Power-Programmierung

home *** CD-ROM | disk | FTP | other *** search

/ Power-Programmierung / CD1.mdf / pascal / library / dos / t_power / chain.asm < prev next >

Wrap

Assembly Source File | 1988-10-27 | 14.3 KB | 321 lines

;******************************************************* ; CHAIN.ASM 5.00 ; Copyright (c) TurboPower Software 1987. ; All rights reserved. ;******************************************************* ;Set the following define to 1 and reassemble CHAIN ;if you need to run under DOS 2.X DOS2X = 0 DSEG SEGMENT WORD PUBLIC EXTRN CloseFilesBeforeChaining:BYTE ;Variable in CHAIN.PAS EXTRN PrefixSeg:WORD ;Variable in SYSTEM DSEG ENDS CSEG SEGMENT BYTE PUBLIC ASSUME CS:CSEG,DS:DSEG PUBLIC Chain4 PUBLIC SetIntVec EXTRN RestoreVectors:NEAR ;Routine to restore vectors ;The following values must be exact ;They'll need changing if anything after label CodeToRelocate changes CodeLen EQU 02Ch ;Bytes of code to relocate MaxCmdLen EQU 052h ;Maximum length of command line ;Although more reliable, the following generates several NOPs in object code ;CodeLen = offset Dummy-offset CodeToRelocate ;Length of code in PSP ;MaxCmdLen = 07Eh-CodeLen ;Maximum length of command line FirstHandle EQU 5 ;First file handle to close ;**************************************************************** SetIntVec ; procedure SetIntVec(Num : Byte; Vec : pointer); ; set interrupt Num to point to Vec SetIntVec PROC NEAR MOV BX,SP ;Stack frame MOV CX,DS ;Save DS MOV AH,25h ;Set vector MOV AL,SS:[BX+6] ;AL = Num LDS DX,SS:[BX+2] ;DS:DX = Vec INT 21h MOV DS,CX ;Restore DS RET 6 SetIntVec ENDP ;**************************************************************** Chain4 ; function Chain4(Path, CmdLine : string) : word; ; Turbo 4 equivalent of chaining ;Parameters PathArg EQU DWORD PTR [BP+10] ;File to chain to CmdLine EQU DWORD PTR [BP+6] ;Command line to pass ;Local variables CsInit EQU WORD PTR [BP-30+16h] ;Fields within EXE header IpInit EQU WORD PTR [BP-30+14h] ; ... StackPtr EQU WORD PTR [BP-30+10h] StackSeg EQU WORD PTR [BP-30+0Eh] MinHeap EQU WORD PTR [BP-30+0Ah] EXEPages EQU WORD PTR [BP-30+04h] EXEHeader EQU WORD PTR [BP-30] ;EXE header from file Path EQU BYTE PTR [BP-94] ;ASCIIZ path string Chain4 PROC FAR PUSH BP MOV BP,SP ;Set up stack frame SUB SP,94 ;Make space for locals ;Validate pathname and convert to ASCIIZ PUSH DS ;Save DS for later PUSH SS POP ES ;ES = SS LEA DI,Path ;ES:DI => ASCIIZ path MOV BX,DI ;Save offset of ASCIIZ LDS SI,PathArg ;DS:SI => file path in Turbo string ASSUME DS:nothing CLD ;Forward LODSB ;Get length byte CMP AL,63 ;Longer than 63 characters? JB StoreASCIIZ MOV AL,63 ;Truncate it StoreASCIIZ: MOV CL,AL ;CX = length XOR CH,CH REP MOVSB ;Copy to local Path XOR AL,AL ;Make ASCIIZ STOSB ;Assure file exists PUSH SS POP DS ;DS = SS MOV DX,BX ;DS:DX => ASCIIZ path MOV AX,3D00h ;Open file read-only INT 21h JNC FileFound ;OK, file was found Error: POP DS ;Restore DS ASSUME DS:DSEG Error1: MOV SP,BP ;Return with error code in AX POP BP ;Restore BP RET 8 ;Remove parameters from stack ;Read file header FileFound: MOV BX,AX ;BX = file handle LEA DX,ExeHeader ;DS:DX => ExeHeader MOV CX,28 ;Read 28 bytes MOV AH,3Fh ;DOS read file INT 21h JC Error ;Error if carry set CMP AX,2 ;At least 2 bytes read? MOV AX,30 ;Prepare for Read Fault error JB Error ;Error if 2 bytes not read ;Determine how much memory program needs CMP ExeHeader,5A4Dh ;Is it EXE format? JE ExeFileSize ;Yes, treat it as such ;Get non-EXE file size MOV AX,4202h ;Seek to end of file XOR CX,CX XOR DX,DX INT 21h JC Error ;Error if carry set MOV CX,4 ;Divide bytes by 16 NextShiftR: SHR DX,1 ;Shift a LongInt right RCR AX,1 LOOP NextShiftR JMP SHORT CloseFile ;DX:AX has paragraphs needed ;Get EXE image size ExeFileSize: MOV AX,EXEPages ;Get pages in EXE image XOR DX,DX MOV CX,5 ;Multiply by 32 NextShiftL: SHL AX,1 ;Shift a LongInt left RCL DX,1 LOOP NextShiftL ;DX:AX has paragraphs ADD AX,MinHeap ;Add minimum data/stack/heap ADC DX,0 ;Close file (DOS will reopen it) CloseFile: MOV CX,AX ;Save paragraphs in CX MOV AH,3Eh ;Close file INT 21h JC Error ;Error if carry set ;See if more than 640K bytes requested MOV AX,8 ;Prepare for insufficient memory OR DX,DX ;DX must be zero JNZ Error ;Error if more than 640K ;Determine available memory space POP DS ;Restore DS ASSUME DS:DSEG MOV ES,PrefixSeg ;Main program segment MOV AH,4Ah ;Setblock IF DOS2X ;Runs under DOS 2.X or 3 MOV BX,CX ADD BX,1000h INT 21h ;BX = Required space+64K bytes ELSE ;Runs only under DOS 3 or later MOV BX,0FFFFh ;Ask for everything INT 21h ;BX has available paragraphs ;Assure sufficient memory available for overlay MOV AX,BX SUB AX,10h ;Leave space for PSP CMP AX,CX ;Sufficient space? MOV AX,8 ;Prepare for insufficient memory JB Error1 ;Error if less ENDIF ;Allocate all available space MOV AH,4Ah ;Ask again for what we can get INT 21h JC Error1 ;Error if carry set now ;Prepare to move stack to top of memory MOV AX,ES ;Base of program ADD AX,BX ;Add all available paragraphs SUB AX,1000h ;Room for full stack segment MOV CS:TmpSS,AX ;Store temporary SS for later ;Close secondary file handles (don't touch StdIn,StdOut,StdErr,StdPrn) CMP CloseFilesBeforeChaining,0 ;Should we close files? JZ RestoreInts ;No, skip this MOV BX,FirstHandle ;Start with handle 5 MOV CX,20-FirstHandle ;20 handles total NextHandle: MOV AH,3Eh ;DOS close file INT 21h INC BX ;Ignore errors LOOP NextHandle ;Restore interrupt vectors taken over by SYSTEM library RestoreInts: PUSH ES CALL RestoreVectors POP ES ;Set up command line for chained program LDS SI,CmdLine ;DS:SI points to command line MOV DI,80h ;ES:DI => command line in PSP LODSB ;Get length byte CMP AL,MaxCmdLen ;Is is too long? JB StoreCmdLine ;No, don't truncate MOV AL,MaxCmdLen ;Truncate StoreCmdLine: STOSB ;Store length byte MOV BX,DI ;Save start of command line MOV CL,AL XOR CH,CH REP MOVSB ;Copy parameter to command line MOV AL,0Dh ;Terminate with <Enter> STOSB ;Initialize FCB's for new program PUSH ES POP DS ;DS = ES MOV SI,BX ;DS:SI => command line to parse MOV DI,005Ch ;ES:DI => FCB1 MOV AX,2901h ;Init FCB1 INT 21h MOV DI,006Ch ;ES:DI => FCB2 MOV AX,2901h ;Init FCB2 INT 21h ;Save initialization data for new program MOV BX,ES ;Store prefix seg in BX MOV CS:NewCS,BX ;Assume COM file MOV CS:NewSS,BX ADD BX,10h ;BX = base segment of image CMP ExeHeader,5A4Dh ;Is it EXE format? JNE MoveCode ;No, COM file already initialized MOV AX,CsInit ;Get initial CS from EXE header, ADD AX,BX ; relocate segment, MOV CS:NewCS,AX ; save it for later MOV AX,IpInit ;Initial IP MOV CS:NewIP,AX MOV AX,StackSeg ;Initial SS ADD AX,BX MOV CS:NewSS,AX MOV AX,StackPtr ;Initial SP MOV CS:NewSP,AX ;Move code into PSP MoveCode: MOV CX,CodeLen ;Bytes to move MOV DI,100h ;DI => end of new code SUB DI,CX ;ES:DI => destination of new code MOV CS:TmpIP,DI ;Store address to jump to MOV CS:TmpCS,ES PUSH CS POP DS ;DS = CS MOV SI,offset CodeToRelocate ;DS:SI => code to relocate REP MOVSB ;Copy the code to PSP ;Prepare for EXEC call MOV AX,BX ;AX = Base segment STOSW STOSW ;Initialize EXEC block PUSH SS POP DS ;DS = SS LEA DX,Path ;DS:DX => Path of file MOV BX,100h ;ES:BX => EXEC block MOV AX,4B03H ;Load Overlay CLI MOV SS,CS:TmpSS ;Put stack at top MOV SP,0FFFEh ; of memory STI DB 0EAh ;JMP FAR to code in PSP TmpIP DW 0 ;Patched in with offset TmpCS DW 0 ;Patched in with segment TmpSS DW 0 ;Temporary stack segment ;----------------------------------------------------------------------------- ;Code relocated to and executed in PSP CodeToRelocate: INT 21h ;Call DOS EXEC JNC GoodLoad ;Check for error INT 20h ;Error is rare ; just halt if EXEC failed GoodLoad: MOV DX,CS ;Get base of program MOV DS,DX ;Initialize DS MOV ES,DX ;Initialize ES MOV AH,4Ah ;DOS SetBlock MOV BX,0FFFFh ;Ask for everything INT 21h ;BX has available paragraphs ADD BX,DX ;Top of memory MOV DS:[0002h],BX ;Store in PSP that Turbo uses CLI ;Interrupts off MOV SS,DS:[0FEh] ;Initialize stack MOV SP,DS:[0FCh] STI ;Interrupts on again DB 0EAh ;JMP FAR to start of code NewIP DW 100h ;Patched in with start offset NewCS DW 0 ;Patched in with start segment NewSP DW 0FFFEh ;Patched in with new SP NewSS DW 0 ;Patched in with new SS Chain4 ENDP Dummy LABEL BYTE ;Used to measure code to move CSEG ENDS END