Rust Programming Language Programmieren in Rust (Full lecture, German), 11 Jan 2017

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From YouTube: Programmieren in Rust (11.01.): Stack und Heap

Description

Vorlesung „Programmieren in Rust“ an der Universität Osnabrück im Wintersemester 2016/17.

Dies ist die Aufnahme des Beamerbildes sowie des Notebook-Mikrofons. Alternative Aufnahme (mit Dozentenvideo): https://video4.virtuos.uos.de/engage/theodul/ui/core.html?id=31d04ddc-80a3-4344-a2c4-b4a0316f2e3a

Slides und weitere Informationen: https://github.com/LukasKalbertodt/programmieren-in-rust

Playlist: https://www.youtube.com/playlist?list=PL0Ur-09iGhpwMbNiVTBeHmIjs0GuIXhNg

A

First tried some more written that it is always difficult. A hamburg rainer decided on his own exam. I.

B

Assume the right way.

A

To register is an account foreign examiner, and everyone should find that even foreign friend has what I wrote there for the foreign exam informatics supplements 600 programming for rast, so everyone should find it there and remember to recognize to report when he.

B

Is watching the video now register.

A

And stop I have never given my product, an error to people that is very funny, but good, we'll continue for now. I got an e-mail about the project by the way that's disappointing, but I had the municipal until friday I had friday was the deadline. Ok, like I said, we'll continue. Likeandt has a last time at smiths cell phone busy. So we know now somehow it works. Super primitive commands one after the other. These are the instructions and we want to analyze a bit sometimes and mainly that the computer doesn't spit out the handwritten race.

A

Hardly anyone writes on the cell phone, like that and dance already did last time seen some funny instructions, the parts of the ceiling she spits out, but only more or less understood and works a nice optimized. So far so good, but maybe you like it. We have 16 registers that it is not exactly much and maybe want to save more data. Because of that we have more memory. We are actually already very luxuriously equipped.

A

I mean before there were only eight and x86 the instruction set and that's a lot of registers compared to other smaller embedded systems or how.

C

A

The division and pretty much it came in rom computers, so great working memory there you probably have four,, eight or 16 gigabytes.

C

A

One memory, enormous pc and problems working memory you can imagine, is somehow slower than register does not have directly on the processor, but that is a bit further away.

A

The physical core work is not quite as decisive, but we say about a factor of 150 the slower, the whole story with performance and speed, how we do it all openly and again later, but we can be ambiguously slow, but it's also significantly more that 's the big advantage, and when we unload from a memory want, then we can do that with the mof instruction and then it would have to be.

C

Such a weird are.

A

Experts in these square brackets, it says its memory address. That means we load a value from bismarck address, 1, 234 hexadecimal in arabic. The stewart just says how a lot of it we want to load. Well, that means somehow we have to specify. Well, I know friends specify in a store of, but one has to say we want to load now, inaugurates or just eight. Our whole register and stewart stands for four words answer is: are two bikes, so that matching proof quite good is now always with us, because not quite right.

A

There is also a more complicated one, namely so that had already been mentioned with this funny teacher instruction that the cdu can do some calculations that these are memory access concerns very quickly, as I said, restrictions that, especially in the case of something like a raid by integrating you somehow have a friend to the status airways and in your airways and elements and integers from the four-legged friend, and you now never have anything that counts highly. What we want to do.

A

You wanted baseband a plus x 4, because your problem was eliminated with the second blast and to cover exactly such cases. The cpu.

B

A

Such very primitive, but still simple calculations that you can use them directly. Otherwise, you would have to use this pointer. The man then only complicated calculation, with your own, add ins plus and so on. So there you can do certain things, certain calculations yourself, but you can somehow multiply normal 2, 4 and 8, with the numbers very limited and as far as good as pure representation.

A

According to him, how to take care of the allocation of virtual addresses that the operating systems haven't heard of them, yet they might ask themselves what it is exactly that means more or less. We are the only process code, computer and the addresses we address accordingly, not in physical addresses. That makes sense for many reasons to do that that hungary, the meanwhile the memory management unit on the processor makes these addresses with the help of the operating system.

A

As always, when we talk about memory, for example,, it's easy with 4, then we speak our virtual and so virtual addresses where it's really in our job market that will be on one second step translates so that is noticed from the virtual physical address. That is of interest now, but not. We are only interested in the virtual addresses and first act as if I had the entire address range.

A

Okay, your trainer, briefly about how the addresses are divided, then, meanwhile, right big and we ca n't grab the address everywhere now, we'll see that our had raich is our addresses. It's 64 bit big in 64 bit systems that theoretically allows us to address. 16 exabytes.

A

You can calculate with 32 bit address my system, four gigabytes so about because the two to the power of 32 cents, so many different banks will address memory if a 32-bit address have hit here.

C

Assume this had for you.

A

Are these addresses extra decima? The dash means that is only for legibility, between the first 32 conquered the second 16 exabytes are a lot, I think so many no areas computer. That's why there is a chronicle reform that 's 48 bits, sometimes more than 130.

A

It allows it to break around 256 terabytes and, I think, we'll come along too 246 ready from at least the whole cdu is now existing implement this form, because that is actually always sufficient, even for huge servers,, which is why it is easier to implement if you only have less bite for the processor.

A

These addresses are split up,, so these 256 gbytes are one grains and jura space. The user space is where our program runs. There are all our things that's down there and they can do it better up there. Now. Why is it divided up? So, strangely classically it's.

C

A

The kernel is always the kernel is the operating system that always the upper area, one, the upper half and the user occupies the lower half that hits here in the middle. Sometimes this kind of graphic is, of course, not really escalated. Then this user would not be able to see it if it would lose properly, because just there is still so much more memory with it. But the good thing is, you can always see from the first picture whether it is a small religious space and that’s. Why.

B

A

Traditionally done this way,, and if this can’t be expanded, reforms and eventually go to 64 bit, then we would like all the old addresses to still work,. That's why half is at the top and half at the bottom or so that it doesn't,.

A

If we could write any program,, we could theoretically address all these addresses somehow in userspace, all the others are already invalid, for you operating system are, of course, not allowed to access this next to spacebook. Let's take a closer look now because we can think about it. Okay, 428 available super, then we'll just do something like we want to talk to our stores so register somewhere between always some random address races. It doesn't work that way. So this is our user space. As I said still 128 days of work, it's just the address range.

A

I don't have to do the physical address. As I said. That means we can also address any addresses up here later, which then also have a much smaller address in the physical world meppen with 100 228 days computer like that and the first area down there and small area that teaches you, then comes the map executed there.

A

The whole executable is typically loaded that I already said the executable file is simply taken from a hard drive and loaded into the memory. There is then, especially in machine code, I think.

B

I have already mentioned these points, data section something.

A

Like string laterale in it or something else so static data, but of course the points text section is also important for our machine contrast combined and what is in machine code, and that is simply written somewhere, an executable all instructions ambush, as you saw last time, that.

D

Must, of course, be loaded somewhere so that.

A

The aisle with which the cdu always save the instruction instructions- loading flap which, as I said,, normally starts in this position. But that's how I found out in the last few days, you gave us a special left spot that allows this text from the apex capital area to always randomly sit somewhere in memory. What that's good for I'll tell you right away at the end of the slide, but sometimes 100. You should never rely on the fact that you always have the same address in memory,, I.e.

A

if you are somewhere in winter and in your country, and if you don’t specify data, the.

B

A

Always somehow related to other addresses,, so that’s the.

B

A

Lag gives me now. There are also three other areas we are interested. In. Other so-called here starts with a class that will also draw the state break and then ends with the program break and the way up. It is a continuous blockers store and we can say that the operating system makes the size makes 100 megabytes in size, specify upwards. This graphic said by also not really escalated, because that would somehow already be many many part already, but I think that now the.

C

A

That grows more or less downwards is usually a size limited. What can be achieved here because it is the used sticks. It grows downwards whereby the size is somehow limited, mostly also like eight megabytes, berlin and system. Then, of course it can remember and exactly once gone and separated are continuous blocks. I have already said: there are no gaps between everything is somehow used and that.

B

A

Stops these white fields: they are now not noted on physical memory. All these other fields, the colored ones, are noted or physical memory. That means every address. I address in between is ok, I get them back very much if I access unnoticed memory and obviously there is unnoticed memory or unnoticed addresses, because we have a large virtual address if our physical rest has, then the compiler throws an exception at me, in the sense of, namely in the sense of but a kind of action or sec rolls, as you also called it you've probably already.

D

Seen seen a result plus.

A

Programmed max.

D

A

D

Clearly said, sorry.

A

The cdu throws the sec section me says he can't know it like that and then caught the third area, that when memory mappings action is appointed, you can also create memory blocks to a certain extent. That is not continuous. Yes, it's somehow there is marriage, but there can also be gaps here. It also says that it grows downwards, but I can somehow delete previous memory again then there's a gap in it and all these white spots that are somehow unused now they're random offsets sla stands for.

A

A

I forgot soon the first one for endo mission. That means somehow the addresses will annoy me now.

A

A

The addresses will definitely be a bit randomized that now stands for security. Someone can imagine what I mean by that reputation. Is that maybe good as far as security is concerned,.

B

C

B

With various further hacker attacks,, for example, love rtl ii, attempts are currently being made to earn instructions, and there is massive for outgoing, extremely difficult stuff for the internal structure of the program. 180.

A

Exactly otherwise, I could organize at some point and solve that always saves on address so and so the password to make it very easy for us.

D

A

Thank you. Yes, they exist. It is inserted in.

B

A

And that's why this random the finished mapping of the executable as I said that threw me off track a bit. I always found it on the internet and.

E

A

Was clearly okay, this 400 address or 400,000 address and other saxon addresses will start at some point and I do n’t have to wonder why that’s the case so well, that’s pretty.

B

A

Complicated that we look at it, how should we use it now? What is it for now that everything is fine? We first have a quick look at thinks about how it works it slides into thinks as a data structure as a basement. That is the deliver principle. That means last in first out that the last thing we put in comes out first,, but that only refers to inserting and deleting,. We can always read anywhere in the store,. So if we remember info ass.tec keller,, we can always only read the top element,.

A

That is not so read here. He can anyway everywhere, but as far as inserting and deleting is concerned, there always delivers principle. This is how the stick can look like. Then there are just different variables in it. I could have drawn the bankruptcy even thicker or thinner, depending on the largest, but it is missing like this, and the management of the.

D

A

Happens all by yourself through a checkpoint, the bag further points to the the top element of the spex or that's the small problem of the bag on the computer growing downwards. They always say or think the deck of such a pile. If it grows upwards, we absolutely have to think that the codex downwards, so the deck band shows that under proof, the last thing that was inserted so and that is stored in the register rsp. It continues to exist. That shows our first about.

C

A

Purpose here on.

C

A

Because it somehow added the last variable game and we can somehow add the other variable calculations to it ourselves.

A

So if you fare negatively right how high and purpose- and you also have other variables now- we would like a new variable- a u 64, variable push on the stack who would like to say how we could manage that with instructions so far, everything according to what you can.

C

E

A

By 1, but exactly we increase, or rather yes, okay, it is almost time we lower. The esp is the important thing since he's going down the little one was the address.

A

Then the bills are still wrong, but that's always.

C

A

Small difficulty with it, but afterwards it's correct, but quite sure exactly, but we're discussing Peter's way for the time being.

A

Eight, because neither eight want to add it soon and then we'll say copied times, please a value, and then it happens like that says the addresses correctly exactly and since this is done so often there is his own institution, for when I push 42 does exactly that. It simply increases the first. The number of bars sees this value probably takes up the most registers and then I look at the value there and the way back looks like this,.

A

We try somehow to get this second one in our registers and then get more for the last one, and then we add that up again, and that gives it it also under its own train zeller, not port the aachener little helper instructions.

A

So far so good. So we can first operate a stack fundamentally and now look and we can simplify one thing, because the difference between this type that we just saw and the memory web area is actually unimportant for us actually didn't know this difference for a long time. Until recently, I got to know difference it's pretty irrelevant for us, therefore, for just that, and definitely as a thief and web area, that's what you usually have got to know some kind of info or something else.

A

If you briefly give what you said, you always meant these two things together. Ultimately, you always talk to an allocator who somehow provides a memory, and he uses these two athlete areas. There is this hit memory mapping, but from now on, I always mean the summary work areas. The only thing that is important to us now you can somehow make blocks of a fixed size and operating system. Queries go to the operating system and say: yes: there is a loco of size, 309 click or the operating system.

A

Really something happens, but rarely so that the only correct- and here again is the comparison of the stack that the administration is extremely simple,, namely only through a further because we increase and decrease and the adding only works later delivery principle. That means we cannot let you prostitution, things somewhere and read that can be anywhere. That is there is. It is more the other way round, deleting.

B

A

Adding can be done in any order. That means we still have holes. That in turn makes administration more difficult, because we would like to use the people again at some point later. Otherwise,.

A

We always save for values. We only expand in one direction and no longer use the old blocks at all, and you somehow want to keep the fragmentation small so that not so many holes arise so and fun it complicated applied. So the two have now so and now in eurovision, then in ras kass programming, then we are usually somehow fn functions or actually almost always everyone kurt yes, something in there.

A

So a little bit of some kind have this function for apple, also, our instructions in a way that other functions can call the content of a function already have somehow noticed, but we can call other functions. So when we start thinking, we realize that we have somehow every function. We can convert machine code, they just pack the different functions in our executable one after the other, and then each function has somehow started one where it starts the first instruction of this function, grandson of it with jump to the individual state addresses I'm so far. So.

B

A

Then you ask yourself if I want to pass function, arguments or a return who wants to return? Try that saved and especially high are the local variables saved that, of course, an important question and we could use it in the type, but that's bad for many reasons, then very slowly for the first time and we might notice that it's perfectly suited for this, because the function the function. Also in a letter principle, that means the last recording function will end first again, so a return that works just.

B

A

C

A

Bit wrong, of course, it's not that god gave us the way and we saw it fits well function. Of course we have that we, the computer scientist, stack or somehow the whole system and memory mecking also developed like this, because it fits well with the function that it's always like that it 's a long development. It's not like. We somehow got everything and now have to think about how we implement it and is mary layout by the way, is n't dictated by the defense in any way. Either we can cast something else.

A

It's important to note here in any case that we need some kind of protocol. We need every function to save their local variables somewhere, then, the end of their careers and they'll be cording people as a whole. If we want to call a function in something from a foreign library,, then we have to agree on where we bake the function arguments,, for example. If that doesn't match, then of course it doesn't work at all and there, as I said,.

A

This corting of people is now several me will now in the further course always about the main calling of people for x86, 64 and also only quite rupture. So how do that now directly use what exactly happened? Each function or each function call. So if I have a function but calls several times, then there are several stack frames so per function, call a stack trace lag frame contains almost everything,, namely arguments and local variables and various being different.

A

If it is the bag for us, then that concerns, for example, we first see three arguments were passed to the function. Apparently, then, there are now two things that don't quite understand yet and then the local ones are waiting for apple, the software to grow. Otherwise every function belongs to this, and only to this to this last entry, if we do n't call any other functions hold up, there are the stack trace of the function. The.

E

A

Which are further up and down it goes the sparks the function we would call, but at this request is not called first points directly to our purpose frame. That is still, nothing else landed his stack and this rbb what you there already loading on the right side. This is the so-called base. Broader. This best father will be responsible for managing our exchange. This is simply the event some things he always shows bp on these songs blog last rpt.

A

If we still understand it, and so he shows the whole thing, so to speak in the middle of the dec frame, and we can do all the things we care about little arguments and local variables, depending on bp indexed, that up hands. These are all the arguments and just address the backlogs. We can all benefit by going plus slightly out to sea bp down.

B

A

Are n't any variants, for.

C

Example, we can do something like that.

A

You'll also see that somewhere, he bp a fixed value, is the country only the way to access local variables or arguments.

A

So far so well, this acquisition is not absolutely necessary, but it often makes sense that we, therefore it is often installed and used for the first time, is not necessary because we can always somehow address all things. First, it becomes more complicated in some cases, but I have it similar and it wants to be container could be pretty clever is somehow manageable, but it will.

C

Make sense to you because.

A

This last rdp introduces you that somehow shows that there is now a pointer in it, and this friend is where the ewp was at the last function. Call that means all of this. You can imagine that any, but leader box injured, rp, that's a list of links. Almost every edelrid, a box points to the previous ni ladebox and our rbb.

A

So the register really always points to the bottom one, the locos should we somewhere a list of links from stec pans and if now at some point, the excavator comes along or in exception, dealer would like to show at some point how our calls history was so which function called, which ones up to the crash or whether it's own way point. Then, of course it makes a lot of sense.

A

If you somehow have that rather wp register can be read out and then the Whole apps can hike up is exactly why it's good for so- called stack traces or something like that.

B

A

Lot of sense makes something easier to read,. Sometimes it's left out because it 's even faster and you save a few instructions,, but anyway it's actually a joke. If we only need the back side,, because you can now call our function from different places, once we program a super general function, the square root or something like that,, then you can well imagine that it is called from various other functions and when we have worked through our institution, that was of course jumping back, and you can now enter a fixed value.

A

Now you have to load an address from somewhere. That has to be specified in the call functions. Please jump back here after you’re done.

A

So far so clear, first of.

C

A

C

A

Now quite long example, so the rest is.

C

A

Want to have a look at the glacis first, that's the mail function where we have a local variable. It's called it's all 64 for us so that it's always the same size makes the register just a bit easier. Then we call the concerts at the same time, but that's.

C

A

From maine, for now we don't have any arguments. We have a retrospective address here. You can of course, think nowhere. Maine has to finally jump when it's finished. It's not that important. Anyway, a few more things come of this and someone jumps back to the os.

A

However, he could this last lp is present in every stack trace and then a local brea. So that's the frame aspect of maine foods worth two arguments and two local variables and do say so.

C

A

Is that the kremper thinks again himself explain these two paraments here the two victims of variables and the two fields in the middle? They are always the upper half of imst extreme. That is, the review dress. The variable or arguments, namely that is created by the calling functions, are, of course, the calls function, defined the value for all the arguments and also defined the return improve, he must say, watch drove back knows from and the lower half is transtec.

A

The environment check frames contains just the local variables from this rwp and that we create a called function ourselves. Clearly, the local variables must be made by the calling function. The.

C

A

Is easy to understand, even if the calling function is acted on.

A

So that jürgen t created it and that is created by schul anyway, this part of the man lay the footbed frame for calling the function, which is part of calling the function of creating it. Okay, we'll be building that for the last time, for fu, so we're just at the beginning of the flight. For us it was already pa and the slide address there packed that's what was prepared for us, the lower half of our beck frame, so the first half we have.

C

A

Everything else: what do you think? What doesn't that? First of all, it's going to happen next.

A

Which hole has to be the stack at least coming next.

B

A

They you live, we get there then I'll start to warm up a bit now bp or register adp shows right here on it. Exactly that's what we want to pack right now on the stack matching, the abb from the last function. It's quite.

C

A

What happened then, the blog formed formed this blog is simply filled with memory, and the sp was increased by 1 the knowledge. Yes, this push function only increased to 1 automatically. So what now has to happen again, this fig that.

C

A

Remained correct.

E

A

Know exactly correct, we say simple: the spd is currently supposed to be in rdp too. So now both point and save more registers to this last rpp so far so good, and now that it can be.

B

A

We make room for our local variables, 1 the complete production next.

D

A

Exactly sums it up, you always do it a bit differently, a little bit.

C

Easier, she makes it so nice.

A

Just says: okay, I.

B

Premiere like that, because right at 4pm.

A

You don't always have to call push so 2 x, 82 x, for our variable and then down somewhere the sp. Of course. We can also use push no question, but that's usually how it's done so now we.

B

A

Somehow get the value of dix so warn about copying if someone has to somehow formulate the marching order. So the correct memory addresses.

A

We can say one thing: first, so target or source.

A

So asm 16 is on the way with windows, 8, so 1 company. That means yes, the execution then arises now so I. My memory was already there before. There was something different and we do that again with the other things with y león touches down, and then the ypsilon is created. Well, that was our function. The hard time did n't do anything which is a bit stupid, but his ministers just have to be able to decide differently.

A

Now we want to come back up now at the end of the session. We didn't do anything, but now that we're getting to the end the function. What do you think we're going to do now that you have ideas.

C

D

16 because they like exactly the way right.

A

That longer, we really throw them away they're still there, the values are still in. There is interested and they're almost Not in all cases,. If we write something like keys and or something else,, then we might have to make sure that we really overwrite this variable with zeros and preferably with random numbers,, but it doesn't matter for most cases,.

A

It doesn't matter when it happens, just leave it out, but for us it doesn't exist anymore, because it's only been back here for a short time, and then we have to restore this rwp story to say once pop kwp. It means that the top element or bottom element from stec will be taken and the rbb saved.

A

So here instead of the distance this further because we win yes, so the flag to save here is the lp saved, and this in front of behind shows on it, and it is p, was reduced by 1, so red or 184, dr because that's just pop and then you just have to jump back back jump address and that even more, for example, just hope again. The top one return the online register say then, together with the register, there are questions about.

C

A

Then quite a lot of detail has already been done. That is probably not quite unanimous, but it is still very helpful to understand that differently, how it works. So fundamentally, I would.

D

Have had three questions number one would be if return value wants to have saved good question.

A

From place, two would.

D

Also be enough city here jump told to execute just the heart command in the Appenzell.

A

D

Were actually really trembling? Yes, exactly.

A

That it saves this portion most of course. Yes,.

A

You could probably describe it like I explained it now at a time with sandy. It is still a bit difficult what you can do there exactly so the registers aren't just for fun,, but most of what you do with things,, I.e. bills or Saturdays,, has to happen in registers, for example,. You ca, n't go directly to memory, for example,, but the addition, firstly, registers, load, add, reserves are what the registers are for and that's why I have now also written that here you have.

B

A

I have not tried everything here,. That means it could be. My institution will tolerate me exactly there,. You could do it in the attic or it has to be in the rain. Probably.

D

Quite the question, certainly a more precise register that differentiates between the current position of.

A

D

A

D

Wannigmann says how far exactly.

A

D

To actually reach needs exactly in this way is because the.

A

D

One would have given her these two things away.

A

D

Above all, admitted to the rc xd were.

C

A

Yes, I mean that he is exactly the rc xd for this the use is stupid. I do n't know if you register the program directly in copenhagen, so that you are saved so, as I.

B

A

Exactly deal with these either instruction, it's also not that important for what you're learning right now that we know the exact instructions in.

B

Any case somehow it works.

A

That way, we'll take a quick look at mail. There are n't going over so slowly now and unfortunately, and there's a great animation on the on the right side. It's a bit complicated but this, for example, always happens.

C

At the beginning,.

A

Of each function,, you can see that researched with the fdp almost once and then the fdp is reset to show a blog, as well as the new deal that happened. Almost always, then, will be more or less always made room for straight variables and in this case, where we then just put the five in here and now.

B

Comes the important thing we have to.

A

Call it up and said what he saw under the lower half of the bag frame or upper half, when turning that the from the exclamation is prepared in function. So the arguments have to have their income somewhere and since you are now increasing the first time again and to have space,, namely first for the two arguments copies to the two arguments there. And then his ambassador in front of that is now again just an income for this position to which we drove up again. The new address or a relative.

B

Address something.

A

Like that then say a shampoo I have that also makes more or less sense. It is mainly only for completeness, because I shouldn’t now my day, I two short things throughout before we discuss a few other things it was. There are again two abbreviations what he said with ambassador ford and gently there for that there is the construction, so it somehow grabs the backlog, address the right one and gets it going then somehow to this action and exactly for the other, something like that is already being discussed.

A

Somehow there is also a single own installation, not knight so red, that's exactly what is done there. The rhythm address you take the original address at the top of the deck just that is taken and spoken to him.

A

Yes, exactly that's just the way it is, and now you can get a very short return value that is actually saved to my rx. That is simply a formation of the return value is saved in this yesterday and is then used by the read out by the calling function,. Of course you ask yourself what happens when the first one evaluates, and then you use a trick called the out pointer,, which means we look at each other first,.

A

So if we were to do something like that,, it would somehow be implemented as something like that That means the calling function has to provide a memory area for the extract and transfers pointers to the functions and the function writes to this pointer,. So you can see that very clearly in this pattern, for example,, because you can’t return any topels.

A

If you want to return several things,, you have to keep typing that is written, so now ultimately only implemented return yesterday, hardly at least not on the bacon and now yes a little disappointment that what I just told is not how it works properly, that there is still a simplification. There are some Optimizations that we can make, for example,. Naturally, thought, we have our 16 registers,. Why do we speak all the arguments on the web, first of all,, the first six arguments in our function are stored in a register in this order,.

A

Someone just came up with it. That's. Why was I what I changed on monday? There was a look at my function and there was the argument he had the idea. That's why there was an alley in it. That means most of the functions. Don't have that many arguments now. That means we can usually access them without the stack. Handing over arguments is, of course, a great thing, now, of course, everything at the moment,, because we always just say everything is only 64 bits in size,.

A

Of course, it gets a bit more complicated with other sizes,, but you can imagine it somehow works and the so-called red is built in a bit more allied. That is ultimately just a zone of work or yes for some time under which esp probably no one can just write there and it belongs to the current function.

A

What does that mean again? That is there for this current function? If you don’t calls other functions like, then, you can simply use this redstone for your local variables,. That means you no longer have to match the first one at all,. You simply write it in at some point in this action,. This now saves an instruction to match the first one,.

A

That's not all that important. If it's in this homework will appear here right after it's, your turn to analyze is then it might be interesting to know that, often, when you look at small functions that there are no local variables on the stick at all,, especially if you use its sheet function as the no other functions. Usually everything is stored in registers and when the deck is used, then sometimes users also use the rap song.

A

As I said it 's all very complicated, and you don't necessarily have to know everything which doesn't interest us, but it 's good to have heard one if you stop sample for sure. That's far from the whole story, there's a lot more because of this convention, so so far, so good now, look that it does n't work that well with the steak, and although there are some limitations for certain now, this station per function is constantly large. We always somehow subtracted a constant number 16 from the first. That makes a lot.

C

Of sense, because then he can.

A

Always easily determine each position of that.

C

A

With the rp can, of course, imagine or the first difficult variant is when you have several types where you don’t have that complicated time know how big the velvet- and you now not only have second in a row, will he start? Second, then I have to save the big ones. According to your words, this type is that means it’s coming clearly now more effort in there and to save how big a guy is.

A

That's, why marca, after the stack, actually only guys who know mw romandie or could look at this, everything means tips and styles, we can't be afraid, means tips on the way that the compiler wants not and don't want to. Yes, so it's just not that good makes everything much more complicated. There are special exceptions where you could sometimes do it without much additional effort, but that doesn't matter for us. It means first of all, we can only put things on the stick: save religious know the? U 64.

A

We know the size, no problem exactly and growing it, for example, also an example for the ca n't map to the deck. Now, because that's why the smartphone to save longer there that gets complicated, because if we also call up other functions that maybe there is still something in it underneath that means we can't just extend it. So that's why.

C

Such a growing airways just doesn't.

A

Work on the stick, and this number of styles are forbidden everywhere. What you could put in the taxi, a local variable, functional arguments and return value of the return values , either in a register, which also has a fixed size or was already found more or less by the calling function.

C

Called blanket,, so in any case it.

A

Is now discarded for us, and this number of styles must be saved on the go. One also speaks of the fact that they are boxed.

A

One actually learns boxing whenever one does not save something in a short about how let the types are constructed from memory layout that is very important to understand,, especially in comparison to other languages. everything all go, the product types he got to know attractive people and so on. They are saved in the memory, almost one after the other. So all fields of these types. If we had two of ours before and we somehow have a lot of functions, a friend would have two and hustle and bustle both like I said always 64.

A

Then it looks like this. A steakhouse that saved a few hours in a row.

A

The problem here, because sometimes I understand it- is a bit difficult because sometimes the compiler adds beijing. What is that now? That comes from the fact that certain values land be calculated as to determine the memory sizes remain, for example, good 64 kbytes in size, and that would like to be at addresses that are divisible by eight, but we are not even sure here. Thanks to the good 230 would definitely only have addresses that are divisible by four.

A

That makes sense for the processor to calculate with them much more easily and so on. So you want such storage alone. If we had 1 tract where first a boullion is or say, 18 and then come 32, then he leads completely pettinger. It was 3 1, so that the second? U 32 is nice again, a yes at a storage size where it is needed because of the pen can sometimes make things a bit complicated. But basically we could say that it's all a stack in a row and you, so to speak, with you too,.

A

We still have to remember a bit of discrimination, which of these values. is because now it's different or something, but that also works somehow,, so everything.

C

A

Stack and hit the every guest you always have to use it explicitly. That's, in contrast to other languages that he may know like obi or java. You always have to do it explicitly like, e.g.

A

finally remove the payload back together, which then tinker doesn't fit at first, but simply call up mail in ten pictures. That's almost these basic functions. We demand a blog of a fixed size and then there's I have n't even spoken about it yet, but we want these sheets will stay again, release it and just look it up with a memory size and say object over the block. Be back.

A

Gaddafi are now c library functions that doesn't really mean the bottom that it's not like, we're talking directly to the operating system. It's comparable! That's fine with us that we build from the operating system and ask exactly these things, and by that the typical memory error can occur. If you can remember the very first one where some of you might have been confused about some things, I said in the motivation section: for example, no memory leaks occur. That is the classic one forgets the tri one says mallow, but forgets to release this memory.

A

There is a blog, then you don’t yell twice for the same address that doesn’t work either that always leads to sex it’s, clear. We can use this memory if it has already been released. All these strange, the concept I had in the first episode are once thrown in rastan that I will now stop the country to prevent these errors. So what can not? Actually do so? You have to be very exhausting, probably even with 111 code, to cause any error memory.

A

Leaks memory league is not considered as an ad,, which means that you can also do the last backup with new safe rast, but the.

B

A

Two are not always prevented outside of the very special. Even now we learn the best news: the box first, like hannah, the junkies, the hip, used mast, one of their own, some example. How have you already worn out.

C

E

E

A

A

That's actually not necessarily a sheep user. We're just saying this. Guy who comes in there could also be called fear, so could live with the blow and stuff like that. What it is not necessarily say that.

C

A

Bit simple everything that actually.

D

I assume that various data stands for the connection. For example, the rector entirely.

A

D

Also not right, these.

A

Are just these dynamically growing it, for example, and also this is the way, is a bit more complicated, but they grow dynamically and have to be saved on the chip, the vector itself.

C

A

Only contains a friend for eray and pano things, but exactly this thing this friend is saved on the stick and if we only have one value on the would like to have a chip country box, this is another data type that might have already seen it on the way to research is used again and again or more often actually- and you can just tell them like. If we put a new box on the 720, then it happened.

B

A

We on our way we had our variable and in this variable in this box instance, only a pointer was stored and this trend now points to the at some point, like my block allocated for this for this 27 and there the father points there and then at the end of the mail, because that does n't happen.

C

A

That's expressed exactly wrong because there's no memory because there's a very high level of what's happening there, because this memory is released again and this box would also.

C

A

By the way, simply use these places, nations could find us our value there again were out for that. The count is also there exactly. As said.

B

A

This ipad, which now means there is then the end of the coup, so awo assumes that you will be free again later. Why does the box take care of itself and this box is a so-called under that means, in contrast to pulling where we simply don't get any back from melo and pinter here means that you take care of it yourself,. They are to be released again or always take care of releasing all resources, and that's what mercedes + knows about. It almost corresponds to june pta again memory layout.

A

Now our many have tree that is typical informatics a tree. A linear trio like two children can have, but don't have to and that option 2 3 and in java very that it looks like that. Do you have any comments about the vice? What do you think how it looks like.

B

The western duel against prepared meeting quite.

A

Clearly it comes this spring and first they complained that we somehow have an infinite size. The share on tries somehow to pack. This runs directly in trier. As I said, everything is parked. One behind the other and option is the one which is a bit more complicated, but I also said everything in the stack. That means the channel dismantled the petri. You then, with her an option step in ok, everything is clear, moister of the option or are again soon win moment.

A

Somehow the compiler would be infinitely large types guarantee that we don't get very much, and this.

B

A

Seems good to us,, so, first of all we can't reverse directly types in rastan. We can only do it box, but down here select, if we've already box driven here, then that works. Why does it work so the the compiler builds the first of these types on vslf option box tree. That really has that a fixed size do.

E

With oxid point there.

A

Correctly, this box is night bus, just keep going, that's why it works. If you remembered it in this could be easy task. I'm a bit of this the whole and the whole topic about business that I just told you now a way for all your children, although he should still have two children. This sector is also noted here, so it also worked, has always been his in direction. Was there that probably works you you're still from a computer scientist? We can just write it like that, because all non-primitive types are automatically saved on the hit.

A

Almost everything that is only created with new is saved on the chip and non-primitive types always have to be created with me. So what the classes and In particular, they are.

B

A

Level,, which means we can also just say both left at the same time, because we have already met more art, talked about it. In, some languages,, almost everything is somehow a reference. How in the year. You can continue to be the original again,, but you actually want that at all.

A

You don't want to say explicitly if a value can't be there. That's why everything looks nicer than this one, but in this.

C

A

Really nice, if you just want to program it, then you should use java right away, but otherwise that's definitely good,. That means he has to explicitly note that we have an optional value and that this value is at the peak,. Of course you have to get used to it and that's more to write,, but it's definitely explicit to be explicit. Well, you have a small question if you find the turning around also say box by roger cheng, and if so, what is the difference that.

D

The bar works out was, in that case there would be no tree on the stupid ones, but a pool of can exactly.

A

Is that better or worse, what.

D

I mean, I would say I would say exactly.

A

Imagine we don't have any more children. We have to do that on the way. If we do it differently than here. In this case, we can have the recordings directly on the stick. That means evaluations are expensive. That means we save that the evaluation for our non- existent children by the way you said you have smaller ones, that's not quite right, so yeah.

C

A

Leads them usually always be discriminating. It's just a number that says which of these variance will have batteries, so you could imagine. Option has there for its zero and for in the name of a 1 in the first ball, and then the water comes the rest. You could imagine option but has a very interesting optimization and that if this guy here then all lonza is whatever else fits. So if this type in can never become 0, so the memory- and this type is never completely 0.

A

He can option use this special value as a name just like that. A target is made or a java. Also, if you a friend, has the new value that he is considered unadapted. That means this option from boxee box is also just a pointer, and it always points to something valid. Is the option box just as big a box? That means there is no additional memory on the stick. Is a.

E

Small optimizations.

A

Yes, ok, ask: we are maybe going to build the node again, so don't make a long list once we have the structures where we want to change the size at runtime, then the deck is not suitable. If we need to have indirect, mainly, for example, at depressive data structures in direction simply means parked it further away from us and have you got a friend with it?

A

That means we can also indirectly also mean that is also an advantage if we and that means want to participate in particular, trade objects that we don’t have yet but know later power form. We would like to have styles, but the order that means we don't want to release as soon as we're almost at the end on saturday. We want to have this level principle of the stacks, but we can't speak them.

A

Then, of course there's the whole city. That's why? If we want to make the lifetime independent of this level principle, that means wanting to write something down in a function,, but this memory,. This memory should live on and that's why we have to somehow get this memory in the other cities,. But it's okay to leave it independent of to be on this level principle and stick to it.

A

You also have to do that if you have extremely large data types, if somewhere else, there are thousands of numbers, then maybe you sometimes want to save them on the chip, although you also save them on the stick for enterprise, a fixed size that it happens rather seldom, usually you only have to do it if your program flies around your ears and said kofler, so just notice, it like you, always use the path by default, so, first of all like massa, does it automatically, and only when we see we finally need it, because he by the way,, it's also expensive, by the way,, a small hint as to why other languages can be slower.

A

Such languages as java or dynamic languages, tend to note everything on the there's: that's slow at 8, which makes certain things much easier, you're a developer kidding once about it when you are somehow desperately stuck with a problem and also say that the complicated the knife still has to take everything into account.

B

A

Shops keep saying, oh if we had just blocked everything the torture. Of course it's a joke because that's exactly what the rast wants to avoid and quickly be, but you joked a bit about it.

A

They were much simpler, well I'll sum up what we've learned this week, the cdu says that our institution, these are very, very primitive commands somehow very.

B

Very succinctly.

A

Coded the few ball and they are executed one after the other. These registers are small memory cells in our cpu directly, which are very fast and all the computers. What I said or anything interesting should actually happen, then registers. That means you typically learn everything memory first in a register, then do things with that and last back so you ca, n't, add memory directly and, roughly speaking, there are two types of memory areas that interest us when we were once on deck, that has a delivery way of life.

A

Very quickly is when an enemy has to argue and document and where we then have local variables and save arguments and love where we somehow have a free division of life means slower, is due to the administration and where we have to query fixed blocks from the operating system. As I said, that's only roughly.

A

We also know at this point data area text area a lot of other smaller things, but if the vines adopt the things somehow want to save something,, then we always have the choice between spec and deep and if we have static variables or such string. Liberals on data section, but that's right and important, again, we'll do that.

C

A

More often visit this statement, the compiler has to have the size of the segway, so do n't worry. It often means it's just around the corner and the hip hop songs in a different way, explicitly explicitly in a certain sense, so you used vector without the same as valued, but leave the language alone in any case, alone does not automatically make good. There are questions about this whole topic.

A

D

Can go back to the example with which he says directions box as and that he says you could also hand over a new reference here. So that would be foreign in the memory. Is that theater? Because then everything.

B

Would probably continue along the.

A

D

That is important, jaguar.

A

The reference can show it at some point: dealer keyboarder stack weekday have here.

D

But why does this help me and who, at this point is probably even clever to use this reference instead of that box, the reference.

A

D

A

And a friend was first, that means the reference does not delete automatically. If the reference goes to the scope, what it shows, what happens, then the reference can go out of the scope, but what it points to is still there for the time.

D

Being not quite like.

A

That create a variable and slow each other down and then open the scope or franz b. Then he goes the vfb out of the scope. But after that it exists, but does.

D

That mean there are more.

A

Somehow, what then we open the coop and say the whole picks you can use now and thus access iks, but you yourself the lifetime of tcn. This is here we can no longer access it.

A

But we can run on it so when it's still valid, so this.

D

Reference doesn't.

A

Support that understandable.

D

Concern why now exactly.

A

D

A

C

Something that should be clear.

A

And you are lying, then it is always for burnt, so the tri there can have a reference, but the compiler wants to assure that every reference is always valid and must now here live on, insert that we will learn next week about not why, probably next week, you have to equip the tri with a lifetime and to say can now again be a reference, but the legal as long as and then we have to create this other child outside of the tri now, and we also have to keep that for our for the entire term of the actual tree,.

A

That means we have to.

A

Take care of the whole lifetime history. What happened here is that this tree really has its children and if we delete the father, if he goes out of scope,, he lets them too its children. That's the advantage here, because it's just like that and pointers pointers we can and we're in the reference use. But in this case not so good.

D

In ras memory create and.

B

That wouldn't intercept.

D

For comfort, I haven't seen an option so far to do that, so maybe we could just see how to do it so that we can prevent that. Okay.

A

You have to make an effort. I actually wanted to tell you about it next week, but okay, I can talk about it very briefly. Now there is not only this and pointer box, which are very simple, but sometimes we would like to have several without this box.

A

If he calls them somewhere, then it is so that the original folder can no longer be used, and if several now want to have without this box, they now live for different lengths of time, and we know it not exactly, but everyone would definitely like to have access to this value. I don't know a global database or anything else. A lot of strange things would like to have access to this database and no matter in which order these things die. Everyone wants everyone case have access to it. There is a so-called reference counted pointer.

A

That tells you how many things point to the part right away. That's called in rossi. If we somehow say asc, I don't know yes spring. We say somehow a lot of different things want to access a screen, and this string sometimes doesn't know how to read, or always, add something, which isn't necessarily the case now,, but it doesn't matter in any case,. Many things want to have access to this string.

A

A

Does ring then discount sk run. 1 then gave a reference to it, namely orrick. We can say oh rick point clown. Is it happens that not this string is cloned, but only this action, this kind, king, the string, but just increases the chorus scout by 14 meetings. It could be 2 if we put that in a scope, then here at the end of the stoxx, goes out of the sco and the aci takes care that the reference comes back down to 11 and at some point this f150 falls and the asc.

A

Then the actual object there in that everything is fine and dandy. Next week, but herewith you can have a so-called asi cycle track,. That means you can have an assi in an ace or maybe a third one, that points to each other and never deletes, because each one is always from the other is referenced. Then it always comes to 1 stays. That's not easy to do with it, so you had to be really strenuous, but it's possible and you can't really prevent it with the basket one. That's why it's not seen as unsafe.

A

It's not really a memory safety. What can go wrong badly? You lose only a little bit of memory is occupied, otherwise questions. Next week we will learn, as I said, about a few things in particular about which are then deleted after it goes out of scope. This is the so-called drop trade and we will also get to know a few other things that was pretty much theoretical. This week, everything next week. He will set off again with all this knowledge that we have accumulated this week,, because otherwise the tasks can be transferred.

A

Theoretically, there are not many tasks for this week on the topic of this week directly. In fact, there is.

A

A

And that is, you should analyze the cell phone?

A

You got a file, it says it now and you are all signaled. What does it actually do? Is there is a function in it now and it should analyze. I wrote down a few tips, then sometimes a bit difficult that we have to analyze.

A

It is somehow all new, and you always have to remember so many funny things- maybe still Another tip that isn't there,, maybe try to write to someone next to the instructions, if that helps, or very lola willing, rastko timmer,, at least that always helps me if I'm going through the offer in a really complicated way, I'll, just write, someone or rast coach who somehow still describes it exactly the way I think about it. Somehow is.

C

A

Than guardian, compare sometime better that you can also help yourself exactly that would have to analyze and comment nicely that that’s exactly what the second task does. That has nothing to do with what this one is week should just program a tool where you can do certain things that somehow has everything to do with randomness,. That means executing certain commands where something is randomly selected from a list or a random number is generated..

A

You have to do that again, use several trades and do certain things not so very important, so not so very important to discuss now what we have to do, there,, which is perhaps still important- that not everything has to be done this week I was so bad at estimating how complex and how much time actually costs something, and that's why you could somehow hand in the second half or the last third of this task in the next week,, but I would still recommend you. If you somehow manage to do all this.

A

This week,, then just focus on the things next week concentrate there. As I said, it's kind of a couple of smaller things that you do there just ask out programming. Ask.

A

Yes, ne second, not quite exactly I, guess that I'll have another week, so the last sheet will probably come out somehow in the first week of the project. Work but I won't promise you anything. So we still have to think about it carefully. I, don't know exactly how long the lectures will continue and what else she would like to tell you but I'll, let you know as soon as I know.

A

What's good, then it can go a long way fun with the test.