/**
* Returns the next unused frame, based on the PROT_READ flag,
* or NO_UNUSED_FRAMES if none are available.
*/
int next_unused_frame(struct page_table *pt) {
int i;
for (i = 0; i < page_table_get_nframes(pt); ++i)
if (ft[i] == -1) return i;
return NO_UNUSED_FRAMES;
}
void page_fault_handler( struct page_table *pt, int page )
{
printf("page_rep_choice=%i\n",page_rep_choice);
int frame,nframes,npages,retframe,bits;
// get max number of pages and frames
nframes = page_table_get_nframes(pt);
npages = page_table_get_npages(pt);
// check if frame number should be page number
if (nframes>=npages){
printf("page fault on page #%d\n",page);
frame = page;
}
// FIFO
else if (nframes<npages){
printf("page fault on page #%d\n",page);
if (page_rep_choice==0){
// RAND
frame = page;
}
else if (page_rep_choice==1){
// FIFO
frame = page % nframes;
}
else if (page_rep_choice==2){
// CUSTOM
frame = page;
}
}
// check permissions
// - no permissions -> read
// - read permissions -> write
// - write permissions -> all
if (bits==0){
page_table_set_entry(pt,page,frame,PROT_READ);
}
else if(bits==1){
page_table_set_entry(pt,page,frame,PROT_WRITE);
}
else{
page_table_set_entry(pt,page,frame,PROT_READ|PROT_WRITE|PROT_EXEC);
}
page_table_get_entry(pt,page,&retframe,&bits);
printf("frame=%i\tbits=%i\n",retframe,bits);
// exit(1);
}
void custom_handler(struct page_table *pt, int page) {
int i, frame, bits,
nframes = page_table_get_nframes(pt),
rand_count = MAX(1, nframes * CUST_RAND_PCT / 100),
rand_frames[rand_count];
for (i = 0; i < rand_count; ++i) {
rand_frames[i] = lrand48() % nframes;
}
for (i = 0; i < rand_count; ++i) {
page_table_get_entry(pt, ft[rand_frames[i]], &frame, &bits);
if (!has_write(bits)) {
swap_page(pt, page, frame);
return;
}
}
swap_page(pt, page, frame);
}
void fifo_handler(struct page_table *pt, int page) {
swap_page(pt, page, fi++ % page_table_get_nframes(pt));
}
void rand_handler(struct page_table *pt, int page) {
// Get page of random frame from ft
int frame = lrand48() % page_table_get_nframes(pt);
swap_page(pt, page, frame);
}