Storing String (Texts) :: ASM

[kuphryn]

Hi.

How do you store a string of characters in a variable or register?

-----
...
.DATA

// This line works.
MyString DB 'testing $'

// This line does not work.
// MASM error is: error A2084: constant value too large

MyString DB ?

.CODE

mov MyString, 'testing 1 2 3'
-----

I would like to know how to move a string of characters to a variable and/or a register at any point of the code instead of just in .DATA.

Thanks,
Kuphryn

[Fordy]

Here's some code for MASM...(though its set for DOS and you will need the old 16 bit linker to get it to work - that's available at http://spiff.tripnet.se/~iczelion/)

.286
.model small

MYSTACK SEGMENT STACK
db 512 DUP('?')		
MYSTACK ENDS

MYDATA SEGMENT   
source db "Hello World",0
string db 50 DUP(0)
MYDATA ENDS

;#####################################################
;#####################################################



.CODE              
start:

	;
	; 1 - Sort out the segemnts
	;
	
	mov ax,MYDATA			;get data segment address
	mov es,ax			;mov into ES...
	mov ds,ax			;...and DS
	
	;
	;2 - Get string length
	;
	
	lea di, source			;load address of string
	xor ax,ax 			;ax = 0 
	mov cx,0FFFFh			;cx = max str len
	repnz scasb			;scan for NULL
	neg cx				;cx = -len..so make pos
	dec cx				;dec for 2s comp
	push cx				;save on stack
	
	;
	;3 - Copy data
	;
	
	cld				;clear direction flag
	lea si,source			;load source
	lea di,string			;load destination
	rep movsb			;copy cx amount of bytes
	
	;
	;4 - Print to screen
	;
	
	pop cx				;restore cx
	lea dx,string			;reload string in dx
	mov ah,40h			;print to screen
	mov bx,1			;output handle 1
	int 21h				;call dos
	
	;
	;5 - Exit prog
	;
	
	mov ax,4C00h			;dos exit
	int 21h				;call dos


end start

Get used to storing data in segments....the other option you have is building stack frames....and if you dont know what you are doing its difficult....

[kuphryn]

Okay. Thanks.

Your solution is a bit more than what I know right now. I will be able to understand your solution within the next three weeks.

Kuphryn