VOID
NTAPI
Fast486SetSegment(PFAST486_STATE State,
FAST486_SEG_REGS Segment,
USHORT Selector)
{
/* Call the internal function */
Fast486LoadSegment(State, Segment, Selector);
}
VOID
NTAPI
Fast486ExecuteAt(PFAST486_STATE State, USHORT Segment, ULONG Offset)
{
/* Load the new CS */
if (!Fast486LoadSegment(State, FAST486_REG_CS, Segment))
{
/* An exception occurred, let the handler execute instead */
return;
}
/* Set the new IP */
State->InstPtr.Long = Offset;
}
VOID
NTAPI
Fast486SetStack(PFAST486_STATE State, USHORT Segment, ULONG Offset)
{
/* Load the new SS */
if (!Fast486LoadSegment(State, FAST486_REG_SS, Segment))
{
/* An exception occurred, let the handler execute instead */
return;
}
/* Set the new SP */
State->GeneralRegs[FAST486_REG_ESP].Long = Offset;
}
BOOLEAN
Fast486InterruptInternal(PFAST486_STATE State,
USHORT SegmentSelector,
ULONG Offset,
ULONG GateType)
{
BOOLEAN GateSize = (GateType == FAST486_IDT_INT_GATE_32)
|| (GateType == FAST486_IDT_TRAP_GATE_32);
/* Check for protected mode */
if (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE)
{
FAST486_TSS Tss;
USHORT OldSs = State->SegmentRegs[FAST486_REG_SS].Selector;
ULONG OldEsp = State->GeneralRegs[FAST486_REG_ESP].Long;
if (GateSize != (State->SegmentRegs[FAST486_REG_CS].Size))
{
/*
* The gate size doesn't match the current operand size, so toggle
* the OPSIZE flag.
*/
State->PrefixFlags ^= FAST486_PREFIX_OPSIZE;
}
/* Check if the interrupt handler is more privileged */
if (Fast486GetCurrentPrivLevel(State) > GET_SEGMENT_RPL(SegmentSelector))
{
/* Read the TSS */
if (!Fast486ReadLinearMemory(State,
State->TaskReg.Base,
&Tss,
sizeof(Tss)))
{
/* Exception occurred */
return FALSE;
}
/* Check the new (higher) privilege level */
switch (GET_SEGMENT_RPL(SegmentSelector))
{
case 0:
{
if (!Fast486LoadSegment(State, FAST486_REG_SS, Tss.Ss0))
{
/* Exception occurred */
return FALSE;
}
State->GeneralRegs[FAST486_REG_ESP].Long = Tss.Esp0;
break;
}
case 1:
{
if (!Fast486LoadSegment(State, FAST486_REG_SS, Tss.Ss1))
{
/* Exception occurred */
return FALSE;
}
State->GeneralRegs[FAST486_REG_ESP].Long = Tss.Esp1;
break;
}
case 2:
{
if (!Fast486LoadSegment(State, FAST486_REG_SS, Tss.Ss2))
{
/* Exception occurred */
return FALSE;
}
State->GeneralRegs[FAST486_REG_ESP].Long = Tss.Esp2;
break;
}
default:
{
/* Should never reach here! */
ASSERT(FALSE);
}
}
/* Push SS selector */
if (!Fast486StackPush(State, OldSs)) return FALSE;
/* Push stack pointer */
if (!Fast486StackPush(State, OldEsp)) return FALSE;
}
}
else
{
if (State->SegmentRegs[FAST486_REG_CS].Size)
{
/* Set OPSIZE, because INT always pushes 16-bit values in real mode */
State->PrefixFlags |= FAST486_PREFIX_OPSIZE;
}
}
/* Push EFLAGS */
if (!Fast486StackPush(State, State->Flags.Long)) return FALSE;
/* Push CS selector */
if (!Fast486StackPush(State, State->SegmentRegs[FAST486_REG_CS].Selector)) return FALSE;
/* Push the instruction pointer */
if (!Fast486StackPush(State, State->InstPtr.Long)) return FALSE;
if ((GateType == FAST486_IDT_INT_GATE) || (GateType == FAST486_IDT_INT_GATE_32))
{
/* Disable interrupts after a jump to an interrupt gate handler */
State->Flags.If = FALSE;
}
/* Load new CS */
if (!Fast486LoadSegment(State, FAST486_REG_CS, SegmentSelector))
{
/* An exception occurred during the jump */
return FALSE;
}
if (GateSize)
{
/* 32-bit code segment, use EIP */
State->InstPtr.Long = Offset;
}
else
{
/* 16-bit code segment, use IP */
State->InstPtr.LowWord = LOWORD(Offset);
}
return TRUE;
}
