Piper's Pit BBS/FTP: ibm 0000

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Assembly Source File | 1989-03-30 | 13.4 KB | 352 lines

name dump page 78,132 title DUMP--Display File Contents ;DUMP--a utility to display the contents ;of a file in hex and ASCII format. MS-DOS 2.00 ;Used in the form: ;A>dump path\filename.ext[>device] ;(item in square bracket is optional) ;version 1.0 March 25, 1984 ;copyright (c) 1984 by Ray Duncan ;may be freely reproduced for noncommercial use cr equ 0dh ;ASCII carriage return lf equ 0ah ;ASCII linefeed blank equ 20h ;ASCII space adr equ 65535 command equ 80h ;buffer for command tail blksize equ 512 ;size of inputfile output_handle equ 1 ;handle of standard output ;device(redirectable) error_handle equ 2 ;handle of standard error device (not ;redirectable) cseg segment para public 'CODE' assume cs:cseg,ds:data,es:data,ss:stack include dump.pub dump proc far ;entry point from DOS push ds ;save DS:0000 for final xor ax,ax ;return to MS-DOS push ax mov ax,data ;make our data segment mov es,ax ;addressable via ES mov ah,30h ;check version DOS int 21h cmp al,2 jae dump1 ;proceed if DOS 2 or greater mov dx,offset msg3 ;DOS 1.x-print error msg mov ax,es ;we must use old DOS mov ds,ax ;string output function mov ah,9 ;since handles not int 21h ;avail this vers DOS ret dump1: call get_filename ;get path and filespec for input ;file from command line tail mov ax,es ;Set DS=ES for remainder mov ds,ax ;of program jnc dump2 ;jump got acceptable name mov dx,offset msg2 ;missing or illegal mov cx,msg2_length ;filespec jmp dump9 ;print error and exit dump2: call open_input ;now try to open input jnc dump3 ;file-jump opened ok mov dx,offset msg1 ;open input file failed mov cx,msg1_length jmp dump9 ;print error and exit dump3: call read_block ;initialize input buffer jnc dump4 ;jump, got a block mov dx,offset msg4 ;empty file,print error mov cx,msg4_length ;message and exit jmp dump9 dump4: call get_char ;file successfully opened jc dump8 ;now convert and display it. inc input_addr ;read 1 char from input ;jump, if end of file ;update file position or bx,bx ;is this 1st char blk jnz dump5 ;no call print_heading ;yes dump5: and bx,0fh ;is this 1st byte of 16? jnz dump6 ;no,jump push ax ;save the byte mov di,offset output ;convert relative file addr mov ax,input_addr ;for output string call conv_word pop ax dump6: ;store ascii vers of ;char if it is alphanumeric mov di,offset outputb add di,bx ;calculate output string mov byte ptr [di],'.' ;addr if it is control cmp al,blank ;char,just print dot jb dump7 ;jump, not alphanumeric cmp al,7eh ja dump7 ;jump,not alphanumeric mov [di],al ;store ascii char dump7: ;now convert binary byte ;to hex ascii equivalent push bx ;save offset 0-15 this ;byte calculates its posn in ;output string mov di,offset outputa add di,bx ;base addr + offset*3 add di,bx add di,bx call conv_byte ;conv data byte to hex pop bx ;restore byte offset cmp bx,0fh ;16 bytes converted yet jne dump4 ;no,get another byte mov dx,offset output mov cx,output_length call write_std ;yes,print line jmp dump4 ;get next char from ;input file dump8: call close_input ;end of file detected ret ;close input file dump9: call write_error ;come here to print msg ret ;on std error device ;and return cntrl to DOS dump endp get_filename proc near ;process name of input file ;return carry=0 if successful ;return carry=1 if unsuccessful ;if no filename DS:SI<-addr command line mov si,offset command ;ES:DI<-addr filespec buffer mov di,offset input_name cld lodsb ;any command line present? or al,al ;return error status if not jz get_filename4 get_filename1: ;scan over leading blank lodsb ;to filename cmp al,cr ;if we hit return je get_filename4 ;yes,exit with code cmp al,20h ;is this a blank je get_filename1 ;if not keep moving get_filename2: ;found 1st char of name stosb ;move last char lodsb ;check next char, found cmp al,cr ;cr yet? je get_filename3 ;yes,exit with success cmp al,20h ;code. is this a blank? jne get_filename2 ;if not keep moving char get_filename3: clc ;exit with carry=0 ret ;for success flag get_filename4: stc ;exit with carry=1 ret ;for error flag get_filename endp open_input proc near ;open input file ;DS:DX=addr filename mov dx,offset input_name mov al,0 ;AL=0 for read only mov ah,3dh ;function 3dh = open int 21h ;handle returned in AX mov input_handle,ax ;save it for later ret ;CY is set if error open_input endp close_input proc near ;close input file mov bx,input_handle ;BX=handle mov ah,3eh int 21h ret close_input endp get_char proc near ;get one char from ;input buffer mov bx,input_ptr ;return AL=char BX=buffer cmp bx,blksize ;offset. CY=1 if eof jne get_char1 ;is ptr at end of buffer mov input_ptr,0 call read_block ;new block read from disk jnc get_char ;got blk start routine ret ;over get_char1: ;get data byte to AL mov al,[input_buffer+bx] inc input_ptr ;bump input buffer ptr clc ;return CY flag=0 since ret ;not end of file get_char endp read_block proc near ;read block of data from mov bx,input_handle ;input file CY=0 if ok mov cx,blksize ;CY=1 if end of file mov dx,offset input_buffer ;request read mov ah,3fh ;from D int 21h inc input_block ;initialize pointers mov input_ptr,0 or ax,ax ;was anything read in? ;or turns off CY flag jnz read_block1 stc ;no, eof return CY=true read_block1: ret read_block endp write_std proc near ;write string to std ;output call DX=addr ;of out string CX=lgth mov bx,output_handle ;of string mov ah,40h ;function 40=write to file int 21h ;or device function call. ret write_std endp write_error proc near ;write str to std error ;device call DX=addr ;of output string ;CX=length of string mov bx,error_handle ;BX=handle for std error mov ah,40h ;device funct 40h=write int 21h ;to device ret write_error endp print_heading proc near push ax ;print record nr and push bx ;heading for block mov di,offset headinga ;of data 1st save reg mov ax,input_block call conv_word ;convert record nr to mov dx,offset heading ;ascii mov cx,heading_length call write_std ;now print heading pop bx pop ax ;restore registers ret ;and exit print_heading endp conv_word proc near ;conv 16 bit word to hex ;call with ax=binary val ;DI=addr to store string ;AX,DI,CX destroyed push ax mov al,ah call conv_byte ;convert upper byte pop ax call conv_byte ;convert lower byte ret conv_word endp conv_byte proc near ;convert binary byte ;to hex ascii ;call with al=binary ;DI=addr to store str sub ah,ah ;clear upper byte mov cl,16 div cl ;div binary by 16 call ascii ;remainder becomes stosb ;second ascii char mov al,ah call ascii stosb ret conv_byte endp ascii proc near ;conv last 4 bits inAL add al,'0' cmp al,'9' jle ascii2 ;jump if range 0-9 add al,'A'-'9'-1 ;offset to range A-F ascii2: ret ;return ascii char AL ascii endp cseg ends data segment para public 'DATA' input_name db 64 dup (0) ;buffer for input file input_handle dw 0 ;token for dos input input_ptr dw 0 ;ptr to input deblocking input_addr dw adr ;relative addr in file input_block dw 0 ;current in block nr. output db 'nnnn',blank,blank outputa db 16 dup ('00',blank) db blank outputb db '0123456789ABCDEF',cr,lf output_length equ $-output heading db cr,lf,'RECORD',blank headinga db 'nnnn',blank,blank,cr,lf db 7 dup(blank) db '0 1 2 3 4 5 6 7 ' db '8 9 A B C D E F',cr,lf heading_length equ $-heading input_buffer db blksize dup(?) msg1 db cr,lf db 'Cannot find input file' db cr,lf msg1_length equ $-msg1 msg2 db cr,lf db 'Missing file name.' db cr,lf msg2_length equ $-msg2 msg3 db cr,lf db 'Requires MS-DOS version 2 or greater' db cr,lf,'$' msg4 db cr,lf,'Empty File.',cr,lf msg4_length equ $-msg4 data ends stack segment para stack 'STACK' db 64 dup(?) stack ends end dump