flat assembler

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pool

Joined: 08 Jan 2007
Posts: 97

pool 03 Jan 2013, 01:03

Last edited by pool on 17 Mar 2013, 12:12; edited 1 time in total

03 Jan 2013, 01:03

nop

Joined: 01 Sep 2008
Posts: 165
Location: right here left there

nop 03 Jan 2013, 01:37

Code:

mov esp,top_of_stack
 

<rest of code>



top_of_stack:
times 256 db ? ;or whateva size stack u want or need

03 Jan 2013, 01:37

pool

Joined: 08 Jan 2007
Posts: 97

pool 03 Jan 2013, 02:12

Last edited by pool on 17 Mar 2013, 12:14; edited 1 time in total

03 Jan 2013, 02:12

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 03 Jan 2013, 03:41

pool wrote:

just that? I thought it be more hard. Can I also do this?:

invoke SomeMemoryAlloc, 256
mov esp, eax

<rest of code>

thanks nop

lol. hahahaha

So where do you want the function to return?

You're using the stack before it's set up.

03 Jan 2013, 03:41

baldr

Joined: 19 Mar 2008
Posts: 1651

baldr 03 Jan 2013, 10:27

Now think of it again: stack grows top-down (i.e. to lower addresses), and both examples set esp to the start of memory block.

03 Jan 2013, 10:27

sinsi

Joined: 10 Aug 2007
Posts: 786
Location: Adelaide

sinsi 03 Jan 2013, 11:00

nop wrote:

Code:

mov esp,top_of_stack
 

<rest of code>



top_of_stack:
times 256 db ? ;or whateva size stack u want or need

Bad

Code:

mov esp,top_of_stack
 

<rest of code>



times 256 db ? ;or whateva size stack u want or need
top_of_stack:

Better

03 Jan 2013, 11:00

pool

Joined: 08 Jan 2007
Posts: 97

pool 03 Jan 2013, 11:22

Last edited by pool on 17 Mar 2013, 12:14; edited 1 time in total

03 Jan 2013, 11:22

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 03 Jan 2013, 17:01

pool wrote:

So my code would be:

Code:


push 256
call SomeMemoryAlloc ;invoke SomeMemoryAlloc, 256

add eax, 256 ;convert it to higher address for stack setup
mov esp, eax

<rest of code>

hahaha. You need to setup the stack itself first before you call any function. Unless it knows where to return.

03 Jan 2013, 17:01

HaHaAnonymous

Joined: 02 Dec 2012
Posts: 1178
Location: Unknown

HaHaAnonymous 03 Jan 2013, 17:08

[ Post removed by author. ]

Last edited by HaHaAnonymous on 28 Feb 2015, 22:06; edited 1 time in total

03 Jan 2013, 17:08

pool

Joined: 08 Jan 2007
Posts: 97

pool 03 Jan 2013, 17:28

Last edited by pool on 17 Mar 2013, 12:14; edited 1 time in total

03 Jan 2013, 17:28

cod3b453

Joined: 25 Aug 2004
Posts: 618

cod3b453 03 Jan 2013, 18:40

Windows will normally allocate separate page regions for each thread stack but the code you have will work too as long as the memory region is a valid read/write area and large enough. In fact, I'm using this to debug thread/virtual-syscall code for my OS project in VS2010.

03 Jan 2013, 18:40

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