From 4b14d9a6720f2c5a39d4703c5e0905f87174d978 Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Wed, 16 Oct 2013 00:41:24 +0000
Subject: [PATCH] [SOFT386] Start implementing call gate support. Implement the
 direct far call opcode (0x9A).

svn path=/branches/ntvdm/; revision=60685
---
 include/reactos/libs/soft386/soft386.h | 13 +++++
 lib/soft386/common.inl                 | 24 ++++++++-
 lib/soft386/opcodes.c                  | 73 ++++++++++++++++++++++++--
 3 files changed, 106 insertions(+), 4 deletions(-)

diff --git a/include/reactos/libs/soft386/soft386.h b/include/reactos/libs/soft386/soft386.h
index d8ced70a1bf..e87810dd66a 100644
--- a/include/reactos/libs/soft386/soft386.h
+++ b/include/reactos/libs/soft386/soft386.h
@@ -228,6 +228,19 @@ typedef struct
     ULONG BaseHigh      : 8;
 } SOFT386_GDT_ENTRY, *PSOFT386_GDT_ENTRY;
 
+typedef struct
+{
+    ULONG Offset : 16;
+    ULONG Selector : 16;
+    ULONG ParamCount : 5;
+    ULONG Reserved : 3;
+    ULONG Type : 4;
+    ULONG SystemType : 1;
+    ULONG Dpl : 2;
+    ULONG Present : 1;
+    ULONG OffsetHigh : 16;
+} SOFT386_CALL_GATE, *PSOFT386_CALL_GATE;
+
 typedef struct
 {
     ULONG Offset        : 16;
diff --git a/lib/soft386/common.inl b/lib/soft386/common.inl
index 7a218d82d2a..072354bf628 100644
--- a/lib/soft386/common.inl
+++ b/lib/soft386/common.inl
@@ -202,15 +202,23 @@ Soft386LoadSegment(PSOFT386_STATE State,
                           sizeof(GdtEntry));
         }
 
-        /* Check if we are loading SS */
         if (Segment == SOFT386_REG_SS)
         {
+            /* Loading the stack segment */
+
             if (GET_SEGMENT_INDEX(Selector) == 0)
             {
                 Soft386Exception(State, SOFT386_EXCEPTION_GP);
                 return FALSE;
             }
 
+            if (!GdtEntry.SystemType)
+            {
+                /* This is a special descriptor */
+                Soft386Exception(State, SOFT386_EXCEPTION_GP);
+                return FALSE;
+            }
+
             if (GdtEntry.Executable || !GdtEntry.ReadWrite)
             {
                 Soft386Exception(State, SOFT386_EXCEPTION_GP);
@@ -230,8 +238,22 @@ Soft386LoadSegment(PSOFT386_STATE State,
                 return FALSE;
             }
         }
+        else if (Segment == SOFT386_REG_CS)
+        {
+            /* Loading the code segment */
+            // TODO: NOT IMPLEMENTED
+        }
         else
         {
+            /* Loading a data segment */
+
+            if (!GdtEntry.SystemType)
+            {
+                /* This is a special descriptor */
+                Soft386Exception(State, SOFT386_EXCEPTION_GP);
+                return FALSE;
+            }
+
             if ((GET_SEGMENT_RPL(Selector) > GdtEntry.Dpl)
                 && (Soft386GetCurrentPrivLevel(State) > GdtEntry.Dpl))
             {
diff --git a/lib/soft386/opcodes.c b/lib/soft386/opcodes.c
index 683b67fe4e8..53533537f84 100644
--- a/lib/soft386/opcodes.c
+++ b/lib/soft386/opcodes.c
@@ -4612,10 +4612,77 @@ SOFT386_OPCODE_HANDLER(Soft386OpcodeCdq)
 
 SOFT386_OPCODE_HANDLER(Soft386OpcodeCallAbs)
 {
-    // TODO: NOT IMPLEMENTED
-    UNIMPLEMENTED;
+    USHORT Segment = 0;
+    ULONG Offset = 0;
+    BOOLEAN Size = State->SegmentRegs[SOFT386_REG_CS].Size;
 
-    return FALSE;
+    /* Make sure this is the right instruction */
+    ASSERT(Opcode == 0x9A);
+
+    if (State->PrefixFlags & SOFT386_PREFIX_OPSIZE)
+    {
+        /* The OPSIZE prefix toggles the size */
+        Size = !Size;
+    }
+
+    if (State->PrefixFlags & SOFT386_PREFIX_LOCK)
+    {
+        /* Invalid prefix */
+        Soft386Exception(State, SOFT386_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    /* Fetch the offset */
+    if (Size)
+    {
+        if (!Soft386FetchDword(State, &Offset))
+        {
+            /* Exception occurred */
+            return FALSE;
+        }
+    }
+    else
+    {
+        if (!Soft386FetchWord(State, (PUSHORT)&Offset))
+        {
+            /* Exception occurred */
+            return FALSE;
+        }
+    }
+
+    /* Fetch the segment */
+    if (!Soft386FetchWord(State, &Segment))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    /* Push the current code segment selector */
+    if (!Soft386StackPush(State, State->SegmentRegs[SOFT386_REG_CS].Selector))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    /* Push the current value of the instruction pointer */
+    if (!Soft386StackPush(State, State->InstPtr.Long))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    /* Load the new CS */
+    if (!Soft386LoadSegment(State, SOFT386_REG_CS, Segment))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
+    /* Load new (E)IP */
+    if (Size) State->InstPtr.Long = Offset;
+    else State->InstPtr.LowWord = LOWORD(Offset);
+
+    return TRUE;
 }
 
 SOFT386_OPCODE_HANDLER(Soft386OpcodeWait)