winedos / Fix instruction emulation regression

[Jukka Heinonen]

Recent instruction emulation changes broke DOS protected mode.
This is a quick and dirty fix for that problem.

STI is now emulated in two places. I don't think it is safe to
remove STI emulation from generic instruction
emulation code because Win16 programs may use that instruction.

Interface of the INSTR_EmulateInstruction function has changed so
its description before the function is no longer correct.





Changelog:
  Make STI work again in DOS protected mode.






Index: dlls/kernel/instr.c
===================================================================
RCS file: /home/wine/wine/dlls/kernel/instr.c,v
retrieving revision 1.1
diff -u -r1.1 instr.c
--- dlls/kernel/instr.c	17 Sep 2003 04:34:31 -0000	1.1
+++ dlls/kernel/instr.c	17 Sep 2003 10:41:35 -0000
@@ -773,13 +773,10 @@
             return 0;
 
         case 0xfb: /* sti */
+            if (NtCurrentTeb()->vm86_pending)
+                break; /* Unable to emulate sti if there are any pending events */
             NtCurrentTeb()->dpmi_vif = 1;
             context->Eip += prefixlen + 1;
-            if (NtCurrentTeb()->vm86_pending)
-            {
-                NtCurrentTeb()->vm86_pending = 0;
-                return EXCEPTION_VM86_STI;
-            }
             return 0;
     }
     return ret;  /* Unable to emulate it */




Index: dlls/winedos/int31.c
===================================================================
RCS file: /home/wine/wine/dlls/winedos/int31.c,v
retrieving revision 1.34
diff -u -r1.34 int31.c
--- dlls/winedos/int31.c	5 Sep 2003 23:08:28 -0000	1.34
+++ dlls/winedos/int31.c	17 Sep 2003 10:41:41 -0000
@@ -88,8 +88,7 @@
 /**********************************************************************
  *          dpmi_exception_handler
  *
- * Handle EXCEPTION_VM86_STI exceptions generated
- * when there are pending asynchronous events.
+ * Handle exceptions generated in DOS protected mode.
  */
 static WINE_EXCEPTION_FILTER(dpmi_exception_handler)
 {
@@ -99,6 +98,9 @@
 
     if (rec->ExceptionCode == EXCEPTION_VM86_STI)
     {
+        /*
+         * Pending asynchronous event has been queued.
+         */
         if (ISV86(context))
             ERR( "Real mode STI caught by protected mode handler!\n" );
         DOSVM_SendQueuedEvents(context);
@@ -106,10 +108,30 @@
     }
     else if (rec->ExceptionCode == EXCEPTION_VM86_INTx)
     {
+        /*
+         * Exit from protected mode due to int21 subfunction 0x4c.
+         * Return back to StartPM function.
+         */
         if (ISV86(context))
             ERR( "Real mode INTx caught by protected mode handler!\n" );
         DPMI_retval = (BYTE)rec->ExceptionInformation[0];
         return EXCEPTION_EXECUTE_HANDLER;
+    }
+    else if (rec->ExceptionCode == EXCEPTION_PRIV_INSTRUCTION)
+    {
+        BYTE *ptr = CTX_SEG_OFF_TO_LIN(context, context->SegCs, context->Eip);
+
+        if(*ptr == 0xfb)
+        {
+            /*
+             * Emulate sti instruction.
+             */
+            NtCurrentTeb()->dpmi_vif = 1;
+            NtCurrentTeb()->vm86_pending = 0;
+            context->Eip += 1;
+            DOSVM_SendQueuedEvents(context);
+            return EXCEPTION_CONTINUE_EXECUTION;
+        }
     }
 
 #endif



-- 
Jukka Heinonen <http://www.iki.fi/jhei/>