Changed priority code implementation

Prioritize M292 to allow custom codes that create blocking message boxes
Priority codes are preferrably sent to idle channels with the same firmware emulation

Author: chrishamm

src/DuetControlServer/Codes/Processor.cs

@@ -155,22 +155,43 @@ public static async ValueTask StartCodeAsync(Commands.Code code)
             // Deal with priority codes
             if (code.Flags.HasFlag(CodeFlags.IsPrioritized))
             {
-                // Check if the code has to be moved to another channel first
+                // Process this priority code here if it is idle
                 if (processor.IsIdle(code))
                 {
                     await processor.WriteCodeAsync(code, stage);
                     return;
                 }
 
-                // Move priority codes to an empty code channel (if possible)
+                // Otherwise move it to another idle code channel with the same emulation type (if possible)
+                using (await Model.Provider.AccessReadOnlyAsync())
+                {
+                    Compatibility compatibility = Model.Provider.Get.Inputs[code.Channel]?.Compatibility ?? Compatibility.RepRapFirmware;
+                    for (int input = 0; input < Inputs.Total; input++)
+                    {
+                        CodeChannel channel = (CodeChannel)input;
+                        if (channel != code.Channel && channel is not CodeChannel.File and not CodeChannel.File2)
+                        {
+                            ChannelProcessor next = _processors[input];
+                            if (Model.Provider.Get.Inputs[channel]?.Compatibility == compatibility && next.IsIdle(code))
+                            {
+                                code.Channel = channel;
+                                await next.WriteCodeAsync(code, stage); // This can't block if the channel is idle
+                                return;
+                            }
+                        }
+                    }
+                }
+
+                // Otherwise move it to an arbitrary idle code channel (if possible)
                 for (int input = 0; input < Inputs.Total; input++)
                 {
-                    if ((CodeChannel)input != code.Channel)
+                    CodeChannel channel = (CodeChannel)input;
+                    if (channel != code.Channel && channel is not CodeChannel.File and not CodeChannel.File2)
                     {
                         ChannelProcessor next = _processors[input];
                         if (next.IsIdle(code))
                         {
-                            code.Channel = (CodeChannel)input;
+                            code.Channel = channel;
                             await next.WriteCodeAsync(code, stage);
                             return;
                         }

src/DuetControlServer/Commands/Generic/SimpleCode.cs

@@ -91,9 +91,9 @@ public override async Task<string> Execute()
                         code.Flags |= CodeFlags.Asynchronous;
                     }
 
-                    // M108, M112, M122, and M999 (B0) always go to an idle channel so we (hopefully) get a low-latency response
+                    // M108, M112, M122, M292, and M999 (B0) always go to an idle channel so we (hopefully) get a low-latency response
                     if (code.Type == CodeType.MCode &&
-                        (code.MajorNumber == 108 || code.MajorNumber == 112 || code.MajorNumber == 122 || (code.MajorNumber == 999 && code.GetInt('B', 0) == 0)))
+                        (code.MajorNumber is 108 or 112 or 122 or 292 || (code.MajorNumber == 999 && code.GetInt('B', 0) == 0)))
                     {
                         code.Flags |= CodeFlags.IsPrioritized;
                         priorityCodes.Add(code);