//调入进程后更新空闲区表信息
private void UpdateFreeMemList_AddProcess(MemBlock freeMemBlock, int size)
{
//若无需删除整个空闲块结点，更改起点与大小
if (freeMemBlock.blockSize != size)
{
freeMemBlock.starting += size;
freeMemBlock.blockSize -= size;
}
//若要删除空闲区表头结点，将下一个结点当做头结点
else if (freeMemBlock == freeMemList.first)
{
freeMemList.first = freeMemBlock.next;
if (freeMemList.first != null)
{
freeMemList.first.last = null;
}
}
//删除某个空闲块结点
else
{
MemBlock lastBlock = freeMemBlock.last;
lastBlock.next = freeMemBlock.next;
if (lastBlock.next != null)
{
lastBlock.next.last = lastBlock;
}
}
//更新空闲区表信息
PrintFreeMemList();
}
//释放进程后更新占用表
private void UpdateUsedMemList_Release(int start, int size)
{
//若删去整个头结点，修改新的头结点
if (usedMemList.first.starting == start && usedMemList.first.blockSize == size)
{
usedMemList.first = usedMemList.first.next;
}
else
{
MemBlock block = usedMemList.first;
while (!(block.starting <= start && block.starting + block.blockSize > start))
{
block = block.next;
}
//若要删去某个节点
if (start == block.starting && size == block.blockSize)
{
block.last.next = block.next;
if (block.next != null)
{
block.next.last = block.last;
}
}
//若要删去某个节点前半部分，更新起址，大小
else if (start == block.starting)
{
block.starting += size;
block.blockSize -= size;
}
//若要删去某个节点后半部分，更新大小
else if (start + size == block.starting + block.blockSize)
{
block.blockSize -= size;
}
//删去某个节点的中间部分，创建新的结点并连接
else
{
MemBlock newBlock = new MemBlock(start + size, block.starting + block.blockSize - start - size);
block.blockSize = start - block.starting;
newBlock.next = block.next;
if (newBlock.next != null)
{
newBlock.next.last = newBlock;
}
block.next = newBlock;
newBlock.last = block;
}
}
PrintUsedMemList();
}
//打印空闲表信息
private void PrintFreeMemList()
{
freeMemListTextBox.Text = string.Empty;
if (freeMemList.first == null)
{
freeMemListTextBox.AppendText("无空闲区");
}
else
{
int i = 1;
for (MemBlock block = freeMemList.first; block != null; block = block.next, i++)
{
freeMemListTextBox.AppendText(
"空闲区" + i + " " +
"起址：" + block.starting + "K " +
"长度：" + block.blockSize + "K\r\n");
}
}
}
//调入进程后更新占用区表信息
private void UpdateUsedMemList_AddProcess(int start, int size)
{
//若占用表为空，创建头结点
if (usedMemList.first == null)
{
usedMemList.first = new MemBlock(start, size);
}
else
{
MemBlock block = usedMemList.first;
//若新表项在表头前，更新头结点
if (start < usedMemList.first.starting)
{
MemBlock newBlock = new MemBlock(start, size);
newBlock.next = block;
block.last = newBlock;
usedMemList.first = newBlock;
block = newBlock;
}
//新表项紧挨某项后方（增大某项体积）
else
{
while (block != null && block.starting + block.blockSize != start)
{
block = block.next;
}
block.blockSize += size;
}
//检测是否要与下一个结点项合并
if (block.next != null && block.starting + block.blockSize == block.next.starting)
{
block.blockSize += block.next.blockSize;
block.next = block.next.next;
if (block.next != null)
{
block.next.last = block;
}
}
}
//更新占用表信息
PrintUsedMemList();
}
//获取调入位置，若无调入空间，返回false
private bool GetPositon(out int p, int size)
{
p = -1;
MemBlock freeMemBlock = null;
//首次适应算法
if (algorithm)
{
freeMemBlock = freeMemList.first;
while (freeMemBlock != null)
{
if (freeMemBlock.blockSize >= size)
{
p = freeMemBlock.starting;
UpdateFreeMemList_AddProcess(freeMemBlock, size);
break;
}
freeMemBlock = freeMemBlock.next;
}
}
//最佳适应算法
else
{
int maxSize = 0;
MemBlock block = freeMemList.first;
//寻找最大且足够大的块
while (block != null)
{
if (block.blockSize >= size && block.blockSize > maxSize)
{
freeMemBlock = block;
maxSize = block.blockSize;
}
block = block.next;
}
if (freeMemBlock != null)
{
p = freeMemBlock.starting;
UpdateFreeMemList_AddProcess(freeMemBlock, size);
}
}
return(p >= 0);
}
public FreeMemList(MemBlock fst)
{
first = fst;
}
//释放进程后更新空闲表
private void UpdateFreeMemList_Release(int start, int size)
{
//若空闲表为空，创建头结点
if (freeMemList.first == null)
{
freeMemList.first = new MemBlock(start, size);
}
else
{
//储存已修改的结点及其上一项，下一项的结点信息，便于执行合并操作
MemBlock block = new MemBlock(start, size);
MemBlock lastBlock = freeMemList.first;
MemBlock nextBlock = null;
//若新表项添加在头结点前，更改头结点
if (start < lastBlock.starting)
{
block.next = lastBlock;
lastBlock.last = block;
freeMemList.first = block;
lastBlock = block;
block = lastBlock.next;
nextBlock = block.next;
}
else
{
//寻找插入的位置（插在哪一结点后方）
while (lastBlock.next != null && lastBlock.next.starting < start)
{
lastBlock = lastBlock.next;
}
//若该结点不是尾节点，连接下一项
if (lastBlock.next != null)
{
nextBlock = lastBlock.next;
block.next = nextBlock;
nextBlock.last = block;
}
//连接上一项
lastBlock.next = block;
block.last = lastBlock;
}
//合并操作
//检查是否要与上一项合并
if (lastBlock != null)
{
if (lastBlock.starting + lastBlock.blockSize == block.starting)
{
lastBlock.blockSize += block.blockSize;
lastBlock.next = nextBlock;
if (nextBlock != null)
{
nextBlock.last = lastBlock;
}
block = lastBlock;
}
}
//检查是否要与下一项合并
if (nextBlock != null)
{
if (block.starting + block.blockSize == nextBlock.starting)
{
block.blockSize += nextBlock.blockSize;
block.next = nextBlock.next;
if (block.next != null)
{
block.next.last = block;
}
}
}
}
//更新空闲表信息
PrintFreeMemList();
}
