Self-modifying code: Difference between revisions

Revision as of 17:34, 22 January 2004

Revision as of 18:02, 22 January 2004

Line 62:

code_starts_here:

xor cx, cx ; zero register cx

xor ax, ax ; zero register ax

Line 80 ⟶ 81:

dw 0 ; and then the code segment (calculated above)

flush_queue:

mov [nop_field+cx], 0x40 ; 0x40 = opcode "inc ax" (INCrease ax)

Line 94 ⟶ 95:

; well. (dw and dx = 16 bit adressing, dd and edx = 32 bit adressing)

;

What this code does is basicly that it changes the execution flow, and determines by [[brute force]] how large the PIQ. "How far away does I have to change the code in front of me for it to change the value in ax?", if it is too near (it is already in the PIQ) the update will not have any affect.