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So guys in the studio, we are going to see another important topic called Stack and Stuckey's refolded

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are structure stands, transfer to foster data structure.

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It means that when you're in certain elements into the stack and it will be the last element you need

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to take back from the stack.

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The example for the stack is stack of books.

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So in this example, let's you have a table and you have 10 books and you will place the books one one

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by one on the top of each other.

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So you'll play the first book on top of the first book.

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You play the second book.

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And on the top of the second book, you play the third book and so on, on top of the ninth president.

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And so in order to take the books, you need to first take the to write.

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You cannot take from sideways.

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You only need to take from the top.

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So that means you need to take the first and the book and then the ninth book and then eight and so

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on a per second book.

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And finally the last book will be the first book.

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So this behavior is called Ashton Foster.

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That's very striking correlation, foster data structure.

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And also we can only perform two operations on the stack.

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Those operations are called push and pop operations.

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Push operation can be construed as placing the book on the table and pop operation can be considered

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as taking the book from the stack of books.

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So pushing means pushing an element to the stack and taking the top of the element furniture.

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So this Abipon and E.S.P are registers are not covering in the resistance will go.

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No, I'm going to cover this.

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EVP is called Base Pointer and EVP points to the base of this time frame.

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It means that EVP points to the starting of the political spectrum and E.S.P, which is the stack pointer

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points to the top of the spectrum.

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So if you keep on pushing the elements out of the stack, then E.S.P will point to the top of the top

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element of the stack frame.

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So if you if this sounds confusing, don't worry.

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I will I will be showing some diagrams now.

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Now, let's consider these two instructions.

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Firstly, the push SBP.

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So actually this is called the function prodrug.

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It means that whenever there is a new function in any other language like C, then a new style frame

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is created for that particular function.

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And whenever that function has been written or exited, then this time frame gets collapse.

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So this is the function product and this creates a new structure.

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And this does by pushing that SBP, which is the previous function stack frame, and this value gets

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pushed out of the stack.

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Now you can see Push EVP has been executed and the theory will be this points to the this function stack

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from previous functions and more will become ISP.

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So we are moving the E.S.P value to the IP so that these Google points to the base of the stack.

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That is the beginning of the stack.

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So these two instructions need to coordinate assembly, but because we will be coding and programming

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that start function.

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So I wetering this concept.

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So our START premise created no E.S.P.

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EBP both points to the starting of the stack.

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There are no elements.

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And from this address, four two three one four eight four, our stack begins.

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This is the third SBP address.

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Not what I'm going to do is I'm going to push an element.

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Let's say I want to push the value.

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So this file will be placed on the top of the stack and E.S.P points to this top are the top element,

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which is fine, as you can see us now.

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Not disastrous for it.

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Two three one four eight eight and disorder's eight four eight eight eight four.

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So the stack grows from I remember I remember that.

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I still remember memory address.

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And whenever you push an element out of the stack, you can see the E.S.P decrements by four by four

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bytes, because in that little bit we generally push the 32 bit value so that it means the forward so

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normal push operation.

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Operation Decrements, the.

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E.S.P by four points, and if I want to push another element, let's push Dirac's seven, then that

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value will be pushed onto the start again E.S.P decrements before and points to the top of the stack,

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which is seven.

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OK, now what if I want to take another step so we cannot fail because we need to take her to tell.

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So the population automatically pops the I mean takes the top element and push prices in the to register.

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So now I want to say popi x so the top of it is seven and it's been placed into the X, the old memory

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or that off the X has been ordered at seven.

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Now as you can see before in the previous E.S.P points to this address.

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So whenever a pop operation has been executed, then E.S.P incremented by four.

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That means E.S.P no longer points to this seven because 05 is the top of the stack and E.S.P increments

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before when a popular pop operation has been performed.

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So what if I want to do the pop operation again?

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And now this.

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I want to say Popke X and the top of the stack before this pop is five and this fight will be copied

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in books.

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And then before E.S.P has been pointed to this eight four address and now after the Operation E.S.P

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point is pointing to the Aetate address, it means that Pusha Operation Decrements, the USP by four

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bytes and pop operation determines the value we increase the value for which.

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So as you can see, guys, when you are referring to the memory, actually you are the difference in

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these two memories addresses.

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So if you have taken my C programming course and you can see I have explained you in the studio and

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these two Artosis will be there on the stack and these values will also be on the stack.

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We are just not referencing this to memory Artosis and the.

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So Noguez will be moving on to the podium and let's do an example.

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That's no, I'm going to create a new car tag, but now some.

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Now, I'm going to write the global underscores.

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Now, I want to define a variable in the data section that I'm going to write the data section.

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Now, that's the variable, that one.

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Let's say over.

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Are we going to the world and we just put the of value onto the stock?

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So this word will point to that word and will be pushing this value onto the stack.

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Now let's create the U.S. to hold our core.

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And we need to define the start.

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OK, guys now will be moving some random values.

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Let's let's copy Google into the eggs and then let's push your eggs one zero three Litsa and we also

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push 066.

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But seven, now, these two values will be pushed onto the stack, now we can say bump into X.

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And this instruction will take the direct where you direct certain value and it in here, because it's

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the recent push and recent pop will take the risk and push value.

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I'm going to say pop Ebix.

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Now, this instruction will be the second pop operation from the last on what's the second push?

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I mean, Trevallyn will be presumably because know there is one more matter I want to show you.

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We can push particular bites of it, which I want to push forward.

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And said Brackett.

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Wear one.

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So what this what this means, push the content at one, but push only the word, I mean, push only

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the two bits of the content, look at it by the point or whatever one address knowledge of this.

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Let's talk about this in two weeks and also we will see.

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Bush Beever.

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There was the what is the four bites and we are going to push the four bites available one, and we

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will again pop this into evicts now we need to exit the program.

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To do that.

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We need to cover the right exit system called.

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Now pressing the one that is the number in two years and the exit of Girot, so we need to place the

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in and we need to call the interprete.

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So let me see the file.

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And we are going to compare it using that nasal.

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Now we will object to using Aldy.

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Now, our tag boundary has been created now later on this.

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So since we are not printing anything, the program just existed normally.

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Now let's open this binary in the bigger GDP, the bigger.

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Now, let's say in four functions.

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And I'm putting the breakpoint at the start function.

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Now, let me run the program now, as you can see, the next U.S. is going to be the movie zero two.

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So now let's run that introduction next time.

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So X condensed two and push three.

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So this is our guys.

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Now, there is already one and the address.

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So as you can see, this is the stack growing from here.

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That means if you place the element, it will be here.

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Now, let's run the step through the code.

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As you can see, three has been executed and the top of the stack contains three previous reads, one

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now it's three.

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As you can see, the address also has been created by four.

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As you can see now, the default Bush operation, sorry, push, Operation Default, KRI Decrements,

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yes, people thought it means that it takes the value and by default, it places the 32 bit where,

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you know, if I step through this again, you can see the direction.

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Now we are going to pop you now yak's contents to allow you to hand the top of the stack.

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So this initial action on execution, but this is the seven into the years.

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So no eggs content, seven in a similar manner directly is the top of the stack.

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And if you pop into buycks now, you can zero.

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It will be replaced by three.

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As you can see, Buycks contains three.

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Now we need to look something somewhat carefully.

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Push already.

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Well, in the previous pusher's, it default taken the B word that we do with and pushed down the stack.

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Now let's run this one.

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But only one operation.

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Now, as you can see now, let's take this to check the contents of this address.

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So the contents of this are 2046, OK?

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These should be placed onto the stack.

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I don't know why there is one.

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OK, now let's step through this.

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Now we are going to.

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Now we are going to push that the whole operation that we started to bits, actually, we have the 123456

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on it and that will be pushed under the stack.

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As you can see, there is Durex, 123456 on it.

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Now, if I pop into SBX this value and put it on, it will be comparable to this value this.

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Now, as you can see, it contains 123456 on it.

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Now, these last instructions tell us that we are calling that exercise stronger now, if I simply run

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this our program at just normal, guess one main thing you need to understand is the other portion of

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operations and the Bush operation decriminalizes people for bits and pop operation increments that.

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Yes.

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Wait for.