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Assembly Source File | 1998-01-14 | 19.6 KB | 437 lines

.model large ;EXECSWAP.ASM ; Swap memory and exec another program ; Copyright (c) 1988 TurboPower Software ; May be used freely as long as due credit is given ;----------------------------------------------------------------------------- ;DATA SEGMENT BYTE PUBLIC .data EXTRN _BytesSwapped:DWORD ;Bytes to swap to EMS/disk EXTRN _EmsAllocated:BYTE ;True when EMS allocated for swap EXTRN _FileAllocated:BYTE ;True when file allocated for swap EXTRN _EmsHandle:WORD ;Handle of EMS allocation block EXTRN _FrameSeg:WORD ;Segment of EMS page frame EXTRN _FileHandle:WORD ;Handle of DOS swap file EXTRN _SwapName:BYTE ;ASCIIZ name of swap file EXTRN _PrefixSeg:WORD ;Base segment of program ;DATA ENDS ;----------------------------------------------------------------------------- ;CODE SEGMENT BYTE PUBLIC .code ; ASSUME CS:CODE,DS:DATA PUBLIC EXECWITHSWAP, _FIRSTTOSAVE PUBLIC ALLOCATESWAPFILE, DEALLOCATESWAPFILE PUBLIC EMSINSTALLED, EMSPAGEFRAME PUBLIC ALLOCATEEMSPAGES, DEALLOCATEEMSHANDLE ;----------------------------------------------------------------------------- FileAttr EQU 0 ;Swap file attribute (hidden+system) EmsPageSize EQU 16384 ;Size of EMS page FileBlockSize EQU 32768 ;Size of a file block StkSize EQU 128 ;Bytes in temporary stack lo EQU (WORD PTR 0) ;Convenient typecasts hi EQU (WORD PTR 2) ofst EQU (WORD PTR 0) segm EQU (WORD PTR 2) ;----------------------------------------------------------------------------- ;Variables in CS EmsDevice DB 'EMMXXXX0',0 ;Name of EMS device driver UsedEms DB 0 ;1 if swapping to EMS, 0 if to file BytesSwappedCS DD 0 ;Bytes to move during a swap EmsHandleCS DW 0 ;EMS handle FrameSegCS DW 0 ;Segment of EMS page window FileHandleCS DW 0 ;DOS file handle PrefixSegCS DW 0 ;Segment of base of program Status DW 0 ;ExecSwap status code LeftToSwap DD 0 ;Bytes left to move SaveSP DW 0 ;Original stack pointer SaveSS DW 0 ;Original stack segment PathPtr DD 0 ;Pointer to program to execute CmdPtr DD 0 ;Pointer to command line to execute ParasWeHave DW 0 ;Paragraphs allocated to process CmdLine DB 128 DUP(0) ;Terminated command line passed to DOS Path DB 64 DUP(0) ;Terminated path name passed to DOS FileBlock1 DB 16 DUP(0) ;FCB passed to DOS FileBlock2 DB 16 DUP(0) ;FCB passed to DOS BooBoo DB '$' ComeBack DB '$' EnvironSeg DW 0 ;Segment of environment for child CmdLinePtr DD 0 ;Pointer to terminated command line FilePtr1 DD 0 ;Pointer to FCB file FilePtr2 DD 0 ;Pointer to FCB file TempStack DB StkSize DUP(0) ;Temporary stack StackTop LABEL WORD ;Initial top of stack ;----------------------------------------------------------------------------- ;Macros MovSeg MACRO Dest,Src ;Set one segment register to another PUSH Src POP Dest ENDM MovMem MACRO Dest,Src ;Move from memory to memory via AX MOV AX,Src MOV Dest,AX ENDM InitSwapCount MACRO ;Initialize counter for bytes to swap MovMem LeftToSwap.lo,BytesSwappedCS.lo MovMem LeftToSwap.hi,BytesSwappedCS.hi ENDM SetSwapCount MACRO BlkSize ;Return CX = bytes to move this block LOCAL FullBlk ;...and reduce total bytes left to move MOV CX,BlkSize ;Assume we'll write a full block CMP LeftToSwap.hi,0 ;Is high word still non-zero? JNZ FullBlk ;Jump if so CMP LeftToSwap.lo,BlkSize ;Low word still a block or more? JAE FullBlk ;Jump if so MOV CX,LeftToSwap.lo ;Otherwise, move what's left FullBlk:SUB LeftToSwap.lo,CX ;Reduce number left to move SBB LeftToSwap.hi,0 ENDM NextBlock MACRO SegReg, BlkSize ;Point SegReg to next block to move MOV AX,SegReg ADD AX,BlkSize/16 ;Add paragraphs to next segment MOV SegReg,AX ;Next block to move MOV AX,LeftToSwap.lo OR AX,LeftToSwap.hi ;Bytes left to move? ENDM EmsCall MACRO FuncAH ;Call EMM and prepare to check result MOV AH,FuncAH ;Set up function INT 67h OR AH,AH ;Error code in AH ENDM DosCallAH MACRO FuncAH ;Call DOS subfunction AH MOV AH,FuncAH INT 21h ENDM DosCallAX MACRO FuncAX ;Call DOS subfunction AX MOV AX,FuncAX INT 21h ENDM InitSwapFile MACRO MOV BX,FileHandleCS ;BX = handle of swap file XOR CX,CX XOR DX,DX ;Start of file DosCallAX 4200h ;DOS file seek ENDM HaltWithError MACRO Level ;Halt if non-recoverable error occurs PUSH CS POP DS MOV DX,OFFSET BooBoo MOV AH,9 INT 21h MOV AL,Level ;Set errorlevel DosCallAH 4Ch ENDM MoveFast MACRO ;Move CX bytes from DS:SI to ES:DI CLD ;Forward RCR CX,1 ;Convert to words REP MOVSW ;Move the words RCL CX,1 ;Get the odd byte, if any REP MOVSB ;Move it ENDM SetTempStack MACRO ;Switch to temporary stack MOV AX,OFFSET StackTop ;Point to top of stack MOV BX,CS ;Temporary stack in this code segment CLI ;Interrupts off MOV SS,BX ;Change stack MOV SP,AX STI ;Interrupts on ENDM ;----------------------------------------------------------------------------- ;function ExecWithSwap(Path, CmdLine : string) : Word; EXECWITHSWAP PROC FAR PUSH BP MOV BP,SP ;Set up stack frame ;Move variables to CS where we can easily access them later MOV Status,1 ;Assume failure LES DI,[BP+6] ;ES:DI -> CmdLine MOV CmdPtr.ofst,DI MOV CmdPtr.segm,ES ;CmdPtr -> command line string LES DI,[BP+10] ;ES:DI -> Path MOV PathPtr.ofst,DI MOV PathPtr.segm,ES ;PathPtr -> path to execute MOV SaveSP,SP ;Save stack position MOV SaveSS,SS MovMem BytesSwappedCS.lo,_BytesSwapped.lo MovMem BytesSwappedCS.hi,_BytesSwapped.hi MovMem EmsHandleCS,_EmsHandle MovMem FrameSegCS,_FrameSeg MovMem FileHandleCS,_FileHandle MovMem PrefixSegCS,_PrefixSeg InitSwapCount ;Initialize bytes LeftToSwap ;Check for swapping to EMS or file CMP _EmsAllocated,0 ;Check flag for EMS method JZ NotEms ;Jump if EMS not used JMP WriteE ;Swap to EMS NotEms: CMP _FileAllocated,0 ;Check flag for swap file method JNZ WriteF ;Swap to file JMP ESDone ;Exit if no swapping method set ;Write to swap file WriteF: MovSeg DS,CS ;DS = CS InitSwapFile ;Seek to start of swap file JNC EF0 ;Jump if success JMP ESDone ;Exit if error EF0: SetSwapCount FileBlockSize ;CX = bytes to write MOV DX,OFFSET _FIRSTTOSAVE ;DS:DX -> start of region to save DosCallAH 40h ;File write JC EF1 ;Jump if write error CMP AX,CX ;All bytes written? JZ EF2 ;Jump if so EF1: JMP ESDone ;Exit if error EF2: NextBlock DS,FileBlockSize ;Point DS to next block to write JNZ EF0 ;Loop if bytes left to write MOV UsedEms,0 ;Flag we used swap file for swapping JMP SwapDone ;Done swapping out ;Write to EMS WriteE: MOV ES,_FrameSeg ;ES -> page window MOV DX,_EmsHandle ;DX = handle of our EMS block XOR BX,BX ;BX = initial logical page MovSeg DS,CS ;DS = CS EE0: XOR AL,AL ;Physical page 0 EmsCall 44h ;Map physical page JZ EE1 ;Jump if success JMP ESDone ;Exit if error EE1: SetSwapCount EmsPageSize ;CX = Bytes to move XOR DI,DI ;ES:DI -> base of EMS page MOV SI,OFFSET _FIRSTTOSAVE ;DS:SI -> region to save MoveFast ;Move CX bytes from DS:SI to ES:DI INC BX ;Next logical page NextBlock DS,EmsPageSize ;Point DS to next page to move JNZ EE0 ;Loop if bytes left to move MOV UsedEms,1 ;Flag we used EMS for swapping ;Shrink memory allocated to this process SwapDone:MOV AX,PrefixSegCS MOV ES,AX ;ES = segment of our memory block DEC AX MOV DS,AX ;DS = segment of memory control block MOV CX,DS:[0003h] ;CX = current paragraphs owned MOV ParasWeHave,CX ;Save current paragraphs owned SetTempStack ;Switch to temporary stack MOV AX,OFFSET _FIRSTTOSAVE+15 MOV CL,4 SHR AX,CL ;Convert offset to paragraphs ADD BX,AX SUB BX,PrefixSegCS ;BX = new paragraphs to keep DosCallAH 4Ah ;SetBlock JNC EX0 ;Jump if successful JMP EX5 ;Swap back and exit ;Set up parameters and call DOS Exec EX0: MOV AX,ES:[002Ch] ;Get environment segment MOV EnvironSeg,AX MovSeg ES,CS ;ES = CS LDS SI,PathPtr ;DS:SI -> path to execute MOV DI,OFFSET Path ;ES:DI -> local ASCIIZ copy CLD ; LODSB ;Read current length ; CMP AL,63 ;Truncate if exceeds space set aside ; JB EX1 ; MOV AL,63 ;EX1: MOV CL,AL ; XOR CH,CH ;CX = bytes to copy MOV CX, 63 REP MOVSB ; XOR AL,AL ; STOSB ;ASCIIZ terminate LDS SI,CmdPtr ;DS:SI -> Command line to pass MOV DI,OFFSET CmdLine ;ES:DI -> Local terminated copy ; LODSB ; CMP AL,126 ;Truncate command if exceeds space ; JB EX2 ; MOV AL,126 ;EX2: STOSB ; MOV CL,AL ; XOR CH,CH ;CX = bytes to copy MOV CX, 127 REP MOVSB ; MOV AL,0DH ;Terminate with ^M ; STOSB MovSeg DS,CS ;DS = CS MOV SI,OFFSET CmdLine MOV CmdLinePtr.ofst,SI MOV CmdLinePtr.segm,DS ;Store pointer to command line ; INC SI MOV DI,OFFSET FileBlock1 MOV FilePtr1.ofst,DI MOV FilePtr1.segm,ES ;Store pointer to filename 1, if any DosCallAX 2901h ;Parse FCB MOV DI,OFFSET FileBlock2 MOV FilePtr2.ofst,DI MOV FilePtr2.segm,ES ;Store pointer to filename 2, if any DosCallAX 2901h ;Parse FCB MOV DX,OFFSET Path MOV BX,OFFSET EnvironSeg DosCallAX 4B00h ;Exec JC EX3 ;Jump if error in DOS call XOR AX,AX ;Return zero for success EX3: MOV Status,AX ;Save DOS error code ;Set up temporary stack and reallocate original memory block SetTempStack ;Set up temporary stack MOV ES,PrefixSegCS MOV BX,ParasWeHave DosCallAH 4Ah ;SetBlock JNC EX4 ;Jump if no error HaltWithError 0FFh ;Must halt if failure here EX4: InitSwapCount ;Initialize LeftToSwap ;Check which swap method is in use EX5: PUSH CS POP DS MOV DX,OFFSET ComeBack MOV AH,9 INT 21h CMP UsedEms,0 JZ ReadF ;Jump to read back from file JMP ReadE ;Read back from EMS ;Read back from swap file ReadF: MovSeg DS,CS ;DS = CS InitSwapFile ;Seek to start of swap file JNC EF3 ;Jump if we succeeded HaltWithError 0FEh ;Must halt if failure here EF3: SetSwapCount FileBlockSize ;CX = bytes to read MOV DX,OFFSET _FIRSTTOSAVE ;DS:DX -> start of region to restore DosCallAH 3Fh ;Read file JNC EF4 ;Jump if no error HaltWithError 0FEh ;Must halt if failure here EF4: CMP AX,CX JZ EF5 ;Jump if full block read HaltWithError 0FEh ;Must halt if failure here EF5: NextBlock DS,FileBlockSize ;Point DS to next page to read JNZ EF3 ;Jump if bytes left to read JMP ESDone ;We're done ;Copy back from EMS ReadE: MOV DS,FrameSegCS ;DS -> page window MOV DX,EmsHandleCS ;DX = handle of our EMS block XOR BX,BX ;BX = initial logical page MovSeg ES,CS ;ES = CS EE3: XOR AL,AL ;Physical page 0 EmsCall 44h ;Map physical page JZ EE4 ;Jump if success HaltWithError 0FDh ;Must halt if failure here EE4: SetSwapCount EmsPageSize ;CX = Bytes to move XOR SI,SI ;DS:SI -> base of EMS page MOV DI,OFFSET _FIRSTTOSAVE ;ES:DI -> region to restore MoveFast ;Move CX bytes from DS:SI to ES:DI INC BX ;Next logical page NextBlock ES,EmsPageSize ;Point ES to next page to move JNZ EE3 ;Jump if so ESDone: CLI ;Switch back to original stack MOV SS,SaveSS MOV SP,SaveSP STI MOV AX,SEG DGROUP MOV DS,AX ;Restore DS MOV AX,Status ;Return status POP BP RET 8 ;Remove parameters and return EXECWITHSWAP ENDP ;----------------------------------------------------------------------------- ;Label marks first location to swap _FIRSTTOSAVE: ;----------------------------------------------------------------------------- ;function AllocateSwapFile : Boolean; ALLOCATESWAPFILE PROC FAR MOV CX,FileAttr ;Attribute for swap file MOV DX,OFFSET _SwapName ;DS:DX -> ASCIIZ swap name DosCallAH 3Ch ;Create file MOV _FileHandle,AX ;Save handle assuming success MOV AL,0 ;Assume failure JC ASDone ;Failed if carry set INC AL ;Return true for success ASDone: RET ALLOCATESWAPFILE ENDP ;----------------------------------------------------------------------------- ;procedure DeallocateSwapFile; DEALLOCATESWAPFILE PROC FAR MOV BX,_FileHandle ;Handle of swap file DosCallAH 3Eh ;Close file XOR CX,CX ;Normal attribute MOV DX,OFFSET _SwapName ;DS:DX -> ASCIIZ swap name DosCallAX 4301h ;Set file attribute DosCallAH 41h ;Delete file RET DEALLOCATESWAPFILE ENDP ;----------------------------------------------------------------------------- ;function EmsInstalled : Boolean; EMSINSTALLED PROC FAR PUSH DS MovSeg DS,CS ;DS = CS MOV DX,OFFSET EmsDevice ;DS:DX -> EMS driver name DosCallAX 3D02h ;Open for read/write POP DS MOV BX,AX ;Save handle in case one returned MOV AL,0 ;Assume FALSE JC EIDone DosCallAH 3Eh ;Close file MOV AL,1 ;Return TRUE EIDone: RET EMSINSTALLED ENDP ;----------------------------------------------------------------------------- ;function EmsPageFrame : Word; EMSPAGEFRAME PROC FAR EmsCall 41h ;Get page frame MOV AX,BX ;AX = segment JZ EPDone ;Done if Error = 0 XOR AX,AX ;Else segment = 0 EPDone: RET EMSPAGEFRAME ENDP ;----------------------------------------------------------------------------- ;function AllocateEmsPages(NumPages : Word) : Word; ALLOCATEEMSPAGES PROC FAR MOV BX,SP ;Set up stack frame MOV BX,SS:[BX+4] ;BX = NumPages EmsCall 43h ;Allocate EMS MOV AX,DX ;Assume success JZ APDone ;Done if not 0 MOV AX,0FFFFh ;$FFFF for failure APDone: RET 2 ;Remove parameter and return ALLOCATEEMSPAGES ENDP ;----------------------------------------------------------------------------- ;procedure DeallocateEmsHandle(Handle : Word); DEALLOCATEEMSHANDLE PROC FAR MOV BX,SP ;Set up stack frame MOV DX,SS:[BX+4] ;DX = Handle EmsCall 45h ;Deallocate EMS RET 2 ;Remove parameter and return DEALLOCATEEMSHANDLE ENDP ;CODE ENDS END