4 files changed, 24 insertions, 13 deletions

diff --git a/fifo.py b/fifo.py
index 7fa55a0..61e70f5 100644
--- a/fifo.py
+++ b/fifo.py
@@ -10,7 +10,6 @@ class FifoPaginator:
   def __init__(self, mem):
     self.mem = mem
     self._main_cursor = 0
-    self._virt_cursor = 0
 
   def _put_main(self, page):
     overwritten = self.mem.main[self._main_cursor]
@@ -18,13 +17,10 @@ class FifoPaginator:
     self._main_cursor = (self._main_cursor + 1) % len(self.mem.main)
     return overwritten
 
-  def _put_virt(self, page):
-    self.mem.virt[self._virt_cursor] = page
-    self._virt_cursor += 1
-
   def load(self, page):
-    if not self.mem.has_page(page): raise IndexError
+    if not self.mem.page_in_range(page): raise IndexError
     if page in self.mem.main: return
+    if page in self.mem.virt: self.mem.remove_virt(page)
     overwritten = self._put_main(page)
-    if overwritten not in self.mem.virt: self._put_virt(overwritten)
+    if overwritten is not None: self.mem.put_virt(overwritten)
 
diff --git a/mem.py b/mem.py
index 7137ede..c83d69d 100644
--- a/mem.py
+++ b/mem.py
@@ -8,6 +8,7 @@ class Memory:
   def __init__(self, main_size, virt_size):
     self.main = [None] * main_size
     self.virt = [None] * virt_size
+    self._virt_cursor = 0
 
   def _mem_to_string(self, mem):
     return ''.join(['%d' % n if n is not None else 'x' for n in mem])
@@ -18,6 +19,18 @@ class Memory:
   def dump_virt(self):
     return self._mem_to_string(self.virt)
 
-  def has_page(self, page):
-    return 0 <= page < len(self.virt)
+  def page_in_range(self, page):
+    return 0 <= page < len(self.main + self.virt)
+
+  def put_virt(self, page):
+    self.virt[self._virt_cursor] = page
+    self._virt_cursor += 1
+
+  def remove_virt(self, page):
+    for i in range(len(self.virt)):
+      if self.virt[i] == page:
+        self._virt_cursor -= 1
+        self.virt[i] = self.virt[self._virt_cursor]
+        self.virt[self._virt_cursor] = None
+        break
 
diff --git a/myMemory.1 b/myMemory.1
index d7a5827..1093e66 100644
--- a/myMemory.1
+++ b/myMemory.1
@@ -62,18 +62,20 @@ can only handle new style baz segments. COBOL
 object libraries are not supported in this version.
 .SH EXAMPLE
 .nf
-% ./myMemory.py -s 3 -v 8 -a fifo
+% ./myMemory.py -s 3 -v 5 -a fifo
 > 7     7xx
 > 0     70x
 > 1     701
 > 2     201
+> p     201     7xxxx
 > 0     201
 > 3     231
-> p     231     70xxxxxx
+> p     231     70xxx
 > 0     230
+> p     230     71xxx
 > 4     430
 > 2     420
-> p     420     70123xxx
+> p     420     713xx
 > x
 .fi
 .SH AUTHORS
diff --git a/myMemory.py b/myMemory.py
index dd2aaa6..2439aae 100755
--- a/myMemory.py
+++ b/myMemory.py
@@ -25,7 +25,7 @@ def main(main_size, virt_size, paginator):
       try:
         pag.load(int(cmd))
         output(cmd, mem.dump_main())
-      except:
+      except IndexError:
         output(cmd, "Error: invalid page.")
     elif cmd == 'p':
       output(cmd, mem.dump_main() + '\t' + mem.dump_virt())