Hello, my name is Stephan, and in this lecture you will learn about the J.
So the assembly language instruction J which stands for Jump.
If above is a conditional jump operation utilized in low level programming to dictate the program's
flow based on a specific comparison condition.
The instruction is commonly used for unsigned integer comparisons, and the J instruction serves the
purpose of deciding whether a jump should occur depending on whether one value is strictly greater than
another value.
So here is how it operates.
The first is comparison.
The instruction initiates by performing a comparison between two values.
These values can be present in registers, immediate values embedded within the instruction itself or
memory locations.
And the second is conditional assessment.
The outcome of the comparison is used to determine whether the jump should take place.
Specifically the J.
The jump above instruction performs a jump if the condition above holds true.
In other words, if the first value is strictly greater than the second value, the jump will be executed.
And the third is jump or sequential execution.
So should the should the condition be satisfied The program's execution flow is altered and the program
jumps to a new location specified by a label or memory address.
Conversely, if the condition is not yet met or not met, the program continues with its sequential
execution without any disruption.
So in assembly language, a instruction is commonly represented by a mnemonic, followed by an operand
indicating the target location for the jump if the condition is met.
So here's an example a hypothetical assembly language syntax, CMP c x, d, x here and a above.
About label.
So here we are comparing values in registers C and D, and with this jump to a label if C is greater
than D.
So in this illustration here, the program compares the values stored in integers or stored in registers
C and D, So if the value in register C x is strictly greater than the value in register D x, the program
will execute a jump to the memory location labeled as a bowl.
A bowl label, if the condition is not yet is not fulfilled, which is not greater than X.
The program proceeds with its sequential execution.
So a j instruction alongside other conditional jump instructions like JB jump below a j e jump if equal
and j z jump if zero which you will learn in next lectures forms the bedrock of control flow with an
assembly language programming.
Collectively, these instructions empower programmers to craft intricate algorithms and logical structures
at an exceptionally low level of abstraction.
By harnessing these instructions, programmers can create a decision based behaviors and sophisticated
branching mechanisms that are crucial for building efficient and functional assembly language programs.
Now, what we're going to always do in this section, we will also create an example skeleton for this
logic.
Now what we're going to do is.
We will.
Again use the defined two values.
And continue our execution.
By execution, I mean the writing, our codes.
So as we always do, we will define again the section data with two values in it.
We will allocate memory for a value one and initialize it with 2025 value, one value one TB and 25.
And we will allocate memory for value two and initialize it with the 20.
And also we will create a section section text.
Action text.
And here we will create a global global start here and in start.
Will.
Move, Al.
Value.
Value one.
Here we are loading the value stored at memory address value one into a l here, which we will do the
same a l register with which we will do the same for the b l as well.
So move b l.
Uh, value to your, uh, we are going to do load the value stored at memory address value two into
BL registers and we will always do a l bl.
So here we are comparing the values in A, L and b l.
And here we will use this jump ball.
And here we will create.
So if l as I explained here at the beginning of this lecture, if l is a bow here is if l is above j
a jump if a ball b l jump to the above label.
So we will create both of these labels here, not above, above and done as we always do, but here
we are comparing L, A and b, L.
So let's firstly create the not a ball.
And here your code here, your code here for the scenario when value one is not above value two and
GMP done.
Here we are jump to the done which we will create as label right now to finalize this section and also
we will create above here above.
So your code here for for the scenario when value one is above value value two and here we will also
create a done here.
I'm here and exit code here.
Like we here we are all the registers and Siskel at the end.
And after that read here.
But we will notice here.
So this is just a skeleton of how this jumping robot works as the previous ones.
So that's, uh.
So this program is not fully functional yet, but we can just add the slightly exit code, but we don't
need that here.
So now I will start from the beginning, as I always do.
So we initiate this exploration by setting up this data section where memory is allocated to accommodate
the variables value one and value two.
So these variables take on a specific values value one being assigned 21, 20, 25 and value two taking
on 20 forming the foundation of our comparisons and here in text section, our focal point of executable
instructions, we encounter this Start label as our entry point.
Our journey into code begins with the Move instruction.
And it is a mechanism through which we transfer the value stored in memory at the address specified
by value one and into the Al register here.
Similarly, the subsequent MOV instruction performs a parallel action for value two loading its value
into PL register and this process sets the stage for comparison.
The comparison comparison unfolds through the CMP instruction, subjecting the value stored in Al and
here if the comparison reveals that the value in Al.
Represses the value in.
The j jump of above instructions ushers us into the above label domain.
In this case, as you know, the value one is 25 and value two is 20.
And in this case the above condition will met.
And.
After that, in cases where the comparison outcomes refuses the notion of value one surpassing value
to the not above.
Here.
In this case, it should be for, for example, ten.
In this case, the note above will execute.
That's it here.
And.
And this is your, uh, here in not above.
This is your arena, uh, to insert instructions, catering to scenarios where value one does not outpace
value two.
And the journey then leads us to the lay down label marking a point of conclusion for this particular
code segment.
On the other hand, the above label offers a contrasting sphere.
This is where you would typically insert instruction designed to address cases where value one is indeed
exceeds value two, and that's it.
After that, here we have done and here our educational odyssey reaches its pinnacle with the done label
encapsulating the conclusion of the program's logic.
This is the appropriate place to include instructions for program termination or any necessary.
And by delving into this assembly code, we have traversed the realm of conditional branching and comparisons.
Armed with the ability to discover scenarios where value one is above value two.
Your comprehension of these intricate mechanisms is a key asset as you delve deeper into the world of
assembly programming.
Continue your journey exploring the intricacies and applications of assembly programming with enthusiasm
and dedication.
Happy Learning.