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PAGE ,132 TITLE DXDMA.ASM -- Dos Extender DMA Services
; Copyright (c) Microsoft Corporation 1989-1991. All Rights Reserved.
;***********************************************************************;; DXDMA.ASM -- Dos Extender DMA Services;;-----------------------------------------------------------------------;; This module provides the protect mode DMA services for the 286 DOS; Extender. It supports a subset of the services documented in; "DMA Services for DOS Virtual 8086 and Protected Mode Environments"; by Microsoft Corporation.;;-----------------------------------------------------------------------;; 12/06/89 jimmat Minor changes to reflect updates in DMA Service Spec.; 11/01/89 jimmat Started.;;***********************************************************************
.286p
; -------------------------------------------------------; INCLUDE FILE DEFINITIONS; -------------------------------------------------------
.xlist .sallinclude segdefs.incinclude gendefs.incinclude pmdefs.incinclude interupt.incif VCPIinclude dxvcpi.incendif .list
; -------------------------------------------------------; GENERAL SYMBOL DEFINITIONS; -------------------------------------------------------
PhysicalPageSize equ 4096 ;size of 80386 physical pagePageShift equ 12
DMAServiceByte equ 7Bh
ChainReserved equ 08h ;set if unsupported services chained
DMAServiceID equ 81h ;Int 4Bh/AH=81h are the DMA servicesFirstValidSvc equ 02h ;First valid DMA service #LastValidSvc equ 0Ch ;Last valid DMA service #
; Get Version information
MajorVersion equ 01h ;Major specification versionMinorVersion equ 00h ;Minor specification version
DOSXProductNumber equ 02h ;286 DOS Extender product numberDOSXProductRevision equ 01h ;286 DOS Extender revision number
MemoryContiguous equ 08h ;All memory physically contigious flagAutoRemapSupported equ 04h ;Automatic remap supported
; DX flags on calls to DMA services
AutoBufferCopy equ 02h ;set if data to be copied into DMA bufNoAutoBufferAlloc equ 04h ;set if NO automatic buff allocationNoAutoRemap equ 08h ;set if NO automatic remap attemptedAlign64k equ 10h ;set if region can't cross 64k boundryAlign128k equ 20h ;set if region can't cross 128k boundryPageTableFmt equ 40h ;set for page table Scatter/Gather lock
ValidDXFlags equ 007Eh ;valid DX register flag bits (above)
; Error return codes
ErrRegionCrossedBoundry equ 02hErrNoBufferAvail equ 04hErrTooManyRegions equ 09hErrInvalidBufferID equ 0AhErrFuncNotSupported equ 0FhErrReservedFlagBits equ 10h
; DMA Descriptor Structure(s)
DDS STRUC ;normal DDSDDS_RegionSize dd ?DDS_Offset dd ?DDS_Selector dw ?DDS_BufferID dw ?DDS_PhyAddress dd ?DDS ENDS
SGDDS1 STRUC ;Extended DDS for Scatter/Gather dd 3 dup (?) ; Region formatDDS_NumAvail dw ?DDS_NumUsed dw ?DDS_Region0Addr dd ?DDS_Region0Size dd ?SGDDS1 ENDS
SGDDS2 STRUC ;Extended DDS for Scatter/Gather dd 4 dup (?) ; Page Table formatDDS_PageTblEnt0 dd ?SGDDS2 ENDS
; -------------------------------------------------------; EXTERNAL SYMBOL DEFINITIONS; -------------------------------------------------------
extrn EnterIntHandler:NEAR extrn LeaveIntHandler:NEAR extrn GetSegmentAddress:NEAR extrn PMIntrEntryVector:NEAR
; -------------------------------------------------------; DATA SEGMENT DEFINITIONS; -------------------------------------------------------
DXDATA segmentifdef NEC_98 extrn fPCH98:BYTEelse ;!NEC_98 ifdef NOT_NTVDM_NOT extrn fMicroChannel:BYTEendifendif ;!NEC_98
if VCPI extrn fVCPI:BYTEendif;; Contains a copy of bit 5 of the byte at 40:7b, that indicates; whether VDS should be used.; public bDMAServiceBitbDMAServiceBit db 0
DXDATA ends
; -------------------------------------------------------; CODE SEGMENT VARIABLES; -------------------------------------------------------
DXCODE segment
DXCODE ends
DXPMCODE segment
extrn selDgroupPM:WORD
DMASvcTbl label word
dw offset DXPMCODE:GetVersion dw offset DXPMCODE:LockDMARegion dw offset DXPMCODE:DoNothing ;UnlockDMARegion dw offset DXPMCODE:ScatterGatherLock dw offset DXPMCODE:DoNothing ;ScatterGatherUnlock dw offset DXPMCODE:Fail4NoBuffer ;RequestDMABuffer dw offset DXPMCODE:DoNothing ;ReleaseDMABuffer dw offset DXPMCODE:Fail4BufferID ;CopyIntoDMABuffer dw offset DXPMCODE:Fail4BufferID ;CopyOutOfDMABuffer dw offset DXPMCODE:DoNothing ;DisableDMATranslation dw offset DXPMCODE:DoNothing ;EnableDMATranalation
DXPMCODE ends
; ------------------------------------------------------- subttl DMA Service Dispatcher page; -------------------------------------------------------; DMA SERVICE DISPATCHER; -------------------------------------------------------
DXPMCODE segment assume cs:DXPMCODE
; -------------------------------------------------------; PMIntr4B -- Entry routine/dispatcher for protected mode DMA; services. The DMA services are invoked with an Int 4Bh; interrupt. The 286 DOS Extender only supports the DMA; services in protected mode. Other systems that use Virtual; 8086 mode on 386 processors will most likely need to support; the services in virtual mode also.;; The following services are supported (Int 4Bh/AH = 81h):;; AL = 00 Reserved; 01 Reserved; 02 Get Version; 03 Lock DMA Region; 04 Unlock DMA Region; 05 Scatter/Gather Lock Region; 06 Scatter/Gather Unlock Region; 07 Request DMA Buffer; 08 Release DMA Buffer; 09 Copy Into DMA Buffer; 0A Copy Out Of DMA Buffer; 0B Disable DMA Translation; 0C Enable DMA Translation; 0D Reserved; ...; FF Reserved
public PMIntr4B assume ds:NOTHING,es:NOTHING,ss:NOTHING
PMIntr4B proc near
; Is this one of the supported DMA services?
cmp ah,DMAServiceID ;is this a DMA service request? jz @f jmp short i4b_other_service ; no, see if it should be chained@@: call EnterIntHandler ;saves regs, switches stacks, etc. assume ds:DGROUP ;sets DS/ES = DGROUP mov es,[bp].pmUserES ; but we want caller's ES
cld ;cya...
cmp al,FirstValidSvc jb i4b_reserved
cmp al,LastValidSvc ja i4b_reserved
test dx,NOT ValidDXFlags ;any reserved flags set? jnz i4b_bad_flags
; -------------------------------------------------------
; Setup local environment and dispatch the service
i4b_valid_svc:
push offset DXPMCODE:i4b_svc_ret ;save dispatch return address
sub al,FirstValidSvc ;get address of service routine cbw shl ax,1 add ax,offset DXPMCODE:DMASvcTbl
xchg ax,bx mov bx,cs:[bx] xchg ax,bx
push ax ;save routine address on stack mov ax,[bp].pmUserAX ;restore entry AX
ret ;invoke service routine
i4b_svc_ret: ;service routines return here
jnc i4b_good_return ;CY set if service failed
i4b_error_return:
or byte ptr [bp].intUserFL,1 ;set CY in caller's flags jmp short i4b_exit
i4b_good_return:
and byte ptr [bp].intUserFL,not 1 ;clear CY in caller's flags
i4b_exit:
call LeaveIntHandler ;resotre stack, regs, etc. iret
; -------------------------------------------------------
; Reserved DMA service 00, 01, 0D-FF; return with CY set and; AL = ErrFuncNotSupported
i4b_reserved:
mov byte ptr [bp].intUserAX,ErrFuncNotSupported jmp short i4b_error_return
; -------------------------------------------------------
; User made a DMA service call with a reserved flag bit set. Fail the; call with AL = ErrReservedFlagBits
i4b_bad_flags:
mov byte ptr [bp].intUserAX,ErrReservedFlagBits jmp short i4b_error_return
; -------------------------------------------------------
; This is a non-DMA Int 4B call. On Micro Channel systems, bit 3; in location 40:007B indicates if we should chain the call along; or not. If the bit is set, we chain. If not Micro Channel, or the; bit is not set, we check the real mode Int 4Bh vector to see if someone; other than the BIOS has it hooked--if so, we chain anyway. If not,; return without changing any regs or flags.
i4b_other_service:
push ds
mov ds,selDgroupPM assume ds:DGROUP
ifdef NOT_NTVDM_NOTifdef NEC_98 test fPCH98,0FFhelse ;!NEC_98 test fMicroChannel,0FFh ;if micro channel systemendif ;!NEC_98 jz i4b_check_vector ; and 40:7B bit 3 set, ; chain the call to real mode push SEL_BIOSDATA or STD_RING pop ds assume ds:NOTHING
test byte ptr ds:DMAServiceByte,ChainReserved jnz i4b_chainendif
i4b_check_vector: ;not micro channel, or bit 3 not set
push ax ;check if the real mode Int 4Bh mov ax,SEL_RMIVT or STD_RING ; points somewhere and not mov ds,ax ; at the BIOS--if so, chain mov ax,word ptr ds:[4Bh*4] ; anyway. or ax,word ptr ds:[4Bh*4+2] pop ax jz i4b_dont_chain
cmp word ptr ds:[4bh*4+2],0E000h jz i4b_dont_chain
cmp word ptr ds:[4bh*4+2],0F000h jz i4b_dont_chain
i4b_chain:
pop ds ;chain the request to real mode jmp PMIntrEntryVector + 5*4Bh ; (no one can have pMode ; hooked before us)
i4b_dont_chain: ;don't chain the interrupt, ; just return quietly pop ds iret
PMIntr4B endp
; ------------------------------------------------------- subttl DMA Service Routines page; -------------------------------------------------------; DMA SERVICE ROUTINES; -------------------------------------------------------
; -------------------------------------------------------; RM4B -- Call the real mode INT 4Bh handler to; perform a DMA service, most likely something to; do with the VCPI provider's buffer when we are; running under VCPI.;; Input: depends on call; Output: Flags, registers from real mode call;; Notes: This is strictly an internal DOSX call,; so if a long pointer is used, then it; is assumed to point into DOSX's data; segment.;cProc RM4B,<NEAR,PUBLIC>cBegin pushf push cs call near ptr PMIntrEntryVector + 3*4BhcEnd
; -------------------------------------------------------; DoNothing -- This routine does nothing other than return; indicating that the DMA service succeeded.;; Input: none; Output: AL = 0, CY clear
assume ds:DGROUP,es:NOTHING,ss:NOTHING
DoNothing proc near
clc ;indicate success ret
DoNothing endp
; -------------------------------------------------------; Fail4BufferID -- This routine does nothing other than return; indicating that the DMA service failed with 'Invalid Buffer ID';; Input: none; Output: AL = 0Ah, CY set
assume ds:DGROUP,es:NOTHING,ss:NOTHING
Fail4BufferID proc near
mov byte ptr [bp].intUserAX,ErrInvalidBufferID stc ret
Fail4BufferID endp
; -------------------------------------------------------; Fail4NoBuffer -- This routine does nothing other than return; indicating that the DMA service failed with 'No Buffer Available';; Input: none; Output: AL = 04h, CY set
assume ds:DGROUP,es:NOTHING,ss:NOTHING
Fail4NoBuffer proc near
mov byte ptr [bp].intUserAX,ErrNoBufferAvail stc ret
Fail4NoBuffer endp
; -------------------------------------------------------; GetVersion -- This routine processes the DMA Get Version; service (AL = 02).;; Input: none; Output: AH/AL - Major/Minor specification level; BX - Product number; CX - Product revision number; DX - flags; SI:DI - 32 bit max buffer size available
assume ds:DGROUP,es:NOTHING,ss:NOTHING
GetVersion proc near
mov [bp].intUserAX,(MajorVersion shl 8) or MinorVersion mov [bp].intUserBX,DOSXProductNumber mov [bp].intUserCX,DOSXProductRevision mov [bp].intUserDX,MemoryContiguous
xor ax,ax ;0 buffer size supported, also clears mov [bp].intUserSI,ax ; carry flag mov [bp].intUserDI,ax
if VCPI cmp fVCPI,0 je gv_x mov ax,8102h xor dx,dx ;DX = 0 cmp bDMAServiceBit,0 ;VCPI provider supports VDS? je gv_e call RM4B jc gv_x mov [bp].intUserSI,si mov [bp].intUserDI,di and dx,NOT (AutoRemapSupported or MemoryContiguous)gv_e: mov [bp].intUserDX,dxgv_x:endif ret
GetVersion endp
; -------------------------------------------------------; LockDMARegion -- This routine processes the Lock DMA Region; service (AL = 03).;; Input: DX - flags; ES:DI - ptr to DDS; Output: if successful, CY clear; else CY set and AL = error code; DDS updated
assume ds:DGROUP,es:NOTHING,ss:NOTHING
LockDMARegion proc near
; Since we don't support paging or anything interesting like that, the only; thing that can fail us is an alignment problem--check for that.
test dl,Align64k or Align128k ;if they don't care, jz lock_ok ; we don't care
mov si,dx ;save flags in SI
call CalcDDSPhyAddress ;see where the region is
push dx ;save start address push ax
mov bx,dx ;bx = hi word start addr
add ax,word ptr es:[di].DDS_RegionSize ;see where it ends adc dx,word ptr es:[di].DDS_RegionSize+2
sub ax,1 ;less 1 to point at sbb dx,0 ; last byte, not next
mov cx,dx ;cx = hi word end addr
test si,Align128k ;64k or 128k alignment wanted? jz @f ; already setup for 64k and bl,not 1 ;mask to 128k alignment and cl,not 1@@: cmp bx,cx ;within the boundry? jz lock_ok_clr_stk ; yes, 'lock' it
; The region crosses an alignment boundary, we need to update the allowed; region size in the DDS, and fail the call.
pop cx pop dx ;dx:cx = region start address
neg cx ;cx = len to next 64k boundry xor bx,bx test si,Align128k jz @f mov bl,dl and bl,1 xor bl,1 ;bx:cx = len to next alignment boundry@@: mov word ptr es:[di].DDS_RegionSize,cx ;update size in DDS mov word ptr es:[di].DDS_RegionSize+2,bx
mov byte ptr [bp].intUserAX,ErrRegionCrossedBoundry ;flag failure stc ret
lock_ok_clr_stk:
add sp,4 ;clear start address from stack
; No alignment problem, we can 'lock' the region.
lock_ok:
call CalcDDSPhyAddress ;get physical address of region DX:AX mov word ptr es:[di].DDS_PhyAddress,ax mov word ptr es:[di].DDS_PhyAddress+2,dx
xor ax,ax ;*** also clears CY! *** mov es:[di].DDS_BufferID,ax ;no buffer used
ret
LockDMARegion endp
; -------------------------------------------------------; ScatterGatterLock -- This routine implements the Scatter/Gather; Lock Region DMA service (AL = 05h).;; Input: DX - flags; ES:DI - ptr to extended DDS; Output: if successful, CY clear; else CY set & AL = error code; DDS updated
assume ds:DGROUP,es:NOTHING,ss:NOTHING
ScatterGatherLock proc near
test dl,PageTableFmt ;Scatter/Gather page table form? jnz do_page_tbl_lock
; This is the region form of Scatter/Gather Lock Region -- for us this; is easy, since memory is contiguous -- one region covers the entire area.
mov ax,1 ;we need one region entry mov es:[di].DDS_NumUsed,ax
cmp es:[di].DDS_NumAvail,ax ; is it available? jb not_enough_entries
call CalcDDSPhyAddress ;get physical address
mov word ptr es:[di].DDS_Region0Addr,ax ;store in extended DDS mov word ptr es:[di].DDS_Region0Addr+2,dx
mov ax,word ptr es:[di].DDS_RegionSize ;copy over the size mov word ptr es:[di].DDS_Region0Size,ax mov ax,word ptr es:[di].DDS_RegionSize+2 mov word ptr es:[di].DDS_Region0Size+2,ax
clc ;indicate success ret
; This is the page table form of Scatter/Gather Lock Region -- we need to; build a fake page table (even though we may be on an 80286!?) to return; in the extended DDS.
do_page_tbl_lock:
call CalcDDSPhyAddress ;get region start address
mov cx,word ptr es:[di].DDS_RegionSize ;calc # pages needed mov bx,word ptr es:[di].DDS_RegionSize+2 ; for region of this add cx,PhysicalPageSize-1 ; size adc bx,0 shr cx,PageShift shl bx,16-PageShift or cx,bx ;cx = # pages
test ax,PhysicalPageSize-1 ;if region doesn't start on a page jz @f ; boundry, add another page to inc cx ; the region size@@: mov es:[di].DDS_NumUsed,cx ;tell caller how many used/needed cmp es:[di].DDS_NumAvail,cx ;did caller supply enough page entries? jb not_enough_entries ; no!
push ax ;save low word of region start address
and ax,NOT PhysicalPageSize-1 ;round down to page boundry or al,1 ;set page present/locked bit mov bx,di ;es:bx -> page table entries
jcxz page_ents_done ;better safe than sorry@@: mov word ptr es:[bx].DDS_PageTblEnt0,ax ;build fake page mov word ptr es:[bx].DDS_PageTblEnt0+2,dx ; table entries... add ax,PhysicalPageSize adc dx,0 add bx,4 loop @b
page_ents_done:
pop ax ;recover low word of start address and ax,PhysicalPageSize-1 ; and get offset into first page mov [bp].intUserBX,ax ; return to caller in BX
clc ;indicate success ret
; Fail the request for insufficient # of region/page tbl entries
not_enough_entries:
mov byte ptr [bp].intUserAX,ErrTooManyRegions ;AL = error code
mov ax,es:[di].DDS_NumAvail ;store max lockable mov dx,ax ; size (bytes) in shl ax,PageShift ; DDS region size shr dx,16-PageShift mov word ptr es:[di].DDS_RegionSize,ax mov word ptr es:[di].DDS_RegionSize+2,dx
stc ;indicate failure ret
ScatterGatherLock endp
; ------------------------------------------------------- subttl DMA Service Utility Routines page; -------------------------------------------------------; DMA SERVICE UTILITY ROUTINES; -------------------------------------------------------
; -------------------------------------------------------; CalcDDSPhyAddress -- This routine calculates the physical; address of the region specified in a DDS.;; Input: ES:DI - ptr to DDS; Output: DX:AX - 32 bit physical address; Uses: none.
assume ds:DGROUP,es:NOTHING,ss:NOTHING
CalcDDSPhyAddress proc near
push bx xor bx,bx mov dx,bx
mov ax,es:[di.DDS_Selector] ;if a selector is given, or ax,ax ; get it's base address jz @f
call GetSegmentAddress ;bx:dx = segment base@@: add dx,word ptr es:[di.DDS_Offset] ;add 32 bit offset adc bx,word ptr es:[di.DDS_Offset+2]
mov ax,dx ;32 bit address to dx:ax mov dx,bx pop bx
ret
CalcDDSPhyAddress endp
DXPMCODE ends
;**************************************************************** end
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