sinclairql: startup code fixes. set the top of the new stack as stack pointer, not the bottom of it. initialize the .bss section following the new linker script. better protection against re-relocation.

git-svn-id: trunk@47429 -

rtl/sinclairql/si_prc.pp

@@ -23,12 +23,16 @@ implementation
 
 var
   stacktop: pointer;
-  stackorig: pointer;
   setjmpbuf: jmp_buf;
   stklen: longint; external name '__stklen';
-  binstart: pointer; external name '_stext';
-  binend: pointer; external name '_etext';
+  binstart: byte; external name '_stext';
+  binend: byte; external name '_etext';
+  bssstart: byte; external name '_sbss';
+  bssend: byte; external name '_ebss';
 
+{ this is const, so it will go into the .data section, not .bss }
+const
+  stackorig: pointer = nil;
 
 procedure PascalMain; external name 'PASCALMAIN';
 
@@ -46,18 +50,28 @@ begin
     { get our actual position in RAM }
     lea.l binstart(pc),a0
     move.l a0,d0
-    { get an offset to the end of the binary. this depends on the
-      fact that at this point the binary is not relocated yet }
+    { get an offset to the end of the binary. this works both
+      relocated and not. The decision if to relocate is done
+      later then }
     lea.l binend,a1
+    lea.l binstart,a0
+    sub.l a0,a1
     add.l d0,a1
+    move.l d0,a0
 
-    { first item in the relocation table is the number of relocs }
-    move.l (a1),d7
+    { read the relocation marker, this is always two padding bytes
+      ad the end of .text, so we're free to poke there }
+    move.w -2(a1),d7
     beq @noreloc
 
-    { zero out the number of relocs in RAM,  so if our code is
+    { zero out the number of relocation marker,  so if our code is
       called again, without reload, it won't relocate itself twice }
-    move.l #0,(a1)+
+    move.w #0,-2(a1)
+
+    { first item in the relocation table is the number of relocs }
+    move.l (a1)+,d7
+    beq @noreloc
+
 @relocloop:
     { we read the offsets and relocate them }
     move.l (a1)+,d1
@@ -72,13 +86,17 @@ begin
     move.l a7,stackorig
   end;
 
+  { initialize .bss }
+  FillChar(bssstart,PtrUInt(@bssend)-PtrUInt(@bssstart),#0);
+
   newstack:=mt_alchp(stklen,nil,-1);
   if not assigned(newstack) then
     _FPC_proc_start:=ERR_OM
   else
     begin
+      stacktop:=pbyte(newstack)+stklen;
       asm
-        move.l newstack,sp
+        move.l stacktop,sp
       end;
       if setjmp(setjmpbuf) = 0 then
         PascalMain;