[aandrejevic] 67320: [FAST486] Whether stack operations use ESP or SP depends on the size of the stack segment.

Author: aandrejevic
Date: Mon Apr 20 00:36:46 2015
New Revision: 67320

URL: http://svn.reactos.org/svn/reactos?rev=67320&view=rev
Log:
[FAST486]
Whether stack operations use ESP or SP depends on the size of the stack segment.

Modified:
    trunk/reactos/lib/fast486/common.inl

Modified: trunk/reactos/lib/fast486/common.inl
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/lib/fast486/common.inl?rev=...
==============================================================================
--- trunk/reactos/lib/fast486/common.inl	[iso-8859-1] (original)
+++ trunk/reactos/lib/fast486/common.inl	[iso-8859-1] Mon Apr 20 00:36:46 2015
@@ -301,6 +301,7 @@
                  ULONG Value)
 {
     BOOLEAN Size = State->SegmentRegs[FAST486_REG_CS].Size;
+    ULONG StackPointer = State->GeneralRegs[FAST486_REG_ESP].Long;

/* The OPSIZE prefix toggles the size */
     TOGGLE_OPSIZE(Size);
@@ -320,7 +321,9 @@
         /* Store the value in SS:[ESP - 4] */
         if (!Fast486WriteMemory(State,
                                 FAST486_REG_SS,
-                                State->GeneralRegs[FAST486_REG_ESP].Long - sizeof(ULONG),
+                                State->SegmentRegs[FAST486_REG_SS].Size
+                                ? StackPointer - sizeof(ULONG)
+                                : LOWORD(StackPointer - sizeof(ULONG)),
                                 &Value,
                                 sizeof(ULONG)))
         {
@@ -328,8 +331,16 @@
             return FALSE;
         }

-        /* Subtract ESP by 4 */
-        State->GeneralRegs[FAST486_REG_ESP].Long -= sizeof(ULONG);
+        if (State->SegmentRegs[FAST486_REG_SS].Size)
+        {
+            /* Subtract ESP by 4 */
+            State->GeneralRegs[FAST486_REG_ESP].Long -= sizeof(ULONG);
+        }
+        else
+        {
+            /* Subtract SP by 4 */
+            State->GeneralRegs[FAST486_REG_ESP].LowWord -= sizeof(ULONG);
+        }
     }
     else
     {
@@ -346,7 +357,9 @@
         /* Store the value in SS:[SP - 2] */
         if (!Fast486WriteMemory(State,
                                 FAST486_REG_SS,
-                                LOWORD(State->GeneralRegs[FAST486_REG_ESP].LowWord - sizeof(USHORT)),
+                                State->SegmentRegs[FAST486_REG_SS].Size
+                                ? StackPointer - sizeof(USHORT)
+                                : LOWORD(StackPointer - sizeof(USHORT)),
                                 &ShortValue,
                                 sizeof(USHORT)))
         {
@@ -354,8 +367,16 @@
             return FALSE;
         }

-        /* Subtract SP by 2 */
-        State->GeneralRegs[FAST486_REG_ESP].LowWord -= sizeof(USHORT);
+        if (State->SegmentRegs[FAST486_REG_SS].Size)
+        {
+            /* Subtract ESP by 2 */
+            State->GeneralRegs[FAST486_REG_ESP].Long -= sizeof(USHORT);
+        }
+        else
+        {
+            /* Subtract SP by 2 */
+            State->GeneralRegs[FAST486_REG_ESP].LowWord -= sizeof(USHORT);
+        }
     }

return TRUE;