--- a/hedgewars/uFLIPC.pas	Fri Sep 19 14:27:41 2014 +0400
+++ b/hedgewars/uFLIPC.pas	Sat Sep 20 00:56:54 2014 +0400
@@ -7,6 +7,7 @@
                    len: Longword;
                    buf: Pointer
                end;
+    TIPCCallback = procedure (p: pointer; s: shortstring);
 
 var msgFrontend, msgEngine: TIPCMessage;
     mutFrontend, mutEngine: PSDL_mutex;
@@ -15,7 +16,7 @@
 procedure initIPC;
 procedure freeIPC;
 
-procedure ipcToEngine(s: shortstring);
+procedure ipcToEngine(s: shortstring); cdecl; export;
 function  ipcReadFromEngine: shortstring;
 function  ipcCheckFromEngine: boolean;
 
@@ -23,17 +24,25 @@
 function ipcReadFromFrontend: shortstring;
 function ipcCheckFromFrontend: boolean;
 
+procedure registerIPCCallback(p: pointer; f: TIPCCallback); cdecl; export;
+
 implementation
 
+var callbackPointer: pointer;
+    callbackFunction: TIPCCallback;
+    callbackListenerThread: PSDL_Thread;
+
 procedure ipcSend(var s: shortstring; var msg: TIPCMessage; mut: PSDL_mutex; cond: PSDL_cond);
 begin
     SDL_LockMutex(mut);
+    writeln(stdout, 'ipc send', s);
     while (msg.str[0] > #0) or (msg.buf <> nil) do
         SDL_CondWait(cond, mut);
 
     msg.str:= s;
     SDL_CondSignal(cond);
-    SDL_UnlockMutex(mut)
+    SDL_UnlockMutex(mut);
+    writeln(stdout, 'ipc sent', s[1])
 end;
 
 function ipcRead(var msg: TIPCMessage; mut: PSDL_mutex; cond: PSDL_cond): shortstring;
@@ -43,6 +52,7 @@
         SDL_CondWait(cond, mut);
 
     ipcRead:= msg.str;
+    writeln(stdout, 'engine ipc received', msg.str[1]);
     msg.str[0]:= #0;
     if msg.buf <> nil then
     begin
@@ -61,7 +71,7 @@
     SDL_UnlockMutex(mut)
 end;
 
-procedure ipcToEngine(s: shortstring);
+procedure ipcToEngine(s: shortstring); cdecl; export;
 begin
     ipcSend(s, msgEngine, mutEngine, condEngine)
 end;
@@ -91,6 +101,21 @@
     ipcCheckFromFrontend:= ipcCheck(msgEngine, mutEngine)
 end;
 
+function  listener(p: pointer): Longint; cdecl; export;
+begin
+    listener:= 0;
+    repeat
+        callbackFunction(callbackPointer, ipcReadFromEngine())
+    until false
+end;
+
+procedure registerIPCCallback(p: pointer; f: TIPCCallback); cdecl; export;
+begin
+    callbackPointer:= p;
+    callbackFunction:= f;
+    callbackListenerThread:= SDL_CreateThread(@listener{$IFDEF SDL2}, 'ipcListener'{$ENDIF}, nil);
+end;
+
 procedure initIPC;
 begin
     msgFrontend.str:= '';
@@ -98,6 +123,9 @@
     msgEngine.str:= '';
     msgEngine.buf:= nil;
 
+    callbackPointer:= nil;
+    callbackListenerThread:= nil;
+
     mutFrontend:= SDL_CreateMutex;
     mutEngine:= SDL_CreateMutex;
     condFrontend:= SDL_CreateCond;
@@ -106,6 +134,7 @@
 
 procedure freeIPC;
 begin
+    SDL_KillThread(callbackListenerThread);
     SDL_DestroyMutex(mutFrontend);
     SDL_DestroyMutex(mutEngine);
     SDL_DestroyCond(condFrontend);