From efa47e1550dbcc529d780e8024a24530d5b73887 Mon Sep 17 00:00:00 2001
From: Dan Albert <dan@gingerhq.net>
Date: Wed, 1 Nov 2023 18:38:23 -0700
Subject: [PATCH] Fix allocation range for Link 4.

Prior to DCS 2.9 Jester was able to use datalink frequencies outside the
range the aircraft was capable of, but this has presumably always been
broken for human RIOs.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/3222.
---
 changelog.md                          | 1 +
 game/missiongenerator/tgogenerator.py | 2 +-
 game/radio/radios.py                  | 7 ++++++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/changelog.md b/changelog.md
index 95f4228a..f0caae9a 100644
--- a/changelog.md
+++ b/changelog.md
@@ -39,6 +39,7 @@ Saves from 8.x are not compatible with 9.0.0.
 * **[Mission Generation]** Fixed "division by zero" error on mission generation when a flight has an "In-Flight" start type and starts on top of a mission waypoint.
 * **[Mission Generation]** Fixed flights not being selectable in the mission editor if fast-forward was used and they were generated at a waypoint that had a fixed TOT (such as a BARCAP that was on-station).
 * **[Mission Generation]** Fixed error when planning TARCAPs on the sole remaining enemy airfield.
+* **[Mission Generation]** Fixed allocation range for carrier Link 4 datalink.
 * **[Modding]** Unit variants can now actually override base unit type properties.
 * **[New Game Wizard]** Factions are reset to default after clicking "Back" to Theater Configuration screen.
 * **[Plugins]** Fixed Lua errors in Skynet plugin that would occur whenever one coalition had no IADS nodes.
diff --git a/game/missiongenerator/tgogenerator.py b/game/missiongenerator/tgogenerator.py
index 0fa538b1..b3866555 100644
--- a/game/missiongenerator/tgogenerator.py
+++ b/game/missiongenerator/tgogenerator.py
@@ -446,7 +446,7 @@ class GenericCarrierGenerator(GroundObjectGenerator):
                 icls = next(self.icls_alloc)
                 link4 = None
                 if carrier_type in [Stennis, CVN_71, CVN_72, CVN_73, CVN_75]:
-                    link4 = self.radio_registry.alloc_uhf()
+                    link4 = self.radio_registry.alloc_link4()
                 self.activate_beacons(ship_group, tacan, tacan_callsign, icls, link4)
                 self.add_runway_data(
                     brc or Heading.from_degrees(0), atc, tacan, tacan_callsign, icls
diff --git a/game/radio/radios.py b/game/radio/radios.py
index 4e91e31f..2d7b28a1 100644
--- a/game/radio/radios.py
+++ b/game/radio/radios.py
@@ -337,11 +337,13 @@ class RadioRegistry:
         "BLUFOR UHF", (RadioRange(MHz(225), MHz(400), MHz(1), Modulation.AM),)
     )
 
+    LINK_4 = Radio("Link 4", (RadioRange(MHz(300), MHz(325), kHz(100), Modulation.AM),))
+
     def __init__(self) -> None:
         self.allocated_channels: Set[RadioFrequency] = set()
         self.radio_allocators: Dict[Radio, Iterator[RadioFrequency]] = {}
 
-        radios = itertools.chain(RADIOS, [self.BLUFOR_UHF])
+        radios = itertools.chain(RADIOS, [self.BLUFOR_UHF, self.LINK_4])
         for radio in radios:
             self.radio_allocators[radio] = radio.range()
 
@@ -386,6 +388,9 @@ class RadioRegistry:
         """
         return self.alloc_for_radio(self.BLUFOR_UHF)
 
+    def alloc_link4(self) -> RadioFrequency:
+        return self.alloc_for_radio(self.LINK_4)
+
     def reserve(self, frequency: RadioFrequency) -> None:
         """Reserves the given channel.