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Assembly Source File | 1998-01-14 | 13.2 KB | 441 lines

; DDIR.ASM -- Double Column Sorted DIR Command ; ======== ; (C) Copyright Charles Petzold, 1985 ; ; COM file format ; CSEG Segment Assume CS:CSEG, DS:CSEG Org 002Ch ; Offset of Environment Environment Label Byte Org 007Bh ; Parameter for COMMAND.COM NewParameter Label Byte Org 0080h ; Parameter passed to program OldParameter Label Byte Org 0100h ; Entry point Entry: Jmp Begin ; All Data ; -------- db '(C) Copyright Charles Petzold, 1985' DosVersMsg db "Needs DOS 2.0 +$" ; Error messages MemAllocMsg db "Memory Problem$" CommandMsg db "COMMAND Problem$" Comspec db "COMSPEC=" ; Search string in environment CommandAsciiz dd ? ; Eventual pointer to COMMAND ParamBlock dw ? ; Parameter Block for EXEC dw NewParameter,? ; First ? must be replaced dw 5Ch,? ; with Environment segment; dw 6Ch,? ; others with this segment OldInterrupt21 dd ? ; For vector address storage BufferPtr dw Offset FileBuffer ; For storing files listing CharCounter dw 0 ; Keeps track of characters NowDoingFile db 0 ; Flagged for file printed WithinFileList db 0 ; Flagged for file list FileCounter dw 0 ; Keeps track of files LineCounter db 0 ; For pausing at screen end PauseMessage db 6 dup (205)," Press any key to continue " db 6 dup (205),181 PauseMsgEnd Label Byte ; Check DOS Version ; ----------------- Begin: Mov AH,30h ; DOS Version function call Int 21h ; Call DOS Cmp AL,2 ; Check if version 2 Jae DosVersOK ; If equal or over, all OK Mov DX,Offset DosVersMsg ; Wrong DOS version message ErrorExit: Mov AH,9 ; Set up for string write Int 21h ; Call DOS for message Int 20h ; Dishonorable discharge ; Adjust stack and un-allocate rest of memory ; ------------------------------------------- DosVersOK: Mov DI,Offset FileBuffer ; Place to save files Mov CX,528 * 39 ; Allow room for 528 files Mov AL,' ' ; Will clear with blanks Cld ; Forward direction Rep Stosb ; Clear the area Mov BX,(Offset FileBuffer) + (528 * 39) + 100h ; New end of program Mov SP,BX ; Set the stack pointer Add BX,15 ; Add 15 for rounding Mov CL,4 ; Number of shifts Shr BX,CL ; Convert AX to segment Mov AH,4Ah ; DOS call to shrink down Int 21h ; allocated memory Mov DX,Offset MemAllocMsg ; Possible error message Jc ErrorExit ; Only print it if Carry set ; Search for Comspec in Environment ; --------------------------------- Mov ES,[Environment] ; Environment Segment Sub DI,DI ; Start search at beginning Cld ; String increment to forward TryThis: Cmp Byte Ptr ES:[DI],0 ; See if end of environment Jz NoFindComSpec ; If so, we have failed Push DI ; Save environment pointer Mov SI,Offset ComSpec ; String to search for Mov CX,8 ; Characters in search string Repz Cmpsb ; Check if strings are same Pop DI ; Get back the pointer Jz FoundComspec ; Found string only zero flag Sub AL,AL ; Zero out AL Mov CX,8000h ; Set for big search Repnz Scasb ; Find the next zero in string Jmp TryThis ; And do the search from there NoFindComSpec: Mov DX,Offset CommandMsg ; Message for COMSPEC error Jmp ErrorExit ; Print it and exit FoundComspec: Add DI,8 ; So points after 'COMSPEC=' Mov Word Ptr [CommandASCIIZ],DI ; Save the address of Mov Word Ptr [CommandASCIIZ + 2],ES ; COMMAND ASCIIZ ; Set up parameter block for EXEC call ; ------------------------------------ Mov [ParamBlock],ES ; Segment of Environment string Mov [ParamBlock + 4],CS ; Segment of this program Mov [ParamBlock + 8],CS ; so points to FCB's Mov [ParamBlock + 12],CS ; and NewParameter ; Save and set Interrupt 21h vector address ; ----------------------------------------- Mov AX,3521h ; DOS call to get Interrupt 21 Int 21h ; vector address Mov Word Ptr [OldInterrupt21],BX ; Save offset Mov Word Ptr [OldInterrupt21 + 2],ES ; And segment Mov DX,Offset NewInterrupt21; Address of new Interrupt 21 Mov AX,2521h ; Do DOS call to Int 21h ; set the new address ; Fix up new parameter for "/C DIR" String ; ------------------------------------ Mov AL,[OldParameter] ; Number of parameter chars Add AL,5 ; We'll be adding five more Mov [NewParameter],AL ; Save it Mov Word Ptr [NewParameter + 1],'C/' ; i.e. "/C" Mov Word Ptr [NewParameter + 3],'ID' ; Then "DI" Mov Byte Ptr [NewParameter + 5],'R' ; And "R" ; Load COMMAND.COM ; ----------------- Push CS ; Push this segment so we can Pop ES ; set ES to it Mov BX,Offset ParamBlock ; ES:BX = address of block Lds DX,[CommandAsciiz] ; DS:DX = address of ASCIIZ Mov AX,4B00h ; EXEC call 4Bh, type 0 Int 21h ; Load command processor ; Return from COMMAND.COM ; ----------------------- Mov AX,CS ; Get this segment in AX Mov DS,AX ; Set DS to it Mov SS,AX ; And SS for stack segment Mov SP,(Offset FileBuffer) + (528 * 39) + 100h ; Set Stack again PushF ; Save Carry for error check Push DS ; Save DS during next call Mov DX,Word Ptr [OldInterrupt21] ; Old Int 21 offset Mov DS,Word Ptr [OldInterrupt21 + 2]; and segment Mov AX,2521h ; Call DOS to set vector Int 21h ; address to original Pop DS ; Restore DS to this segment PopF ; Get back Carry flage Jnc NormalEnd ; Continue if no error Mov DX,Offset CommandMsg ; Otherwise we'll print error Jmp ErrorExit ; message and exit NormalEnd: Int 20h ; Terminate program ; New Interrupt 21h ; ----------------- NewInterrupt21 Proc Far Sti ; Allow further interrupts Cmp AH,40h ; Check if file / device write Je CheckHandle ; If so, continue checks SkipIntercept: Jmp CS:[OldInterrupt21] ; Just jump to old interrupt CheckHandle: Cmp BX,1 ; Check if standard output Jne SkipIntercept ; Not interested if not PushF ; Push all registers that Push AX ; we'll be messing with Push CX Push SI Push DI Push ES Push CS ; Push the code segment Pop ES ; So we can set ES to it Cld ; Forward for string transfers Mov SI,DX ; Now DS:SI = text source Mov DI,CS:[BufferPtr] ; And ES:DI = text destination Cmp CX,2 ; See if two chars to write Jne RegularChars ; If not, can't be CR/LF Cmp Word Ptr DS:[SI],0A0Dh ; See if CR/LF being written Jne RegularChars ; Skip rest if not CR/LF Mov CX,CS:[CharCounter] ; Get characters in line Mov CS:[CharCounter],0 ; Start at new line Cmp CS:[NowDoingFile],1 ; See if CR/LF terminates file Jnz AllowTransfer ; If not, just write to screen Mov AX,39 ; Max characters per line Sub AX,CX ; Subtract those passed Add CS:[BufferPtr],AX ; Kick up pointer by that Mov CS:[NowDoingFile],0 ; Finished with file Jmp PopAndReturn ; So just return to COMMAND RegularChars: Add CS:[CharCounter],CX ; Kick up counter by number Cmp CS:[CharCounter],CX ; See if beginning of line Jne NotLineBegin ; If not, must be in middle Cmp Byte Ptr DS:[SI],' ' ; See if first char is blank Jne ItsAFile ; If not, it's a file line Cmp CS:[WithinFileList],1 ; See if doing file listing Jne AllowTransfer ; If not, just print stuff Call SortAndList ; Files done -- sort and list Mov CS:[WithinFileList],0 ; Not doing files now Jmp Short AllowTransfer ; So just print the stuff ItsAFile: Cmp CS:[FileCounter],528 ; See if 11 buffer filled up Jb NotTooManyFiles ; If not just continue Push CX ; Otherwise, save this register Call SortAndList ; Print all up to now Mov CS:[FileCounter],0 ; Reset the counter Mov DI,Offset FileBuffer ; And the pointer Mov CS:[BufferPtr],DI ; Save the pointer Mov CX,528 * 39 ; Will clear for 528 files Mov AL,' ' ; With a blank Rep Stosb ; Clear it out Pop CX ; And get back register NotTooManyFiles:Mov CS:[WithinFileList],1 ; We're doing files now Mov CS:[NowDoingFile],1 ; And a file in particular Inc CS:[FileCounter] ; So kick up this counter NotLineBegin: Cmp CS:[NowDoingFile],1 ; See if doing files Je StoreCharacters ; If so, store the stuff AllowTransfer: Pop ES ; Pop all the registers Pop DI Pop SI Pop CX Pop AX PopF Jmp SkipIntercept ; And go to DOS for print StoreCharacters:Mov DI,CS:[BufferPtr] ; Set destination Rep Movsb ; Move characters to buffer Mov CS:[BufferPtr],DI ; And save new pointer PopAndReturn: Pop ES ; Pop all the registers Pop DI Pop SI Pop CX Pop AX PopF Mov AX,CX ; Set for COMMAND.COM Clc ; No error here Ret 2 ; Return with CY flag cleared NewInterrupt21 EndP ; Sort Files ; ---------- SortAndList: Push BX ; Push a bunch of registers Push DX Push SI Push DS Push CS ; Push CS Pop DS ; so we can set DS to it Assume DS:CSEG ; And inform the assembler Mov DI,Offset FileBuffer ; This is the beginning Mov CX,[FileCounter] ; Number of files to sort Dec CX ; Loop needs one less than that Jcxz AllSorted ; But zero means only one file SortLoop1: Push CX ; Save the file counter Mov SI,DI ; Set source to destination SortLoop2: Add SI,39 ; Set source to next file Push CX ; Save the counter, Push SI ; compare source, Push DI ; and compare destination Mov CX,39 ; 39 characters to compare Repz Cmpsb ; Do the compare Jae NoSwitch ; Jump if already in order Pop DI ; Get back these registers Pop SI Push SI ; And push them again for move Push DI Mov CX,39 ; 39 characters SwitchLoop: Mov AL,ES:[DI] ; Character from destination Movsb ; Source to destination Mov DS:[SI - 1],AL ; Character to source Loop SwitchLoop ; For the rest of the line NoSwitch: Pop DI ; Get back the registers Pop SI Pop CX Loop SortLoop2 ; And loop for next file Pop CX ; Get back file counter Add DI,39 ; Compare with next file Loop SortLoop1 ; And loop again ; Now Display Sorted Files ; ------------------------ AllSorted: Mov SI,Offset FileBuffer ; This is the beginning Mov CX,[FileCounter] ; Number of files to list Inc CX ; In case CX is odd Shr CX,1 ; CX now is number of lines SetIncrement: Mov BX,24 * 39 ; Increment for double list Cmp CX,24 ; But use it only if a full Jae LineLoop ; screen is printed Mov AX,39 ; Otherwise find increment Mul CX ; by multiplying CX by 39 Mov BX,AX ; And make that the increment LineLoop: Call PrintFile ; Print the first column file Mov AL,' ' ; Skip one space Call PrintChar ; by printing blank Mov AL,179 ; Put a line down the middle Call PrintChar Mov AL,' ' ; Skip another space Call PrintChar Add SI,BX ; Bump up source by increment Sub SI,39 ; But kick down by 39 Call PrintFile ; Print the second column file Call CRLF ; And terminate line Sub SI,BX ; Bring pointer back down Inc [LineCounter] ; One more line completed Cmp [LineCounter],24 ; Have we done whole screen? Jz PauseAtEnd ; If so, gotta pause now Loop LineLoop ; Otherwise just loop Jmp Short AllFinished ; And jump out when done PauseAtEnd: Mov [LineCounter],0 ; Reset the counter Add SI,BX ; Go to next file Push BX ; Save these registers Push CX Mov DX,Offset PauseMessage ; Test to print Mov CX,Offset PauseMsgEnd - Offset PauseMessage ; Number of characters Mov BX,2 ; Standard ERROR Output Mov AH,40h ; Display to screen Int 21h ; By calling DOS Pop CX ; Retrieve pushed registers Pop BX Mov AH,8 ; Wait for character Int 21h ; Through DOS call Call CRLF ; Go to next line Loop SetIncrement ; And recalculate increment AllFinished: Pop DS ; Done with subroutine Pop SI Pop DX Pop BX Ret ; So return to caller ; Display Routines ; ---------------- PrintChar: Mov DL,AL ; Print character in AL Mov AH,2 ; By simple DOS call Int 21h Ret ; And return CRLF: Mov AL,13 ; Print a carriage return Call PrintChar Mov AL,10 ; And a line feed Call PrintChar Ret ; And return PrintString: Lodsb ; Get character from SI Call PrintChar ; Print it Loop PrintString ; Do that CX times Ret ; And return PrintFile: Push CX ; Save the counter Mov CX,32 ; Bytes for Name, Size, & Date Call PrintString ; Print it Inc SI ; Skip one space before time Mov CX,6 ; Bytes for Time Call PrintString ; It's a print! Pop CX Ret ; And return FileBuffer Label Byte ; Points to end of code CSEG EndS ; End of segment End Entry ; Denotes entry point