Can Someone Explain What Is The Push Opcode?

[exassasinx]

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[DrummerIX]

In most cases the register rsp or esp holds the address of the top of the stack

[MartaLabieniec]

But what means push? What means push 00000163?

[Bloodybone]

But what means push? What means push 00000163?

It loads("pushes") the hex value of 163 onto the top of the stack. That means that the value will be in [esp] for x32 or [rsp] in the case of x64. If there is another push after that instruction for example push 00000100 then [esp]/[rsp] contains the hex value of 100 and [esp+4]/[rsp+4] contains the hex value of 163. At least if the second value pushed onto the stack is 4 bytes big, if it is 8 bytes big then [esp+8]/[rsp+8] would contain the first value pushed onto the stack.

Instead of push 163 you could also write:

Code: Select all

sub esp,4 // or rsp and sub 8 for 8-Bytes big values 
mov [esp],163

Edit: If you want more information you can read these:

[Link]

[Link]

And maybe this:

[Link]