[solved] Xor qword

flat assembler
Message board for the users of flat assembler.

Index > Main > [solved] Xor qword

Author

Thread

AE

Joined: 07 Apr 2022
Posts: 72

AE 11 Apr 2022, 17:37

What would be the shortest way to implement such a pseudocode

Code:

xor rax, 7E7E7E7E7E7E7E7Eh

11 Apr 2022, 17:37

ProMiNick

Joined: 24 Mar 2012
Posts: 817
Location: Russian Federation, Sochi

ProMiNick 11 Apr 2022, 17:48

if operand cannot be encoded as imm part of instruction fastest way to place it in initialized data:

Code:

format PE64 GUI
entry start

section '.text' code readable executable

  start:
        xor     rax,qword[xorpattern]

section '.data' data readable writeable

  xorpattern db 8 dup ($7E)

11 Apr 2022, 17:48

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20513
Location: In your JS exploiting you and your system

revolution 11 Apr 2022, 20:05

You can do 64-bit loads into an unused register.

Code:

mov r8, 0x7E7E7E7E7E7E7E7E
xor rax, r8

11 Apr 2022, 20:05

AE

Joined: 07 Apr 2022
Posts: 72

AE 11 Apr 2022, 20:27

Thanks! That's it.

11 Apr 2022, 20:27

< 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