Question

edit – i figured out the arithmetic error but I still have the return error

For some reason my program is giving me two errors. First error is that the “return” at the end of each of my methods() are not ending the method and bring me back to main. My second question is at line 23 where pfNum = mainSize/pageSize; is giving me a “SIGFPE, arithmetic exception” not sure why both of these are occuring can anyone help me out?

Thanks

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

/* Define page table as dynamic structure containing virtual page and page frame 
   and initialize variable as pointer to structure */
struct table{
    int vp;
    int pf;
}*pageTable = NULL;
/* Declare global var's */
int mainSize,pageSize,policy,pfNum;
/**********************************************************************/
void option1(){
/* Declare local var's */
    int k;
/* Prompt for main memory size, page size, and replacement policy */
    printf("Enter main memory size(words): ");
    scanf("%d",&mainSize);
    printf("Enter page size(words/page): ");
    scanf("%d",&pageSize);
    printf("Enter replacement policy(0=LRU, 1=FIFO): ");
    scanf("%d",&policy);
    pfNum = mainSize/pageSize;
/* Allocate and initialize page table based on number of entries */
    pageTable = malloc(pfNum *sizeof(pageTable));
    for(k=0;k<pfNum;k++){
        pageTable[k].vp=-1;
        pageTable[k].pf=k;
    }
return;
}
/**********************************************************************/
void option2(){
/* Declare local var's */
    int va,page,offset,i=0,temp;
/* Prompt for virtual address */
    printf("Enter virtual memory address to access: ");
    scanf("%d",&va);
/* Translate virtual mem addr to virtual page and offset*/
    page = va/pageSize;
    offset = va%pageSize;
/* Check for end of table, unallocated entry, or matched entry in table 
and update table appropriately; while none of three cases, keep looping */

    while(i<pfNum && pageTable[i].vp!=1 && pageTable[i].vp!=page)
        i++;
    if(i<=pfNum){
        int j;
        temp = pageTable[0].pf;
        for(j=1;j<pfNum;j++)
            pageTable[j-1]=pageTable[j];
        pageTable[j].vp=page;
        pageTable[j].pf=temp;
        printf("Page Fault!");
    }
    else if(pageTable[i].vp==-1){
        pageTable[i].vp = page;
        printf("Page fault!");
    }
    else if(pageTable[i].vp==page){
        temp = pageTable[i].pf;
        int l,address;
        for(l=i+1;l<pfNum-1;l++)
            pageTable[l-1]=pageTable[l];
        pageTable[l].vp = page;
        pageTable[l].pf = temp;
        address = (temp*pageSize)+offset;
        printf("Virtual address %d maps to physical address %d",va,address);
    }
 return;
}
 /**********************************************************************/
void option3(){
 /* Declare local var's */
    int u;
    for(u=0;u<pfNum;u++ && pageTable[u].vp!=-1)
        printf("VP %d --> PF %d",pageTable[u].vp,pageTable[u].pf);
 /* Print out each valid virtual page and page frame pair in table */

 return;
}


 /**********************************************************************/
 int main(){
 /* Declare local var's */
    int choice;
 /* Until user quits, print menu of options, prompt for user input, and select     appropriate option */
    printf("/n");
    printf("Virtual memory to Main memory mapping:\n");
    printf("--------------------------------------\n");
    printf("1) Set parameters\n");
    printf("2) Map virtual address\n");
    printf("3) Print page table\n");
    printf("4) Quit\n");
    printf("\n");
    printf("Enter Selection: ");
    scanf("%d",&choice);
    printf("\n");
    while(choice!=4){
        if(choice==1)
            option1();
        else if(choice==2){
            option2();
        }
        else if(choice==3)
            option3();
    }
    printf("Goodbye. Have a nice day.");
return 1;
}

Answer 1

The “SIGFPE, arithmetic exception” exception is most likely caused by division by zero.