Source code of Windows XP (NT5)
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PAGE ,132
TITLE DXVCPI.ASM -- Dos Extender VCPI Support Code
; Copyright (c) Microsoft Corporation 1990-1991. All Rights Reserved.
;*** dxvcpi.asm - vcpi detection/maintenance/cleanup code (resident)
;
; Copyright <C> 1990, Microsoft Corporation
;
; Purpose:
;
; Revision History:
;
;
; 08-07-90 earleh Allow program to boot without LIM 3.2 page frame.
; 05/07/90 jimmat Started incorporating VCPI changes from languages group.
;
; [] 20-Feb-1990 Dans Created
;
;************************************************************************/
.286p
; -------------------------------------------------------
; INCLUDE FILE DEFINITIONS
; -------------------------------------------------------
.xlist
.sall
include segdefs.inc
include gendefs.inc
include pmdefs.inc
.list
; This entire file is only for VCPI support
if VCPI
.xlist
.sall
include dxvcpi.inc
.list
;
; miscellaneous equates
;
;
; also in dxmmgr.asm
;
.ERRE CB_MEMHDR EQ 10h ;size of memory block header
;
; also in dxmmgr.asm
;
;
; data
;
DXDATA segment
;
; Externs
;
extrn idCpuType:word
extrn bpGDT:fword
extrn cKbInitialHeapSize:word
extrn cbHeapSize:dword
extrn dsegCurrent:word
extrn hmemHeap:word
extrn lpfnXMSFunc:DWORD
extrn selGDT:WORD
;
; Definitions, data
;
public fEms
fEMS db 0 ; ems present
public fVCPI
fVCPI db 0 ; vcpi present
public iddxsystype
iddxsystype db DXINDOS ; type of memory used to hold
; final dx Pmode data.
public segBootPmode
segBootPmode dw 0 ; segment of block used to
; build system tables in real
align 4
public cFreePages
cFreePages dd 0 ; free 4k pages, updated on each
; allocation.
public bpdxsyspages
bpdxsyspages dd DXPMPAGES-1 dup(0)
;
; pointer (off of SEL_DXPT) where next free page table entry is
;
; we initialize dxpt1 to have cptdx+2 entries in it (see
; SetupPageTables in dxvcpibt.asm)
;
;
; Offset in zeroth page table of first page table entry that belongs
; to DX. Set by initial call to GetVCPIInterface.
;
public pPteFirst
pPteFirst dd 0
;
; Offset in block pointed to by SEL_DXPT of where to put next page
; table entry when allocating extended memory by the page.
;
public pPteNext
pPteNext dd 0
;
; Maximum number of user page table entries that will fit in our
; original page table buffers.
;
public cPteMax
cPteMax dd 0
EXTRN hmem_XMS_Table:WORD
EXTRN hmem_XMS_Count:WORD
public hmem_System_Block
hmem_System_Block dw 0
DXDATA ends
DXPMCODE segment
IFDEF ROM
%OUT VCPI Support not compatible with ROM! Code segment variables!
.ERR
ENDIF
;
; Data set up in real mode prior to relocation of DX into vcpi
; (read only after init time anyway)
;
public fnVCPIPM, fnVCPIPMoff
fnVCPIPM label fword ; vcpi interface entrypoint
fnVCPIPMoff dd 0 ; set up in GetVCPIInterface
dw SEL_VCPI ; we know what this is.
externFP NSetSegmentDscr
extrn XMScontrol:FAR
pmxmssvc macro fcn
ifnb <fcn>
mov ah, fcn
endif
call XMScontrol
endm
DXPMCODE ends
DXCODE segment
;
; Data set up in real mode prior to relocation of DX into vcpi
; (read only after init time anyway)
;
public WdebVCPI, fnVCPI, fnVCPIoff
;--------- WdebVCPIInfo structure -----------
public laVTP, V86ToPm
;
; Begin WDEB386 VCPI notification structure. The following variables
; are copied by WDEB386 when we send it a VCPI presence notification,
; just after entering protected mode. The structure of this block of variables
; must not be changed without also changing the format of the data
; structure used by WDEB386.
;
;--------- WdebVCPIInfo structure -----------
WdebVCPI LABEL BYTE
fnVCPI label fword ; vcpi interface entrypoint
fnVCPIoff dd 0 ; set up in GetVCPIInterface
dw SEL_VCPI ; we know what this is.
dw SEL_VCPIALLMEM ; for Wdeb386 information
laVTP dd 0 ; linear address of next structure
;
; End WDEB386 VCPI notification structure.
;
; Structure for switching from v86 mode to protect mode via VCPI
EXTRN epmVCPI:BYTE
V86ToPm VTP <,,, SEL_LDT, SEL_TSS, OFFSET epmVCPI, 0, SEL_DXCODE0>
externFP AddXMStoVCPIHeap
DXCODE ends
DXCODE segment
assume cs:DXCODE, ds:DXDATA, es:nothing
;*** FreeEMSHandle - free DX system memory
;
; Purpose: free the VCPI pages OR XMS block we allocated for system use
;
; Register
; Usage: eax, edx, si, cx
;
; Input: none
;
; Output: VCPI DOS Extender system pages freed
; XMS handle deallocated
;
; Returns: nothing
;
; Exceptions: No operation if none of these entities have been
; allocated yet
;
; Notes:
;
;************************************************************************/
cProc FreeEMSHandle,<NEAR,PUBLIC,<>
cBegin
lea si,bpdxsyspages ; Load VCPI system pages array.
mov cx,DXPMPAGES-1 ; (First page was in PSP block.)
cld
.386
FreeVCPI_syspage:
lodsd ; fetch next page
or eax,eax ; page present?
jz FreeVCPI_Done ; No, could have been XMS.
and ax,0f000h ; Yes, clear lower 12 bits.
mov edx,eax
RMvcpi vcpiFREEPAGE ; and free it.
loop FreeVCPI_syspage ; loop until all freed
.286p
FreeVCPI_Done:
test iddxsystype,DXINXMS ; loaded in XMS?
jz FreeEMSHandle_ret ; No.
mov dx,hmem_System_Block ; Yes, load block
xmssvc 0dh ; unlock XMS block
mov dx,hmem_System_Block
xmssvc 0ah ; free XMS block
FreeEMSHandle_ret:
cEnd
DXCODE ends
;**************************************************************
; 386 only code from here on down!!!
;**************************************************************
.386p
include prot386.inc
DXCODE segment
assume cs:DXCODE, ds:DXDATA, es:nothing
DXCODE ends
DXPMCODE segment
assume cs:DXPMCODE
;**************************************************************
;*** CallVCPIPM
;
; Utility routine to call VCPI server in protected mode. Masks out
; interrupts during the call because QEMM enables the processor
; interrupt flag when you call it.
;
; Entry: AX = VCPI function code.
; Uses: Depends upon call.
;
; Note: There is a copy of this routine in dxvcpi.asm and another
; in dxvcpibt.asm. This is to allow near calls. The copy
; in dxvcpibt.asm is discarded after initialization time.
;
;**************************************************************
cProc CallVCPIPM,<NEAR>,<si>
cBegin
push ax ; save function code
;
; Shut out all interrupts.
; QEMM 5.0 enables interrupts during this call. All our interrupt
; handlers are in the user code ring. A workaround is to shut off
; hardware interrupts during the call.
;
in al,INTA01
IO_Delay
mov si, ax
mov al,0FFh
out INTA01,al
IO_Delay
pop ax ;restore function code
db 9Ah ;call far SEL_CALLVCPI:0
dw 0,SEL_CALLVCPI or STD_RING
; Restore the state of the interrupt mask register
xchg si, ax
out INTA01,al
IO_Delay
xchg si, ax
cEnd
;************************************************************************/
;*** AllocVCPIMem
;
; Purpose: to allocate a block of memory from VCPI
;
; Register
; Usage: eax, ebx, edx, ecx, es
;
; Input: ECX has number of 4k pages to allocate
; ES:EDI points to page table entries to fill.
;
; Output: pPteNext updated with next free pte
; cFreePages updated with number of free 4k pages from vcpi
;
; Returns: if success, linear ptr in eax
; if fail, eax 0, ebx has number of 4k pages available.
;
; Exceptions:
;
; Notes: maximum allocation is 65535 4k pages (more than enough)
; at one time.
; Also, this is PROTECT MODE ONLY.
;
;************************************************************************/
cProc AllocVCPIMem,<NEAR,PUBLIC>,<bx,dx>
cBegin
;
; Compute the number of entries free in our page table
;
mov edx, cPteMax
cmp ecx, edx ; compare request with PTEs
jb @F
;
; our page tables have less room than the vcpi server can allocate,
; so adjust our count downward to reflect that
;
mov ecx, edx
@@:
cmp ecx, cFreePages ; compare request with pages we are
; allowed to allocate
jb @F ; request < max.?
mov ecx, cFreePages ; No, clip.
@@:
jecxz AVM_exit ; ECX = pages to allocate
AVM_getpage:
PMvcpi vcpiALLOCPAGE
or ah, ah
jnz AVM_exit ; something happened...not as much
; as vcpi said was there.
dec cPteMax ; fix up free PTEs
dec cFreePages ; and free VCPI pages
;
; make it a page table entry, and store into page table
; don't need to worry about the tlb here, since not-present
; pages are not cached in the tlb.
;
or dx, NEWPTEMASK
mov eax, edx
stos dword ptr es:[edi]
dec ecx
jnz AVM_getpage ; next allocate
AVM_exit:
cEnd
;************************************************************************/
;*** VCPISpace
;
; Purpose: Return maximum possible VCPI memory allocation.
;
; Uses:
;
; Input:
;
; Output:
;
; Return: EAX = maximum possible VCPI pages we can get.
;
; Exceptions:
;
; Notes:
;
;************************************************************************/
cProc VCPISpace,<NEAR,PUBLIC>,<edx>
cBegin
PMvcpi vcpiCFREEPAGES ; EDX = free VCPI pages
cmp edx,cFreePages ; clip to maximum EMS allocation
jb VS_00
mov edx,cFreePages
VS_00:
mov eax,cPteMax ; clip to space in page tables
cmp edx,eax
jb VS_01
mov edx,eax
VS_01:
mov eax,edx
cEnd
;************************************************************************/
;*** FreeVCPIHeap
;
; Purpose: To free the Extended Memory heap memory.
;
; Register
; Usage: eax, ebx, ecx, edx
;
; Input:
;
; Output: All VCPI pages allocated for the heap are freed.
; All XMS blocks allocated for the heap are freed.
; Page table entries are set to zero.
;
;
; Returns: nothing
;
; Exceptions: none
;
; Notes: Protect mode only
;
;************************************************************************/
cProc FreeVCPIHeap,<NEAR,PUBLIC>,<es,edi,si,eax,edx>
cBegin
mov ax, SEL_DXPT ; set up es with the selector
mov es, ax ; for our page tables
mov edi, pPteFirst ; point to first page allocated
mov ecx, pPteNext ; point to first unallocated PTE
sub ecx, edi
jbe Free_XMS_Handles
shr ecx, 2 ; ECX = pages to free
startloop:
mov edx, es:[edi] ; get pte into edx
and dx, 0f000h ; mask off 12 lsb's
PMvcpi vcpiFREEPAGE ; free the page
xor eax, eax
stos dword ptr es:[edi] ; clear out PTE
dec ecx
jnz startloop
@@:
Free_XMS_Handles:
lea si, hmem_XMS_Table ; si points to XMS handle array
mov cx,[hmem_XMS_Count]
jcxz No_XMS_Handles
Free_XMS_Handles_Loop:
mov dx,[si]
pmxmssvc 0dh ; unlock any XMS blocks
mov dx,[si]
pmxmssvc 0ah ; free any XMS blocks
add si,2 ; point to next slot in handle array
loop Free_XMS_Handles_Loop ; loop if more handle slots
No_XMS_Handles:
cEnd
AddXMStoVCPIHeapCall label dword
dw offset dxcode:AddXMStoVCPIHeap,SEL_DXCODE or STD_RING
;*** AddVCPIHeap
;
; Purpose: to replace the himem specific code in AddToXmemHeap
;
; Register
; Usage: all preserved except return values in bx:dx
;
; Input: dx:cx is the minimum block length required (bytes).
;
; Output: cbHeapSize is updated if a heap is allocated
;
; Returns: bx:dx is 32bit linear address of allocated block if success,
; cy clear, else cy set
;
; Exceptions:
;
; Notes:
;
;************************************************************************/
cProc AddVCPIHeap,<NEAR,PUBLIC>,<eax,ecx>
localD cbNeeded
cBegin
push ebx ; save extended registers
push edx
add cx, CB_MEMHDR * 3 ; add memory manager overhead
adc dx, 0
movzx ecx,cx
shl edx,16d
or ecx,edx ; ECX = minimum bytes wanted
mov cbNeeded,ecx
add ecx,CBPAGE386-1
shr ecx,12d ; ECX = minimum pages wanted
mov eax, cPteMax
cmp ecx,eax ; make sure we have enough
jna AVH_00 ; page table entries
mov ecx,eax ; ECX = minimum pages wanted
AVH_00:
mov cbHeapSize,0
mov ax, SEL_DXPT ; ES -> user page tables
mov es, ax
mov edi, pPteNext ; Point to first unused PTE
or edi, edi ; Initialized?
jnz AVH_10 ; Yes, skip XMS allocate.
mov edi, pPteFirst ; No, initialize first unused PTE.
mov pPteNext, edi
cCall AddXMStoVCPIHeapCall
mov pPteFirst,edi ; VCPI allocations start here
AVH_10:
mov ebx, pPteNext ; EBX = first PTE
shl ebx, 10d ; EBX = linear address of start of block
mov dx, bx
shr ebx, 16d ; DX:BX = linear address of block
mov eax, edi
sub eax, pPteNext
shr eax, 2 ; AX = count of pages allocated
sub ecx, eax ; Get what we asked for?
jbe AVH_Done ; Yes.
cCall AllocVCPIMem ; allocate it from VCPI
; cx has number of 4k pages
AVH_Done:
mov eax, edi
sub eax, pPteNext
mov pPteNext, edi
or eax, eax
jz AVH_BadExit
shl eax, 10d ; EAX = count of bytes allocated
sub eax, CB_MEMHDR * 3 ; deduct overhead
mov cbHeapSize, eax
clc
jmp AVH_Exit
AVH_BadExit:
stc
AVH_Exit:
;
; Result is in BX:DX, but we have to save restore the MSW of EBX and
; that of EDX before we return to our caller.
;
mov ax,dx
pop edx
mov dx,ax
mov ax,bx
pop ebx
mov bx,ax
cEnd
DXPMCODE ends
endif ;VCPI
end