[aandrejevic] 67512: [FAST486] When storing a segment selector, the operand size attribute is only ignored when writing to memory (where it's treated as if it's always 16-bit).

Author: aandrejevic
Date: Sat May  2 16:09:00 2015
New Revision: 67512

URL: http://svn.reactos.org/svn/reactos?rev=67512&view=rev
Log:
[FAST486]
When storing a segment selector, the operand size attribute is only ignored when
writing to memory (where it's treated as if it's always 16-bit).

Modified:
    trunk/reactos/lib/fast486/opcodes.c

Modified: trunk/reactos/lib/fast486/opcodes.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/lib/fast486/opcodes.c?rev=6...
==============================================================================
--- trunk/reactos/lib/fast486/opcodes.c	[iso-8859-1] (original)
+++ trunk/reactos/lib/fast486/opcodes.c	[iso-8859-1] Sat May  2 16:09:00 2015
@@ -3832,13 +3832,16 @@

FAST486_OPCODE_HANDLER(Fast486OpcodeMovStoreSeg)
 {
-    BOOLEAN AddressSize = State->SegmentRegs[FAST486_REG_CS].Size;
+    BOOLEAN OperandSize, AddressSize;
     FAST486_MOD_REG_RM ModRegRm;

/* Make sure this is the right instruction */
     ASSERT(Opcode == 0x8C);

+    OperandSize = AddressSize = State->SegmentRegs[FAST486_REG_CS].Size;
+
     TOGGLE_ADSIZE(AddressSize);
+    TOGGLE_OPSIZE(OperandSize);

/* Get the operands */
     if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
@@ -3854,10 +3857,21 @@
         return;
     }

-    Fast486WriteModrmWordOperands(State,
-                                  &ModRegRm,
-                                  FALSE,
-                                  State->SegmentRegs[ModRegRm.Register].Selector);
+    /* When the other operand is a memory location, always use 16-bit */
+    if (OperandSize && !ModRegRm.Memory)
+    {
+        Fast486WriteModrmDwordOperands(State,
+                                       &ModRegRm,
+                                       FALSE,
+                                       State->SegmentRegs[ModRegRm.Register].Selector);
+    }
+    else
+    {
+        Fast486WriteModrmWordOperands(State,
+                                      &ModRegRm,
+                                      FALSE,
+                                      State->SegmentRegs[ModRegRm.Register].Selector);
+    }
 }

FAST486_OPCODE_HANDLER(Fast486OpcodeLea)