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Assembly Source File | 1995-11-01 | 11.1 KB | 260 lines

;----------------------------------------------- ; DUMP.ASM -- OS/2 Hex Dump Program ; (c) 1988, Ziff Communications Co. ;----------------------------------------------- EXTRN DosOpen:FAR, DosRead:FAR, DosWrite:FAR EXTRN DosClose:FAR, DosExit:FAR DOSSEG .286 .MODEL SMALL .STACK 200h ;-------------------------- .DATA ; Initialized Data Segment ;-------------------------- SyntaxMsg db 13, 10, "Syntax: DUMP filename" db 13, 10, 10, "DUMP (c) 1988, Ziff Communications Co." db 13, 10, "PC Magazine ", 254," Charles Petzold - 12/87" db 13, 10 SyntaxMsgLen equ $ - SyntaxMsg FileSpecMsg db "DUMP: File not found or cannot be opened" FileSpecMsgLen equ $ - FileSpecMsg Delimiters db 9, " ,;=", 0 Address dw 0, 0 ;---------------------------- .DATA? ; Uninitialized Data Segment ;---------------------------- FileHandle dw ? OpenAction dw ? BytesRead dw ? BytesWritten dw ? InputBuffer db 16 dup (?) OutputBuffer db 80 dup (?) ;-------------- .CODE ; Code Segment ;-------------- ;---------------------------------------------- ; Parse command line to get file specification ;---------------------------------------------- Entry: Push DS ; Data segment selector Pop ES ; Transfer it to ES Mov DS, AX ; DS = Environment selector Mov SI, BX ; SI = Start of command line SkipProgName: Lodsb ; Pull a command line byte Or AL, AL ; Check if it's zero Jnz SkipProgName ; If not, continue SkipDelims: Lodsb ; Get byte from parameter Or AL, AL ; Check if it's zero Jz DisplaySyntax ; If so, exit with message Mov DI, Offset Delimiters ; Check if delimiter Mov CX, 5 ; There are 5 of them Repne Scasb ; Scan the string Jz SkipDelims ; If delimiter, loop back Mov DX, SI ; Pointer to file name + 1 Dec DX ; Pointer to file name SearchFileEnd: Lodsb ; Get a byte Mov DI, Offset Delimiters ; Check if delimiter Mov CX, 6 ; 6 of them now including 0 Repne Scasb ; Scan the string Jnz SearchFileEnd ; If not delimiter, do it again Mov Byte Ptr [SI - 1], 0 ; Terminate with zero byte Jmp Short OpenFile ;------------ ; Error Exit ;------------ DisplaySyntax: Push ES ; Otherwise, set DS to Pop DS ; data segment Mov DX, Offset SyntaxMsg ; Syntax message offset Mov CX, SyntaxMsgLen ; Syntax message length ErrorExit: Push 2 ; Standard error handle Push DS ; Segment of string Push DX ; Offset of string Push CX ; Length of string Push DS ; Segment for bytes written Push Offset BytesWritten ; Offset for bytes written Call DosWrite ; Display the message Push 1 ; Terminte all threads Push 1 ; Return code Call DosExit ; Exit ;------------------------- ; Open file using DosOpen ;------------------------- OpenFile: Push DS ; Exchange DS and ES Push ES Pop DS Pop ES Push ES ; Segment of file name Push DX ; Offset of file name Push DS ; Segment for file handle Push Offset FileHandle ; Offset for file handle Push DS ; Segment for action Push Offset OpenAction ; Offset for action Push 0 ; High size (not used) Push 0 ; Low size (not used) Push 0 ; Attribute (not used) Push 1 ; Open flag (open if file exists) Push 20h ; Open mode (read, deny write) Push 0 ; Reserved Push 0 ; Reserved Call DosOpen ; Open the file Or AX, AX ; Check for error Jz ReadAndDump ; If none, continue Mov DX, Offset FileSpecMsg ; Error message Mov CX, FileSpecMsgLen ; Length of message Jmp ErrorExit ; Print it and exit ;--------------------------------------------- ; Read 16 bytes from file and display address ;--------------------------------------------- ReadAndDump: Push DS ; Set ES to DS Pop ES MainLoop: Push [FileHandle] ; File Handle Push DS ; Segment of buffer Push Offset InputBuffer ; Offset of buffer Push 16 ; Length of buffer Push DS ; Segment for bytes read Push Offset BytesRead ; Offset for bytes read Call DosRead ; Read the file Cmp [BytesRead], 0 ; See if no bytes read Jnz DoLine ; If bytes read, continue Jmp AllDone ; If zero bytes read, end program DoLine: Mov DI, Offset OutputBuffer ; Destination Mov AX, [Address + 2] ; High address within file Call HexWordOut ; Display the value Mov AL, '-' ; A dash Stosb Mov AX, [Address] ; Low offset within file Call HexWordOut ; Display it Mov AL, ' ' ; Follow it with a blank Stosb ;--------------------- ; Prepare Hex Display ;--------------------- Mov SI, Offset InputBuffer ; Source Mov CX, [BytesRead] ; Number of bytes read Sub BX, BX ; Initialize counter HexLoop: Mov AL, ' ' ; A blank normally precedes Cmp BX, 8 ; But check if counter is 8 Jnz DoTheSpace ; If not, a blank is OK Mov AL, '-' ; Otherwise, use a dash DoTheSpace: Stosb ; Display it Lodsb ; Get a byte Call HexByteOut ; Convert it to hex Inc BX ; Kick up the counter Loop HexLoop ; And loop for next byte Mov CX, 16 ; 16 possible bytes Sub CX, BX ; Subtract those already done IMul CX, 3 ; Multiply by 3 Add CX, 2 ; And add 2 for the end Mov AL, ' ' ; This is all blank Rep Stosb ; Store the blanks ;--------------------------- ; Prepare Character Display ;--------------------------- Mov SI, Offset InputBuffer ; Source Mov CX, [BytesRead] ; Number of bytes CharLoop: Lodsb ; Get the character Cmp AL, ' ' ; See if displayable ASCII Jb DisplayPeriod ; If below space, use dot Cmp AL, 7Fh ; If DEL or above, use dot Jb DisplayChar DisplayPeriod: Mov AL, '.' ; Display period DisplayChar: Stosb ; Display character Loop CharLoop ; Do next character Mov AL, 13 ; Carriage return Stosb Mov AL, 10 ; And line feed Stosb ;----------------------------- ; Display Line using DosWrite ;----------------------------- Sub DI, Offset OutputBuffer ; Length of output line Push 1 ; File Handle: Standard Output Push DS ; Segment of buffer Push Offset OutputBuffer ; Offset of buffer Push DI ; Length of buffer Push DS ; Segment for bytes written Push Offset BytesWritten ; Offset for bytes written Call DosWrite ; Display it Add [Address], 16 ; Kick up address Adc [Address + 2], 0 Jmp MainLoop ; Do another line AllDone: Push [FileHandle] ; File handle Call DosClose ; Close the file Push 1 ; Exit program Push 0 Call DosExit ;---------------------------------- ; Subroutines to store line output ;---------------------------------- HexWordOut: Xchg AL, AH Call HexByteOut ; Do high byte first Xchg AL, AH ; Fall through HexByteOut: Push AX Shr AL, 4 Call HexDigitOut ; Do high digit first Pop AX And AL, 0Fh ; Fall through HexDigitOut: Add AL, 90h Daa ; Common trick to convert Adc AL, 40h ; hex digit to ASCII Daa Stosb ; Store in line buffer Ret END Entry