From f3df799dc287792157b08d706c8e677924144e93 Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Mon, 11 Nov 2013 03:14:18 +0000
Subject: [PATCH] [FAST486] Implement the LSS instruction. Fix a bug in LFS and
 LGS.

svn path=/branches/ntvdm/; revision=60935
---
 lib/fast486/extraops.c | 71 +++++++++++++++++++++++++++++++++++++++++-
 lib/fast486/extraops.h |  1 +
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/lib/fast486/extraops.c b/lib/fast486/extraops.c
index 64ae8ba7310..ba2b5bd263f 100644
--- a/lib/fast486/extraops.c
+++ b/lib/fast486/extraops.c
@@ -215,7 +215,7 @@ Fast486ExtendedHandlers[FAST486_NUM_OPCODE_HANDLERS] =
     Fast486ExtOpcodeImul,
     Fast486ExtOpcodeCmpXchgByte,
     Fast486ExtOpcodeCmpXchg,
-    NULL, // TODO: OPCODE 0xB2 NOT IMPLEMENTED
+    Fast486ExtOpcodeLss,
     Fast486ExtOpcodeBtr,
     Fast486ExtOpcodeLfsLgs,
     Fast486ExtOpcodeLfsLgs,
@@ -1102,6 +1102,74 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeCmpXchg)
     return TRUE;
 }
 
+FAST486_OPCODE_HANDLER(Fast486ExtOpcodeLss)
+{
+    UCHAR FarPointer[6];
+    BOOLEAN OperandSize, AddressSize;
+    FAST486_MOD_REG_RM ModRegRm;
+
+    /* Make sure this is the right instruction */
+    ASSERT(Opcode == 0xB2);
+
+    OperandSize = AddressSize = State->SegmentRegs[FAST486_REG_CS].Size;
+
+    TOGGLE_OPSIZE(OperandSize);
+    TOGGLE_ADSIZE(AddressSize);
+
+    /* Get the operands */
+    if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    if (!ModRegRm.Memory)
+    {
+        /* Invalid */
+        Fast486Exception(State, FAST486_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    if (!Fast486ReadMemory(State,
+                           (State->PrefixFlags & FAST486_PREFIX_SEG)
+                           ? State->SegmentOverride : FAST486_REG_DS,
+                           ModRegRm.MemoryAddress,
+                           FALSE,
+                           FarPointer,
+                           OperandSize ? 6 : 4))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    if (OperandSize)
+    {
+        ULONG Offset = *((PULONG)FarPointer);
+        USHORT Segment = *((PUSHORT)&FarPointer[sizeof(ULONG)]);
+
+        /* Set the register to the offset */
+        State->GeneralRegs[ModRegRm.Register].Long = Offset;
+
+        /* Load the segment */
+        return Fast486LoadSegment(State,
+                                  FAST486_REG_SS,
+                                  Segment);
+    }
+    else
+    {
+        USHORT Offset = *((PUSHORT)FarPointer);
+        USHORT Segment = *((PUSHORT)&FarPointer[sizeof(USHORT)]);
+
+        /* Set the register to the offset */
+        State->GeneralRegs[ModRegRm.Register].LowWord = Offset;
+
+        /* Load the segment */
+        return Fast486LoadSegment(State,
+                                  FAST486_REG_SS,
+                                  Segment);
+    }
+}
+
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeBtr)
 {
     BOOLEAN OperandSize, AddressSize;
@@ -1204,6 +1272,7 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeLfsLgs)
 
     OperandSize = AddressSize = State->SegmentRegs[FAST486_REG_CS].Size;
 
+    TOGGLE_OPSIZE(OperandSize);
     TOGGLE_ADSIZE(AddressSize);
 
     /* Get the operands */
diff --git a/lib/fast486/extraops.h b/lib/fast486/extraops.h
index 0e6ff21b709..5996e811233 100644
--- a/lib/fast486/extraops.h
+++ b/lib/fast486/extraops.h
@@ -42,6 +42,7 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeShrd);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeImul);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeCmpXchgByte);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeCmpXchg);
+FAST486_OPCODE_HANDLER(Fast486ExtOpcodeLss);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeBtr);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeLfsLgs);
 FAST486_OPCODE_HANDLER(Fast486ExtOpcodeMovzxByte);