;************************************************************************;*;* SHOWMEM (C) 1997 RonSoft. *;* *;* A little utility thats shows what's in a given mem position. *;* Usage: *;* Showmem *;* Where segment and offset are 16 bit hexadecimal values or *;* a single 32 bit value. *;* Just like this: *;* Showmem 00000000 or Showmem 0. *;* *;* Ronald Nordberg. *;* Silverv刧en 3 *;* 907 50 Ume? *;* Sweden *;* christine.martinson@swipnet.se *;* http://home2.swipnet.se/~w-20064 *;* *;* THIS IS ALL PUBLIC DOMAIN FREEWARE. *;* LET EM KNOW IF YOU USE MY CODE. *;* *;************************************************************************ ;some euqates for readabilitykbd equ 16h ;keyboard irqmsdos equ 21h ;MSDOS irqreset equ 0dh ;disk resetdfopen equ 0fh ;open disk filedfclose equ 10h ;close disk filesearchf equ 11h ;search firstsearchn equ 12h ;search nextseqread equ 14h ;sequential disk readseqwrite equ 15h ; " " writesetdta equ 1ah ;set disk transfer area addresscreatef equ 3ch ;create file with handleopenf equ 3dh ;open file with handleclosef equ 3eh ;close file with handlereadf equ 3fh ;read from file with handlewritef equ 40h ;write to file with handlesetfp equ 42h ;set file pointerallocmem equ 48h ;allocate memoryfreemem equ 49h ;free memorychangebs equ 4ah ;change block sizefindfirst equ 4eh ;find first fileexit equ 4c00h ;msdos exit[BITS 16] ;NASM stuff[ORG 0x100]s1: mov ax,cs ;get code segment mov ds,ax ;use it now mov [comseg],ds ;save it there mov si,0080h ;DOS command line page 0 lodsb ;load size of command line cmp al,0 ;anything on command line ? jbe usage ;noo, show usage cbw ;extend AL to AX xchg bx,ax ;swap size to bx for indexing mov byte [bx+si],0 ;null terminate command line call parse ;parse command line jmp main ;go on with mainusage: mov bx,utext ;pointer usage text jmp errout ;skip thismain: mov si,inbuff ;check for valid HEX input mov bx,errt1 ;proper textishex: lodsb ;get the char cmp al,'0' jb errout and al,0dfh ;force UPPERCASE cmp al,'F' ;>F ? ja errout ;yeahh, dump this loop ishex call hexbin ;make hex bin ;start address now in EDX mov ax,dx ;get low word (segment) mov es,ax ;start segment shr edx,16 ;shift in offset mov di,dx ;start offsetdopage: push es ;save registers push di push ds push si mov ax,es mov ds,ax ;make ds=es mov si,di ;and si=di call showpage ;show it pop si ;restore registers pop ds pop di pop es add di,512 ;adjust memory position ;xor ah,ah ;wait for ANY key ;int kbd mov bx,text ;show message call write mov ah,0 ;wanna see next screen ? int kbd ;chek out keyboard buffer and al,0DFh ;force UPPER CASE cmp al,"Q" ;wanna quit ? je quit ;yeahh jmp dopageerrout: call writequit: mov ax,exit int msdos;***********************************************************;* Convert ascii hex to 32 bit binary;* Input = command line buffer, output EDX;***********************************************************hexbin: mov si,inbuff ;pointer command line buffer xor edx,edx ;clear binary outputaschexbin: lodsb cmp al,'0' ;< 0 jb notasc ;yes invalid character cmp al,'9' ;<= 9 jbe astrip ;yes, strip high 4 bits and al,05fh ;force upper case cmp al,'A' ;< ascii A jb notasc ;yes, invalid character cmp al,'F' ;> ascii F ja notasc ;yes, invalid character add al,9 ;ok, add 9 for stripastrip: and al,0fh ;strip high 4 bits mov cx,4 ;set shift count shl edx,cl ;rotate EDX 4 bits xor ah,ah ;zero out AH cbw add edx,eax ;add digit to value jmp aschexbin ;continuenotasc: ret;*********************************************************************;* Format and show the stuff in a "sector";* Input SI;*********************************************************************showpage: mov cx,32 ;32*16=512arow: push cx mov di,outline ;output buffer mov cx,16 ;process 16 byteshexrow: push cx lodsb ;load al with byte mov dl,al ;get value mov cx,2 ;2 nibbleschexb: push cx ;save that mov cl,4 ;4 bits rol dl,cl ;rotate source left mov al,dl ;move digit into AL and al,15 ;clear high nibble daa ;adjust AL if A through F add al,240 ;bump the carry adc al,40h ;convert HEX to ASCII stosb ;copy to buffer pop cx ;get digit counter loop chexb ;next digit mov al,32 ;copy a SPACE stosb pop cx ;restore loop counter loop hexrow ;loop on mov al,32 ;copy 2 spaces stosb stosb sub si,16 ;adjust source back mov cx,16 ;copy ASCII bytescccp: lodsb cmp al,32 ;< SPACE ? jb noa ;yeahh, skip it stosb ;no, store in buffer jmp nextnoa: mov al,'.' stosbnext loop cccp mov al,13 stosb mov al,10 stosb mov al,0 ;null terminate line stosb mov bx,outline ;show the line call write pop cx cmp cx,17 jne nopause push ds mov ax,cs mov ds,ax mov bx,text1 call write pop ds xor ah,ah int kbdnopause: loop arow ;next 16 bytes ret;************************************************************************';* Convert bin WORD to HEX ascii. Input DX. Result in Numbuff *;************************************************************************binhex: pusha mov di,numbuff ;destination buffer mov dx,[count] ;binary number mov cx,4 ;four nibblesconvhex: push cx ;save counter mov cl, 4 ;4 bits rol dx, cl ;rotate source left mov al, dl ;move digit into AL and al, 15 ;clear high nibble daa ;adjust AL if A through F add al, 240 ;bump the carry adc al, 40h ;convert HEX to ASCII stosb ;copy to buffer pop cx ;get digit counter loop convhex ;next digit mov al,32 ;copy a space stosb mov al,0 ;null terminate stosb popa ret;*************************************************************************;* Writes out the NULL terminated text supplied in BX. *;* OR writes out data,BX and size,CX if called at lwrite. *;*************************************************************************write: pusha mov si,bx ;copy to SI mov cx,0 ;clear countwloop: lodsb ;load AL with SI cmp al,0 ;end of line ? je lwrite ;yeahh inc cx ;no, incrase byte count jmp wloop ;test next bytelwrite: mov dx,bx ;text address in DX mov bx,1 ;filehandle standard output = 1 mov ah,writef ;MS-DOS writefile with handle is 040 int msdos ;write buffer to standard output popa ret ;done;*************************************************************************;* My kind of command line parsing. It just checks if there飐;* any blankspaces between the options. The parameters ends up;* in the inbuff separated by 0:s, binary zeroes.;*************************************************************************parse: mov di,inbuff ;our bufferifspc: cmp byte [si],32 ;leading space ? jne nospc ;noo inc si ;yeahh, dump that jmp ifspc ;check nextnospc: mov cx,1 ;were here, so we got one argcopy1: lodsb ;load byte SI to AL cmp al,0 ;0 ?(end of line) je done ;yeahh cmp al,32 ;SPACE ? je cop2 ;yeah stosb ;noo, move AL to DI, incrase DI jmp copy1 ;go oncop2: mov byte [di],0 ;null terminate add cx,1 inc di ;dump that byte(SPACE) jmp copy1 ;backdone: mov byte [di],0 ;null terminate ret ;return;*************************** DATA STUFF **********************************XMS_SEGMENT dw 0XMS_OFFSET dw 0inbuff times 64 dw 0 ;128 byte command line bufferoutline times 40 dw 0 ;buffer output linenumbuff times 7 dw 0 ;word ascii number buffercomseg dw 0count dw 0bcount dw 0acount dw 0;outbuff times 512 db 0utext db 'Showmem (C) 1997 RonSoft.',13,10 db 'Usage: Showmem [start address].',13,10 db 'Start address = Hexadecimal.',13,10,0text: db 13,10,'Q = Quit. Any key = Next page.',13,10,0text1: db 13,10,'Any Key = Next 256 Bytes.',13,10,0errt1: db 'That address is not hexadecimal.',13,10,0s2:END
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