Source code of Windows XP (NT5)
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/*++
Copyright (c) 1996 Microsoft Corporation
Module Name:
dosmem.c
Abstract:
This module contains routines for allocating and freeing DOS memory.
Author:
Neil Sandlin (neilsa) 12-Dec-1996
Notes:
Revision History:
--*/
#include "precomp.h"
#pragma hdrstop
#include "softpc.h"
#include <malloc.h>
#include <xlathlp.h>
#define DOSERR_NOT_ENOUGH_MEMORY 8
#define DOSERR_INVALID_BLOCK 9
MEM_DPMI DosMemHead = { NULL, 0, &DosMemHead, &DosMemHead, 0};
VOID
DpmiAllocateDosMem(
VOID
)
/*++
Routine Description:
This routine allocates a block of DOS memory. The client is switched
to V86 mode, and DOS is called to allocate the memory. Then a selector
is allocated for the PM app to reference the memory.
Arguments:
None.
Return Value:
None.
--*/
{
DECLARE_LocalVdmContext;
PMEM_DPMI DosMemBlock;
CLIENT_REGS SaveRegs;
USHORT Sel;
USHORT Seg;
ULONG ParaSize = getBX();
ULONG MemSize = ((ULONG)ParaSize) << 4;
USHORT DosError = 0;
USHORT SizeLargest = 0;
SAVE_CLIENT_REGS(SaveRegs);
if (WOWAllocSeg) {
PUCHAR VdmStackPointer;
ULONG NewSP;
//
// WOW is doing the allocation
//
BuildStackFrame(4, &VdmStackPointer, &NewSP);
setCS(WOWAllocSeg);
setIP(WOWAllocFunc);
*(PDWORD16)(VdmStackPointer-4) = MemSize;
*(PWORD16)(VdmStackPointer-6) = (USHORT) (PmBopFe >> 16);
*(PWORD16)(VdmStackPointer-8) = (USHORT) PmBopFe;
setSP((WORD)NewSP);
host_simulate();
Sel = getAX();
Seg = getDX();
if (!Sel) {
DosError = DOSERR_NOT_ENOUGH_MEMORY;
}
} else {
USHORT SelCount;
//
// DOS is doing the allocation
// First get a mem_block to track the allocation
//
DosMemBlock = malloc(sizeof(MEM_DPMI));
if (!DosMemBlock) {
// Couldn't get the MEM_DPMI
DosError = DOSERR_NOT_ENOUGH_MEMORY;
} else {
//
// Next allocate the selector array
//
SelCount = (USHORT) ((MemSize+65535)>>16);
Sel = ALLOCATE_SELECTORS(SelCount);
if (!Sel) {
// Couldn't get the selectors
DosError = DOSERR_NOT_ENOUGH_MEMORY;
free(DosMemBlock);
} else {
//
// Now have DOS allocate the memory
//
DpmiSwitchToRealMode();
setBX((WORD)ParaSize);
setAX(0x4800);
DPMI_EXEC_INT(0x21);
if (getCF()) {
USHORT i;
// Couldn't get the memory
DosError = getAX();
SizeLargest = getBX();
for (i = 0; i < SelCount; i++, Sel+=8) {
FreeSelector(Sel);
}
free(DosMemBlock);
} else {
ULONG Base;
//
// Got the block. Save the allocation info, and set
// up the descriptors
//
Seg = getAX();
Base = ((ULONG)Seg) << 4;
DosMemBlock->Address = (PVOID)Seg;
DosMemBlock->Length = (ULONG)ParaSize;
DosMemBlock->Sel = Sel;
DosMemBlock->SelCount = SelCount;
INSERT_BLOCK(DosMemBlock, DosMemHead);
SetDescriptorArray(Sel, Base, MemSize);
}
DpmiSwitchToProtectedMode();
}
}
}
SET_CLIENT_REGS(SaveRegs);
if (DosError) {
setAX(DosError);
setBX(SizeLargest);
setCF(1);
} else {
setDX(Sel);
setAX(Seg);
setCF(0);
}
}
VOID
DpmiFreeDosMem(
VOID
)
/*++
Routine Description:
This routine frees a block of DOS memory.
Arguments:
None.
Return Value:
None.
--*/
{
DECLARE_LocalVdmContext;
PMEM_DPMI DosMemBlock;
CLIENT_REGS SaveRegs;
USHORT Sel = getDX();
USHORT DosError = 0;
SAVE_CLIENT_REGS(SaveRegs);
if (WOWFreeSeg) {
PUCHAR VdmStackPointer;
ULONG NewSP;
//
// WOW is doing the free
//
BuildStackFrame(3, &VdmStackPointer, &NewSP);
setCS(WOWFreeSeg);
setIP(WOWFreeFunc);
*(PWORD16)(VdmStackPointer-2) = Sel;
*(PWORD16)(VdmStackPointer-4) = (USHORT) (PmBopFe >> 16);
*(PWORD16)(VdmStackPointer-6) = (USHORT) PmBopFe;
setSP((WORD)NewSP);
host_simulate();
Sel = getAX();
if (!Sel) {
DosError = DOSERR_INVALID_BLOCK;
}
} else {
USHORT i;
DosError = DOSERR_INVALID_BLOCK; // assume failure
//
// DOS is doing the free
// First find the mem_block for this allocation
//
DosMemBlock = DosMemHead.Next;
while(DosMemBlock != &DosMemHead) {
if (DosMemBlock->Sel == Sel) {
DpmiSwitchToRealMode();
setES((WORD)DosMemBlock->Address);
setAX(0x4900);
DPMI_EXEC_INT(0x21);
if (getCF()) {
USHORT i;
// Couldn't free the memory
DosError = getAX();
} else {
for (i = 0; i < DosMemBlock->SelCount; i++, Sel+=8) {
FreeSelector(Sel);
}
DosError = 0;
}
DpmiSwitchToProtectedMode();
DELETE_BLOCK(DosMemBlock);
free(DosMemBlock);
break;
}
DosMemBlock = DosMemBlock->Next;
}
}
SET_CLIENT_REGS(SaveRegs);
if (DosError) {
setAX(DosError);
setCF(1);
} else {
setCF(0);
}
}
VOID
DpmiSizeDosMem(
VOID
)
/*++
Routine Description:
This routine calls DOS to resize a DOS memory block, or to get
the largest available block.
Arguments:
None.
Return Value:
None.
--*/
{
DECLARE_LocalVdmContext;
PMEM_DPMI DosMemBlock;
CLIENT_REGS SaveRegs;
USHORT Sel = getDX();
ULONG ParaSize = getBX();
ULONG MemSize = ((ULONG)ParaSize) << 4;
USHORT DosError = 0;
SAVE_CLIENT_REGS(SaveRegs);
if (WOWFreeSeg) {
//
// WOW is doing the resize
//
// Not implemented
DosError = DOSERR_NOT_ENOUGH_MEMORY;
} else {
USHORT SelCount;
USHORT i;
//
// DOS is doing the resize
// Find the mem_block for this allocation
// First see if we need a new selector array
//
DosError = DOSERR_INVALID_BLOCK; // assume failure
DosMemBlock = DosMemHead.Next;
while(DosMemBlock != &DosMemHead) {
if (DosMemBlock->Sel == Sel) {
USHORT NewSel = 0;
USHORT NewSelCount = 0;
//
// If we have to grow the selector array, make sure
// we can grow it in place
//
SelCount = (USHORT) ((MemSize+65535)>>16);
if (SelCount > DosMemBlock->SelCount) {
USHORT TmpSel;
NewSel = Sel+(DosMemBlock->SelCount*8);
NewSelCount = SelCount - DosMemBlock->SelCount;
//
// First check to see if the selectors are really all free
//
for (i=0,TmpSel = NewSel; i < NewSelCount; i++, TmpSel+=8) {
if (!IS_SELECTOR_FREE(TmpSel)) {
DosError = DOSERR_NOT_ENOUGH_MEMORY;
goto dpmi_size_error;
}
}
//
// Now attempt to remove them off the free list
//
for (i=0; i < NewSelCount; i++, NewSel+=8) {
if (!RemoveFreeSelector(NewSel)) {
// If this happens, we must have a bogus free
// selector list
DosError = DOSERR_NOT_ENOUGH_MEMORY;
goto dpmi_size_error;
}
}
}
DpmiSwitchToRealMode();
setBX((WORD)ParaSize);
setES((WORD)DosMemBlock->Address);
setAX(0x4A00);
DPMI_EXEC_INT(0x21);
if (getCF()) {
USHORT i;
// Couldn't resize the memory
DosError = getAX();
// Free selectors, if we got new ones
if (NewSelCount) {
for (i = 0; i < NewSelCount; i++, NewSel+=8) {
FreeSelector(NewSel);
}
}
} else {
ULONG Base;
//
// Resized the block. Update the allocation info, and set
// up the descriptors
//
if (SelCount < DosMemBlock->SelCount) {
USHORT OldSel = Sel+SelCount*8;
USHORT OldSelCount = DosMemBlock->SelCount - SelCount;
//
// Count of selectors has shrunk. Free 'em up.
//
for (i = 0; i < OldSelCount; i++, OldSel+=8) {
FreeSelector(OldSel);
}
}
DosMemBlock->Length = (ULONG)ParaSize;
DosMemBlock->SelCount = SelCount;
Base = ((ULONG)DosMemBlock->Address) << 4;
SetDescriptorArray(Sel, Base, MemSize);
DosError = 0;
}
DpmiSwitchToProtectedMode();
break;
}
DosMemBlock = DosMemBlock->Next;
}
}
dpmi_size_error:
SET_CLIENT_REGS(SaveRegs);
if (DosError) {
setAX(DosError);
setCF(1);
} else {
setCF(0);
}
}