What is the x86 “ret” instruction equivalent to?

Question

Say I\'m writing a routine in x86 assembly, like, \"add\" which adds two numbers passed as arguments.

For the most part this is a very simple method:

Answer 1

This does not need any free registers to simulate ret, but it needs 4 bytes of memory (a dword). Uses indirect jmp. Edit: As noted by Ira Baxter, this code is not reentrant. Works fine in single-threaded code. Will crash if used in multithreaded code.

push ebp
mov  ebp, esp
mov  eax, [ebp+8]
add  eax, [ebp+12]
mov  ebp, [ebp+4]
mov  [return_address], ebp
pop  ebp

add  esp,4
jmp  [return_address]

.data
return_address dd 0

To replace only the ret instruction, without changing the rest of the code. Not reentrant. Do not use in multithreaded code. Edit: fixed bug in below code.

push ebp
mov  ebp, esp
mov  ebp, [ebp+4]
mov  [return_address], ebp
pop  ebp

add  esp,4
jmp  [return_address]

.data
return_address dd 0