Programming Forums > Application Development > Assembly

headzoo · Jan 1st, 2008, 11:53 AM

Howdy all,
I'm kind of new to assembly, and I'm using NASM 2.00. I've learned that you can dereference a value from an address stored in a register, or in memory, by enclosing the memory address in brackets, like this:

mov eax, [memory_location]

As far as I can tell, this is similar to using * to dereference a pointer in C.

I can't figure out how to do the same for an address pushed on the stack, from inside a procedure.

Example:

(Toggle Plain Text)

	push memory_location
	call my_procedure
	
my_procedure:
	push ebp
	mov ebp, esp
	
	mov eax, [ebp + 8]

The last instruction will move the address stored at [ebp + 8] into the eax register. What I'd like to do is dereference the value stored at [ebp + 8], and store that in eax.

Can that be done in one instruction? Or do I have to do something like this:

(Toggle Plain Text)

	mov eax, [ebp + 8]
	mov edx, [eax]

Jan 1st, 2008, 11:53 AM	#1
headzoo Newbie Join Date: Oct 2006 Posts: 14 Rep Power: 0	Dereference Value on the Stack Howdy all, I'm kind of new to assembly, and I'm using NASM 2.00. I've learned that you can dereference a value from an address stored in a register, or in memory, by enclosing the memory address in brackets, like this: mov eax, [memory_location] As far as I can tell, this is similar to using * to dereference a pointer in C. I can't figure out how to do the same for an address pushed on the stack, from inside a procedure. Example: (Toggle Plain Text) push memory_location call my_procedure my_procedure: push ebp mov ebp, esp mov eax, [ebp + 8] push memory_location call my_procedure my_procedure: push ebp mov ebp, esp mov eax, [ebp + 8] The last instruction will move the address stored at [ebp + 8] into the eax register. What I'd like to do is dereference the value stored at [ebp + 8], and store that in eax. Can that be done in one instruction? Or do I have to do something like this: (Toggle Plain Text) mov eax, [ebp + 8] mov edx, [eax] mov eax, [ebp + 8] mov edx, [eax]

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Programming Forums > Application Development > Assembly

Dereference Value on the Stack