/**
* This program simulates FIFO and LRU page replacement algorithms in memory management.
* Author: Your Name
* PantherID: Your PantherID
*/
#include <stdio.h>
#include <stdlib.h>
#define MAX_REFERENCES 1000
// Function to simulate the FIFO page replacement algorithm
int fifo(int pageReferences[], int referenceCount, int frames, int finalState[]) {
int pageFaults = 0;
int buffer[frames];
int insertionPoint = 0;
for (int i = 0; i < frames; i++)
buffer[i] = -1;
for (int i = 0; i < referenceCount; i++) {
int page = pageReferences[i];
int found = 0;
for (int j = 0; j < frames; j++) {
if (buffer[j] == page) {
found = 1;
break;
}
}
if (!found) {
buffer[insertionPoint] = page;
insertionPoint = (insertionPoint + 1) % frames;
pageFaults++;
}
}
for (int i = 0; i < frames; i++)
finalState[i] = buffer[i];
return pageFaults;
}
// Function to simulate the LRU page replacement algorithm
int lru(int pageReferences[], int referenceCount, int frames, int finalState[]) {
int pageFaults = 0;
int buffer[frames];
int recentlyUsed[frames];
int time = 0;
for (int i = 0; i < frames; i++) {
buffer[i] = -1;
recentlyUsed[i] = 0;
}
for (int i = 0; i < referenceCount; i++) {
int page = pageReferences[i];
int found = 0;
int leastRecentlyUsed = time, replacementIndex = 0;
for (int j = 0; j < frames; j++) {
if (buffer[j] == page) {
found = 1;
recentlyUsed[j] = time;
break;
}
}
if (!found) {
for (int j = 0; j < frames; j++) {
if (recentlyUsed[j] < leastRecentlyUsed) {
leastRecentlyUsed = recentlyUsed[j];
replacementIndex = j;
}
}
buffer[replacementIndex] = page;
recentlyUsed[replacementIndex] = time;
pageFaults++;
}
time++;
}
for (int i = 0; i < frames; i++)
finalState[i] = buffer[i];
return pageFaults;
}
int main(int argc, char *argv[]) {
if (argc != 3) {
printf("Usage: %s pagereffile numberofframes\n", argv[0]);
return 1;
}
int frames = atoi(argv[2]);
if (frames < 1 || frames > 10) {
printf("Number of frames must be between 1 and 10.\n");
return 1;
}
FILE *file = fopen(argv[1], "r");
if (!file) {
perror("Error opening file");
return 1;
}
int pageReferences[MAX_REFERENCES];
int referenceCount = 0;
while (fscanf(file, "%d", &pageReferences[referenceCount]) != EOF) {
referenceCount++;
}
fclose(file);
int finalStateFIFO[frames];
int finalStateLRU[frames];
int fifoFaults = fifo(pageReferences, referenceCount, frames, finalStateFIFO);
int lruFaults = lru(pageReferences, referenceCount, frames, finalStateLRU);
printf("FIFO: %d page faults\n", fifoFaults);
printf("Final state of memory: ");
for (int i = 0; i < frames; i++)
printf("%d ", finalStateFIFO[i]);
printf("\n");
printf("LRU: %d page faults\n", lruFaults);
printf("Final state of memory: ");
for (int i = 0; i < frames; i++)
printf("%d ", finalStateLRU[i]);
printf("\n");
return 0;
}
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C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.
When ever you want to perform a set of operations based on a condition if-else is used.
if(conditional-expression) {
// code
} else {
// code
}
You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.
Switch is an alternative to if-else-if ladder.
switch(conditional-expression) {
case value1:
// code
break; // optional
case value2:
// code
break; // optional
...
default:
// code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
// code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while(condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.
data-type array-name[size];
data-type array-name[size][size];
Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
Two types of functions are present in C
Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,
User defined functions are the ones which are written by the programmer based on the requirement.
return_type function_name(parameters);
function_name (parameters)
return_type function_name(parameters) {
//code
}