From 01ea38a6278122491b9a0805f8ec5a6003434e29 Mon Sep 17 00:00:00 2001
From: pierre <pierre@freepascal.org>
Date: Wed, 11 May 2016 14:29:11 +0000
Subject: [PATCH]  Implement basic SysOSAlloc using MSDOS Interrrupt 0x21,
 AH=0x48 function

git-svn-id: trunk@33676 -
---
 rtl/msdos/sysheap.inc | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/rtl/msdos/sysheap.inc b/rtl/msdos/sysheap.inc
index a8e786e353..9ed6b7992e 100644
--- a/rtl/msdos/sysheap.inc
+++ b/rtl/msdos/sysheap.inc
@@ -21,8 +21,41 @@
 *****************************************************************************}
 
 function SysOSAlloc (size: ptruint): pointer;
+var
+  regs : Registers;
+  nb_para : longint;
 begin
+{$ifdef DEBUG_TINY_HEAP}
+  writeln('SysOSAlloc called size=',size);
+{$endif}
+{$if defined(FPC_X86_DATA_FAR) or defined(FPC_X86_DATA_HUGE)}
+  regs.ax:=$4800;
+  nb_para:=size div 16;
+  if nb_para > $ffff then
+    result:=nil
+  else
+    begin
+      regs.bx:=nb_para;
+      msdos(regs);
+      if (regs.Flags and fCarry) <> 0 then
+        begin
+{$ifdef DEBUG_TINY_HEAP}
+          writeln('SysOSAlloc failed, err = ',regs.AX);
+{$endif}
+          GetInOutRes(regs.AX);
   Result := nil;
+        end
+      else
+        begin
+          result:=ptr(regs.ax,0);
+{$ifdef DEBUG_TINY_HEAP}
+          writeln('SysOSAlloc returned= $',hexstr(seg(result),4),':$',hexstr(ofs(result),4));
+{$endif}
+        end;
+    end;
+{$else not DATA_FAR}
+  Result := nil;
+{$endif not DATA_FAR}
 end;
 
 procedure SysOSFree(p: pointer; size: ptruint);