8 files changed, 40 insertions, 21 deletions
diff --git a/Game/Code/Classes/UAudioDecoder_FFMpeg.pas b/Game/Code/Classes/UAudioDecoder_FFMpeg.pas
index f4c22254..18d6c03b 100644
--- a/Game/Code/Classes/UAudioDecoder_FFMpeg.pas
+++ b/Game/Code/Classes/UAudioDecoder_FFMpeg.pas
@@ -17,7 +17,7 @@ interface
   {$MODE Delphi}
 {$ENDIF}
 
-{$I ../switches.inc}
+{$I switches.inc}
 
 //{$DEFINE DebugFFMpegDecode}
 
@@ -109,9 +109,9 @@ type
       audio_buf_size  : cardinal;
       audio_buf       : TAudioBuffer;
 
-      procedure Lock(); inline;
-      procedure Unlock(); inline;
-      function GetLockMutex(): PSDL_Mutex; inline;
+      procedure Lock(); {$IFDEF HasInline}inline;{$ENDIF}
+      procedure Unlock(); {$IFDEF HasInline}inline;{$ENDIF}
+      function GetLockMutex(): PSDL_Mutex; {$IFDEF HasInline}inline;{$ENDIF}
 
       procedure ParseAudio();
       function DecodeFrame(var buffer: TAudioBuffer; bufSize: integer): integer;
diff --git a/Game/Code/Classes/UAudioPlayback_SoftMixer.pas b/Game/Code/Classes/UAudioPlayback_SoftMixer.pas
index 1dc28dcd..e145587c 100644
--- a/Game/Code/Classes/UAudioPlayback_SoftMixer.pas
+++ b/Game/Code/Classes/UAudioPlayback_SoftMixer.pas
@@ -39,8 +39,8 @@ type
       class function ConvertAudioFormatToSDL(fmt: TAudioSampleFormat): UInt16;
       function InitFormatConversion(): boolean;
 
-      procedure Lock(); inline;
-      procedure Unlock(); inline;
+      procedure Lock(); {$IFDEF HasInline}inline;{$ENDIF}
+      procedure Unlock(); {$IFDEF HasInline}inline;{$ENDIF}
     public
       constructor Create(Engine: TAudioPlayback_SoftMixer);
       destructor Destroy(); override;
@@ -75,8 +75,8 @@ type
 
       _volume: integer;
 
-      procedure Lock(); inline;
-      procedure Unlock(); inline;
+      procedure Lock(); {$IFDEF HasInline}inline;{$ENDIF}
+      procedure Unlock(); {$IFDEF HasInline}inline;{$ENDIF}
 
       function GetVolume(): integer;
       procedure SetVolume(volume: integer);
@@ -100,7 +100,7 @@ type
       function InitializeAudioPlaybackEngine(): boolean; virtual; abstract;
       function StartAudioPlaybackEngine(): boolean;      virtual; abstract;
       procedure StopAudioPlaybackEngine();               virtual; abstract;
-      procedure AudioCallback(buffer: PChar; size: integer); inline;
+      procedure AudioCallback(buffer: PChar; size: integer); {$IFDEF HasInline}inline;{$ENDIF}
     public
       function  GetName: String;                         virtual; abstract;
 
@@ -130,7 +130,7 @@ type
       // Interface for Visualizer
       function GetPCMData(var data: TPCMData): Cardinal;
 
-      function GetMixer(): TAudioMixerStream; inline;
+      function GetMixer(): TAudioMixerStream; {$IFDEF HasInline}inline;{$ENDIF}
       function GetAudioFormatInfo(): TAudioFormatInfo;
 
       // Sounds
diff --git a/Game/Code/Classes/ULog.pas b/Game/Code/Classes/ULog.pas
index 15c590ae..6380b10a 100644
--- a/Game/Code/Classes/ULog.pas
+++ b/Game/Code/Classes/ULog.pas
@@ -52,7 +52,7 @@ type
     procedure LogBuffer(const buf : Pointer; const bufLength : Integer; filename : string);
   end;
 
-procedure SafeWriteLn(const msg: string); inline;
+procedure SafeWriteLn(const msg: string); {$IFDEF HasInline}inline;{$ENDIF}
 
 var
   Log:    TLog;
diff --git a/Game/Code/lib/ffmpeg/avformat.pas b/Game/Code/lib/ffmpeg/avformat.pas
index 7a5678a5..dd99e18b 100644
--- a/Game/Code/lib/ffmpeg/avformat.pas
+++ b/Game/Code/lib/ffmpeg/avformat.pas
@@ -37,6 +37,8 @@ unit avformat;
   {$MINENUMSIZE 4} (* use 4-byte enums *)
 {$ENDIF}
 
+{$I switches.inc}
+
 interface
 
 uses
@@ -133,7 +135,7 @@ function av_dup_packet (pkt: PAVPacket): integer;
  *
  * @param pkt packet to free
  *)
-procedure av_free_packet (pkt: PAVPacket); inline;
+procedure av_free_packet (pkt: PAVPacket); {$IFDEF HasInline}inline;{$ENDIF}
 
 (*************************************************)
 (* fractional numbers for exact pts handling *)
diff --git a/Game/Code/lib/ffmpeg/avio.pas b/Game/Code/lib/ffmpeg/avio.pas
index f3a4f05f..46d847b0 100644
--- a/Game/Code/lib/ffmpeg/avio.pas
+++ b/Game/Code/lib/ffmpeg/avio.pas
@@ -37,6 +37,8 @@ unit avio;
   {$MINENUMSIZE 4} (* use 4-byte enums *)
 {$ENDIF}
 
+{$I switches.inc}
+
 interface
 
 uses
@@ -366,7 +368,7 @@ function ff_get_v(bc: PByteIOContext): uint64;
   cdecl; external av__format;
 {$IFEND}
 
-function url_is_streamed(s: PByteIOContext): integer; inline;
+function url_is_streamed(s: PByteIOContext): integer; {$IFDEF HasInline}inline;{$ENDIF}
 
 (** @note when opened as read/write, the buffers are only used for
    writing *)
diff --git a/Game/Code/lib/ffmpeg/rational.pas b/Game/Code/lib/ffmpeg/rational.pas
index 0d6f76b6..14d28162 100644
--- a/Game/Code/lib/ffmpeg/rational.pas
+++ b/Game/Code/lib/ffmpeg/rational.pas
@@ -36,6 +36,8 @@ unit rational;
   {$MINENUMSIZE 4} (* use 4-byte enums *)
 {$ENDIF}
 
+{$I switches.inc}
+
 interface
 
 uses
@@ -57,14 +59,14 @@ type
  * @param b second rational
  * @return 0 if a==b, 1 if a>b and -1 if a<b.
  *)
-function av_cmp_q(a: TAVRational; b: TAVRational): integer; inline;
+function av_cmp_q(a: TAVRational; b: TAVRational): integer; {$IFDEF HasInline}inline;{$ENDIF}
 
 (**
  * Rational to double conversion.
  * @param a rational to convert
  * @return (double) a
  *)
-function av_q2d(a: TAVRational): double; inline;
+function av_q2d(a: TAVRational): double; {$IFDEF HasInline}inline;{$ENDIF}
 
 (**
  * Reduce a fraction.
diff --git a/Game/Code/lib/fft/UFFT.pas b/Game/Code/lib/fft/UFFT.pas
index e97812f6..1c4c3e75 100644
--- a/Game/Code/lib/fft/UFFT.pas
+++ b/Game/Code/lib/fft/UFFT.pas
@@ -45,9 +45,11 @@ Fast Fourier Transform routines.
 
 unit UFFT;
 
-{$ifdef fpc}
-  {$mode delphi}{$H+}
-{$endif}
+{$IFDEF FPC}
+  {$MODE Delphi}
+{$ENDIF}
+
+{$I switches.inc}
 
 interface
 type
@@ -55,7 +57,7 @@ type
   PSingleArray = ^TSingleArray;
 
 procedure PowerSpectrum(NumSamples: Integer; In_, Out_: PSingleArray);
-procedure WindowFunc(NumSamples: Integer; in_: PSingleArray); inline;
+procedure WindowFunc(NumSamples: Integer; in_: PSingleArray); {$IFDEF HasInline}inline;{$ENDIF}
 
 implementation
 
@@ -124,7 +126,7 @@ begin
    end;
 end;
 
-function FastReverseBits(i, NumBits: Integer): Integer; inline;
+function FastReverseBits(i, NumBits: Integer): Integer; {$IFDEF HasInline}inline;{$ENDIF}
 begin
   if (NumBits <= MaxFastBits) then
     result := gFFTBitTable[NumBits - 1][i]
@@ -334,7 +336,7 @@ begin
    FreeMem(ImagOut);
 end;
 
-procedure WindowFunc(NumSamples: Integer; in_: PSingleArray); inline;
+procedure WindowFunc(NumSamples: Integer; in_: PSingleArray); {$IFDEF HasInline}inline;{$ENDIF}
 var
   i: Integer;
 begin
diff --git a/Game/Code/switches.inc b/Game/Code/switches.inc
index 46997405..9b31f3af 100644
--- a/Game/Code/switches.inc
+++ b/Game/Code/switches.inc
@@ -23,9 +23,20 @@
   {$ENDIF}
 
   {$DEFINE DLL_CDECL}
+  {$DEFINE HasInline}
   {$UNDEF UseSerialPort}
 {$ELSE}
   {$DEFINE Delphi}
+
+  // Delphi version numbers (ignore versions released before Delphi 6 as they miss the $IF directive):
+  // Delphi 6 (VER140), Delphi 7 (VER150), Delphi 8 (VER160)
+  // Delphi 9/2005 (VER170), Delphi 10/2006 (VER180)
+
+  // the inline-procedure directive was introduced with Delphi 2005
+  {$IF not (Defined(VER140) or Defined(VER150) or Defined(VER160))}
+    {$DEFINE HasInline}
+  {$IFEND}
+
   {$DEFINE DLL_STDCALL}
   {$UNDEF UseSerialPort}
 {$ENDIF}