From 2da0e38fbcbad9f35e311834f0fc025d0936074e Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Tue, 12 Nov 2013 19:25:50 +0000
Subject: [PATCH] [FAST486] In rotate operations, the count is always masked
 with 0x1F, regardless of the operand size.

svn path=/branches/ntvdm/; revision=60966
---
 lib/fast486/extraops.c |  6 ++----
 lib/fast486/opgroups.c | 16 ++++++----------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/lib/fast486/extraops.c b/lib/fast486/extraops.c
index 6f66e565b7c..046ad9e1a5f 100644
--- a/lib/fast486/extraops.c
+++ b/lib/fast486/extraops.c
@@ -637,8 +637,7 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeShld)
     }
 
     /* Normalize the count */
-    if (OperandSize) Count &= 0x1F;
-    else Count &= 0x0F;
+    Count &= 0x1F;
 
     /* Do nothing if the count is zero */
     if (Count == 0) return TRUE;
@@ -840,8 +839,7 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeShrd)
     }
 
     /* Normalize the count */
-    if (OperandSize) Count &= 0x1F;
-    else Count &= 0x0F;
+    Count &= 0x1F;
 
     /* Do nothing if the count is zero */
     if (Count == 0) return TRUE;
diff --git a/lib/fast486/opgroups.c b/lib/fast486/opgroups.c
index 21aa95e2ed3..a944e8d8939 100644
--- a/lib/fast486/opgroups.c
+++ b/lib/fast486/opgroups.c
@@ -163,16 +163,11 @@ Fast486RotateOperation(PFAST486_STATE State,
     ULONG HighestBit = 1 << (Bits - 1);
     ULONG Result;
 
-    if ((Operation != 2) && (Operation != 3))
-    {
-        /* Mask the count */
-        Count &= Bits - 1;
-    }
-    else
-    {
-        /* For RCL and RCR, the CF is included in the value */
-        Count %= Bits + 1;
-    }
+    /* Normalize the count */
+    Count &= 0x1F;
+
+    /* If the count is zero, do nothing */
+    if (Count == 0) goto SetFlags;
 
     /* Check which operation is this */
     switch (Operation)
@@ -275,6 +270,7 @@ Fast486RotateOperation(PFAST486_STATE State,
         }
     }
 
+SetFlags:
     if (Operation >= 4)
     {
         /* Update ZF, SF and PF */