WEBVTT

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Hello, my name is Stephan, and in this video lecture we will delve into the assembly code, which

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we will write in calculator, dot, asme file, and this code will demonstrate various arithmetic operations

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on numbers using the x86 64 assembly language, and I will also provide comprehensive explanation for

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each register and variable used in the code, helping you to understand how the calculations and operations

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are carried out step by step.

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Now let's open our assembly here and close our previously open terminal.

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We will develop it using this and create a new project.

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Clear the previous project here.

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PM.

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I mean the the default code here and here.

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We will save it on the assembly.

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We will create a new folder, let's name it Calculator.

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And calculators.

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That's it.

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Now, let's name it the calculator.

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Calculator.

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Dot.

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We will declare an external function print f for later use.

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So external print f.

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Actually decrease the brightness a little bit.

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Okay, that's better.

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Now what we're going to do is we will section.

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Section.

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We will cut the section data.

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Here.

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We will define a 64 bit floating point number with a value of one.

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To right.

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And number one.

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BC for creating floating point numbers.

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And we will, uh, give it the value.

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One 128.

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Number two is going to be, uh, 19 as well.

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We will define another 64 bit floating point number with the value of 19.

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And we will define a signed 64 bit integer with the value of -12.

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Negative number.

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So let's make it.

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Here, so a negative number DQ as well.

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So.

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And 12.

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And also keep in mind that these are not necessarily floating point numbers.

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So you can you can also they can also behave like integers here.

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And this is the first number for arithmetic operations.

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This is the second number for arithmetic operations.

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And this is a negative number to demonstrate sign extension.

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And it can also be positive.

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We just name it just nick number and we will format the strings for printf function as well.

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So we will define fmt DB.

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And here the numbers are old.

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And here.

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Ten zero and we will use fmt int.

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I will explain all of this.

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After completing this section here.

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Like the code section.

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I will explain after writing this code.

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So s d here again.

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And zero.

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So me here.

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The be here.

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The sum is.

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And TV.

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They pay the difference?

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Null terminated strings here.

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These are all the null terminated strings.

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And I see.

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I.

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So here.

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Number one, incremented.

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Null termination.

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E.

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A c i.

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Keep.

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Number one incremented here.

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Zero as well.

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Sally.

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EB.

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Number one shift.

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Left.

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Shifts left to here.

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X four.

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Zero again.

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S s a r.

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A here.

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Number one shift, right?

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Right to.

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Which is divide by 2 or 4.

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Zero and s a r i.

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X.

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Number one.

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Shift, right?

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But this one will be shifted with the sign expression.

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Us with.

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So in the expression here.

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Let's add a termination.

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Add multi.

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We just need to write three lines of code and after that I will explain registers and everything here.

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Here.

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TB.

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This is the the product.

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And here this is the integer coefficient.

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The integer.

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And as.

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And lastly, we have the Remy here.

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The be here the modulo.

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Is.

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Zero.

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Now that's it with our code for now.

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Here we will add also, we will also add more codes here.

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Here we just developed a section data here.

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Now the the registers, um, like the general purpose registers are used to hold data and perform arithmetic

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operation, which we will learn that in next lecture.

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But firstly, what we're going to sing here is at the second line of our program here we are declaring

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an external function printf that is used in another module like C library, and this allows the assembly

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code to call the printf function for output.

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And in this data here we are declaring a section of memory where initialized data is stored.

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The number one, number two and the negative number are initialized with a specific values for arithmetic

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operations.

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And.

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And we also have the format strings here.

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And here the first format string does that here, this fmt here.

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So this format string is used to display the values of two long integers.

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The LD and the LD here, as you can see.

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So LD is a placeholder that will be placed with the actual values of the long integers.

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And ten here represents the Ascii code for a new line character like the new line character.

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This here.

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And after that, so we have the new line and this is the zero indicates the end of the string, which

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is a null terminated string here to mark its completion.

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And also we have here is let me actually fix this mask.

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Also, we have here the fmt, uh, integer here.

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So the this form of string is used to display a string followed by a long integer.

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As you can see here, this is a string.

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This is a long integer and the S is a placeholder for a string.

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And the L is a placeholder for a long integer.

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And ten here represents the Ascii code for a new line character as well.

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The this is the new line character and.

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This will cause the new line to be printed after this value.

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And this zero here indicates the end of a string.

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It's also called the null terminated string.

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And we also have the Sumi here as.

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You, am I?

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So this format string is a message to be printed before displaying the sum of two numbers.

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The string simply states the sum is and zero here indicates the end of the string, which is a null

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terminated string.

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And we also have d here d i f i.

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Similar to the previous one.

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The this format string is a message to be printed before displaying the difference.

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Uh, with the difference of two numbers.

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The string states, the the differences and zero indicates the end of the string.

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And also we have a i n c i.

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This is the format string message is to be printed before displaying the increment value of the first

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one.

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The string just simply states number one incremented and zero indicates the end of the string.

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So.

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We have the same here.

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And that's it.

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And yeah, that they are basically the same here.

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They are just a string we are attaching to this variable names and so on.

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So this format strings are essential for presenting clear and informative output messages when performing

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arithmetic operations and manipulations on the provided numbers so the placeholders within the format

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string will be replaced with the actual values like these placeholders.

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Here's LD and so on.

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Uh, so they will they will be replaced with the actual values during the printf function called the

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null termination at the end of every string here is crucial for proper string handling in C and other

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low level languages, like in assembly language as well.

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So this code essentially sets, but actually so you don't add the null terminated string characters

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manually just handles it automatically.

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Now, this code here essentially sets sets up data values for my strings and external function declarations

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for performing arithmetic operations on the provided numbers and demonstrating various manipulations.

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So the format strings are used with the printf function to display the messages and computed results.

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So the x86 64 assembly registers are key elements in executing the arithmetic, operations and manipulations

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outlined in this code.

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I'm awaiting you in next lecture for continuing our project.