Assignment 8 and 9: Structure struct Node

Combined Assignment 8 and 9 (200 points)
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1 Instructions
For this assignment:
• Answer the questions individually. Group effort is not allowed.
• Reading: http://c-faq.com, K&R C, chapter 1-6.
• You are allowed to use resources from the internet as long as you refer them in your
repository README file.
• You will note that none of the files in the repository have been populated except the
Makefile (and even that only specifies the targets you must implement and includes
our testing Makefile into your Makefile). As we are in the last half of the semester,
you should be able to do these tasks with much less guidance.
2 Questions
2.1 sort nodes
(80 points) You are given structure struct Node below, where next points to the next
node in the list (or NULL if it is the last node in the list), and prev presents to the previous
node in the list (or NULL if it is the first node).(see Figure 1):
1 s t r u c t Node {
s t r u c t Node ∗ nex t ;
3 s t r u c t Node ∗ prev ;
} ;
5 t y p e d e f s t r u c t Node Node ;
Implement a function Node *sort nodes(Node *head) that returns head of list such that:
&node1 &n2 &n3 ... &last node You will submit sorter.c and node.h. sorter.c
will contain the sort nodes function. node.h will contain the definition of the Node
structure and the prototype for the sort nodes function.
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Figure 1: Lists before and after sorting. Arrows going left to right indicate “next” pointers,
and arrows going right to left indicate the “prev” pointers.
struct _Node
0x1300
struct _Node
0x1000
struct _Node
0x3000
struct _Node
0x2000
next next next next
NULL NULL
prev prev prev prev
Node* head
struct _Node
0x3000
struct _Node
0x2000
struct _Node
0x1300
struct _Node
0x1000
next next next next
NULL NULL
prev prev prev prev
Node* head
Input
Output
N1 N2 N3 N4
N3 N4 N1 N2
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2.1.1 Hints and Notes
• You should mix nodes from stack (local variables), heap (dynamic variables) and
global variables to generate a list comprising of nodes of varying addresses.
• Although you are free to use any sorting algorithm, it might be easier to use selection
sort. In simple words, selection sort is where you iterate through the list to select the
largest element and move it to the beginning of the list. (https://en.wikipedia.
org/wiki/Selection_sort).
• You are guaranteed that your function will be tested against lists that contain at
least 3 elements. So, you are not required to handle lists of smaller size.
• You are not allowed to make copies of the nodes. You are required to sort them by
altering the next and prev pointers.
2.2 Estimator
(60 points) You are to write a program to estimate the throughput of nop instructions.
That is, you are to find the number of nop instructions that the processor can execute in
1 second. Your program must be called estimator ands its implementation is in estimator.c. It should print a single number in scientific notation indicating the number of nop
instructions the processor can execute in 1 second with a trailing newline and nothing else.
This number of instructions should reflect the average of at least 5 trials.
2.2.1 Hints and Notes
Using the timer code given in the Labs, run an assembly function comprising of 100 nop
instruction a large number of times (e.g., (unsigned int) 0xffffffff), and run another
assembly function that contains 0 nop instructions (only a ret instruction) the same number of times. In both cases, measure the time consumed over at least 5 trials. Compute
the average number of nop instructions the processor executes per second. You can expect
at least 2 x 109 nop’s per second.
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2.3 Toggle
(60 points) You are to implement the following function in 64 bit assembly in file toggle.S,
with the function prototype in toggle.h.
unsigned long toggle_bit(unsigned long num, unsigned long bit_num);
The function accepts an unsigned long num and toggles (A 0 bit changes to 1 and a 1 bit
changes to 0) the bit at bit num position (0 ≤ bit num ≤ 64, where 0 is the least significant
bit and 63 is the most significant bit).
3 Submission
Submit the 7-digit SHA hash as a student comment to a MyCourses submission.
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