pageFault.c

/* placement round */
    for(i=0; i< numPageFrames; i++) {
        /* if we've reached a page not in memory, use that index */
        if(pageTable[i].valid == 0) {
            pageTable[i].vmPage = pageNumber;
            pageTable[i].valid = 1;
            pageTable[i].referenced = 0;
            pageTable[i].modified = 0;
            return (0);
        }
    }

    /* Replacement Loop, because placement failed */
    loopStart = clockHand;
    do {
        /* if current spot is not referenced, replace it */
        if(pageTable[clockHand].referenced == 0) {
//            freeFrame(logicalAddress); <-----------------DO WE EVER NEED TO FREEFRAME() ??
            pageTable[clockHand].vmPage = pageNumber;
            pageTable[clockHand].valid = 1;
            pageTable[clockHand].referenced = 0;
            clockHand++; /* increment clock pointer for next time */
            if(pageTable[clockHand].modified == 1) {
                pageTable[clockHand].modified = 0;
                return (2);
            } else return (1);
        } else { /* if spot has already been referenced, set it to unreferenced and move on */
            pageTable[clockHand].referenced = 0;
        }
        /* if we failed for this index, increment clockHand, if over threshold, reset to 0 */
        clockHand++;
        if(clockHand >= numPageFrames) clockHand = 0;
    } while(clockHand != loopStart);