I have created a Round Robin Algorithm with C. The output I get for 5 processes with the same arrival time is correct but incorrect for different arrival times. Below is an example,
RRB.C
#include <stdio.h>#include <stdlib.h>#include <stdbool.h>#include <ctype.h>typedef struct Process { int burst_time; int arrival_time; int remaining_time; double wait_time; double turnaround_time; double response_time;} Process;Process *processes;// Function to check if input is a valid non-negative integerint check_is_int(char input[10]) { char *endptr; int num = strtol(input, &endptr, 10); if ((!isspace(*endptr) && *endptr != 0) || num < 0) { return -1; // Return -1 for invalid input } return num; // Return the integer if input is valid}// Function to calculate the response time of each processvoid calc_response_time(int i) { int prev_process_cpu_time = processes[i - 1].burst_time - processes[i - 1].remaining_time; processes[i].response_time = processes[i - 1].response_time + prev_process_cpu_time;}// Function to simulate the execution of a process by the CPUvoid execute_process(int i, int time_slice, double *utilised_cpu_time, int *num_processes_completed, double *total_wait_time, double *total_turnaround_time, double *total_response_time) { if (processes[i].remaining_time > time_slice) { *utilised_cpu_time += time_slice; processes[i].remaining_time -= time_slice; } else if (processes[i].remaining_time <= time_slice) { *utilised_cpu_time += processes[i].remaining_time; processes[i].remaining_time = 0; processes[i].turnaround_time = *utilised_cpu_time; processes[i].wait_time = *utilised_cpu_time - processes[i].burst_time; *total_wait_time += processes[i].wait_time; *total_turnaround_time += processes[i].turnaround_time; *total_response_time += processes[i].response_time; (*num_processes_completed)++; }}// Function to print header for process timingsvoid print_header() { printf("PROCESS\t\tBurst Times\t\tArrival Times\t\tWaiting Times\t\tTurnaround Times\t\tResponse Times\n");}// Function to print timings for an individual processvoid print_process_timings(int i, int burst_time, int arrival_time, double wait_time, double turnaround_time, double response_time) { printf("P%d\t\t\t%d\t\t\t\t%d\t\t\t\t%.0f\t\t\t\t%.0f\t\t\t\t%.0f\n", i + 1, burst_time, arrival_time, wait_time, turnaround_time, response_time);}int main(void) { char input[12]; bool first_run = true; int num_processes_completed = 0; double utilised_cpu_time = 0; double total_wait_time = 0; double total_turnaround_time = 0; double total_response_time = 0; // Print introduction printf("CPU scheduling method: Round Robin (RR)\n\n"); // Prompt user to enter the number of processes printf("Enter the number of processes: "); fgets(input, sizeof(input), stdin); int num_processes = check_is_int(input); // Check if input is valid printf("\n"); if (num_processes == -1) { // Check if input is invalid printf("Please input a valid non-negative integer!\n"); return 1; } processes = (Process *)malloc(num_processes * sizeof(Process)); // Allocate memory for processes if (processes == NULL) { // Check if memory allocation failed printf("Memory allocation failed!\n"); return 1; } // Input burst times and arrival times for each process for (int i = 0; i < num_processes; i++) { printf("Enter Burst Time for process %d: ", i + 1); fgets(input, sizeof(input), stdin); int burst_time = check_is_int(input); // Check if input is valid printf("Enter Arrival Time for process %d: ", i + 1); fgets(input, sizeof(input), stdin); int arrival_time = check_is_int(input); // Check if input is valid printf("\n"); if (burst_time < 0 || arrival_time < 0) { // Check if input is invalid printf("Please input valid non-negative integers!\n"); free(processes); return 1; } else { // Initialize a new process instance Process p; p.response_time = 0; p.arrival_time = arrival_time; p.turnaround_time = 0; p.wait_time = 0; p.burst_time = burst_time; p.remaining_time = burst_time; processes[i] = p; } } // Input the size of time slice printf("Enter the size of time slice: "); fgets(input, sizeof(input), stdin); printf("\n"); int time_slice = check_is_int(input); // Check if input is valid if (time_slice == -1) { // Check if input is invalid printf("Please input a valid non-negative integer!\n"); free(processes); return 1; } print_header(); // Print header for process timings // Execute processes and calculate timings for (int i = 0; i < num_processes; i++) { if (processes[i].remaining_time != 0) { execute_process(i, time_slice, &utilised_cpu_time, &num_processes_completed, &total_wait_time, &total_turnaround_time, &total_response_time); } if (i > 0 && first_run) { calc_response_time(i); if (i == num_processes - 1) { first_run = false; } } if (i == num_processes - 1 && num_processes_completed < num_processes) { i = -1; // Reset loop if there are outstanding processes } else if (num_processes_completed == num_processes) { break; // Exit loop if all processes are completed } } // Print timings for each process for (int i = 0; i < num_processes; i++) { print_process_timings(i, processes[i].burst_time, processes[i].arrival_time, processes[i].wait_time, processes[i].turnaround_time, processes[i].response_time); } printf("\n"); // Print average waiting time, turnaround time, and response time printf("Average Waiting Time: %.1f\n", total_wait_time / (double)num_processes); printf("Average Turnaround Time: %.1f\n", total_turnaround_time / (double)num_processes); printf("Average Response Time: %.1f\n", total_response_time / (double)num_processes); free(processes); // Free allocated memory for processes return 0;}Output for Different Arrival Time
CPU scheduling method: Round Robin (RR)Enter the number of processes: 5Enter Burst Time for process 1: 45Enter Arrival Time for process 1: 0Enter Burst Time for process 2: 90Enter Arrival Time for process 2: 5Enter Burst Time for process 3: 70Enter Arrival Time for process 3: 8Enter Burst Time for process 4: 38Enter Arrival Time for process 4: 15Enter Burst Time for process 5: 55Enter Arrival Time for process 5: 20Enter the size of time slice: 10PROCESS Burst Times Arrival Times Waiting Times Turnaround Times Response TimesP1 45 0 158 203 0P2 90 5 208 298 10P3 70 8 208 278 20P4 38 15 150 188 30P5 55 20 203 258 40Average Waiting Time: 185.4Average Turnaround Time: 245.0Average Response Time: 20.0However, according to https://process-scheduling-solver.boonsuen.com/, the average waiting time and average turnaround time are 173.2 and 232.8 respectively, which differs from my output. I've tried to tweak my code but am still unable to figure out why my average waiting time and average turnaround time. Please help to correct my code if there's any discrepancy. Thanks.