| 1 |
- (window.webpackJsonp=window.webpackJsonp||[]).push([[60],{350:function(t,s,a){"use strict";a.r(s);var n=a(14),e=Object(n.a)({},(function(){var t=this,s=t._self._c;return s("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[s("h1",{attrs:{id:"时钟页面置换算法-clock"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#时钟页面置换算法-clock"}},[t._v("#")]),t._v(" 时钟页面置换算法(CLOCK)")]),t._v(" "),s("h2",{attrs:{id:"置换策略与算法原理"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#置换策略与算法原理"}},[t._v("#")]),t._v(" 置换策略与算法原理")]),t._v(" "),s("p",[t._v("\tCLOCK页面置换算法的置换策略是淘汰最近未使用的页面，选择在内存中最长时间没有被访问的页面予以淘汰，而替换此时需要调用的页面。")]),t._v(" "),s("p",[t._v("\tCLOCK页面置换算法的算法原理是利用一个循环队列来模拟内存中的页面，并为每个页面设置一个访问位。当某个页面首次装入内存中时，或者该页面被访问到时，将其访问位设置为1。当需要淘汰一个页面时，从当前指针所指的位置开始，检查每个页面的访问位。如果是0，则选择该页面换出，并将新页面放入该位置，并将其访问位设置为1；如果是1，则将其访问位置为0，并继续检查下一个位置。如果一轮扫描后所有页面的访问位都是1，则将所有访问位清零，并重新扫描。")]),t._v(" "),s("p",[t._v("\tCLOCK页面置换算法的优点是实现起来比较简单，只需要维护一个循环队列和一个指针，不需要移动队列中的元素。CLOCK算法也是一种LRU置换算法的近似算法，能够较好地反映程序局部性原理。")]),t._v(" "),s("p",[s("strong",[t._v("扩展：")])]),t._v(" "),s("p",[t._v("\tCLOCK页面置换算法的缺点是没有考虑到页面是否被修改过的情况，如果一个页面被修改过，则在换出时需要写回磁盘，这会增加I/O开销。")]),t._v(" "),s("p",[t._v("\t因此，有一种改进型CLOCK算法，除了访问位外，还增加了一个修改位，用于记录每个页面是否被修改过，并根据不同的情况进行优先级排序。")]),t._v(" "),s("h2",{attrs:{id:"实验步骤"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#实验步骤"}},[t._v("#")]),t._v(" 实验步骤")]),t._v(" "),s("p",[t._v("\t接上文，在这里继续完成置换算法的实现。")]),t._v(" "),s("div",{staticClass:"language-cpp extra-class"},[s("pre",{pre:!0,attrs:{class:"language-cpp"}},[s("code",[s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 假设页面的结构体定义如下")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("struct")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("Page")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" read"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 读标志")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" write"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 写标志")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" time_arrive"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 到达时间")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" access"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 访问位")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 定义一个页面置换算法CLOCK类")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("CLOCK")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("private")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" page_num"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 页面数量")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 内存大小")]),t._v("\n Page"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),t._v(" pages"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 页面数组")]),t._v("\n Page"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),t._v(" memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 内存数组，用于存放当前正在内存中的页面")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" pointer"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 指针，用于指向当前检查的位置")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" page_faults"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 缺页次数")]),t._v("\n\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 构造函数，根据给定的页面数量，内存大小和页面数组初始化类的成员变量")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("CLOCK")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" pn"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" ms"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" Page"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),t._v(" ps"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n page_num "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" pn"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n mem_size "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" ms"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n pages "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" ps"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n memory "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("new")]),t._v(" Page"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 动态分配内存数组的空间")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v(" mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 初始化内存数组，开始时都为空")]),t._v("\n memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("nullptr")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n pointer "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 初始化指针为0，指向第一个位置")]),t._v("\n page_faults "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n\n "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 析构函数，释放内存数组的空间")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("~")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("CLOCK")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("delete")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n\n "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 执行页面置换算法的函数，根据给定的页面访问序列进行操作，并输出结果")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("run")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("Page"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),t._v(" query"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" len"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v(" len"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 遍历所有页面访问序列")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("bool")]),t._v(" hit "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("false")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 是否命中标志")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" j "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" j "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v(" mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" j"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 遍历所有内存块")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("j"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("==")]),t._v(" query"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 如果当前访问的页面已经在内存中")]),t._v("\n hit "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("true")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 设置命中标志为真")]),t._v("\n memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("j"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("->")]),t._v("access "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("1")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 更新该页面的访问位为1")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("break")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 跳出循环")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("!")]),t._v("hit"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 如果没有命中")]),t._v("\n page_faults"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 缺页次数加一")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("bool")]),t._v(" replaced "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("false")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 是否替换标志")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("while")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("!")]),t._v("replaced"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 循环直到找到一个可以替换的位置为止")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("pointer"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("->")]),t._v("access "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("==")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 如果当前指针所指的位置的访问位为0，则可以替换该位置的页面")]),t._v("\n memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("pointer"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" query"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 将当前访问的页面放入该位置，并将其访问位设置为1")]),t._v("\n memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("pointer"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("->")]),t._v("access "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("1")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n replaced "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("true")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 设置替换标志为真，跳出循环")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("else")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 如果当前指针所指的位置的访问位为1，则将其访问位清零，并继续检查下一个位置")]),t._v("\n memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("pointer"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("->")]),t._v("access "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n pointer "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("pointer "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("1")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("%")]),t._v(" mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 指针向前移动一位，如果到达末尾，则回到开头，形成循环队列")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n\n "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 输出结果")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"CLOCK page replacement algorithm results:"')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" endl"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"Page faults: "')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" page_faults "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" endl"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"Memory contents: "')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" endl"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v(" mem_size"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"Memory block "')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('": "')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("!=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("nullptr")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"Page "')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" memory"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v(" pages "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" endl"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("else")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n cout "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"Empty"')]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<<")]),t._v(" endl"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n")])])]),s("h2",{attrs:{id:"实验样例"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#实验样例"}},[t._v("#")]),t._v(" 实验样例")])])}),[],!1,null,null,null);s.default=e.exports}}]);
|
