[FAST486][NTVDM]

Use FASTCALL instead of NTAPI. Merge EmulatorReadMemory with MemRead and
EmulatorWriteMemory with MemWrite.


svn path=/trunk/; revision=68109

reactos/include/reactos/libs/fast486/fast486.h

@@ -182,7 +182,7 @@ typedef enum _FAST486_EXCEPTIONS
 
 typedef
 VOID
-(NTAPI *FAST486_MEM_READ_PROC)
+(FASTCALL *FAST486_MEM_READ_PROC)
 (
     PFAST486_STATE State,
     ULONG Address,
@@ -192,7 +192,7 @@ VOID
 
 typedef
 VOID
-(NTAPI *FAST486_MEM_WRITE_PROC)
+(FASTCALL *FAST486_MEM_WRITE_PROC)
 (
     PFAST486_STATE State,
     ULONG Address,
@@ -202,7 +202,7 @@ VOID
 
 typedef
 VOID
-(NTAPI *FAST486_IO_READ_PROC)
+(FASTCALL *FAST486_IO_READ_PROC)
 (
     PFAST486_STATE State,
     USHORT Port,
@@ -213,7 +213,7 @@ VOID
 
 typedef
 VOID
-(NTAPI *FAST486_IO_WRITE_PROC)
+(FASTCALL *FAST486_IO_WRITE_PROC)
 (
     PFAST486_STATE State,
     USHORT Port,
@@ -224,7 +224,7 @@ VOID
 
 typedef
 VOID
-(NTAPI *FAST486_BOP_PROC)
+(FASTCALL *FAST486_BOP_PROC)
 (
     PFAST486_STATE State,
     UCHAR BopCode
@@ -232,14 +232,14 @@ VOID
 
 typedef
 UCHAR
-(NTAPI *FAST486_INT_ACK_PROC)
+(FASTCALL *FAST486_INT_ACK_PROC)
 (
     PFAST486_STATE State
 );
 
 typedef
 VOID
-(NTAPI *FAST486_FPU_PROC)
+(FASTCALL *FAST486_FPU_PROC)
 (
     PFAST486_STATE State
 );

reactos/lib/fast486/debug.c

@@ -43,91 +43,82 @@ typedef enum
 
 /* PRIVATE FUNCTIONS **********************************************************/
 
-#if 0
+FORCEINLINE
-static inline VOID
+VOID
-NTAPI
+FASTCALL
 Fast486ExecutionControl(PFAST486_STATE State, FAST486_EXEC_CMD Command)
 {
     UCHAR Opcode;
     FAST486_OPCODE_HANDLER_PROC CurrentHandler;
     INT ProcedureCallCount = 0;
+    BOOLEAN Trap;
 
     /* Main execution loop */
     do
     {
-NextInst:
+        Trap = State->Flags.Tf;
-        /* Check if this is a new instruction */
-        if (State->PrefixFlags == 0) State->SavedInstPtr = State->InstPtr;
 
-        /* Perform an instruction fetch */
+        if (!State->Halted)
-        if (!Fast486FetchByte(State, &Opcode))
         {
-            /* Exception occurred */
+NextInst:
+            /* Check if this is a new instruction */
+            if (State->PrefixFlags == 0)
+            {
+                State->SavedInstPtr = State->InstPtr;
+                State->SavedStackPtr = State->GeneralRegs[FAST486_REG_ESP];
+            }
+
+            /* Perform an instruction fetch */
+            if (!Fast486FetchByte(State, &Opcode))
+            {
+                /* Exception occurred */
+                State->PrefixFlags = 0;
+                continue;
+            }
+
+            // TODO: Check for CALL/RET to update ProcedureCallCount.
+
+            /* Call the opcode handler */
+            CurrentHandler = Fast486OpcodeHandlers[Opcode];
+            CurrentHandler(State, Opcode);
+
+            /* If this is a prefix, go to the next instruction immediately */
+            if (CurrentHandler == Fast486OpcodePrefix) goto NextInst;
+
+            /* A non-prefix opcode has been executed, reset the prefix flags */
             State->PrefixFlags = 0;
-            continue;
         }
 
-        // TODO: Check for CALL/RET to update ProcedureCallCount.
-
-        /* Call the opcode handler */
-        CurrentHandler = Fast486OpcodeHandlers[Opcode];
-        CurrentHandler(State, Opcode);
-
-        /* If this is a prefix, go to the next instruction immediately */
-        if (CurrentHandler == Fast486OpcodePrefix) goto NextInst;
-
-        /* A non-prefix opcode has been executed, reset the prefix flags */
-        State->PrefixFlags = 0;
-
         /*
          * Check if there is an interrupt to execute, or a hardware interrupt signal
          * while interrupts are enabled.
          */
-        if (State->Flags.Tf)
+        if (State->DoNotInterrupt)
         {
-            /* Perform the interrupt */
+            /* Clear the interrupt delay flag */
-            Fast486PerformInterrupt(State, 0x01);
+            State->DoNotInterrupt = FALSE;
-
-            /*
-             * Flags and TF are pushed on stack so we can reset TF now,
-             * to not break into the INT 0x01 handler.
-             * After the INT 0x01 handler returns, the flags and therefore
-             * TF are popped back off the stack and restored, so TF will be
-             * automatically reset to its previous state.
-             */
-            State->Flags.Tf = FALSE;
         }
-        else if (State->IntStatus == FAST486_INT_EXECUTE)
+        else if (Trap && !State->Halted)
         {
             /* Perform the interrupt */
-            Fast486PerformInterrupt(State, State->PendingIntNum);
+            Fast486PerformInterrupt(State, FAST486_EXCEPTION_DB);
+        }
+        else if (State->Flags.If && State->IntSignaled)
+        {
+            /* No longer halted */
+            State->Halted = FALSE;
+
+            /* Acknowledge the interrupt and perform it */
+            Fast486PerformInterrupt(State, State->IntAckCallback(State));
 
             /* Clear the interrupt status */
-            State->IntStatus = FAST486_INT_NONE;
+            State->IntSignaled = FALSE;
-        }
-        else if (State->Flags.If && (State->IntStatus == FAST486_INT_SIGNAL))
-        {
-            /* Acknowledge the interrupt to get the number */
-            State->PendingIntNum = State->IntAckCallback(State);
-
-            /* Set the interrupt status to execute on the next instruction */
-            State->IntStatus = FAST486_INT_EXECUTE;
-        }
-        else if (State->IntStatus == FAST486_INT_DELAYED)
-        {
-            /* Restore the old state */
-            State->IntStatus = FAST486_INT_EXECUTE;
         }
     }
     while ((Command == FAST486_CONTINUE) ||
            (Command == FAST486_STEP_OVER && ProcedureCallCount > 0) ||
            (Command == FAST486_STEP_OUT && ProcedureCallCount >= 0));
 }
-#else
-VOID
-NTAPI
-Fast486ExecutionControl(PFAST486_STATE State, FAST486_EXEC_CMD Command);
-#endif
 
 /* PUBLIC FUNCTIONS ***********************************************************/
 

reactos/lib/fast486/fast486.c

@@ -31,98 +31,10 @@
 #include "opcodes.h"
 #include "fpu.h"
 
-/* DEFINES ********************************************************************/
-
-typedef enum
-{
-    FAST486_STEP_INTO,
-    FAST486_STEP_OVER,
-    FAST486_STEP_OUT,
-    FAST486_CONTINUE
-} FAST486_EXEC_CMD;
-
-/* PRIVATE FUNCTIONS **********************************************************/
-
-VOID
-NTAPI
-Fast486ExecutionControl(PFAST486_STATE State, FAST486_EXEC_CMD Command)
-{
-    UCHAR Opcode;
-    FAST486_OPCODE_HANDLER_PROC CurrentHandler;
-    INT ProcedureCallCount = 0;
-    BOOLEAN Trap;
-
-    /* Main execution loop */
-    do
-    {
-        Trap = State->Flags.Tf;
-
-        if (!State->Halted)
-        {
-NextInst:
-            /* Check if this is a new instruction */
-            if (State->PrefixFlags == 0)
-            {
-                State->SavedInstPtr = State->InstPtr;
-                State->SavedStackPtr = State->GeneralRegs[FAST486_REG_ESP];
-            }
-
-            /* Perform an instruction fetch */
-            if (!Fast486FetchByte(State, &Opcode))
-            {
-                /* Exception occurred */
-                State->PrefixFlags = 0;
-                continue;
-            }
-
-            // TODO: Check for CALL/RET to update ProcedureCallCount.
-
-            /* Call the opcode handler */
-            CurrentHandler = Fast486OpcodeHandlers[Opcode];
-            CurrentHandler(State, Opcode);
-
-            /* If this is a prefix, go to the next instruction immediately */
-            if (CurrentHandler == Fast486OpcodePrefix) goto NextInst;
-
-            /* A non-prefix opcode has been executed, reset the prefix flags */
-            State->PrefixFlags = 0;
-        }
-
-        /*
-         * Check if there is an interrupt to execute, or a hardware interrupt signal
-         * while interrupts are enabled.
-         */
-        if (State->DoNotInterrupt)
-        {
-            /* Clear the interrupt delay flag */
-            State->DoNotInterrupt = FALSE;
-        }
-        else if (Trap && !State->Halted)
-        {
-            /* Perform the interrupt */
-            Fast486PerformInterrupt(State, FAST486_EXCEPTION_DB);
-        }
-        else if (State->Flags.If && State->IntSignaled)
-        {
-            /* No longer halted */
-            State->Halted = FALSE;
-
-            /* Acknowledge the interrupt and perform it */
-            Fast486PerformInterrupt(State, State->IntAckCallback(State));
-
-            /* Clear the interrupt status */
-            State->IntSignaled = FALSE;
-        }
-    }
-    while ((Command == FAST486_CONTINUE) ||
-           (Command == FAST486_STEP_OVER && ProcedureCallCount > 0) ||
-           (Command == FAST486_STEP_OUT && ProcedureCallCount >= 0));
-}
-
 /* DEFAULT CALLBACKS **********************************************************/
 
 static VOID
-NTAPI
+FASTCALL
 Fast486MemReadCallback(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
 {
     UNREFERENCED_PARAMETER(State);
@@ -130,7 +42,7 @@ Fast486MemReadCallback(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG
 }
 
 static VOID
-NTAPI
+FASTCALL
 Fast486MemWriteCallback(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
 {
     UNREFERENCED_PARAMETER(State);
@@ -138,7 +50,7 @@ Fast486MemWriteCallback(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG
 }
 
 static VOID
-NTAPI
+FASTCALL
 Fast486IoReadCallback(PFAST486_STATE State, USHORT Port, PVOID Buffer, ULONG DataCount, UCHAR DataSize)
 {
     UNREFERENCED_PARAMETER(State);
@@ -149,7 +61,7 @@ Fast486IoReadCallback(PFAST486_STATE State, USHORT Port, PVOID Buffer, ULONG Dat
 }
 
 static VOID
-NTAPI
+FASTCALL
 Fast486IoWriteCallback(PFAST486_STATE State, USHORT Port, PVOID Buffer, ULONG DataCount, UCHAR DataSize)
 {
     UNREFERENCED_PARAMETER(State);
@@ -160,7 +72,7 @@ Fast486IoWriteCallback(PFAST486_STATE State, USHORT Port, PVOID Buffer, ULONG Da
 }
 
 static VOID
-NTAPI
+FASTCALL
 Fast486BopCallback(PFAST486_STATE State, UCHAR BopCode)
 {
     UNREFERENCED_PARAMETER(State);
@@ -168,7 +80,7 @@ Fast486BopCallback(PFAST486_STATE State, UCHAR BopCode)
 }
 
 static UCHAR
-NTAPI
+FASTCALL
 Fast486IntAckCallback(PFAST486_STATE State)
 {
     UNREFERENCED_PARAMETER(State);
@@ -177,7 +89,8 @@ Fast486IntAckCallback(PFAST486_STATE State)
     return 0x01;
 }
 
-static VOID NTAPI
+static VOID
+FASTCALL
 Fast486FpuCallback(PFAST486_STATE State)
 {
     UNREFERENCED_PARAMETER(State);

reactos/subsystems/mvdm/ntvdm/bios/vidbios.c

@@ -15,6 +15,7 @@
 #include "emulator.h"
 #include "cpu/cpu.h"
 #include "cpu/bop.h"
+#include "memory.h"
 
 #include "bios.h"
 // #include "vidbios.h"

reactos/subsystems/mvdm/ntvdm/cpu/bop.c

@@ -29,7 +29,7 @@ VOID RegisterBop(BYTE BopCode, EMULATOR_BOP_PROC BopHandler)
     BopProc[BopCode] = BopHandler;
 }
 
-VOID WINAPI EmulatorBiosOperation(PFAST486_STATE State, UCHAR BopCode)
+VOID FASTCALL EmulatorBiosOperation(PFAST486_STATE State, UCHAR BopCode)
 {
     WORD StackSegment, StackPointer;
     LPWORD Stack;

reactos/subsystems/mvdm/ntvdm/cpu/bop.h

@@ -21,7 +21,7 @@
 typedef VOID (WINAPI *EMULATOR_BOP_PROC)(LPWORD Stack);
 
 VOID RegisterBop(BYTE BopCode, EMULATOR_BOP_PROC BopHandler);
-VOID WINAPI EmulatorBiosOperation(PFAST486_STATE State, UCHAR BopCode);
+VOID FASTCALL EmulatorBiosOperation(PFAST486_STATE State, UCHAR BopCode);
 
 #endif // _BOP_H_
 

reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/dosfiles.c

@@ -704,7 +704,10 @@ WORD DosReadFile(WORD FileHandle,
         if (ReadFile(Descriptor->Win32Handle, LocalBuffer, Count, &BytesRead32, NULL))
         {
             /* Write to the memory */
-            MemWrite(TO_LINEAR(HIWORD(Buffer), LOWORD(Buffer)), LocalBuffer, LOWORD(BytesRead32));
+            EmulatorWriteMemory(&EmulatorContext,
+                                TO_LINEAR(HIWORD(Buffer), LOWORD(Buffer)),
+                                LocalBuffer,
+                                LOWORD(BytesRead32));
 
             /* Update the position */
             Descriptor->Position += BytesRead32;
@@ -756,7 +759,11 @@ WORD DosWriteFile(WORD FileHandle,
         ASSERT(LocalBuffer != NULL);
 
         /* Read from the memory */
-        MemRead(TO_LINEAR(HIWORD(Buffer), LOWORD(Buffer)), LocalBuffer, Count);
+        EmulatorReadMemory(&EmulatorContext,
+                           TO_LINEAR(HIWORD(Buffer),
+                           LOWORD(Buffer)),
+                           LocalBuffer,
+                           Count);
 
         /* Write the file */
         if (WriteFile(Descriptor->Win32Handle, LocalBuffer, Count, &BytesWritten32, NULL))

reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c

@@ -13,6 +13,7 @@
 #include "ntvdm.h"
 #include "emulator.h"
 #include "cpu/bop.h"
+#include "../../memory.h"
 #include "io.h"
 #include "hardware/ps2.h"
 

reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.h

@@ -6,8 +6,8 @@
  * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
  */
 
-#ifndef _MEMORY_H_
+#ifndef _DOS_MEMORY_H_
-#define _MEMORY_H_
+#define _DOS_MEMORY_H_
 
 /* TYPEDEFS *******************************************************************/
 
@@ -45,6 +45,6 @@ BOOLEAN DosLinkUmb(VOID);
 BOOLEAN DosUnlinkUmb(VOID);
 VOID DosChangeMemoryOwner(WORD Segment, WORD NewOwner);
 
-#endif // _MEMORY_H_
+#endif // _DOS_MEMORY_H_
 
 /* EOF */

reactos/subsystems/mvdm/ntvdm/dos/mouse32.c

@@ -24,6 +24,7 @@
 #include "bios/bios.h"
 #include "bios/bios32/bios32p.h"
 
+#include "memory.h"
 #include "io.h"
 #include "dos32krnl/dos.h"
 

reactos/subsystems/mvdm/ntvdm/emulator.c

@@ -42,8 +42,6 @@
 LPVOID  BaseAddress = NULL;
 BOOLEAN VdmRunning  = TRUE;
 
-static BOOLEAN A20Line = FALSE;
-
 static HANDLE InputThread = NULL;
 
 LPCWSTR ExceptionName[] =
@@ -63,46 +61,7 @@ LPCWSTR ExceptionName[] =
 
 /* PRIVATE FUNCTIONS **********************************************************/
 
-VOID WINAPI EmulatorReadMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
+UCHAR FASTCALL EmulatorIntAcknowledge(PFAST486_STATE State)
-{
-    UNREFERENCED_PARAMETER(State);
-
-    /* Mirror 0x000FFFF0 at 0xFFFFFFF0 */
-    if (Address >= 0xFFFFFFF0) Address -= 0xFFF00000;
-
-    /* If the A20 line is disabled, mask bit 20 */
-    if (!A20Line) Address &= ~(1 << 20); 
-
-    if ((Address + Size - 1) >= MAX_ADDRESS)
-    {
-        ULONG ExtraStart = (Address < MAX_ADDRESS) ? MAX_ADDRESS - Address : 0;
-
-        /* Fill the memory that was above the limit with 0xFF */
-        RtlFillMemory((PVOID)((ULONG_PTR)Buffer + ExtraStart), Size - ExtraStart, 0xFF);
-
-        if (Address < MAX_ADDRESS) Size = MAX_ADDRESS - Address;
-        else return;
-    }
-
-    /* Read while calling fast memory hooks */
-    MemRead(Address, Buffer, Size);
-}
-
-VOID WINAPI EmulatorWriteMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
-{
-    UNREFERENCED_PARAMETER(State);
-
-    /* If the A20 line is disabled, mask bit 20 */
-    if (!A20Line) Address &= ~(1 << 20); 
-
-    if (Address >= MAX_ADDRESS) return;
-    Size = min(Size, MAX_ADDRESS - Address);
-
-    /* Write while calling fast memory hooks */
-    MemWrite(Address, Buffer, Size);
-}
-
-UCHAR WINAPI EmulatorIntAcknowledge(PFAST486_STATE State)
 {
     UNREFERENCED_PARAMETER(State);
 
@@ -110,7 +69,7 @@ UCHAR WINAPI EmulatorIntAcknowledge(PFAST486_STATE State)
     return PicGetInterrupt();
 }
 
-VOID WINAPI EmulatorFpu(PFAST486_STATE State)
+VOID FASTCALL EmulatorFpu(PFAST486_STATE State)
 {
     /* The FPU is wired to IRQ 13 */
     PicInterruptRequest(13);
@@ -164,16 +123,6 @@ VOID EmulatorInterruptSignal(VOID)
     Fast486InterruptSignal(&EmulatorContext);
 }
 
-VOID EmulatorSetA20(BOOLEAN Enabled)
-{
-    A20Line = Enabled;
-}
-
-BOOLEAN EmulatorGetA20(VOID)
-{
-    return A20Line;
-}
-
 static VOID WINAPI EmulatorDebugBreakBop(LPWORD Stack)
 {
     DPRINT1("NTVDM: BOP_DEBUGGER\n");

reactos/subsystems/mvdm/ntvdm/emulator.h

@@ -90,7 +90,7 @@ enum
     EMULATOR_EXCEPTION_PAGE_FAULT
 };
 
-// extern FAST486_STATE EmulatorContext;
+extern FAST486_STATE EmulatorContext;
 extern LPVOID  BaseAddress;
 extern BOOLEAN VdmRunning;
 
@@ -98,28 +98,12 @@ extern BOOLEAN VdmRunning;
 
 VOID DumpMemory(BOOLEAN TextFormat);
 
-VOID WINAPI EmulatorReadMemory
+UCHAR FASTCALL EmulatorIntAcknowledge
-(
-    PFAST486_STATE State,
-    ULONG Address,
-    PVOID Buffer,
-    ULONG Size
-);
-
-VOID WINAPI EmulatorWriteMemory
-(
-    PFAST486_STATE State,
-    ULONG Address,
-    PVOID Buffer,
-    ULONG Size
-);
-
-UCHAR WINAPI EmulatorIntAcknowledge
 (
     PFAST486_STATE State
 );
 
-VOID WINAPI EmulatorFpu
+VOID FASTCALL EmulatorFpu
 (
     PFAST486_STATE State
 );
@@ -129,8 +113,6 @@ VOID EmulatorException(BYTE ExceptionNumber, LPWORD Stack);
 VOID EmulatorTerminate(VOID);
 
 VOID EmulatorInterruptSignal(VOID);
-VOID EmulatorSetA20(BOOLEAN Enabled);
-BOOLEAN EmulatorGetA20(VOID);
 
 BOOLEAN EmulatorInitialize(HANDLE ConsoleInput, HANDLE ConsoleOutput);
 VOID EmulatorCleanup(VOID);

reactos/subsystems/mvdm/ntvdm/hardware/dma.c

@@ -477,13 +477,13 @@ DWORD DmaRequest(IN WORD      iChannel,
 
             if (Increment)
             {
-                MemWrite(CurrAddress, dmabuf, length);
+                EmulatorWriteMemory(&EmulatorContext, CurrAddress, dmabuf, length);
             }
             else
             {
                 for (i = 0; i < length; i++)
                 {
-                    MemWrite(CurrAddress - i, dmabuf + i, sizeof(BYTE));
+                    EmulatorWriteMemory(&EmulatorContext, CurrAddress - i, dmabuf + i, sizeof(BYTE));
                 }
             }
 
@@ -498,13 +498,13 @@ DWORD DmaRequest(IN WORD      iChannel,
 
             if (Increment)
             {
-                MemRead(CurrAddress, dmabuf, length);
+                EmulatorReadMemory(&EmulatorContext, CurrAddress, dmabuf, length);
             }
             else
             {
                 for (i = 0; i < length; i++)
                 {
-                    MemRead(CurrAddress - i, dmabuf + i, sizeof(BYTE));
+                    EmulatorReadMemory(&EmulatorContext, CurrAddress - i, dmabuf + i, sizeof(BYTE));
                 }
             }
 

reactos/subsystems/mvdm/ntvdm/hardware/ps2.c

@@ -15,6 +15,7 @@
 #include "emulator.h"
 #include "ps2.h"
 
+#include "memory.h"
 #include "io.h"
 #include "pic.h"
 #include "clock.h"

reactos/subsystems/mvdm/ntvdm/io.c

@@ -343,7 +343,7 @@ VOID UnregisterIoPort(USHORT Port)
     RtlZeroMemory(&IoPortProc[Port], sizeof(IoPortProc[Port]));
 }
 
-VOID WINAPI
+VOID FASTCALL
 EmulatorReadIo(PFAST486_STATE State,
                USHORT Port,
                PVOID Buffer,
@@ -418,7 +418,7 @@ EmulatorReadIo(PFAST486_STATE State,
     }
 }
 
-VOID WINAPI
+VOID FASTCALL
 EmulatorWriteIo(PFAST486_STATE State,
                 USHORT Port,
                 PVOID Buffer,

reactos/subsystems/mvdm/ntvdm/io.h

@@ -85,7 +85,7 @@ VOID RegisterIoPort(USHORT Port,
 
 VOID UnregisterIoPort(USHORT Port);
 
-VOID WINAPI EmulatorReadIo
+VOID FASTCALL EmulatorReadIo
 (
     PFAST486_STATE State,
     USHORT Port,
@@ -94,7 +94,7 @@ VOID WINAPI EmulatorReadIo
     UCHAR DataSize
 );
 
-VOID WINAPI EmulatorWriteIo
+VOID FASTCALL EmulatorWriteIo
 (
     PFAST486_STATE State,
     USHORT Port,

reactos/subsystems/mvdm/ntvdm/memory.c

@@ -36,6 +36,7 @@ typedef struct _MEM_HOOK
 
 static LIST_ENTRY HookList;
 static PMEM_HOOK PageTable[TOTAL_PAGES] = { NULL };
+static BOOLEAN A20Line = FALSE;
 
 /* PRIVATE FUNCTIONS **********************************************************/
 
@@ -137,12 +138,32 @@ WritePage(PMEM_HOOK Hook, ULONG Address, PVOID Buffer, ULONG Size)
 
 /* PUBLIC FUNCTIONS ***********************************************************/
 
-VOID
+VOID FASTCALL EmulatorReadMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
-MemRead(ULONG Address, PVOID Buffer, ULONG Size)
 {
     ULONG i, Offset, Length;
-    ULONG FirstPage = Address >> 12;
+    ULONG FirstPage, LastPage;
-    ULONG LastPage = (Address + Size - 1) >> 12;
+
+    UNREFERENCED_PARAMETER(State);
+
+    /* Mirror 0x000FFFF0 at 0xFFFFFFF0 */
+    if (Address >= 0xFFFFFFF0) Address -= 0xFFF00000;
+
+    /* If the A20 line is disabled, mask bit 20 */
+    if (!A20Line) Address &= ~(1 << 20); 
+
+    if ((Address + Size - 1) >= MAX_ADDRESS)
+    {
+        ULONG ExtraStart = (Address < MAX_ADDRESS) ? MAX_ADDRESS - Address : 0;
+
+        /* Fill the memory that was above the limit with 0xFF */
+        RtlFillMemory((PVOID)((ULONG_PTR)Buffer + ExtraStart), Size - ExtraStart, 0xFF);
+
+        if (Address < MAX_ADDRESS) Size = MAX_ADDRESS - Address;
+        else return;
+    }
+
+    FirstPage = Address >> 12;
+    LastPage = (Address + Size - 1) >> 12;
 
     if (FirstPage == LastPage)
     {
@@ -161,12 +182,21 @@ MemRead(ULONG Address, PVOID Buffer, ULONG Size)
     }
 }
 
-VOID
+VOID FASTCALL EmulatorWriteMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
-MemWrite(ULONG Address, PVOID Buffer, ULONG Size)
 {
     ULONG i, Offset, Length;
-    ULONG FirstPage = Address >> 12;
+    ULONG FirstPage, LastPage;
-    ULONG LastPage = (Address + Size - 1) >> 12;
+
+    UNREFERENCED_PARAMETER(State);
+
+    /* If the A20 line is disabled, mask bit 20 */
+    if (!A20Line) Address &= ~(1 << 20); 
+
+    if (Address >= MAX_ADDRESS) return;
+    Size = min(Size, MAX_ADDRESS - Address);
+
+    FirstPage = Address >> 12;
+    LastPage = (Address + Size - 1) >> 12;
 
     if (FirstPage == LastPage)
     {
@@ -185,6 +215,16 @@ MemWrite(ULONG Address, PVOID Buffer, ULONG Size)
     }
 }
 
+VOID EmulatorSetA20(BOOLEAN Enabled)
+{
+    A20Line = Enabled;
+}
+
+BOOLEAN EmulatorGetA20(VOID)
+{
+    return A20Line;
+}
+
 VOID
 MemExceptionHandler(ULONG FaultAddress, BOOLEAN Writing)
 {

reactos/subsystems/mvdm/ntvdm/memory.h

@@ -36,21 +36,28 @@ VOID MemCleanup(VOID);
 VOID MemExceptionHandler(ULONG FaultAddress, BOOLEAN Writing);
 
 VOID
-MemRead
+FASTCALL
+EmulatorReadMemory
 (
+    PFAST486_STATE State,
     ULONG Address,
     PVOID Buffer,
     ULONG Size
 );
 
 VOID
-MemWrite
+FASTCALL
+EmulatorWriteMemory
 (
+    PFAST486_STATE State,
     ULONG Address,
     PVOID Buffer,
     ULONG Size
 );
 
+VOID EmulatorSetA20(BOOLEAN Enabled);
+BOOLEAN EmulatorGetA20(VOID);
+
 BOOL
 MemInstallFastMemoryHook
 (