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

flat assembler
Message board for the users of flat assembler.

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

Author

Thread

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: 1898

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

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum