283 lines
12 KiB
NASM
283 lines
12 KiB
NASM
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kbd equ 16h ;keyboard irq
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msdos equ 21h ;MSDOS irq
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reset equ 0dh ;disk reset
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dfopen equ 0fh ;open disk file
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dfclose equ 10h ;close disk file
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searchf equ 11h ;search first
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searchn equ 12h ;search next
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seqread equ 14h ;sequential disk read
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seqwrite equ 15h ; " " write
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setdta equ 1ah ;set disk transfer area address
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createf equ 3ch ;create file with handle
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openf equ 3dh ;open file with handle
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closef equ 3eh ;close file with handle
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readf equ 3fh ;read from file with handle
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writef equ 40h ;write to file with handle
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setfp equ 42h ;set file pointer
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allocmem equ 48h ;allocate memory
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freemem equ 49h ;free memory
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changebs equ 4ah ;change block size
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findfirst equ 4eh ;find first file
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exit equ 4c00h ;msdos exit
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[BITS 16] ;NASM stuff
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[ORG 0x100]
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s1:
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mov ax,cs ;get code segment
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mov ds,ax ;use it now
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mov [comseg],ds ;save it there
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mov si,0080h ;DOS command line page 0
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lodsb ;load size of command line
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cmp al,0 ;anything on command line ?
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jbe usage ;noo, show usage
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cbw ;extend AL to AX
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xchg bx,ax ;swap size to bx for indexing
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mov byte [bx+si],0 ;null terminate command line
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call parse ;parse command line
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jmp main ;go on with main
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usage: mov bx,utext ;pointer usage text
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jmp errout ;skip this
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main:
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mov si,inbuff ;check for valid HEX input
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mov bx,errt1 ;proper text
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ishex: lodsb ;get the char
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cmp al,'0'
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jb errout
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and al,0dfh ;force UPPERCASE
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cmp al,'F' ;>F ?
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ja errout ;yeahh, dump this
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loop ishex
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call hexbin ;make hex bin
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;start address now in EDX
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mov ax,dx ;get low word (segment)
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mov es,ax ;start segment
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shr edx,16 ;shift in offset
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mov di,dx ;start offset
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dopage:
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push es ;save registers
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push di
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push ds
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push si
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mov ax,es
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mov ds,ax ;make ds=es
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mov si,di ;and si=di
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call showpage ;show it
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pop si ;restore registers
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pop ds
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pop di
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pop es
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add di,512 ;adjust memory position
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;xor ah,ah ;wait for ANY key
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;int kbd
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mov bx,text ;show message
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call write
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mov ah,0 ;wanna see next screen ?
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int kbd ;chek out keyboard buffer
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and al,0DFh ;force UPPER CASE
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cmp al,"Q" ;wanna quit ?
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je quit ;yeahh
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jmp dopage
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errout:
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call write
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quit:
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mov ax,exit
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int msdos
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;***********************************************************
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;* Convert ascii hex to 32 bit binary
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;* Input = command line buffer, output EDX
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;***********************************************************
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hexbin:
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mov si,inbuff ;pointer command line buffer
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xor edx,edx ;clear binary output
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aschexbin:
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lodsb
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cmp al,'0' ;< 0
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jb notasc ;yes invalid character
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cmp al,'9' ;<= 9
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jbe astrip ;yes, strip high 4 bits
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and al,05fh ;force upper case
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cmp al,'A' ;< ascii A
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jb notasc ;yes, invalid character
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cmp al,'F' ;> ascii F
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ja notasc ;yes, invalid character
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add al,9 ;ok, add 9 for strip
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astrip:
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and al,0fh ;strip high 4 bits
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mov cx,4 ;set shift count
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shl edx,cl ;rotate EDX 4 bits
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xor ah,ah ;zero out AH
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cbw
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add edx,eax ;add digit to value
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jmp aschexbin ;continue
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notasc: ret
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;*********************************************************************
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;* Format and show the stuff in a "sector"
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;* Input SI
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;*********************************************************************
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showpage:
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mov cx,32 ;32*16=512
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arow: push cx
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mov di,outline ;output buffer
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mov cx,16 ;process 16 bytes
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hexrow: push cx
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lodsb ;load al with byte
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mov dl,al ;get value
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mov cx,2 ;2 nibbles
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chexb: push cx ;save that
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mov cl,4 ;4 bits
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rol dl,cl ;rotate source left
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mov al,dl ;move digit into AL
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and al,15 ;clear high nibble
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daa ;adjust AL if A through F
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add al,240 ;bump the carry
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adc al,40h ;convert HEX to ASCII
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stosb ;copy to buffer
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pop cx ;get digit counter
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loop chexb ;next digit
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mov al,32 ;copy a SPACE
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stosb
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pop cx ;restore loop counter
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loop hexrow ;loop on
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mov al,32 ;copy 2 spaces
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stosb
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stosb
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sub si,16 ;adjust source back
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mov cx,16 ;copy ASCII bytes
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cccp: lodsb
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cmp al,32 ;< SPACE ?
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jb noa ;yeahh, skip it
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stosb ;no, store in buffer
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jmp next
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noa: mov al,'.'
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stosb
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next loop cccp
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mov al,13
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stosb
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mov al,10
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stosb
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mov al,0 ;null terminate line
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stosb
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mov bx,outline ;show the line
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call write
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pop cx
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cmp cx,17
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jne nopause
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push ds
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mov ax,cs
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mov ds,ax
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mov bx,text1
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call write
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pop ds
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xor ah,ah
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int kbd
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nopause:
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loop arow ;next 16 bytes
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ret
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;************************************************************************'
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;* Convert bin WORD to HEX ascii. Input DX. Result in Numbuff *
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;************************************************************************
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binhex: pusha
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mov di,numbuff ;destination buffer
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mov dx,[count] ;binary number
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mov cx,4 ;four nibbles
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convhex:
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push cx ;save counter
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mov cl, 4 ;4 bits
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rol dx, cl ;rotate source left
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mov al, dl ;move digit into AL
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and al, 15 ;clear high nibble
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daa ;adjust AL if A through F
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add al, 240 ;bump the carry
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adc al, 40h ;convert HEX to ASCII
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stosb ;copy to buffer
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pop cx ;get digit counter
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loop convhex ;next digit
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mov al,32 ;copy a space
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stosb
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mov al,0 ;null terminate
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stosb
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popa
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ret
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;*************************************************************************
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;* Writes out the NULL terminated text supplied in BX. *
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;* OR writes out data,BX and size,CX if called at lwrite. *
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;*************************************************************************
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write: pusha
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mov si,bx ;copy to SI
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mov cx,0 ;clear count
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wloop: lodsb ;load AL with SI
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cmp al,0 ;end of line ?
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je lwrite ;yeahh
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inc cx ;no, incrase byte count
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jmp wloop ;test next byte
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lwrite: mov dx,bx ;text address in DX
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mov bx,1 ;filehandle standard output = 1
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mov ah,writef ;MS-DOS writefile with handle is 040
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int msdos ;write buffer to standard output
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popa
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ret ;done
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;*************************************************************************
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;* My kind of command line parsing. It just checks if there<72>s
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;* any blankspaces between the options. The parameters ends up
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;* in the inbuff separated by 0:s, binary zeroes.
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;*************************************************************************
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parse:
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mov di,inbuff ;our buffer
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ifspc: cmp byte [si],32 ;leading space ?
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jne nospc ;noo
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inc si ;yeahh, dump that
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jmp ifspc ;check next
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nospc: mov cx,1 ;were here, so we got one arg
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copy1: lodsb ;load byte SI to AL
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cmp al,0 ;0 ?(end of line)
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je done ;yeahh
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cmp al,32 ;SPACE ?
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je cop2 ;yeah
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stosb ;noo, move AL to DI, incrase DI
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jmp copy1 ;go on
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cop2: mov byte [di],0 ;null terminate
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add cx,1
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inc di ;dump that byte(SPACE)
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jmp copy1 ;back
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done: mov byte [di],0 ;null terminate
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ret ;return
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;*************************** DATA STUFF **********************************
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XMS_SEGMENT dw 0
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XMS_OFFSET dw 0
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inbuff times 64 dw 0 ;128 byte command line buffer
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outline times 40 dw 0 ;buffer output line
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numbuff times 7 dw 0 ;word ascii number buffer
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comseg dw 0
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count dw 0
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bcount dw 0
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acount dw 0
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;outbuff times 512 db 0
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utext db 'WWW',13,10
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db 'Usage: Showmem [start address].',13,10
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db 'Start address = Hexadecimal.',13,10,0
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text: db 13,10,'Q = Quit. Any key = Next page.',13,10,0
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text1: db 13,10,'Any Key = Next 256 Bytes.',13,10,0
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errt1: db 'That address is not hexadecimal.',13,10,0
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s2:
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END
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