/*++
Copyright (c) 1994 Microsoft Corporation
Module Name:
ctrlops.c
Abstract:
This module implements the code to emulate call, retunr, and various
control operations.
Author:
David N. Cutler (davec) 10-Nov-1994
Environment:
Kernel mode only.
Revision History:
--*/
#include "nthal.h"
#include "emulate.h"
VOID
XmCallOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates a call opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
ULONG Target;
ULONG Source;
//
// Save the target address, push the current segment, if required, and
// push the current IP, set the destination segment, if required, and
// set the new IP.
//
Target = P->DstValue.Long;
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
} else {
P->DataType = WORD_DATA;
}
if ((P->CurrentOpcode == 0x9a) || (P->FunctionIndex != X86_CALL_OP)) {
XmPushStack(P, P->SegmentRegister[CS]);
XmPushStack(P, P->Eip);
P->SegmentRegister[CS] = P->DstSegment;
} else {
XmPushStack(P, P->Eip);
}
P->Eip = Target;
XmTraceJumps(P);
return;
}
VOID
XmEnterOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates an enter opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
ULONG Allocate;
ULONG Frame;
ULONG Number;
//
// set the number of bytes to allocate on the stack and the number
// of nesting levels.
//
Allocate = P->SrcValue.Long;
Number = P->DstValue.Long;
//
// Set the data type and save the frame pointer on the stack.
//
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
XmPushStack(P, P->Gpr[EBP].Exx);
Frame = P->Gpr[ESP].Exx;
} else {
P->DataType = WORD_DATA;
XmPushStack(P, P->Gpr[BP].Xx);
Frame = P->Gpr[SP].Xx;
}
//
// Save the current stack pointer and push parameters on the stack.
//
if (Number != 0) {
//
// If the level number is not one, then raise an exception.
//
// N.B. Level numbers greater than one are not supported.
//
if (Number != 1) {
longjmp(&P->JumpBuffer[0], XM_ILLEGAL_LEVEL_NUMBER);
}
XmPushStack(P, Frame);
}
//
// Allocate local storage on stack.
//
if (P->OpsizePrefixActive != FALSE) {
P->Gpr[EBP].Exx = Frame;
P->Gpr[ESP].Exx = P->Gpr[ESP].Exx - Allocate;
} else {
P->Gpr[BP].Xx = (USHORT)Frame;
P->Gpr[SP].Xx = (USHORT)(P->Gpr[SP].Xx - Allocate);
}
return;
}
VOID
XmHltOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates a hlt opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
//
// Halt instructions are not supported by the emulator.
//
longjmp(&P->JumpBuffer[0], XM_HALT_INSTRUCTION);
return;
}
VOID
XmIntOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates an int opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
ULONG Number;
PULONG Vector;
//
// If the int instruction is an int 3, then set the interrupt vector
// to 3. Otherwise, if the int instruction is an into, then set the
// vector to 4 if OF is set. use the source interrupt vector.
//
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
} else {
P->DataType = WORD_DATA;
}
if (P->CurrentOpcode == 0xcc) {
Number = 3;
} else if (P->CurrentOpcode == 0xce) {
if (P->Eflags.OF == 0) {
return;
}
Number = 4;
} else {
Number = P->SrcValue.Byte;
}
//
// If the vector number is 0x42, then nop the interrupt. This is the
// standard EGA video driver entry point in a PC's motherboard BIOS
// for which there is no code.
//
#if !defined(_PURE_EMULATION_)
if (Number == 0x42) {
return;
}
#endif
//
// If the vector number is 0x1a, then attempt to emulate the PCI BIOS
// if it is enabled.
//
#if !defined(_PURE_EMULATION_)
if ((Number == 0x1a) && (XmExecuteInt1a(P) != FALSE)) {
return;
}
#endif
//
// Push the current flags, code segment, and EIP on the stack.
//
XmPushStack(P, P->AllFlags);
XmPushStack(P, P->SegmentRegister[CS]);
XmPushStack(P, P->Eip);
//
// Set the new coded segment and IP from the specified interrupt
// vector.
//
Vector = (PULONG)(P->TranslateAddress)(0, 0);
P->SegmentRegister[CS] = (USHORT)(Vector[Number] >> 16);
P->Eip = (USHORT)(Vector[Number] & 0xffff);
XmTraceJumps(P);
return;
}
VOID
XmIretOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates an iret opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
//
// Set the data type and restore the return address, code segment,
// and flags.
//
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
} else {
P->DataType = WORD_DATA;
}
P->Eip = XmPopStack(P);
P->SegmentRegister[CS] = (USHORT)XmPopStack(P);
P->AllFlags = XmPopStack(P);
XmTraceJumps(P);
//
// Check for emulator exit conditions.
//
if ((P->Eip == 0xffff) && (P->SegmentRegister[CS] == 0xffff)) {
longjmp(&P->JumpBuffer[0], XM_SUCCESS);
}
return;
}
VOID
XmLeaveOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates a leave opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
//
// Set the data type, restore the stack pointer, and restore the frame
// pointer.
//
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
P->Gpr[ESP].Exx = P->Gpr[EBP].Exx;
P->Gpr[EBP].Exx = XmPopStack(P);
} else {
P->DataType = WORD_DATA;
P->Gpr[SP].Xx = P->Gpr[BP].Xx;
P->Gpr[BP].Xx = (USHORT)XmPopStack(P);
}
return;
}
VOID
XmRetOp (
PRXM_CONTEXT P
)
/*++
Routine Description:
This function emulates a ret opcode.
Arguments:
P - Supplies a pointer to an emulator context structure.
Return Value:
None.
--*/
{
ULONG Adjust;
//
// Compute the number of bytes that are to be removed from the stack
// after having removed the return address and optionally the new CS
// segment value.
//
if ((P->CurrentOpcode & 0x1) == 0) {
Adjust = XmGetWordImmediate(P);
} else {
Adjust = 0;
}
//
// Remove the return address from the stack and set the new IP.
//
if (P->OpsizePrefixActive != FALSE) {
P->DataType = LONG_DATA;
} else {
P->DataType = WORD_DATA;
}
P->Eip = XmPopStack(P);
//
// If the current opcode is a far return, then remove the new CS segment
// value from the stack.
//
if ((P->CurrentOpcode & 0x8) != 0) {
P->SegmentRegister[CS] = (USHORT)XmPopStack(P);
}
//
// Remove the specified number of bytes from the stack.
//
P->Gpr[ESP].Exx += Adjust;
XmTraceJumps(P);
//
// Check for emulator exit conditions.
//
if ((P->Eip == 0xffff) && (P->SegmentRegister[CS] == 0xffff)) {
longjmp(&P->JumpBuffer[0], XM_SUCCESS);
}
return;
}
