Cobra Utilities for Doom & Doom II

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Wrap

Assembly Source File | 1994-05-02 | 26.9 KB | 711 lines

;**************************************************************************; ;* S W A P A . A S M *; ;*------------------------------------------------------------------------*; ;* Task : Assembler module for the SWAP unit *; ;*------------------------------------------------------------------------*; ;* Author : MICHAEL TISCHER *; ;* developed on : 06/01/1989 *; ;* last update : 02/28/1990 *; ;*------------------------------------------------------------------------*; ;* assembly : TASM - /MX SWAPA *; ;* ... bind to the SWAP unit *; ;**************************************************************************; ;== Constants =============================================================== STACK_LEN equ 64 ;Number of words in the internal stack ;== Structures ============================================================= ExecStruc struc ;Data structure for EXEC function EsSegEnv dw ? ;Segment address of environment blocks EsCmdPAdr dd ? ;Pointer to command line parameters EsFCB1Adr dd ? ;Pointer to FCB #1 EsFCB2Adr dd ? ;Pointer to FCB #2 ExecStruc ends public SwapOutAndExec ;Gives a Turbo Pascal program the ;ability to pass the address of ;the assembler handler public InitSwapa ;Initialization procedure ;== Data segment =========================================================== DATA segment word public extrn PrefixSeg : word ;Segment address of PSP in Turbo variables DATA ends ;== Program =============================================================== CODE segment byte public ;Program segment ;== Variables in code segment =============================================== CodeStart equ this word ;Code begins here which is copied to ;the Turbo program ;-- Variables needed by the Swap routines for uploading and downloading ---- CoStAddr dd ? ;Orig. address of PARA(CodeStart) CoStLen dw ? ;Number of words swapped w/ CoStAddr StackPtr dw ? ;Gets old stack pointer StackSeg dw ? ;Gets old stack segment TurboSeg dw ? ;Segment address - Turbo code segment ;-- Variables needed for program configuration and command execution ------- NewStack dw STACK_LEN dup (?) ;New stack EndStack equ this word ;End of stack Command dd ? ;Pointer to command CmdPara dd ? ;Pointer to command line parameters ToDisk db ? ;True when disk swapping occurs Handle dw ? ;Disk or EMS handle Len dd ? ;Number of bytes saved FCB1 db 16 dup ( 0 ) ;FCB #1 for PSP FCB2 db 16 dup ( 0 ) ;FCB #2 for PSP CmdBuf db 128 dup ( 0 ) ;Commands following prg. name PrgName db 64 dup ( 0 ) ;Program name ExecData ExecStruc < 0, CmdBuf, FCB1, FCB2 > ;Data structure for EXEC OldPara dw ? ;Number of previously reserved paragraphs FrameSeg dw ? ;Segment address of EMS page frame Error_Code db 0 ;Error code for caller TerMes db 13,10,13,10 db "╔═══════════════════════════════════════════════════╗",13,10 db "║ Done_Swap: Stored Turbo Pascal program could ║",13,10 db "║ not be reloaded back into memory. ║",13,10 db "║ Program execution terminated! ║",13,10 db "╚═══════════════════════════════════════════════════╝" db 13,10,13,10,"$" Msg1 db 13,10,13,10 db "╔════════════════════════════╗",13,10 db "║ Init_Swap: Swapping out ║",13,10 db "╚════════════════════════════╝" db 13,10,13,10,"$" ;== Procedures ============================================================= ;--------------------------------------------------------------------------- ;-- StartSwap : Coordinate swapping of Turbo Pascal program StartSwap proc far assume cs:code, ds:nothing ;-- Store current stack and initialize new stack ---------------- cli ;Suppress interrupts mov StackPtr,sp ;Mark current stack mov StackSeg,ss push cs ;Install new stack pop ss mov sp,offset EndStack - 2 sti ;Re-enable interrupts push cs ;Set DS to CS pop ds assume cs:code, ds:code ;-- Overwrite unnecessary memory -------------------------------- cmp ToDisk,0 ;Write to EMS memory? je Ems ;Yes ---> Ems call Write2File ;No ---> Write to file jnc ShrinkMem ;No error ---> ShrinkMem mov Error_Code, 1 ;File output error? jmp short GetBack ;return to Turbo Ems: mov ah,41h ;Pass segment address of the page frame int 67h ;Call EMM mov FrameSeg,bx ;Place result in variables call Write2Ems ;Write program to EMS ;-- Provide number of currently allocated paragraphs ------------ ShrinkMem: mov ax,TurboSeg ;Segment address of Turbo code segment sub ax,11h ;Allocate 10 paragraphs for PSP and 1 ;for MCB mov es,ax ;ES now pointer to Turbo prog. MCB mov bx,es:[3] ;Get number of paragraphs allocated mov OldPara,bx ;and place in variable ;-- Calculate the number of paragraphs needed and reduce -- ;-- memory requirements by this amount -- inc ax ;AX now points to the PSP mov es,ax ;for function call to ES mov bx,CostLen ;Number of words needed by Swap routine add bx,128+7 ;Recalculate and round off PSP mov cl,3 ;Divide by 8 words (per paragraph) shr bx,cl mov ah,4Ah ;Function number for "change size" int 21h ;Call DOS interrupt ;-- Execute specified command line using the EXE function ------ mov bp,ds ;Store DS mov ax,cs ;Set ES and DS to CS mov es,ax mov ds,ax ;-- Enter segment address of code segments in the pointer ----- ;-- to the EXEC structure mov word ptr ExecData.EsFCB1Adr + 2,ax mov word ptr ExecData.EsFCB1Adr + 2,ax mov word ptr ExecData.EsCmdPAdr + 2,ax mov bx,offset ExecData ;ES:BX point to parameter block mov dx,offset PrgName ;DS:DX point to command string mov ax,4B00h ;Function number for "EXEC" int 21h ;Call DOS interrupt mov ds,bp ;Move DS jnc ReMem ;No error ---> ReMem mov Error_Code,ah ;Note ErrorCode ;-- Return memory to original size ------------------------------ ReMem: mov ax,TurboSeg ;Set Turbo code segment address sub ax,10h ;to start of PSP mov es,ax ;and load into ES mov bx,OldPara ;Old number of paragraphs mov ah,4Ah ;Function number for "change size" int 21h ;Call DOS interrupt jnc GetBack ;No error ---> GetBack jmp Terminate ;Error in ReMem --> End program ;-- Return to program ------------------------------------------- GetBack: cmp ToDisk,0 ;Write to EMS memory? je Ems1 ;Yes ---> Ems1 call GetFromFile ;No, reload as file jnc CloseUp ;No error ---> CloseUp jmp Terminate ;Read error, end program Ems1: call GetFromEms ;Get Turbp Pascal program from EMS memory ;-- Restore old stack ------------------------------------------- CloseUp: cli ;Suppress interrupts mov ss,StackSeg mov sp,StackPtr sti ;Re-enable interrupts ;-- Prepare registers for swap ---------------------------------- push cs ;Push DS to CS pop ds assume cs:code, ds:code mov cx,CoStLen ;Number of words to be swapped mov di,cx ;Move number of words to DI dec di ;Decrement by one word shl di,1 ;Double it mov si,di ;move to SI add di,word ptr CostAddr ;DI+offset addr. of Swap routine mov es,word ptr CostAddr + 2 ;ES gets old CS of Swap routine mov ds,TurboSeg ;Seg addr. of start of code ret ;Return to SwapOutAndExec StartSwap endp ;--------------------------------------------------------------------------- ;-- Write2Ems : Write program to be swapped to EMS memory ;-- Input : BX = Segment address of EMS page frame ;-- DS = Codesegment EMS_PLEN equ 16384 ;Length of an EMS page HiWLen dw ? ;Remaining Hi-Word length Write2Ems proc near push ds ;Push DS onto stack cld ;Increment on string instructions mov es,bx ;ES points to the page frame mov bp,word ptr Len ;Move Lo-Word length to BP mov ax,word ptr Len + 2 ;Move Hi-Word length to AX mov HiWLen,ax ;and then to variable mov dx,Handle ;Move EMS Handle to DX xor bx,bx ;Start with first logical page assume cs:code, ds:nothing jmp short WriECalc ;Jump in the loop WriELoop: ;-- Register allocation within this loop ----------------------- ; ; AX = Times this, times that ; BX = Number of logical EMS pages to be addressed ; CX = Number of bytes to be copied in this execution ; DX = EMS handle ; ES:DI = Pointer to first page in EMS page frame (Target) ; DS:SI = Pointer to first word to be copied (Start) ; HiWLen:BP = Number of bytes remaining to be copied mov ax,4400h ;Function number for illustration int 67h ;Call EMM mov si,offset CodeEnd ;Offset for Swapping xor di,di ;Write to the start of the EMS page mov ax,cx ;Move number to AX rep movsb ;Copy memory sub bp,ax ;Remainder of written bytes sbb HiWLen,0 ;Decrement inc bx ;Increment number of logical page mov ax,ds ;Starting segment to AX add ax,EMS_PLEN shr 4 ;Increment by written paragraphs mov ds,ax ;and move to DS WriECalc: mov cx,EMS_PLEN ;Write EMS_PLEN bytes cmp HiWLen,0 ;More than 64K? ja WriELoop ;Yes ---> WriELoop cmp bp,cx ;No ---> More than EMS_PLEN bytes? jae WriELoop ;Yes ---> Continue writing mov cx,bp ;No ---> Write remainder or cx,cx ;No more bytes to write? jne WriELoop ;No ---> WriELoop WriERet: pop ds ;Pop DS off of stack ret ;Return to caller Write2Ems endp ;--------------------------------------------------------------------------- ;-- GetFromEms : Get the swapped program from EMS memory ;-- Input : DS = Code segment GetFromEms proc near push ds ;Push DS onto the stack cld ;Increment on string instructions mov bp,word ptr Len ;Move Lo-Word length to BP mov ax,word ptr Len + 2 ;Move Hi-Word length to AX mov HiWLen,ax ;and from there to variable mov dx,Handle ;Move EMS handle to DX xor bx,bx ;Start with first logical page mov ds,FrameSeg ;DS points to the page frame push cs ;Set ES to the code segment pop es assume cs:code, ds:nothing jmp short GetECalc ;Jump to the loop GetELoop: ;-- Register allocation within this loop ----------------------- ; ; AX = times this, times that ; BX = Number of logical EMS pages to be swapped ; CX = Number of bytes to be copied in this execution ; DX = EMS handle ; DS:SI = Pointer to first page in EMS page frame (Start) ; ES:DI = Pointer to target address in memory ; HiWLen:BP = Number of bytes still to be copied mov ax,4400h ;Function number for illustration int 67h ;Call EMM mov di,offset CodeEnd ;Offset for Swapping xor si,si ;Write to the start of the EMS page mov ax,cx ;Move number to AX rep movsb ;Copy memory sub bp,ax ;Remainder of written bytes sbb HiWLen,0 ;Decrement inc bx ;Increment number of logical page mov ax,es ;Move starting segment to AX add ax,EMS_PLEN shr 4 ;Increment by written paragraphs mov es,ax ;and move it to ES GetECalc: mov cx,EMS_PLEN ;Write EMS_PLEN bytes cmp HiWLen,0 ;More than 64K? ja GetELoop ;Yes ---> GetELoop cmp bp,cx ;No ---> More than EMS_PLEN bytes? jae GetELoop ;Yes ---> Continue writing mov cx,bp ;No ---> Write remainder or cx,cx ;No more bytes to write? jne GetELoop ;No ---> GetELoop GetERet: pop ds ;Pop DS off of stack ret ;Return to caller GetFromEms endp ;--------------------------------------------------------------------------- ;-- Write2File : Write the program to be swapped to a file ;-- Returns : Carry-Flag = 1 : Error Write2File proc near NUM_WRITE = 2048 ;Bytes to be written per execution ;to power of 2 (max. 2^16) assume cs:code, ds:code push ds ;Push DS onto stack mov bp,4000h ;Function number for "Write" mov bx,Handle ;Load file handle WriFStart: mov di,word ptr Len ;Move Lo-Word length to DI mov si,word ptr Len + 2 ;Move Hi-Word length to SI mov dx,offset CodeEnd ;Write offset address jmp short WriFCalc ;Compute no. of bytes to be written WriFLoop: ;-- Register allocation within this loop ----------------- ; ; AX = times this, times that ; BX = DOS file handle ; CX = Number of bytes to be read/written ; DS:DX = Address at which they should be read/written ; DI:SI = Number of bytes still to be copied ; BP = Number of DOS funtion to be called mov ax,bp ;Load DOS function number int 21h ;Call DOS interrupt jc WriFEnd ;Error ---> WriFEnd mov ax,ds ;Starting segment to AX add ax,NUM_WRITE shr 4 ;Increment by written paragraphs mov ds,ax ;and move to DS sub di,cx ;Decrement remainder of sbb si,0 ;written bytes WriFCalc: mov cx,NUM_WRITE ;Write NUM_WRITE bytes cmp si,0 ;More than 64K? ja WriFLoop ;Yes ---> WriFLoop cmp di,cx ;No ---> More than NUM_WRITE bytes? jae WriFLoop ;Yes ---> Continue writing mov cx,di ;No ---> Write remainder or cx,cx ;No more bytes to write? jne WriFLoop ;No ---> WriFLoop WriFEnd: pop ds ;Reload DS WriFRet: ret ;Return to caller Write2File endp ;--------------------------------------------------------------------------- ;-- GetFromFile : Return the swapped program to memory ;-- Returns : Carry-Flag = 1 : Error GetFromFile proc near assume cs:code, ds:code push ds ;Push DS onto the stack ;-- Move file pointer to the start of file ---------------- mov ax,4200h ;DOS function number mov bx,Handle ;Load file handle xor cx,cx ;CX:DX gives its position mov dx,cx int 21h ;Call DOS interrupt jc WriFRet ;Error ---> WriFRet ;-- Load file into memory with the help of Write2File ----- mov bp,3F00h ;Function number for "Read" jmp WriFStart ;Jump to Write2File GetFromFile endp ;--------------------------------------------------------------------------- ;-- Terminate : The system can't return to the original Turbo Pascal ;-- program. The program ends with an error code. Terminate label near ;-- Display error message --------------------------------------- push cs ;Set DS to CS pop ds mov dx,offset TerMes ;DS:DX points to the error message mov ah,9 ;Function number for "Display string" int 21h ;Display DOS interrupt mov ax,4C01h ;End program with error code int 21h ;=========================================================================== CodeEnd equ this byte ;Copy code from the start of the Turbo ;Pascal program to this point ;--------------------------------------------------------------------------- ;-- SwapOutAndExec : Swaps the current program to EMS memory or hard disk ;-- and starts another program using the DOS EXEC function ;-- Call from Turbo: SwapOutAndExec( Command, ;-- CmdPara : string; ;-- ToDisk : boolean; ;-- Handle : word; ;-- Len : longint ); ;-- Info : The Command and CmdPara parameters must be configured ;-- as strings in DOS format. SwapOutAndExec proc near ACommand equ dword ptr [bp+16] ;Constants for accessing the ACmdPara equ dword ptr [bp+12] ;specified arguments AToDisk equ byte ptr [bp+10] AHandle equ word ptr [bp+ 8] ALen equ dword ptr [bp+ 4] ARG_LEN equ 16 ;Lengths of arguments assume cs:code, ds:data push bp ;Enable access to the arguments mov bp,sp ;-- Copy program name to buffer in code segment ----------------- push ds push ax push dx push cs pop ds mov ah,9 mov dx,offset Msg1 int 21h pop dx pop ax pop ds mov dx,ds ;Mark DS push cs ;Set ES to CS pop es lds si,ACommand ;DS:SI points to command buffer mov di,offset PrgName ;ES:DI points to PrgName cld ;Increment on string instructions lodsb ;Read length of Pascal string cmp al,64 ;More than 64 characters? jbe CmdCopy ;No ---> CmdCopy mov al,64 ;Yes ---> Copy a maximum of 64 characters CmdCopy: xor ah,ah ;Set Hi-Byte to 0 length and mov cx,ax ;load into the counter rep movsb ;Copy string ;-- Copy command line in buffer in code segment ----------------- lds si,ACmdPara ;DS:SI points to CmdPara buffer mov di,offset CmdBuf ;ES:DI points to CmdBuf lodsb ;Read length of Pascal string cmp al,126 ;More than 126 characters? jbe ParaCopy ;No ---> ParaCopy mov al,126 ;Yes ---> Copy maximum of 126 characters ParaCopy: stosb ;Store length as first byte xor ah,ah ;Set Hi-Byte to 0 length and mov cx,ax ;load into the counter rep movsb ;Copy string mov al,0dH ;Add carriage return stosb ;-- Transfer filename from command line to FCBs ----------------- push cs ;Transfer CS to DS pop ds mov si,offset CmdBuf+1 ;DS:SI points to CmdBuf + 1 mov di,offset FCB1 ;ES:DI points to FCB #1 mov ax,2901h ;Function no.:"Transfer filename to FCB" int 21h ;Call DOS interrupt mov di,offset FCB2 ;ES:DI now points to FCB #2 mov ax,2901h ;Function no.: "Transfer filename to FCB" int 21h ;Call DOS interrupt mov ds,dx ;Move old value into DS ;-- Transfer remaining parameters to variables ------------------ les ax,ALen ;Change length mov word ptr Len + 2,es mov word ptr Len,ax mov al,AToDisk ;Change disk flag mov ToDisk,al mov ax,AHandle ;Change handle mov Handle,ax push ds ;Push DS onto the stack ;-- Exchange variables and program code between labels CodeStart - ;-- and CodeEnd with the contents of the PSP code segment mov ax,PrefixSeg ;ES:DI points to start of Turbo add ax,10h ;program following PSP mov TurboSeg,ax ;Mark addr. of Turbo code segment mov es,ax xor di,di push cs ;Set DS to CS pop ds assume cs:code, ds:code mov si,offset CodeStart ;DS:SI points to CodeStart and si,0FFF0h ;Round off at start of paragraph mov cx,CostLen ;Get number of words to be swapped mov word ptr CoStAddr,si ;Mark address of mov word ptr CoStAddr + 2,ds ;PARA(Codestart) mov dx,es ;Mark target segment in DX cld ;Increment on SI/DI string instructions ;-- Swap loop --------------------------------------------------- dl_loop: mov ax,[si] ;Load word from assembler module mov bx,es:[di] ;Load word from Turbo Pascal program stosw ;Write assm. module word to Turbo program mov [si],bx ;Write Turbo program word to assm. module inc si ;Set SI to next word inc si ;(increment SI through STOSW) loop dl_loop ;Use all words ;-- Adapt segment address of code segment before calling the --- ;-- StartSwap procedure so that variable references to the code ;-- segment remain unchanged mov ax,offset CodeStart ;Compute number of paragraphs between mov cl,4 ;CodeStart and the start of the shr ax,cl ;segment, and get segment address in sub dx,ax ;DX push cs ;Return address to BACK label mov ax,offset back ;Move onto the stack push ax push dx ;Push segment address onto stack mov ax,offset StartSwap ;Move offset address onto stack push ax retf ;FAR-RET to StartSwap Msg2 db 13,10,13,10 db "╔════════════════════════════╗",13,10 db "║ Done_Swap: Swapping in ║",13,10 db "╚════════════════════════════╝" db 13,10,13,10,"$" back: ;---------------------------------------------------------------- ;-- Returns original program to main memory and executes the ;-- program. ;-- Registers have the following contents: ;-- DS:SI = End of assembler code following the PSP ;-- ES:DI = End of Turbo code in the SWAP unit ;-- CX = Number of words ;---------------------------------------------------------------- assume cs:code, ds:nothing std ;Decrement string instructions by SI/DI ;-- Swap back loop ---------------------------------------------- push ds push ax push dx push cs pop ds mov ah,9 mov dx,offset Msg2 int 21h pop dx pop ax pop ds ul_loop: mov bx,es:[di] ;Get byte from old memory range mov ax,[si] ;Get byte from current memory range mov [si],bx ;Byte from old memory rng to current rng dec si ;Set SI to previous word dec si stosw ;Byte from current memory rng to old rng loop ul_loop ;Repeat until memory ranges are exchanged pop ds ;Pop DS off of stack assume ds:data pop bp ;Pop BP ;-- MOV SP,BP must not be given, since SP doesn't change xor ah,ah ;Place error code in AX mov al,Error_Code ret ARG_LEN ;Return to caller, clear arguments ;from stack SwapOutAndExec endp ;--------------------------------------------------------------------------- ;-- InitSwapa : Computes the number of bytes/words allocated for a program ;-- swap with the start of the Turbo program in memory ;-- Input : none ;-- Output : number of bytes ;-- Pascal call : function InitSWapa : word; ;-- Info : This procedure must be called before the ;-- first call to SwapOutAndExec! InitSwapa proc near assume cs:code, ds:data mov bx,offset CodeStart ;AX points to start of code and bx,0FFF0h ;Round off at start of paragraph mov ax,offset CodeEnd ;BX points to end of code sub ax,bx ;Compute number of bytes inc ax ;Convert CX to words shr ax,1 mov CoStLen,ax ;Mark number of words to be swapped shl ax,1 ;Convert to bytes ;-- Return contents of AX as function result ret ;Return to caller InitSwapa endp ;--------------------------------------------------------------------------- CODE ends ;End of code segment end ;End of program