[ros-diffs] [aandrejevic] 60984: [FAST486] XADD: Fix the order of operations. POP <modrm>: The value must be popped from the stack before parsing the Mod-Reg-R/M, because of the "POP DWORD [ESP]" case.

Author: aandrejevic
Date: Wed Nov 13 22:33:37 2013
New Revision: 60984

URL: http://svn.reactos.org/svn/reactos?rev=60984&view=rev
Log:
[FAST486]
XADD: Fix the order of operations.
POP <modrm>: The value must be popped from the stack before parsing the
Mod-Reg-R/M, because of the "POP DWORD [ESP]" case.

Modified:
    branches/ntvdm/lib/fast486/common.inl
    branches/ntvdm/lib/fast486/extraops.c
    branches/ntvdm/lib/fast486/opgroups.c

Modified: branches/ntvdm/lib/fast486/common.inl
URL: http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/common.inl?rev...
==============================================================================
--- branches/ntvdm/lib/fast486/common.inl	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/common.inl	[iso-8859-1] Wed Nov 13 22:33:37 2013
@@ -326,7 +326,7 @@
     BOOLEAN Size = State->SegmentRegs[FAST486_REG_SS].Size;

/* The OPSIZE prefix toggles the size */
-    if (State->PrefixFlags & FAST486_PREFIX_OPSIZE) Size = !Size;
+    TOGGLE_OPSIZE(Size);

if (Size)
     {

Modified: branches/ntvdm/lib/fast486/extraops.c
URL: http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/extraops.c?rev...
==============================================================================
--- branches/ntvdm/lib/fast486/extraops.c	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/extraops.c	[iso-8859-1] Wed Nov 13 22:33:37 2013
@@ -2032,15 +2032,15 @@
         State->Flags.Sf = ((Result & SIGN_FLAG_LONG) != 0);
         State->Flags.Pf = Fast486CalculateParity(Result);

+        /* Write the old value of the destination to the source */
+        if (!Fast486WriteModrmDwordOperands(State, &ModRegRm, TRUE, Destination))
+        {
+            /* Exception occurred */
+            return FALSE;
+        }
+
         /* Write the sum to the destination */
         if (!Fast486WriteModrmDwordOperands(State, &ModRegRm, FALSE, Result))
-        {
-            /* Exception occurred */
-            return FALSE;
-        }
-
-        /* Write the old value of the destination to the source */
-        if (!Fast486WriteModrmDwordOperands(State, &ModRegRm, TRUE, Destination))
         {
             /* Exception occurred */
             return FALSE;
@@ -2071,15 +2071,15 @@
         State->Flags.Sf = ((Result & SIGN_FLAG_WORD) != 0);
         State->Flags.Pf = Fast486CalculateParity(Result);

+        /* Write the old value of the destination to the source */
+        if (!Fast486WriteModrmWordOperands(State, &ModRegRm, TRUE, Destination))
+        {
+            /* Exception occurred */
+            return FALSE;
+        }
+
         /* Write the sum to the destination */
         if (!Fast486WriteModrmWordOperands(State, &ModRegRm, FALSE, Result))
-        {
-            /* Exception occurred */
-            return FALSE;
-        }
-
-        /* Write the old value of the destination to the source */
-        if (!Fast486WriteModrmWordOperands(State, &ModRegRm, TRUE, Destination))
         {
             /* Exception occurred */
             return FALSE;

Modified: branches/ntvdm/lib/fast486/opgroups.c
URL: http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/opgroups.c?rev...
==============================================================================
--- branches/ntvdm/lib/fast486/opgroups.c	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/opgroups.c	[iso-8859-1] Wed Nov 13 22:33:37 2013
@@ -486,9 +486,19 @@
     TOGGLE_OPSIZE(OperandSize);
     TOGGLE_ADSIZE(AddressSize);

+    /* Pop a value from the stack - this must be done first */
+    if (!Fast486StackPop(State, &Value))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
     if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
     {
-        /* Exception occurred */
+        /* Exception occurred - restore SP */
+        if (OperandSize) State->GeneralRegs[FAST486_REG_ESP].Long += sizeof(ULONG);
+        else State->GeneralRegs[FAST486_REG_ESP].LowWord += sizeof(USHORT);
+
         return FALSE;
     }

@@ -496,13 +506,6 @@
     {
         /* Invalid */
         Fast486Exception(State, FAST486_EXCEPTION_UD);
-        return FALSE;
-    }
-
-    /* Pop a value from the stack */
-    if (!Fast486StackPop(State, &Value))
-    {
-        /* Exception occurred */
         return FALSE;
     }