Amiga/m68k: software atomic operations implementation for multithreading

git-svn-id: trunk@30901 -

.gitattributes

@@ -8046,6 +8046,7 @@ rtl/amiga/doslibd.inc svneol=native#text/plain
 rtl/amiga/m68k/doslibf.inc svneol=native#text/plain
 rtl/amiga/m68k/execd.inc svneol=native#text/plain
 rtl/amiga/m68k/execf.inc svneol=native#text/plain
+rtl/amiga/m68k/m68kamiga.inc svneol=native#text/plain
 rtl/amiga/m68k/prt0.as svneol=native#text/plain
 rtl/amiga/m68k/utild1.inc svneol=native#text/plain
 rtl/amiga/m68k/utild2.inc svneol=native#text/plain

rtl/amiga/m68k/m68kamiga.inc

@@ -0,0 +1,66 @@
+{
+    This file is part of the Free Pascal run time library.
+    Copyright (c) 2015 by Karoly Balogh,
+    member of the Free Pascal development team.
+
+    m68k/Amiga atomic operations implementation
+
+    See the file COPYING.FPC, included in this distribution,
+    for details about the copyright.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+
+{ The Amiga hardware doesn't support the m68k CPU's atomic operations
+  like TAS, CAS, CAS2 and so on. Therefore we must "emulate" them from
+  software. The easiest way is the Forbid()/Permit() OS call pair around
+  the ops themselves. It of course won't be hardware-atomic, but should
+  be safe for multithreading. (KB) }
+
+function InterLockedDecrement (var Target: longint) : longint;
+  begin
+    Forbid();
+    Dec(Target);
+    Result := Target;
+    Permit();
+  end;
+
+
+function InterLockedIncrement (var Target: longint) : longint;
+  begin
+    Forbid()
+    Inc(Target);
+    Result := Target;
+    Permit();
+  end;
+
+
+function InterLockedExchange (var Target: longint;Source : longint) : longint;
+  begin
+    Forbid();
+    Result := Target;
+    Target := Source;
+    Permit();
+  end;
+
+
+function InterLockedExchangeAdd (var Target: longint;Source : longint) : longint;
+  begin
+    Forbid();
+    Result := Target;
+    Target := Target + Source;
+    Permit();
+  end;
+
+
+function InterlockedCompareExchange(var Target: longint; NewValue: longint; Comperand: longint): longint;
+  begin
+    Forbid();
+    Result := Target;
+    if Target = Comperand then
+      Target := NewValue;
+    Permit();
+  end;