adding 14

labs/14_smart_memory/stop_and_copy.cpp

@@ -0,0 +1,96 @@
+#include "stop_and_copy.h"
+
+
+// Return the node corresponding to a particular address
+Node& StopAndCopy::operator[](Address addr) { 
+  if (addr == MY_NULL) {
+    std::cerr << "ERROR: NULL POINTER EXCEPTION!" << std::endl; exit(1); }
+  if (addr < OFFSET || addr >= OFFSET+CAPACITY) {
+    std::cerr << "ERROR: SEGMENTATION FAULT!" << std::endl; exit(1); }
+  return memory[addr-OFFSET]; 
+}
+
+
+Address StopAndCopy::my_new(char v, Address l, Address r) {
+  // if we are out of memory, collect garbage
+  if (next == partition_offset+CAPACITY/2) { 
+    collect_garbage(); 
+    // update the addresses (since memory has been shuffled!)
+    if (l != MY_NULL) l = memory[l-OFFSET].left;
+    if (r != MY_NULL) r = memory[r-OFFSET].left;
+  }
+  // if we are still out of memory, we can't continue
+  if (next == partition_offset+CAPACITY/2) { 
+    std::cerr << "ERROR: OUT OF MEMORY!" << std::endl; exit(1); }
+  // assign the next available node
+  memory[next].value = v;
+  memory[next].left = l;
+  memory[next].right = r;
+  return OFFSET + next++;
+}
+
+
+// Print function for debugging
+std::ostream& operator<<(std::ostream &ostr, StopAndCopy &m) {
+  ostr << "root-> " << m.root << std::endl;
+  for (int i = 0; i < CAPACITY; i++) {
+    ostr.width(4); ostr << i+OFFSET << " "; }
+  ostr << std::endl;
+  for (int i = 0; i < CAPACITY; i++) {
+    ostr << "   "; ostr.width(1); ostr << m.memory[i].value << " "; }
+  ostr << std::endl;
+  for (int i = 0; i < CAPACITY; i++) {
+    ostr.width(4); ostr << m.memory[i].left << " "; }
+  ostr << std::endl;
+  for (int i = 0; i < CAPACITY; i++) {
+    ostr.width(4); ostr << m.memory[i].right << " "; }
+  ostr << std::endl;
+  // print "FREE" or "used" for each node in the current partition
+  for (int i = 0; i < CAPACITY; i++) {
+    if (i >= m.next && i < m.partition_offset+CAPACITY/2)
+      ostr << "FREE ";
+    else if (i >= m.partition_offset && i < m.partition_offset+CAPACITY/2)
+      ostr << "used ";
+    else  // print nothing for the other half of memory
+      ostr << "     "; }
+  ostr << std::endl;
+  return ostr;
+}
+ 
+
+void StopAndCopy::collect_garbage() {
+  // switch to the other partition
+  partition_offset = (partition_offset == 0) ? CAPACITY/2 : 0;
+  // scan & next start at the beginning of the new partition
+  Address scan;
+  next = scan = partition_offset;
+  // copy the root
+  copy_help(root);
+  // scan through the newly copied nodes
+  while (scan != next) {
+    // copy the left & right pointers
+    copy_help(memory[scan].left);
+    copy_help(memory[scan].right);
+    scan++;
+  }
+}
+
+
+void StopAndCopy::copy_help(Address &old) {
+  // do nothing for NULL Address
+  if (old == MY_NULL) return;
+  // look for a valid forwarding address to the new partition
+  int forward = memory[old-OFFSET].left;
+  if (forward-OFFSET >= partition_offset &&
+      forward-OFFSET < partition_offset+CAPACITY/2) {
+    // if already copied, change pointer to new address
+    old = forward;
+    return;
+  } 
+  // otherwise copy it to a free slot and leave a forwarding address
+  memory[next] = memory[old-OFFSET];
+  memory[old-OFFSET].left = next+OFFSET;
+  old = next+OFFSET;
+  next++;
+}
+