc
+++ b/src/wifi/model/wifi-phy.cc
@@ -1228,6 +1228,7 @@ WifiPhy::DoChannelSwitch()
     m_channelAccessRequested = false;
 
     // Update unspecified parameters with default values
+    std::optional<uint8_t> prevChannelNumber{};
     for (auto& [number, width, band, primary20] : m_channelSettings)
     {
         if (band == WIFI_PHY_BAND_UNSPECIFIED)
@@ -1243,8 +1244,10 @@ WifiPhy::DoChannelSwitch()
             number =
                 WifiPhyOperatingChannel::GetDefaultChannelNumber(width,
                                                                  m_standard,
-                                                                 static_cast<WifiPhyBand>(band));
+                                                                 static_cast<WifiPhyBand>(band),
+                                                                 prevChannelNumber);
         }
+        prevChannelNumber = number;
     }
 
     // We need to call SetStandard if this is the first time we set a channel or we