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#!/usr/bin/env python3
# UPEM / System programming / Project: Memory paging simulator
# Pacien TRAN-GIRARD, Adam NAILI
from mem import Memory
from pageexception import *
class SecondChancePaginator:
def __init__(self, mem):
self.mem = mem
self._check_table = [0 for _ in range(len(mem.main)+len(mem.virt))]
self._main_cursor = 0
def _put_main(self, page):
overwritten = self.mem.main[self._main_cursor]
while(overwritten is not None and self._check_table[overwritten] == 1):
self._main_cursor=(self._main_cursor + 1) % len(self.mem.main)
self._check_table[overwritten] = 0
overwritten = self.mem.main[self._main_cursor]
self.mem.main[self._main_cursor] = page
self._main_cursor = (self._main_cursor + 1) % len(self.mem.main)
return overwritten
def load(self, page):
if not self.mem.page_in_range(page): raise PageException
if page in self.mem.main:
self._check_table[page] = 1
return
if page in self.mem.virt: self.mem.remove_virt(page)
overwritten = self._put_main(page)
if overwritten is not None: self.mem.put_virt(overwritten)
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