山大操作系统课程设计报告（全套）(12)

check=MinimumPages; int j=0; if(Mmbmp->NumClear()Create(virtualName,size); execFile=fileSystem->Open(virtualName); printf(\ } size1=check*PageSize; ASSERT(check <= Mmbmp -> NumClear());//检测是否有执行线程所需的最少物理页数，没有则不启动任务 DEBUG('a', \

/*初始化count，为可以装入内存的code page 的页数*/ count = divRoundUp(noffH.code.size,PageSize); if(count>CodePages)//可以装入主存的代码页数 count=CodePages; count1=count; pageTable = new TranslationEntry[numPages]; /*为可以装入内存的code page 分配页表*/ printf(\ for (i = 0; i < count; i++) { pageTable[i].virtualPage = i; pageTable[i].physicalPage = Mmbmp->Find(); pageTable[i].valid = FALSE; pageTable[i].use = FALSE; pageTable[i].dirty = FALSE; pageTable[i].readOnly = FALSE; // if the code segment was entirely on // a separate page, we could set its pages to be read-only } /*为不能装载如内存的虚拟页分配页表，即不分配物理祯*/ int last=numPages-1; for (;i < last;i++) {

pageTable[i].virtualPage = i; pageTable[i].physicalPage = -1; pageTable[i].valid = FALSE; pageTable[i].use = FALSE; pageTable[i].dirty = FALSE; pageTable[i].readOnly = FALSE; }

/*为装入内存的1个用户堆栈段分配一个物理祯*/ printf(\ for(i=numPages-1;iFind(); pageTable[i].valid = TRUE; pageTable[i].use = FALSE; pageTable[i].dirty = FALSE; pageTable[i].readOnly = FALSE; /*使用的物理页数加1*/ count++; } /*在内存和swap中加载可执行文件的内容*/

if (noffH.code.size > 0) {

DEBUG('a', \ noffH.code.virtualAddr, noffH.code.size); printf(\ unsigned int numP,firstP,c,amount; firstP = divRoundUp(noffH.code.virtualAddr,PageSize); numP = firstP + count1; for (i=firstP;iReadAt(&(machine->mainMemory[pageTable[i].physicalPage*PageSize]), PageSize,noffH.code.inFileAddr+i*PageSize); printf(\ pageTable[i].valid = TRUE; }

/*如果有没有加入内存的页，就把所有的Code页写入到Swap中*/ if(numPages>MinimumPages){//Load code of the executable into the virtual memory buffer = new char[PageSize];