Kernel Implementations I 15 January 2019 OSU CSE 1 So, Whats - - PowerPoint PPT Presentation

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Oct 28, 2023 405 likes •685 views

Kernel Implementations I 15 January 2019 OSU CSE 1 So, Whats Inside the Computer? Consider any popular video game, e.g., Nintendo Wii bowling Are there bowling balls and bowling pins inside the game consoles computer? 15

SLIDE 1

Kernel Implementations I

15 January 2019 OSU CSE 1

SLIDE 2

So, What’s Inside the Computer?

Consider any popular video game, e.g.,

Nintendo Wii bowling

Are there bowling balls and bowling pins

inside the game console’s computer?

15 January 2019 OSU CSE 2

SLIDE 3

Consider any popular video game, e.g.,

Nintendo Wii bowling

Are there bowling balls and bowling pins

inside the game console’s computer?

– Of course not!

What’s really inside the computer, then,

that makes bowling-like behavior?

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So, What’s Inside the Computer?

SLIDE 4

Consider any popular video game, e.g.,

Nintendo Wii bowling

Are there bowling balls and bowling pins

inside the game console computer?

– Of course not!

What’s really inside the computer, then,

that makes bowling-like behavior?

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A thought experiment: What dynamic behavior would you see if you had a magical magnifying glass and could see inside the computer at any level of detail while it’s running?

So, What’s Inside the Computer?

SLIDE 5

A Useful Metaphor

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SLIDE 6

A Tower of Abstractions

Bowling pins?
Vectors?
Numbers?
Bits?
Voltages?
Electrons?
???

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SLIDE 7

A Tower of Abstractions

Bowling pins?
Vectors?
Numbers?
Bits?
Voltages?
Electrons?
???

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These are all “just” mathematical models, i.e., abstractions used to explain and predict behavior.

SLIDE 8

A Tower of Abstractions

Bowling pins?
Vectors?
Numbers?
Bits?
Voltages?
Electrons?
???

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Domain: Physics These models are supposed to match physical reality, and are discarded if they do not; limited by the physical world.

SLIDE 9

A Tower of Abstractions

Bowling pins?
Vectors?
Numbers?
Bits?
Voltages?
Electrons?
???

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Domain: Computing These models are entirely artificial (need not match physical reality); limited only by the creativity of the software engineer.

SLIDE 10

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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SLIDE 11

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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Numbers may be built on top of bits…

SLIDE 12

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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Bits may be built on top

f voltages…

SLIDE 13

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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Voltages may be built on top of (?) electrons…

SLIDE 14

Interpretation of Representation

Let’s not take the tower-building metaphor

too far!

A better approach is to think about

interpreting a lower-level configuration (a.k.a. a representation) to get a higher- level value

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SLIDE 15

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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(Configurations of) bits may be interpreted as numbers...

SLIDE 16

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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(Configurations of) voltages may be interpreted as bits…

SLIDE 17

A Tower of Abstractions

Bowling pins
Vectors
Numbers
Bits
Voltages
Electrons
???

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(Configurations of) electrons may be interpreted as voltages…

SLIDE 18

First Example: QueueKernel

For QueueKernel, one idea is to

represent a Queue variable’s value by using a java.util.List variable

By convention (of the OSU CSE

components), a kernel class that directly represents the new type using a component from the Java libraries that is very similar, has a name ending in “L”

– In this case, it is called Queue1L

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SLIDE 19

Detailed Example: Queue1L

What existing components (including built-

in types of Java, and the Java libraries) could you build it on top of?

– In other words, what could you use as a data representation that could be interpreted as a Queue value?

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SLIDE 20

Context of Queue1L

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Queue Queue1L implements QueueKernel extends QueueSecondary extends Object extends Standard extends

Has bodies for the constructor, plus the 7 methods from Standard and QueueKernel.

Iterable extends

SLIDE 21

Context of Queue1L

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Queue Queue1L implements QueueKernel extends QueueSecondary extends Object extends Standard extends Iterable extends newInstance clear transferFrom constructor enqueue dequeue length iterator

SLIDE 22

Instance Variables

Each separate Queue1L object has its
wn distinct java.util.List variable

that represents its object value

Note: In the code we will examine for

Queue1L, there is a declaration of a private instance variable whose value is the java.util.List that represents

ne Queue1L object (namely, this)

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SLIDE 23

Instance Variables

Each separate Queue1L object has its
wn distinct java.util.List variable

that represents its object value

Note: In the code we will examine for

Queue1L, there is a declaration of a private instance variable whose value is the java.util.List that represents

ne Queue1L object (namely, this)

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The adjective instance means there is a distinct variable (with the same name) for each instance (i.e., each distinct object) of the class in which it is declared.

SLIDE 24

Let’s Look at Queue1L.java

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SLIDE 25

Other Representations?

Is there any other way to use a

java.util.List to represent an object value of type Queue?

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SLIDE 26

Other Representations?

Is there any other way to use a

java.util.List to represent an object value of type Queue?

Yes!

– What if you simply thought of the front of the Queue as being at the right end of the java.util.List rather than the left? – How would the code change with this “reversed” interpretation?

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SLIDE 27

Resources

OSU CSE Components API: Queue

– http://cse.osu.edu/software/common/doc/

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