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/*++
Copyright (c) 1992 Microsoft Corporation
Module Name:
Stack.c
Abstract:
This module implements routines for manipulating the 16 bit stack
Author:
Dave Hastings (daveh) 24-Nov-1992
Revision History:
--*/
#include "precomp.h"
#pragma hdrstop
#include "softpc.h"
VOID
DpmiSwitchToDosxStack(
BOOL ProtectedMode
)
/*++
Routine Description:
This routine switches to the dos extender stack, and allocates a
new frame.
Arguments:
None.
Return Value:
None.
--*/
{
if (ProtectedMode) {
setSS(DosxPmDataSelector);
} else {
setSS(DosxStackSegment);
}
setSP(*DosxStackFramePointer);
*DosxStackFramePointer -= DosxStackFrameSize;
}
VOID
DpmiSwitchFromDosxStack(
VOID
)
/*++
Routine Description:
This routine deallocates a frame from the dosx stack
Arguments:
None.
Return Value:
None.
--*/
{
*DosxStackFramePointer += DosxStackFrameSize;
}
VOID
DpmiPushRmInt(
USHORT InterruptNumber
)
/*++
Routine Description:
This routine pushes an interrupt frame on the stack and sets up cs:ip
for the specified interrupt.
Arguments:
InterruptNumber -- Specifies the index of the interrupt
Return Value:
None.
--*/
{
PWORD16 StackPointer;
PULONG Ivt;
// bugbug stack wrap???
ASSERT((getSP() > 6));
ASSERT((!(getMSW() & MSW_PE)));
StackPointer = (PWORD16)Sim32GetVDMPointer(
((getSS() << 16) | getSP()),
1,
FALSE
);
*(StackPointer - 3) = (USHORT)(RmBopFe & 0x0000FFFF);
*(StackPointer - 2) = (USHORT)(RmBopFe >> 16);
*(StackPointer - 1) = getSTATUS();
setSP(getSP() - 6);
Ivt = (PULONG)Sim32GetVDMPointer(
0,
1,
FALSE
);
setCS((USHORT) (Ivt[InterruptNumber] >> 16));
setIP((USHORT) (Ivt[InterruptNumber] & 0xFFFF));
}
VOID
DpmiSimulateIretCF(
VOID
)
/*++
Routine Description:
This routine simulates a far return
Arguments:
None
Return Value:
None.
Notes:
This routine does not have to deal with 32 bit stacks, because by
the time we get here we know we are running on a stack that only
has 16 bits worth of sp information. Either the int 21 was executed
on a 16 bit stack, or we have switched stacks.
--*/
{
PWORD16 StackPointer;
StackPointer = (PWORD16)Sim32GetVDMPointer(
(((ULONG)getSS() << 16) | getSP()),
1,
// (UCHAR) (getMSW() & MSW_PE)
TRUE
);
//
// Return the carry flag from the int 21
//
setSTATUS((*(StackPointer + 2) & ~1) | (getSTATUS() & 1));
setCS(*(StackPointer + 1));
setIP(*StackPointer);
setSP(getSP() + 6);
}
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