[$2 vs $ + 2] How to declare jump to relative address

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Art Vandelay

Joined: 23 Jan 2015
Posts: 2
Location: Canada

Art Vandelay 23 Jan 2015, 20:53

How can I jump ahead by a certain number of bytes? Doing something like jmp 2 attempts to jump to the address 0x00000002 in memory, instead of EB 02.

Aside from entering it in bytes, I can't figure out how to do it. Is there something I can enter that specifies the address is relative? I'm trying to play around with jump tables and things like that, and writing in hex is a pain to read.

23 Jan 2015, 20:53

RIxRIpt

Joined: 18 Apr 2013
Posts: 50

RIxRIpt 23 Jan 2015, 20:56

1.2.4 Numerical expressions:

Quote:

There are also some special symbols that can be used inside the numerical expression. First is $, which is always equal to the value of current offset, while $$ is equal to base address of current addressing space.

Code:

jmp $ + 2 ;EB 02

23 Jan 2015, 20:56

Art Vandelay

Joined: 23 Jan 2015
Posts: 2
Location: Canada

Art Vandelay 23 Jan 2015, 21:02

thanks

I tried doing jmp $2 when I read that section of the documentation *facepalm*

23 Jan 2015, 21:02

DOS386

Joined: 08 Dec 2006
Posts: 1903

DOS386 30 Jan 2015, 10:27

Welcome to the FASM forum. The dollar symbol can also prefix HEX numbers:

Code:

MOV CL, $2 ; Same as "MOV CL, 2"
MOV EAX, $FFFF'FFFF
INC EAX ; Will be ZERO now

30 Jan 2015, 10:27

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