CnC_Remastered_Collection/TIBERIANDAWN/IPXREAL.ASM

317 lines
13 KiB
NASM

;
; Copyright 2020 Electronic Arts Inc.
;
; TiberianDawn.DLL and RedAlert.dll and corresponding source code is free
; software: you can redistribute it and/or modify it under the terms of
; the GNU General Public License as published by the Free Software Foundation,
; either version 3 of the License, or (at your option) any later version.
; TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
; in the hope that it will be useful, but with permitted additional restrictions
; under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
; distributed with this program. You should have received a copy of the
; GNU General Public License along with permitted additional restrictions
; with this program. If not, see [https://github.com/electronicarts/CnC_Remastered_Collection]>.
;***************************************************************************
;** C O N F I D E N T I A L --- W E S T W O O D S T U D I O S **
;***************************************************************************
;* *
;* Project Name : VQLIB *
;* *
;* File Name : HANDLER.ASM *
;* *
;* Programmer : Bill Randolph *
;* *
;* Start Date : April 7, 1995 *
;* *
;* Last Update : April 7, 1995 [BRR] *
;* *
;*-------------------------------------------------------------------------*
;* Functions: *
;* IPXHandler -- callback routine for IPX *
;* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
;********************* Model & Processor Directives ************************
IDEAL
MODEL LARGE
P386N
LOCALS ??
;******************************** Includes *********************************
;******************************** Defines ***********************************
;****************************** Declarations ********************************
global C IPXHandler:FAR
;********************************* Code ************************************
CODESEG
;---------------------------------------------------------------------------
; The markers let the application verify that it's mapping this memory
; correctly.
;---------------------------------------------------------------------------
Marker1 DW 1111h ; placeholder to find data start
;---------------------------------------------------------------------------
; This is the IPX Event Control Block:
;---------------------------------------------------------------------------
ECB_LinkAddress DD ?
ECB_EventServiceRoutine DD ? ; Event Handler ptr
ECB_InUse DB ? ; 0 = event is complete
ECB_CompletionCode DB ? ; 0 = OK, IPX error otherwise
ECB_SocketNumber DW ? ; socket to listen/send on
ECB_ConnectionID DW ?
ECB_RestOfWorkspace DW ?
ECB_DriverWorkSpace DB 12 DUP (?)
ECB_ImmediateAddress DB 6 DUP (?) ; bridge address
ECB_PacketCount DW ? ; # data areas (2)
ECB_HeaderAddress DD ? ; ptr to IPX header buffer
ECB_HeaderLength DW ? ; length of IPX header buffer
ECB_PacketAddress DD ? ; ptr to packet buffer
ECB_PacketLength DW ? ; length of packet buffer
;---------------------------------------------------------------------------
; The rest of the variables are for telling IPX which buffer to store the
; next incoming packet in. They must be initialized by the application.
;---------------------------------------------------------------------------
NumBufs DW 0 ; # buffers provided by app
BufferFlags DD 0 ; array of in-use flags (1 = in use)
PacketSize DW 0 ; total size of 1 buf (incl IPX hdr)
FirstPacketBuf DD 0 ; ptr to 1st packet buffer
CurIndex DW 0 ; current packet/flag index
CurPacketBuf DD 0 ; ptr to current packet buf
FuncOffset DW StartLabel ; offset of our routine
;---------------------------------------------------------------------------
; These values are for preventing re-entrancy; they're currently not used.
;---------------------------------------------------------------------------
Semaphore DB 0 ; prevents re-entrancy
ReEntrantCount DW 0 ; times we've been called re-entrantly
;---------------------------------------------------------------------------
; Local stack space
;---------------------------------------------------------------------------
StackPtr DW 0 ; saved copy of stack ptr
StackSeg DW 0 ; saved copy of stack seg
StackPtr_int DW 0 ; our internal stack ptr
StackSeg_int DW 0 ; our internal stack seg
StackCheck DW 1234h ; check for stack overflow
DW 256 DUP (0) ; stack storage space
StackSpace DW 0 ; label for our stack space
;---------------------------------------------------------------------------
; These bytes mark the end of the real-mode data area
;---------------------------------------------------------------------------
Marker2 DW 2222h ; placeholder to find data end
;***************************************************************************
;* IPXHandler -- IPX callback routine *
;* *
;* This routine is assembled as a stand-alone executable, then loaded *
;* into low DOS memory by a protected-mode application. *
;* *
;* INPUT: *
;* none. *
;* *
;* OUTPUT: *
;* none. *
;* *
;* WARNINGS: *
;* none. *
;* *
;* HISTORY: *
;* 04/07/1995 BRR : Created. *
;*=========================================================================*
label StartLabel
PROC IPXHandler C FAR USES
;...................................................................
; Turn off interrupts; make sure memory copies go forward
;...................................................................
pushf
cli
cld
;...................................................................
; Set up segment registers to point DS to CS
;...................................................................
push ds
push ax
mov ax,cs
mov ds,ax
;...................................................................
; Set up our local stack; save SS & SP first.
;...................................................................
mov [StackSeg],ss
mov [StackPtr],sp
mov [StackPtr_int], OFFSET StackSpace
mov [StackSeg_int], SEG StackSpace
lss sp, [DWORD PTR StackPtr_int]
;...................................................................
; Save all registers
;...................................................................
pushad
push es
;...................................................................
; If we've been called re-entrantly, just exit
;...................................................................
cmp [Semaphore],0
jz ??Start_Handler
add [ReEntrantCount],1
jmp ??Exit_Handler
??Start_Handler:
;...................................................................
; Set our semaphore
;...................................................................
mov [Semaphore],1
;-------------------------------------------------------------------
; Set 'CurIndex' to the index of the next-available receive buffer,
; and 'CurPacketBuf to the next-available packet buffer
;-------------------------------------------------------------------
;...................................................................
; Get 'CurIndex' & increment it. Wrap to 0 if we reach 'NumBufs'
; Since I'm treating 'CurPacketBuf' as a long integer (and not as
; a segment:offset), the entire data area can't be larger than 64K.
;...................................................................
mov dx,[CurIndex] ; DX = CurIndex
mov eax,[CurPacketBuf] ; EAX = current packet buffer addr
inc dx ; DX = next index
add ax,[PacketSize] ; EAX = next buffer ptr
cmp dx,[NumBufs] ; see if DX is past # buffers
jb ??Get_Flag
mov dx,0 ; wrap to 1st index
mov eax,[FirstPacketBuf] ; wrap to 1st packet buffer
??Get_Flag:
;...................................................................
; Get the next buffer-in-use flag; if it's 0, load [CurIndex] with
; the value of SI (the next index). If it's 1, skip the updating of
; the index, flag & buffer ptr.
; DX = new CurIndex
; EAX = new CurPacketBuf
;...................................................................
les di,[BufferFlags] ; ES:DI = BufferFlags address
mov bx,di ; BX = DI + new CurIndex
add bx,dx
cmp [BYTE PTR es:bx],0 ; compare next flag to 0 (avail)
jne ??Set_ECB ; if not avail, skip setting new values
;...................................................................
; The next buffer is available; so, set this buffer's In-Use flag
; to 1, and move on to the next buffer. Do not set this buffer's
; flag to 1 until we move on to the next buffer, to prevent the
; application from reading the currently-in-use packet buffer.
; DX = new CurIndex
; EAX = new CurPacketBuf
; ES:DI = BufferFlags address
;...................................................................
mov bx,di ; BX = DI + old CurIndex
add bx,[CurIndex]
mov [BYTE PTR es:bx],1 ; set old BufferFlags value to in-use
mov [CurIndex],dx ; save new index
mov [CurPacketBuf],eax ; save new packet address
;-------------------------------------------------------------------
; Set up the Event Control Block to tell IPX to start listening.
; The following entries are filled in by the app, and should be left
; alone:
; - EventServiceRoutine
; - SocketNumber
; The rest should be re-initialized. Note that EBX is now pointing
; to an unavailable buffer if the next buffer was already in use;
; so it must be reloaded with the correct buffer address from
; [CurPacketBuf].
;-------------------------------------------------------------------
??Set_ECB:
mov [ECB_LinkAddress],0 ; default
mov [ECB_InUse],0 ; default
mov [ECB_CompletionCode],0 ; default
mov [ECB_ConnectionID],0 ; default
mov [ECB_RestOfWorkspace],0 ; default
mov [ECB_DriverWorkSpace],0 ; default
mov [ECB_ImmediateAddress],0 ; default
mov [ECB_PacketCount],2 ; use 2 data areas
mov ebx,[CurPacketBuf] ; get current buffer address
mov [ECB_HeaderAddress],ebx ; set header address
mov [ECB_HeaderLength],30 ; size of IPX header
add ebx,30 ; point to past the header
mov [ECB_PacketAddress],ebx ; set packet data address
mov ax,[PacketSize] ; get size of one buffer
sub ax,30 ; remove size of IPX header
mov [ECB_PacketLength],ax ; set size of packet data
;-------------------------------------------------------------------
; Clear the IPX header for this packet
;-------------------------------------------------------------------
les di,[ECB_HeaderAddress] ; ES:DI = IPX Listen Header
mov cx,30 ; (30 bytes = size of header)
mov al,0
rep stosb ; clear to 0's
;-------------------------------------------------------------------
; Command IPX to start listening again.
;-------------------------------------------------------------------
mov bx,4 ; IPX code for Listen
mov ax,ds ; ES = segment of ListenECB
mov es,ax
mov ax,OFFSET ECB_LinkAddress
mov si,ax ; ES:SI = address of ECB
int 07ah ; call IPX interrupt
;...................................................................
; Clear our semaphore
;...................................................................
mov [Semaphore],0
??Exit_Handler:
;...................................................................
; Pop values from our local stack
;...................................................................
pop es
popad
;...................................................................
; Check our stack-check value; if the stack has overflowed, generate
; a debugger break.
;...................................................................
cmp [StackCheck],1234h
je ??Restore_Stack
int 3
;...................................................................
; Restore the stack to its previous value
;...................................................................
??Restore_Stack:
lss sp, [DWORD PTR StackPtr]
;...................................................................
; Pop the rest of the registers
;...................................................................
pop ax
pop ds
popf
ret
ENDP IPXHandler
END
;************************** End of handler.asm *****************************