在自己的操作系统中使用 FAT12 从磁盘读取文件/文件夹

问题描述

我正在开发一个操作系统，我正在尝试从其他操作系统的源代码中实现 FAT12 文件系统，最后，我可以挂载一个 FAT12 格式的磁盘并获取其 FAT12 信息。

它可以读取 DriveName（当 'Location = 0' 时）。 但是当我尝试从磁盘列出目录时，它不起作用！

这是我获取目录的代码，

void FAT12_PrintDirectories(uint32_t Location,uint32_t numEntries,uint8_t DriveNum)
{

   uint8_t read[((numEntries*32)/4096)+1];

   AHCI::Port* port = AHCI::GlobalAHCI->ports[0];

   port->Configure();

   port->buffer = (uint8_t*)GlobalAllocator.RequestPage();
        
   memset(port->buffer,((numEntries*32)/4096)+1);

   
   port->Read(Location /* If I write here '0' Instead of Location,then Output is Image2 */,Location+((numEntries*32)/4096)+1,port->buffer);

   for (int n = 0; n < sizeof(port->buffer); n++)
   {
        GlobalRenderer->PutChar(port->buffer[n]);
        read[n] = port->buffer[n];
   }


   char drivename[12];

   memset(&drivename,12);

   memcpy(drivename,read,8);


    if(read[9] != ' ')
    {

        drivename[8] = '.';

        memcpy(drivename + 9,read + 8,3);

    }


    drivename[11] = 0;


    // Print test read

    GlobalRenderer->Next();

    for (int n = 0; n < sizeof(read); n++)
    {
        GlobalRenderer->Print("=");
        GlobalRenderer->Print(to_string((uint64_t)read[n]));
    }
    


    GlobalRenderer->Next();
    GlobalRenderer->Print("Listing Dirs!");

    GlobalRenderer->Next();
    GlobalRenderer->Print("DriveName : ");
    GlobalRenderer->Print(drivename);
    GlobalRenderer->Next();


    uint8_t *reads = read;


    GlobalRenderer->Print("Dirs : ");
    GlobalRenderer->Next();

    for (unsigned int i = 0; i < numEntries; i++)
    {
        
        if(!reads[11] & 0x08 || reads[11] & 0x02 || reads[0] == 0 || reads[0] == 0xE5)
        {

            // Print FileName
            for (uint8_t j = 0; j < 11; j++)
            {
                
                if(j == 8 && reads[j] != ' ')
                {
                    GlobalRenderer->Print(".");

                }


                if(reads[j] != 0x20)
                {
                    GlobalRenderer->Print(to_string((uint64_t)reads[j]));

                }


                if(reads[11] & 0x10 && j == 10)
                {
                    
                    GlobalRenderer->Print("/");

                }



                uint32_t nextCluster = (reads[27] << 8) | reads[26];

                uint32_t size = *(uint32_t *)&reads[28];



            }


            reads += 32;
            

        }


        GlobalRenderer->Print("-");


    }


}

这是我对该函数的调用代码 FAT12_PrintDirectories(dirOff,32,0);

这次dirOff = 2097153

输出：

在“Dirs”文本之后 - Image1

图片2

Location =          ((FAT12_MOUNT *)getdiskMount(numActiveMounts).mount)->RootDirectoryOffset*512+1;

解决方法

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