rtl: make STACK_MARGIN a variable instead of a const. this allows adjusting margin size on system unit init, based on the actual stack length of the executable. useful for small systems running with little stack. allow overwriting SysBackTraceStr with a platform-specific implementation

git-svn-id: trunk@49200 -

rtl/inc/system.inc

@@ -45,12 +45,13 @@ type
 
 const
 {$if defined(CPUAVR)}
-  STACK_MARGIN = 64;    { Stack size margin for stack checking }
+  STACK_MARGIN_MAX = 64;    { Stack size margin for stack checking }
 {$elseif defined(CPUZ80)}
-  STACK_MARGIN = 64;    { Stack size margin for stack checking }
+  STACK_MARGIN_MAX = 64;    { Stack size margin for stack checking }
 {$else}
-  STACK_MARGIN = 16384;    { Stack size margin for stack checking }
+  STACK_MARGIN_MAX = 16384;    { Stack size margin for stack checking }
 {$endif}
+  StackMargin: ptruint = STACK_MARGIN_MAX;
 { Random / Randomize constants }
   OldRandSeed : Cardinal = 0;
 
@@ -1042,7 +1043,7 @@ begin
   { don't use stack_size, since the stack pointer has already been
     decreased when this routine is called
   }
-  c := Sptr - STACK_MARGIN;
+  c := Sptr - StackMargin;
   if (c <= StackBottom) then
     begin
       StackError:=true;
@@ -1289,10 +1290,12 @@ Begin
 end;
 
 
+{$ifndef FPC_SYSTEM_HAS_BACKTRACESTR}
 function SysBackTraceStr (Addr: CodePointer): ShortString;
 begin
   SysBackTraceStr:='  $'+hexstr(addr);
 end;
+{$endif FPC_SYSTEM_HAS_BACKTRACESTR}
 
 
 {$ifndef FPC_SYSTEM_HAS_CAPTUREBACKTRACE}