Week 8 - Jumps

Question 1

What does jmp mean?

Answer 1

Unconditional jump

Question 2

What does jg mean?

Answer 2

Jump if greater

Question 3

What does goto do?

Answer 3

Unconditionally jumps to a labelled statement

Question 4

Write an example goto statement.

Answer 4

label:

<statements>
goto label;
</statements>

Question 5

Why is goto considered harmful?

Answer 5

Because the flow of control in code is not clear

Spaghetti code is difficult to read and maintain

All programming constructs can be written without jumps

Question 6

What does the state of an executing program depend on?

Answer 6

Virtual address space:
- code (the executing program code)
- data/BSS (static variables)
- stack (function return address, parameters, auto variables)
- heap (dynamically allocated variables)

Registers, including:
- sp (stack pointer)
- bp (base pointer)
- pc (program counter)

Question 7

What does setjmp do?

Answer 7

Saves the contents of the registers to a buffer

Question 8

What does longjmp do?

Answer 8

Restores the contents of the registers from a buffer

Question 9

What is the difference between concurrency and parallelism?

Answer 9

Concurrency is multiple processes accessing one disk and sharing one CPU (with time slicing and context switching)

Parallelism is multiple processes running on separate CPUS

Question 10

Are coroutines concurrent and/or parallel?

Answer 10

They are concurrent but not parallel

Question 11

Give an example usage for coroutines.

Answer 11

Computer games to maintain an high framerate as the program can switch between the coroutine and the game loop