updated week7, week8

OS/C/Week8/q1.c

@@ -0,0 +1,134 @@
+// Develop a program to simulate banker’s algorithm. (Consider safety and resource-request algorithms)
+
+#include <stdio.h>
+
+#define MAX_PROCESSES 10
+#define MAX_RESOURCES 10
+
+int processes, resources;
+int available[MAX_RESOURCES];
+int maximum[MAX_PROCESSES][MAX_RESOURCES];
+int allocation[MAX_PROCESSES][MAX_RESOURCES];
+int need[MAX_PROCESSES][MAX_RESOURCES];
+
+int safeSequence[MAX_PROCESSES];
+
+void initialize() {
+    printf("Enter number of processes: ");
+    scanf("%d", &processes);
+
+    printf("Enter number of resources: ");
+    scanf("%d", &resources);
+
+    printf("\nEnter available resources:\n");
+    for(int i=0; i<resources; i++) {
+        scanf("%d", &available[i]);
+    }
+
+    printf("\nEnter maximum matrix:\n");
+    for(int i=0; i<processes; i++) {
+        for(int j=0; j<resources; j++) {
+            scanf("%d", &maximum[i][j]);
+        }
+    }
+
+    printf("\nEnter allocation matrix:\n");
+    for(int i=0; i<processes; i++) {
+        for(int j=0; j<resources; j++) {
+            scanf("%d", &allocation[i][j]);
+            need[i][j] = maximum[i][j] - allocation[i][j];
+        }
+    }
+}
+
+int isSafe() {
+    int work[MAX_RESOURCES];
+    int finish[MAX_PROCESSES] = {0};
+    int count = 0;
+
+    for(int i=0; i<resources; i++)
+        work[i] = available[i];
+
+    while(count < processes) {
+        int found = 0;
+        for(int p=0; p<processes; p++) {
+            if(!finish[p]) {
+                int j;
+                for(j=0; j<resources; j++) {
+                    if(need[p][j] > work[j])
+                        break;
+                }
+                if(j == resources) {
+                    for(int k=0; k<resources; k++)
+                        work[k] += allocation[p][k];
+                    safeSequence[count] = p;
+                    finish[p] = 1;
+                    count++;
+                    found = 1;
+                }
+            }
+        }
+        if(!found) return 0;
+    }
+    return 1;
+}
+
+void resourceRequest(int process) {
+    int request[MAX_RESOURCES];
+
+    printf("\nEnter resource request for process %d:\n", process);
+    for(int i=0; i<resources; i++) {
+        scanf("%d", &request[i]);
+    }
+
+    // Check if request is valid
+    for(int i=0; i<resources; i++) {
+        if(request[i] > need[process][i]) {
+            printf("Error: Request exceeds maximum claim\n");
+            return;
+        }
+        if(request[i] > available[i]) {
+            printf("Error: Resources not available\n");
+            return;
+        }
+    }
+
+    // Try to allocate
+    for(int i=0; i<resources; i++) {
+        available[i] -= request[i];
+        allocation[process][i] += request[i];
+        need[process][i] -= request[i];
+    }
+
+    if(isSafe()) {
+        printf("Request granted\n");
+    } else {
+        printf("Request denied - unsafe state\n");
+        // Rollback
+        for(int i=0; i<resources; i++) {
+            available[i] += request[i];
+            allocation[process][i] -= request[i];
+            need[process][i] += request[i];
+        }
+    }
+}
+
+int main() {
+    initialize();
+
+    if(isSafe()) {
+        printf("\nSystem is in safe state.\nSafe sequence: ");
+        for(int i=0; i<processes; i++)
+            printf("P%d ", safeSequence[i]);
+        printf("\n");
+
+        int process;
+        printf("\nEnter process number (0-%d) to request resources: ", processes-1);
+        scanf("%d", &process);
+        resourceRequest(process);
+    } else {
+        printf("\nSystem is not in safe state!\n");
+    }
+
+    return 0;
+}