vmm.rar_虚存管理

#include <stdio.h> #include <stdlib.h> #include <time.h> #include <windows.h> #include "vmm.h" //页表 PageTableItem pageTable[PAGE_SUM]; //实存空间 BYTE actMem[ACTUAL_MEMORY_SIZE]; //用文件模拟辅存空间 FILE *ptr_auxMem; //物理块使用标识 BOOL blockStatus[BLOCK_SUM]; //访存请求 Ptr_MemoryAccessRequest ptr_memAccReq; //初始化环境 void do_init() { srand((unsigned int) time(NULL)); int i,j; for (i = 0; i < PAGE_SUM; i++) { pageTable[i].filled = FALSE; pageTable[i].edited = FALSE; pageTable[i].count = 0; //使用随机数设置该页的保护类型 switch (rand() % 7) { case 0: { pageTable[i].proType = READABLE; break; } case 1: { pageTable[i].proType = WRITABLE; break; } case 2: { pageTable[i].proType = EXECUTABLE; break; } case 3: { pageTable[i].proType = READABLE | WRITABLE; break; } case 4: { pageTable[i].proType = READABLE | EXECUTABLE; break; } case 5: { pageTable[i].proType = WRITABLE | EXECUTABLE; break; } case 6: { pageTable[i].proType = READABLE | WRITABLE | EXECUTABLE; break; } default: break; } //设置该页对应的辅存地址，本程序为实现简单采用顺序设置的方式，可替换成其他设置方式，但须注意每个页表项对应的辅存地址均应为PAGE_SIZE的整数倍 pageTable[i].auxAddr = i * PAGE_SIZE * 2; } for (j = 0; j < BLOCK_SUM; j++) { //随机选择一些物理块进行页面装入 if (rand() % 2 == 0) { do_page_in(&pageTable[j], j); pageTable[j].blockNum = j; pageTable[j].filled = TRUE; blockStatus[j] = TRUE; } else blockStatus[j] = FALSE; } } //响应请求 void do_response() { Ptr_PageTableItem ptr_pageTabIt; unsigned int pageNum, offAddr; unsigned int actAddr; //检查地址是否越界 if (ptr_memAccReq->virAddr < 0 || ptr_memAccReq->virAddr >= VIRTUAL_MEMORY_SIZE) { do_error(ERROR_OVER_BOUNDARY); return; } //计算页号和页内偏移值 pageNum = ptr_memAccReq->virAddr / PAGE_SIZE; offAddr = ptr_memAccReq->virAddr % PAGE_SIZE; printf("页号为：%u\t页内偏移为：%u\n", pageNum, offAddr); //获取对应页表项 ptr_pageTabIt = &pageTable[pageNum]; //根据特征位决定是否产生缺页中断 if (!ptr_pageTabIt->filled) { do_page_fault(ptr_pageTabIt); } actAddr = ptr_pageTabIt->blockNum * PAGE_SIZE + offAddr; printf("实地址为：%u\n", actAddr); //检查页面访问权限并处理访存请求 switch (ptr_memAccReq->reqType) { case REQUEST_READ: //读请求 { ptr_pageTabIt->count++; if (!(ptr_pageTabIt->proType & READABLE)) //页面不可读 { do_error(ERROR_READ_DENY); return; } //读取实存中的内容 printf("读操作成功：值为%02X\n", actMem[actAddr]); break; } case REQUEST_WRITE: //写请求 { ptr_pageTabIt->count++; if (!(ptr_pageTabIt->proType & WRITABLE)) //页面不可写 { do_error(ERROR_WRITE_DENY); return; } //向实存中写入请求的内容 actMem[actAddr] = ptr_memAccReq->value; ptr_pageTabIt->edited = TRUE; printf("写操作成功\n"); break; } case REQUEST_EXECUTE: //执行请求 { ptr_pageTabIt->count++; if (!(ptr_pageTabIt->proType & EXECUTABLE)) //页面不可执行 { do_error(ERROR_EXECUTE_DENY); return; } printf("执行成功\n"); break; } default: //非法请求类型 { do_error(ERROR_INVALID_REQUEST); return; } } } //处理缺页中断 void do_page_fault(Ptr_PageTableItem ptr_pageTabIt) { printf("产生缺页中断，开始进行调页...\n"); unsigned int i; for (i = 0; i < BLOCK_SUM; i++) { if (!blockStatus[i]) { //读辅存内容，写入到实存 do_page_in(ptr_pageTabIt, i); //更新页表内容 ptr_pageTabIt->blockNum = i; ptr_pageTabIt->filled = TRUE; ptr_pageTabIt->edited = FALSE; ptr_pageTabIt->count = 0; blockStatus[i] = TRUE; return; } } //没有空闲物理块，进行页面替换 do_LFU(ptr_pageTabIt); } //根据LFU算法进行页面替换 void do_LFU(Ptr_PageTableItem ptr_pageTabIt) { printf("没有空闲物理块，开始进行LFU页面替换...\n"); unsigned int i, min, page; for (i = 0, min = 0xFFFFFFFF, page = 0; i < PAGE_SUM; i++) { if (pageTable[i].count < min) { min = pageTable[i].count; page = i; } } printf("选择第%u页进行替换\n", page); if (pageTable[page].edited) { //页面内容有修改，需要写回至辅存 printf("该页内容有修改，写回至辅存\n"); do_page_out(&pageTable[page]); } pageTable[page].filled = FALSE; pageTable[page].count = 0; //读辅存内容，写入到实存 do_page_in(ptr_pageTabIt, pageTable[page].blockNum); //更新页表内容 ptr_pageTabIt->blockNum = pageTable[page].blockNum; ptr_pageTabIt->filled = TRUE; ptr_pageTabIt->edited = FALSE; ptr_pageTabIt->count = 0; printf("页面替换成功\n"); } //将辅存内容写入实存 void do_page_in(Ptr_PageTableItem ptr_pageTabIt, unsigned int blockNum) { unsigned int readNum; if (fseek(ptr_auxMem, ptr_pageTabIt->auxAddr, SEEK_SET) < 0) { exit(1); } if ((readNum = fread(actMem + blockNum * PAGE_SIZE, sizeof(BYTE), PAGE_SIZE, ptr_auxMem)) < PAGE_SIZE) { exit(1); } printf("调页成功：辅存地址%u-->>物理块%u\n", ptr_pageTabIt->auxAddr, blockNum); } //将被替换页面的内容写回辅存 void do_page_out(Ptr_PageTableItem ptr_pageTabIt) { unsigned int writeNum; if (fseek(ptr_auxMem, ptr_pageTabIt->auxAddr, SEEK_SET) < 0) { exit(1); } if ((writeNum = fwrite(actMem + ptr_pageTabIt->blockNum * PAGE_SIZE, sizeof(BYTE), PAGE_SIZE, ptr_auxMem)) < PAGE_SIZE) { do_error(ERROR_FILE_WRITE_FAILED); exit(1); } printf("写回成功：物理块%u-->>辅存地址%u\n", ptr_pageTabIt->auxAddr, ptr_pageTabIt->blockNum); } //错误处理 void do_error(ERROR_CODE code) { switch (code) { case ERROR_READ_DENY: { printf("访存失败：该地址内容不可读\n"); break; } case ERROR_WRITE_DENY: { printf("访存失败：该地址内容不可写\n"); break; } case ERROR_EXECUTE_DENY: { printf("访存失败：该地址内容不可执行\n"); break; } case ERROR_INVALID_REQUEST: { printf("访存失败：非法访存请求\n"); break; } case ERROR_OVER_BOUNDARY: { printf("访存失败：地址越界\n"); break; } case ERROR_FILE_OPEN_FAILED: { printf("系统错误：打开文件失败\n"); break; } case ERROR_FILE_CLOSE_FAILED: { printf("系统错误：关闭文件失败\n"); break; } case ERROR_FILE_SEEK_FAILED: { printf("系统错误：文件指针定位失败\n"); break; } case ERROR_FILE_READ_FAILED: { printf("系统错误：读取文件失败\n"); break; } case ERROR_FILE_WRITE_FAILED: { printf("系统错误：写入文件失败\n"); break; } default:{ printf("未知错误：没有这个错误代码\n"); } } } //产生访存请求 void do_request() { //随机产生请求地址 ptr_memAccReq->virAddr = rand() % VIRTUAL_MEMORY_SIZE; //随机产生请求类型 switch (rand() % 3) { case 0: //读请求 { ptr_memAccReq->reqType = REQUEST_READ; printf("产生请求：\n地址：%u\t类型：读取\n", ptr_memAccReq->virAddr); break; } case 1: //写请求 { ptr_memAccReq->reqType = REQUEST_WRITE; //随机产生待写入的值 ptr_memAccReq->value = rand() % 0xFFu; printf("产生请求：\n地址：%u\t类型：写入\t值：%02X\n", ptr_memAccReq->virAddr, ptr_memAccReq->value); break; } case 2: { ptr_memAccReq->reqType = REQUEST_EXECUTE; printf("产生请求：\n地址：%u\t类型：执行\n", ptr_memAccReq->virAddr); break; }default: break; } } //打印页表 void do_print_info() { char str[4]; printf("页号\t块号\t