mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-28 18:02:48 +00:00
231 lines
13 KiB
NASM
231 lines
13 KiB
NASM
CODE_SEG SEGMENT
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ASSUME CS:CODE_SEG,DS:CODE_SEG,ES:CODE_SEG
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ORG 100H ;Start off right for a .COM file
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ENTRY: JMP LOCATE ;Skip over Data area
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COPY_RIGHT DB '(C)1985 S.Holzner' ;Author's Mark
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FOUND_MSG DB 13,10,13,10,'FOUND IN $' ;Like it says
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LEN DW 1 ;The file length (low word)
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PATH_LEN DW 0 ;Length of Path.Dat
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NUMBER DW 0 ;Number of bytes read from file
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EXTRA_PATHS DB 0 ;=1 if we open & use Path.Dat
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OLD_BX DW 0 ;Save pointer to path at CS:DBH
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OLD_SI DW 0 ;Save SI as pointer also
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START_FLAG DB 0 ;For searches in Path.Dat
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PATH_DAT DB "\PATH.DAT",0 ;ASCIIZ string of Path.Dat
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LOCATE PROC NEAR ;Here we go
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MOV DX,0B0H ;Move Disk Transfer Area to CS:0B0H
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MOV AH,1AH ;Matched file information goes there
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INT 21H
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MOV DI,5CH ;Use CS:5CH to put '*.*'0 at for search
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CALL PUT ; in current directory
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MOV DX,5CH ;Point to '*.*'0 for search
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MOV AH,4EH ; and find first matching file
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INT 21H ;Match now at DTA, 0B0H
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LOOP: ;Loop over matches now
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MOV BX,0CAH ;Get file length, came from match
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MOV DX,[BX]
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MOV LEN,DX ;Store in Len
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CMP DX,60*1024 ;Don't write over stack, allow < 64K files
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JB NOT_BIG ;Range extender (Find > 127 bytes ahead)
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JMP FIND
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NOT_BIG:CMP DX,0 ;Was this a 0 length file (disk dir or label)?
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JA FILE_OK ;No, go on and read it
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JMP FIND ;Yes, find next file and skip this one
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FILE_OK:CALL READ_FILE ;Get the file into memory
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MOV CX,NUMBER ;Prepare to loop over all read bytes
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MOV DI,OFFSET PATHS+300 ;File starts at Offset Paths+300
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SEARCH: ;Use Repne Scasb & DI to search for the
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MOV BX,82H ;first letter of the string, which is at CS:82H
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MOV AL,BYTE PTR [BX] ;Load into AL for Repne Scasb
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REPNE SCASB ;Find first letter
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JCXZ FIND ;If out of file to search, find next file
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MOV BX,80H ;How many chars in string? Get from CS:80H
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XOR DX,DX ;Set DX to zero
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MOV DL,[BX] ;Get # of chars in string
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DEC DX ;Get rid of space typed after 'Locate'
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MOV SI,83H ;Search from second typed letter (1st matched)
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CPLOOP: DEC DX ;Loop counter
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CMPSB ;See how far we get until no match
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JZ CPLOOP
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DEC DI ;At end, reset DI (Scasb increments 1 too much)
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CMP DX,0 ;If DX is not zero, all letters did not match
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JA SEARCH ;If not a match, go back and get next one
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LEA DX,FOUND_MSG ;FILE HAS BEEN FOUND, so say so.
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MOV AH,9 ;Request string search
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INT 21H
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MOV AH,2 ;Now to print filename. Without Path.Dat, at
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MOV BX,0DBH ; CS:CEH, with Path.Dat at CS:DBH
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CMP EXTRA_PATHS,1 ; Using Path.Dat yet?
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JE PRINT ;Yes, print
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MOV BX,0CEH ;No, reset BX to point to CS:CEH
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PRINT: MOV DL,[BX] ;Print out the filename until 0 found
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CMP DL,0 ;Is it 0?
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JE MORE ;If yes,print out sample at More:
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INT 21H ;Print filename character
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INC BX ;Point to next character
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JMP PRINT ;Go back relentlessly until done
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MORE: PUSH DI ;Save DI,BX,CX
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PUSH BX
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PUSH CX
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MOV CX,40 ;Prepare to type out total of 40 characters
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MOV AH,2 ;With Int 21H service 2
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MOV DL,':' ;But first, add ':' to filename
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INT 21H ;And a carriage return linefeed
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MOV DL,13
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INT 21H
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MOV DL,10
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INT 21H
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SUB DI,20 ;DI points to end of found string, move back
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MOV BX,OFFSET PATHS+300 ;Beginning of file
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CMP DI,BX ;If before beginning, start at beginning
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JA GO
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MOV DI,BX
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GO: ADD BX,LEN ;Now BX=end of file (to check if we're past it)
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SHOW: MOV DL,[DI] ;Get character from file
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INC DI ;And point to next one
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CMP DI,BX ;Past end?
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JA SHOWS_OVER ;Yes, jump out, look for next match
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CMP DL,30 ;Unprintable character?
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JA POK ;No, OK
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MOV DL,' ' ;Yes, make it a space
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POK: INT 21H ;Print Character
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LOOP SHOW ;And return for the next one
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SHOWS_OVER: ;End of printout
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POP CX ;Restore the registers used above
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POP BX
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POP DI
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JMP SEARCH ;Return to search more of the file
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FIND: CALL FIND_FILE ;This file done, find next match
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CMP AL,18 ;AL=18 --> no match
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JE OUT ;And so we leave
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JMP LOOP ;If match found, go back once again
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OUT: INT 20H ;End of Main Program
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LOCATE ENDP
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PUT PROC NEAR ;This little gem puts a '*.*'0
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MOV BYTE PTR [DI],'*' ;Wherever you want it--just send
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MOV BYTE PTR [DI+1],'.' ; it a value in DI. '*.*'0 is used as
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MOV BYTE PTR [DI+2],'*' ; a universal wilcard in searches
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MOV BYTE PTR [DI+3],0
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RET
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PUT ENDP
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WS PROC NEAR ;Strip the bits for WordStar
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CMP CX,0 ;If there is a length of 0, e.g.
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JE FIN ;Directory entries, etc. do nothing.
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WSLOOP: AND BYTE PTR [BX],127 ;Set top bit to zero
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INC BX ;Point to next unsuspecting byte
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LOOP WSLOOP ;And get it too.
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FIN: RET ;To use, send this program BX and CX
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WS ENDP
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FIND_FILE PROC NEAR ;The file finder
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MOV AH,4FH ;Try service 4FH, find next match, first
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INT 21H
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CMP AL,18 ;AL = 18 --> no match
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JE CHECK ;Range extender.
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JMP NEW
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CHECK: CMP EXTRA_PATHS,1 ;Have we used path.Dat?
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JE NEXT_PATH ;Yes, get next path, this one's used up
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INC EXTRA_PATHS ;No, set it to 1
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MOV AX,3D00H ;Request file opening for Path.Dat
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LEA DX,PATH_DAT ;Point to '\PATH.DAT'0
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INT 21H
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JNC READ ;If there was a carry, Path.Dat not found
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DONE: MOV AL,18 ;And so we exit with AL=18
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JMP END
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READ: MOV CX,300 ;Assume the max length for Path.Dat, 300.
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MOV BX,AX ;Move found file handle into BX for read
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MOV AH,3FH ;Set up for file read
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LEA DX,PATHS ;Put the file at location Paths (at end)
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INT 21H ;Read in the file
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ADD AX,OFFSET PATHS ;Full offset of end of Path.Dat
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MOV PATH_LEN,AX ;Get Path.Dat end point for loop
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MOV AH,3EH ;Now close the file
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INT 21H ;Close file
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MOV OLD_SI,OFFSET PATHS ;Save for future path-readings
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MOV CX,300 ;Get ready to Un-WordStar
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MOV BX,OFFSET PATHS ;300 bytes at location Paths
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CALL WS ;Strip high bit for WS
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NEXT_PATH: ;Come here to find next path to search for files
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MOV SI,OLD_SI ;Point to start of next path
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MOV DI,5CH ;Move will be to CS:5CH for '\path\*.*0' file find
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MOV BX,0DBH ;Also to CS:DBH; will assemble full path & filename
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MOV START_FLAG,0 ;Start the path search
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CHAR: CMP SI,PATH_LEN ;Past end of possible path names?
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JGE DONE ;Yes, we're done. Leave with AL=18
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CMP BYTE PTR [SI],30 ;Carriage return or linefeed?
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JB NEXT ;Yes, get next char
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MOV START_FLAG,1 ;First char, stop skipping chars
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MOV AL,[SI] ;Get char from Path.Dat
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MOV [BX],AL ;Move char to DBH
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INC BX ;And increment to next location there
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MOVSB ;Also move to 5CH area
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JMP CHAR ;And go back for more
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NEXT: CMP START_FLAG,1 ;Bad char, have we been reading a real pathname?
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JE PDONE ;Yes, we've reached the end of it.
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INC SI ;No, keep skipping chars to find pathname
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JMP CHAR
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PDONE: MOV OLD_SI,SI ;Save SI for the next path.
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MOV BYTE PTR [DI],'\' ;Add '\' to both paths
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MOV BYTE PTR [BX],'\'
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INC BX ;Move BX on for next time
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MOV OLD_BX,BX ;And save it.
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INC DI ;Move to next location at 5CH and
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CALL PUT ;Put '*.*'0 there to find all files.
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MOV DX,5CH ;Start the search for all files in
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MOV AH,4EH ; the new path.
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MOV CX,0 ;Set the file attribute to 0
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INT 21H
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CMP AL,18 ;Did we find any new files in new path?
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JE NEXT_PATH ;No, get the next path.
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NEW: CMP EXTRA_PATHS,1 ;Yes,Move found filename to DBH area to
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JNE END ; read it in-only if DBH area is active
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MOV BX,OLD_BX ; (i.e. Extra_Paths=1). Restore BX
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MOV SI,0CDH ;And point to found filename in DTA
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CLOOP: INC SI ;Next letter from found filename
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MOV AH,[SI] ;Move it to the DBH area so we can read
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MOV [BX],AH ; in the file (needs pathname\filename)
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INC BX ;Next character in 5CH area.
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CMP BYTE PTR [SI],0 ;Is this the last character?
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JNE CLOOP ;Nope, get next one
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END: RET ;After path & filename assembled, return
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FIND_FILE ENDP
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READ_FILE PROC NEAR ;Looks for filename at CEH or DBH & reads it
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PUSH AX ;Push everything to save it.
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PUSH BX
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PUSH CX
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PUSH DX
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MOV DX,0DBH ;Try the DBH area
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CMP EXTRA_PATHS,1 ;Has it been used?
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JE OK ;Yes
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MOV DX,0CEH ;No, not using paths yet, use filename only, at CEH
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OK: MOV AX,3D00H ;Prepare for file reading
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INT 21H ;And do so.
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MOV BX,AX ;Move file handle into BX to read
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MOV DX,OFFSET PATHS+300 ;Read into data area at Paths+300 bytes
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MOV CX,LEN ;Read the full file's length in bytes
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MOV AH,3FH ;Read it in at last
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INT 21H
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MOV NUMBER,AX ;Number of bytes actually read.
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MOV AH,3EH ;Close file
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INT 21H
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MOV BX,OFFSET PATHS+300 ;Clean up the Word Star high bit.
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MOV CX,LEN ;For the full file
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CALL WS ;Strip high bit for ws
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POP DX ;Pop evrything and return
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POP CX
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POP BX
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POP AX
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RET ;Fin of Read_File
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READ_FILE ENDP
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PATHS: ;Here's the end of program marker
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CODE_SEG ENDS
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END ENTRY ;End 'Entry' so DOS starts at 'Entry'
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