public MemBlock allocate(int size) throws Exception {
if (size <= MemList.sumOfEmptySize()) {
int i;
int addr;
for (i = 0; i < MemList.EMPTY_LIST.size(); i++) {
if (size <= MemList.EMPTY_LIST.get(i).getSize()) {
if (size == MemList.EMPTY_LIST.get(i).getSize()) { // 刚好找到一块大小与需求相等的空闲块
addr = MemList.EMPTY_LIST.get(i).getAddress();
MemBlock block = new MemBlock(addr, size);
block.setColor(colors[count]);
count++;
if (count == colors.length) {
count = 0;
}
MemList.OCCUPY_LIST.add(block);
MemList.EMPTY_LIST.remove(i);
setChanged();
notifyObservers();
return new MemBlock(addr, size);
} else {
addr = MemList.EMPTY_LIST.get(i).getAddress(); // 申请的空间需要分割已有空闲块
MemBlock block = new MemBlock(addr, size);
block.setColor(colors[count]);
count++;
if (count == colors.length) {
count = 0;
}
MemList.OCCUPY_LIST.add(block);
MemList.EMPTY_LIST.get(i).setAddress(addr + size);
int emptysize = MemList.EMPTY_LIST.get(i).getSize();
MemList.EMPTY_LIST.get(i).setSize(emptysize - size);
setChanged();
notifyObservers();
return new MemBlock(addr, size);
}
}
}
}
throw new IllegalArgumentException("Can not allocate memory, too large: " + size);
}
public void free(MemBlock location) throws Exception {
int i;
int j;
out:
for (i = 0; i < MemList.OCCUPY_LIST.size(); i++) {
if (location.getAddress() == MemList.OCCUPY_LIST.get(i).getAddress()) {
MemBlock block = MemList.OCCUPY_LIST.get(i);
block.setColor(null);
MemList.OCCUPY_LIST.remove(block); // 找到并将块从占用线性表中释放
int addrnsize = block.getAddress() + block.getSize();
for (j = 0; j < MemList.EMPTY_LIST.size(); j++) {
if (location.getAddress() < MemList.EMPTY_LIST.get(j).getAddress()) {
MemList.EMPTY_LIST.add(j, block); // 将释放的空闲块按地址高低插入空闲线性表
if (j == 0) { // 若插入在表首，检查是否能与第二块合并
if (addrnsize == MemList.EMPTY_LIST.get(j + 1).getAddress()) {
MemList.EMPTY_LIST
.get(j)
.setSize(block.getSize() + MemList.EMPTY_LIST.get(j + 1).getSize());
MemList.EMPTY_LIST.remove(j + 1);
break out;
}
break out;
}
int former =
MemList.EMPTY_LIST.get(j - 1).getAddress()
+ MemList.EMPTY_LIST.get(j - 1).getSize(); // 前一个空闲块的地址与大小之和
if ((former == block.getAddress())
&& (addrnsize
== MemList.EMPTY_LIST.get(j + 1).getAddress())) { // 在表中插入，检查前后是否能够同时合并
MemList.EMPTY_LIST
.get(j - 1)
.setSize(
block.getSize()
+ MemList.EMPTY_LIST.get(j - 1).getSize()
+ MemList.EMPTY_LIST.get(j + 1).getSize());
MemList.EMPTY_LIST.remove(j + 1);
MemList.EMPTY_LIST.remove(j);
break out;
} else if (former == block.getAddress()) { // 在表中插入，只能与前者合并
MemList.EMPTY_LIST
.get(j - 1)
.setSize(block.getSize() + MemList.EMPTY_LIST.get(j - 1).getSize());
MemList.EMPTY_LIST.remove(j);
break out;
} else if (addrnsize == MemList.EMPTY_LIST.get(j + 1).getAddress()) { // 在表中插入，只能与后者合并
MemList.EMPTY_LIST
.get(j)
.setSize(block.getSize() + MemList.EMPTY_LIST.get(j + 1).getSize());
MemList.EMPTY_LIST.remove(j + 1);
break out;
}
break out;
}
}
MemList.EMPTY_LIST.add(block); // 将空闲块插至线性表最后
j = MemList.EMPTY_LIST.size();
if (j > 1) {
if ((MemList.EMPTY_LIST.get(j - 2).getAddress() + MemList.EMPTY_LIST.get(j - 2).getSize())
== block.getAddress()) { // 如果空闲块与前一块能合并就合并
int newsize = MemList.EMPTY_LIST.get(j - 2).getSize() + block.getSize();
MemList.EMPTY_LIST.get(j - 2).setSize(newsize);
MemList.EMPTY_LIST.remove(j - 1);
break;
}
}
break;
}
}
setChanged();
notifyObservers();
}
public void InitArrayList() {
MemBlock block = new MemBlock(0, 512);
MemList.OCCUPY_LIST = new ArrayList<>();
MemList.EMPTY_LIST = new ArrayList<>();
MemList.EMPTY_LIST.add(block);
}
