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

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/*
* COPYRIGHT: GPL - See COPYING in the top level directory
* PROJECT: ReactOS Virtual DOS Machine
* FILE: subsystems/mvdm/ntvdm/cpu/callback.c
* PURPOSE: 16 and 32-bit Callbacks Support
* PROGRAMMERS: Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
* Hermes Belusca-Maito (hermes.belusca@sfr.fr)
*/
/******************************************************************************\
| WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!
|
| Callbacks support supposes implicitly that the callbacks are used
| in the SAME thread as the CPU thread, otherwise messing in parallel
| with the CPU registers is 100% prone to bugs!!
\******************************************************************************/
/* INCLUDES *******************************************************************/
#include "ntvdm.h"
#define NDEBUG
#include <debug.h>
#include "emulator.h"
#include "callback.h"
#include "cpu.h"
#include "bop.h"
#include <isvbop.h>
/* PRIVATE VARIABLES **********************************************************/
#if 0
/* FIXME: Are we going to use this somewhere? */
static BYTE Yield[] =
{
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // 13x nop
BOP(BOP_UNSIMULATE), // UnSimulate16 BOP
};
C_ASSERT(sizeof(Yield) == 16 * sizeof(BYTE));
#endif
/* PUBLIC FUNCTIONS ***********************************************************/
VOID
InitializeContextEx(IN PCALLBACK16 Context,
IN ULONG TrampolineSize,
IN USHORT Segment,
IN USHORT Offset)
{
Context->TrampolineFarPtr = MAKELONG(Offset, Segment);
Context->TrampolineSize = max(TRAMPOLINE_SIZE, TrampolineSize);
Context->Segment = Segment;
Context->NextOffset = Offset + Context->TrampolineSize;
}
VOID
InitializeContext(IN PCALLBACK16 Context,
IN USHORT Segment,
IN USHORT Offset)
{
InitializeContextEx(Context,
TRAMPOLINE_SIZE,
Segment,
Offset);
}
VOID
Call16(IN USHORT Segment,
IN USHORT Offset)
{
/* Save CS:IP */
USHORT OrgCS = getCS();
USHORT OrgIP = getIP();
/* Set the new CS:IP */
setCS(Segment);
setIP(Offset);
DPRINT("Call16(%04X:%04X)\n", Segment, Offset);
/* Start CPU simulation */
CpuSimulate();
/* Restore CS:IP */
setCS(OrgCS);
setIP(OrgIP);
}
VOID
RunCallback16(IN PCALLBACK16 Context,
IN ULONG FarPtr)
{
PUCHAR TrampolineBase = (PUCHAR)FAR_POINTER(Context->TrampolineFarPtr);
PUCHAR Trampoline = TrampolineBase;
UCHAR OldTrampoline[TRAMPOLINE_SIZE];
/* Save the old trampoline */
((PULONGLONG)&OldTrampoline)[0] = ((PULONGLONG)TrampolineBase)[0];
DPRINT("RunCallback16(0x%p)\n", FarPtr);
/* Build the generic entry-point for 16-bit far calls */
*Trampoline++ = 0x9A; // Call far seg:off
*(PULONG)Trampoline = FarPtr;
Trampoline += sizeof(ULONG);
UnSimulate16(Trampoline);
/* Perform the call */
Call16(HIWORD(Context->TrampolineFarPtr),
LOWORD(Context->TrampolineFarPtr));
/* Restore the old trampoline */
((PULONGLONG)TrampolineBase)[0] = ((PULONGLONG)&OldTrampoline)[0];
}
ULONG
RegisterCallback16(IN ULONG FarPtr,
IN LPBYTE CallbackCode,
IN SIZE_T CallbackSize,
OUT PSIZE_T CodeSize OPTIONAL)
{
LPBYTE CodeStart = (LPBYTE)FAR_POINTER(FarPtr);
LPBYTE Code = CodeStart;
SIZE_T OurCodeSize = CallbackSize;
if (CallbackCode == NULL) CallbackSize = 0;
if (CallbackCode)
{
/* 16-bit interrupt code */
RtlCopyMemory(Code, CallbackCode, CallbackSize);
Code += CallbackSize;
}
/* Return the real size of the code if needed */
if (CodeSize) *CodeSize = OurCodeSize; // == (ULONG_PTR)Code - (ULONG_PTR)CodeStart;
// /* Return the entry-point address for 32-bit calls */
// return (ULONG_PTR)(CodeStart + CallbackSize);
return OurCodeSize;
}
/* EOF */