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Assembly Source File | 1993-02-11 | 36.5 KB | 919 lines

;EXECWSWP.ASM ; Swap memory and exec another program, keeping child process's video ; output to a specified portion of the screen ; Copyright (c) 1988,1990 TurboPower Software ; May be used freely as long as due credit is given ; ;----------------------------------------------------------------------------- DATA SEGMENT WORD PUBLIC 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 EXTRN NewInt10Addr:WORD; ;Hold addr on our int 10 handler EXTRN NewInt21Addr:WORD; ;Hold addr on our int 21 handler EXTRN NewInt29Addr:WORD; ;Hold addr on our int 29 handler DATA ENDS ;----------------------------------------------------------------------------- CODE SEGMENT WORD PUBLIC ASSUME CS:CODE,DS:DATA PUBLIC ExecWinWithSwap, FirstToSave PUBLIC AllocateSwapFile, DeallocateSwapFile PUBLIC DefaultDrive, DiskFree PUBLIC EmsInstalled, EmsPageFrame PUBLIC AllocateEmsPages, DeallocateEmsHandle PUBLIC InstallInt21, RestoreInt21, CheckCursor PUBLIC UpdateCsVars ;----------------------------------------------------------------------------- FileAttr EQU 6 ;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) col EQU (BYTE PTR 0) row EQU (BYTE PTR 1) ;----------------------------------------------------------------------------- ;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 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 OrigInt10 DD 0 ;Previous $10 vector OrigInt21 DD 0 ;Previous $21 vector OrigInt29 DD 0 ;Previous $29 vector WindPos DW 0 ;Cursor position in window WindLo DW 0 ;Top left corner of window WindHi DW 0 ; and bottom right corner. WindAttr DB 0 ;Attribute with which to Old1B DD 0 ;Saves old 1B Old23 DD 0 ;Saves old 23 IRetOp DB 0CFh ;IRET instruction of break ints 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 MOV AL,Level ;Set errorlevel DosCallAH 4Ch ENDM MoveFast MACRO ;Move CX bytes from DS:SI to ES:DI CLD ;Forward SHR 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 ToDos MACRO ;Transfer control to DOS JMP DWORD PTR OrigInt21 ENDM Video MACRO PUSHF ;Fake int 10 CALL DWORD PTR OrigInt10 ENDM ToApp MACRO ;Transfer control back to caller CLC ;Clear error flag RET 2 ;Return with flags intact ENDM ;----------------------------------------------------------------------------- ;procedure CheckCursor ; CheckCursor PROC NEAR PUSH BP MOV BP,SP ;Set up stack frame MOV AH,3 XOR BH,BH INT 10h ;Get cursor position MOV CX,WindLo CMP DH,CH ;Row above minimum? JAE CC1 ;Jump if so MOV DH,CH ;Force to minimum CC1: CMP DL,CL ;Col above minimum? JAE CC2 ;Jump is so MOV DL,CL ;Force to minimum CC2: MOV CX, WindHi CMP DH,CH ;Row below maximum? JBE CC3 ;Jump if so MOV DH,CH ;Force to maximum CC3: CMP DL,CL ;Col below maximum? JBE CC4 ;Jump if so MOV DL,CL ;Force to maximum CC4: MOV WindPos,DX ;Save current position MOV AH,2 XOR BH,BH INT 10h ;Make it so POP BP RET ;Return CheckCursor ENDP ;---------------------------------------------------------------------------- ;procedure InstallInt21 ; InstallInt21 PROC NEAR PUSH BP MOV BP,SP ;Set up stack frame ;Get the current Int21 vector DosCallAX 3521h ;ES:BX = vector MOV OrigInt21.ofst, BX ;Save as pointer in OrigInt21 MOV OrigInt21.segm, ES ;Get the current Int10 vector DosCallAX 3510h ;ES:BX = vector MOV OrigInt10.ofst, BX ;Save as pointer in OrigInt10 MOV OrigInt10.segm, ES ;Get the current Int29 vector DosCallAX 3529h ;ES:BX = vector MOV OrigInt29.ofst, BX ;Save as pointer in OrigInt29 MOV OrigInt29.segm, ES ;Install our Int21 handler PUSH DS MOV DX, SEG NewInt21 ;Segment of our handler MOV DS, DX MOV DX, OFFSET NewInt21 ;Offset of our handler DosCallAX 2521h ;Set it POP DS MOV NewInt21Addr, OFFSET NewInt21 MOV NewInt21Addr+2, SEG NewInt21 ;Show addr to caller ;Install our Int10 handler PUSH DS MOV DX, SEG NewInt10 ;Segment of our handler MOV DS, DX MOV DX, OFFSET NewInt10 ;Offset of our handler DosCallAX 2510h ;Set it POP DS MOV NewInt10Addr, OFFSET NewInt10 MOV NewInt10Addr+2, SEG NewInt10 ;Show addr to caller ;Install our Int29 handler PUSH DS MOV DX, SEG NewInt29 ;Segment of our handler MOV DS, DX MOV DX, OFFSET NewInt29 ;Offset of our handler DosCallAX 2529h ;Set it POP DS MOV NewInt29Addr, OFFSET NewInt29 MOV NewInt29Addr+2, SEG NewInt29 ;Show addr to caller POP BP RET ;Return InstallInt21 ENDP ;----------------------------------------------------------------------------- ;procedure RestoreInt21 ; RestoreInt21 PROC NEAR PUSH BP MOV BP,SP ;Set up stack frame PUSH DS LDS DX, OrigInt21 ;DS:DX = OrigInt21 DosCallAX 2521h ;Restore it LDS DX, OrigInt10 ;DS:DX = OrigInt10 DosCallAX 2510h ;Restore it LDS DX, OrigInt29 ;DS:DX = OrigInt29 DosCallAX 2529h ;Restore it POP DS POP BP RET ;Return RestoreInt21 ENDP ;----------------------------------------------------------------------------- ;procedure UpdateCsVars(Xlo, Ylo, Xhi, Yhi, Attr : Byte); ; UpdateCsVars PROC NEAR PUSH BP MOV BP,SP ;Set up stack frame ;Move passed values to CS variables MOV AX,[BP+12] DEC AX MOV BYTE PTR WindLo.Col, AL ;Lo(WindLo) = Xlo MOV AX,[BP+10] DEC AX MOV BYTE PTR WindLo.Row, AL ;Hi(WindLo) = Ylo MOV AX,[BP+8] DEC AX MOV BYTE PTR WindHi.Col,AL ;Lo(WindHi) = Xhi MOV AX, [BP+6] DEC AX MOV BYTE PTR WindHi.Row, AL ;Hi(WindHi) = Yhi MOV AX,[BP+4] MOV WindAttr, AL ;Get attribute POP BP RET 10 UpdateCsVars ENDP ;----------------------------------------------------------------------------- ;function ExecWithSwap(Path, CmdLine : string; ; Xlo, Ylo, Xhi, Yhi, Attr : Byte ) : Word; ExecWinWithSwap 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+20] ;ES:DI -> Path MOV PathPtr.ofst,DI MOV PathPtr.segm,ES ;PathPtr -> path to execute LES DI,[BP+16] ;ES:DI -> CmdLine MOV CmdPtr.ofst,DI MOV CmdPtr.segm,ES ;CmdPtr -> command line string PUSH [BP+14] PUSH [BP+12] PUSH [BP+10] PUSH [BP+8] PUSH [BP+6] CALL UpdateCsVars ;Transfer parms to CS vars ;Make sure cursor is within window CALL CheckCursor ;Continue with swapping 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 ;Install our Int21 handler CALL InstallInt21 ;Point break vectors somewhere harmless PUSH DS PUSH CS POP DS ASSUME DS:CODE MOV AX,351Bh ;Save old vectors INT 21h MOV Old1B.ofst,BX MOV Old1B.segm,ES MOV AX,3523h INT 21h MOV Old23.ofst,BX MOV Old23.segm,ES MOV AX,251Bh ;Force breaks to IRET MOV DX,OFFSET IretOp INT 21h MOV AL,23h INT 21h POP DS ASSUME DS:DATA ;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 DosCallAH 45h ;DUP handle JC EF2a ;Jump if failed MOV BX,AX ;Prepare to close dup'ed handle DosCallAH 3Eh ;Flush swap file EF2a: JMP SwapDone ;Done swapping out ;Write to EMS WriteE: MOV ES,FrameSeg ;ES -> page window MOV DX,EmsHandle ;DX = handle of our EMS block EmsCall 47h ;Save EMS context 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 EmsCall 48h ;Restore EMS context 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 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 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: 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 DX,EmsHandleCS ;DX = handle of our EMS block EmsCall 47h ;Save EMS context for next time MOV DS,FrameSegCS ;DS -> page window 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 EmsCall 48h ;Restore EMS context ESDone: CLI ;Switch back to original stack MOV SS,SaveSS MOV SP,SaveSP STI CALL RestoreInt21 ;Restore original int21 ;Restore the break vectors; MOV AX,251Bh ;Restore break vectors MOV DX,Old1B.ofst MOV DS,Old1B.segm INT 21h MOV AX,2523h ;Restore break vectors MOV DX,Old23.ofst MOV DS,Old23.segm INT 21h MOV AX,SEG DATA MOV DS,AX ;Restore DS MOV AX,Status ;Return status POP BP RET 18 ;Remove parameters and return ExecWinWithSwap ENDP ;---------------------------------------------------------------------- ; Handle interrupt 29 to trap output calls NewInt29 PROC FAR JMP TtyOut NewInt29 ENDP ;---------------------------------------------------------------------- ; Handle interrupt 10 to trap output calls NewInt10 PROC FAR CMP AH,0Eh JZ TtyOut CMP AH,09h JZ MultOut CMP AH,0Ah JZ MultOut CMP AH,02h JZ SetCurPos JMP DWORD PTR OrigInt10 NewInt10 ENDP ;----------- TtyOut: PUSH AX CALL WriteChar POP AX IRET ;----------- MultOut: PUSH AX PUSH CX MultOut1: CALL WriteChar LOOP MultOut1 POP CX POP AX IRET ;----------- SetCurPos: PUSH AX PUSH DS MOV AX,SEG DATA MOV DS,AX CMP DL,WindLo.Col JAE SetOKCLo MOV DL,WindLo.Col SetOKCLo: CMP DL,WindHi.Col JBE SetOKCHi MOV DL,WindHi.Col SetOKCHi: CMP DH,WindLo.Row JAE SetOKRLo MOV DH,WindLo.Row SetOKRLo: CMP DH,WindHi.Row JBE SetOKRHi MOV DH,WindHi.Row SetOKRHi: MOV WindPos,dx POP DS POP AX JMP DWORD PTR OrigInt10 ;--------------------------------------------------------------------------- ;procedure NewInt21 ; Handle interrupt 21 to trap output calls NewInt21 PROC FAR STI CMP AH,2 ;Just get functions that go to StdOut JZ DispOut CMP AH,6 JZ DirectOut CMP AH,9 JZ StringOut CMP AH,40h ;Or maybe to StdErr JZ BlockOut ToDos ;----------- DispOut: ;DOS function 2 PUSH AX MOV AL,DL ;Character to write in AL CALL WriteChar ;Write via video BIOS POP AX ToApp ;Return successfully ;----------- DirectOut: ;DOS function 6 CMP DL,0FFh ;Console input? JNZ DispOut ;Jump if not ToDos ;Else transfer to DOS ;------------ StringOut: ;DOS function 9 PUSH AX ;Save AX PUSH BX ;Save string index MOV BX,DX ;DS:BX -> string StringOut1: MOV AL,[BX] ;AL = next character to write CMP AL,'$' ;Terminator? JZ StringOut2 ;Exit if so CALL WriteChar ;Write it INC BX ;Next character JMP StringOut1 ;Loop StringOut2: POP BX POP AX ToApp ;Back to application ;------------ BlockOut: ;DOS function 40h CMP BX,1 ;To StdOut? JZ BlockOut1 ;Jump if so CMP BX,2 ;To StdErr? JZ BlockOut1 ;Jump if so ToDos ;Else let DOS handle it BlockOut1: JCXZ BlockOut3 ;Get out if none to write PUSH AX PUSH BX PUSH CX ;Save loop counter MOV BX,DX ;DS:BX -> stuff to write BlockOut2: MOV AL,[BX] ;Next character to write CALL WriteChar ;Write it INC BX ;Next index LOOP BlockOut2 ;Loop for all the characters POP CX POP BX POP AX MOV AX,CX ;Wrote all the characters BlockOut3: ToApp ;Back to application NewInt21 ENDP ;------------ ; Write a character to current position via BIOS ; Entry: AL is character to write ; Must preserve all but AX WriteChar proc near PUSH BP ;some versions of int 10 BIOS trash BP PUSH BX PUSH CX PUSH DX PUSH DS CMP AL,7 ;Bell character? JZ BiosWriteDone ;Don't write MOV DX,WindPos ;Current cursor pos in DX CMP AL,8 ;Backspace? JNZ NotBack JMP BackSpace NotBack: CMP AL,9 ;Tab? JZ Tab CMP AL,10 ;Line feed? JZ LineFeed CMP AL,13 ;Carriage return? JZ Carriage CALL WriteOne ;Write one normal character BiosSetCursor: ;Position cursor XOR BH,BH MOV AH,2 Video MOV WindPos,DX ;Save new cursor position BiosWriteDone: POP DS POP DX POP CX POP BX POP BP RET Carriage: MOV dl,WindLo.col ;Move to left edge JMP BiosSetCursor LineFeed: CMP dh,WindHi.row ;Room to increment row? JB LineFeed1 MOV ax,0601h ;Scroll up one line MOV cx,WindLo MOV dx,WindHi MOV bh,WindAttr Video JMP BiosWriteDone LineFeed1: INC dh ;Increment row JMP BiosSetCursor ;Set cursor Tab: MOV cl,dl SUB cl,WindLo.Col ;Characters beyond left edge ADD cl,8 AND cl,0F8h ;To next tab stop ADD cl,WindLo.Col ;Window coords SUB cl,dl ;Spaces to write XOR ch,ch ;CX = spaces to write Tab1: MOV al,20h ;Write spaces PUSH cx CALL WriteOne ;One at a time XOR bh,bh MOV ah,2 Video MOV WindPos,dx ;Save new cursor position POP CX LOOP Tab1 ;Do all of them JMP BiosWriteDone BackSpace: CMP DL,WindLo.col ;Beyond left edge? JBE BiosWriteDone ;Exit if not DEC DL ;One left XOR BH,BH MOV AH,2 ;Position cursor Video MOV WindPos,dx MOV CX,1 ;Write character MOV BL,WindAttr MOV AX,0920h ;Write a space Video JMP BiosWriteDone ;Done now WriteChar endp ;--------------- ; Write one character and update cursor variable WriteOne PROC NEAR MOV CX,1 ;Write character MOV BL,WindAttr XOR BH,BH MOV AH,9 Video CMP DL,WindHi.col ;Below right border? JB IncCol ;If so, just increment column CMP DH,WindHi.row ;Room for CR/LF? JB IncRow ;Jump if so MOV AX,0601h ;Scroll up one line MOV CX,WindLo MOV DX,WindHi MOV BH,WindAttr Video DEC DH ;Compensate for inc to follow IncRow: INC DH ;Next row MOV DL,WindLo.col ;First col DEC DL ;Compensate for inc to follow IncCol: INC DL ;Increment column RET WriteOne ENDP ;----------------------------------------------------------------------------- ;Label marks first location to swap EVEN FirstToSave: ;----------------------------------------------------------------------------- ;function AllocateSwapFile : Boolean; AllocateSwapFile PROC NEAR MOV CX,FileAttr ;Attribute for swap file MOV DX,OFFSET SwapName+1 ;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 NEAR MOV BX,FileHandle ;Handle of swap file DosCallAH 3Eh ;Close file XOR CX,CX ;Normal attribute MOV DX,OFFSET SwapName+1 ;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 ;----------------------------------------------------------------------------- ;function DefaultDrive : Char; DefaultDrive PROC FAR DosCallAH 19h ;Get default drive ADD AL,'A' ;Convert to character RET DefaultDrive ENDP ;----------------------------------------------------------------------------- ;function DiskFree(Drive : Byte) : LongInt; DiskFree PROC FAR MOV BX,SP ;Set up stack frame MOV DL,SS:[BX+4] ;DL = Drive to check DosCallAH 36h ;Get disk space MOV DX,AX ;Return 0FFFFFFFFh for failure CMP AX,0FFFFh ;Bad drive number? JZ DFDone ;Jump if so MUL CX ;AX = bytes/cluster MUL BX ;DX:AX = bytes free DFDone: RET 2 ;Remove parameter and return DiskFree ENDP ;----------------------------------------------------------------------------- CODE ENDS END