DiskImageUtils.hh

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#ifndef DISK_IMAGE_UTILS_HH
#define DISK_IMAGE_UTILS_HH
 
#include "AlignedBuffer.hh"
#include "endian.hh"
#include "openmsx.hh"
#include <span>
 
namespace openmsx {
 
class SectorAccessibleDisk;
 
struct MSXBootSector {
        byte           jumpCode[3];   // + 0 0xE5 to bootprogram
        byte           name[8];       // + 3
        Endian::UA_L16 bpSector;      // +11 bytes per sector (always 512)
        byte           spCluster;     // +13 sectors per cluster (always 2)
        Endian::L16    resvSectors;   // +14 nb of non-data sectors (ex bootsector)
        byte           nrFats;        // +16 nb of fats
        Endian::UA_L16 dirEntries;    // +17 max nb of files in root directory
        Endian::UA_L16 nrSectors;     // +19 nb of sectors on this disk
        byte           descriptor;    // +21 media descriptor
        Endian::L16    sectorsFat;    // +22 sectors per FAT
        Endian::L16    sectorsTrack;  // +24 sectors per track
        Endian::L16    nrSides;       // +26 number of side
        Endian::L16    hiddenSectors; // +28 not used
        byte           pad1[9];       // +30
        Endian::UA_L32 vol_id;        // +39
        byte           pad2[512-43];  // +43
};
static_assert(sizeof(MSXBootSector) == 512);
 
struct MSXDirEntry {
        static constexpr byte ATT_REGULAR   = 0x00; // Normal file
        static constexpr byte ATT_READONLY  = 0x01; // Read-Only file
        static constexpr byte ATT_HIDDEN    = 0x02; // Hidden file
        static constexpr byte ATT_SYSTEM    = 0x04; // System file
        static constexpr byte ATT_VOLUME    = 0x08; // filename is Volume Label
        static constexpr byte ATT_DIRECTORY = 0x10; // entry is a subdir
        static constexpr byte ATT_ARCHIVE   = 0x20; // Archive bit
 
        union {
                struct {
                        char base[8];// + 0
                        char ext [3];// + 8
                } name;
                char filename[8 + 3];// + 0
        };
        byte        attrib;          // +11
        byte        reserved[10];    // +12 unused
        Endian::L16 time;            // +22
        Endian::L16 date;            // +24
        Endian::L16 startCluster;    // +26
        Endian::L32 size;            // +28
};
static_assert(sizeof(MSXDirEntry) == 32);
 
// Note: can't use Endian::L32 for 'start' and 'size' because the Partition
//       struct itself is not 4-bytes aligned.
struct Partition {
        byte           boot_ind;   // + 0 0x80 - active
        byte           head;       // + 1 starting head
        byte           sector;     // + 2 tarting sector
        byte           cyl;        // + 3 starting cylinder
        byte           sys_ind;    // + 4 what partition type
        byte           end_head;   // + 5 end head
        byte           end_sector; // + 6 end sector
        byte           end_cyl;    // + 7 end cylinder
        Endian::UA_L32 start;      // + 8 starting sector counting from 0
        Endian::UA_L32 size;       // +12 nr of sectors in partition
};
static_assert(sizeof(Partition) == 16);
static_assert(alignof(Partition) == 1, "must not have alignment requirements");
 
struct PartitionTable {
        char        header[11]; // +  0
        char        pad[3];     // +  3
        Partition   part[31];   // + 14,+30,..,+494    Not 4-byte aligned!!
        Endian::L16 end;        // +510
};
static_assert(sizeof(PartitionTable) == 512);
 
 
// Buffer that can hold a (512-byte) disk sector.
// The main advantages of this type over something like 'byte buf[512]' are:
//  - No need for reinterpret_cast<> when interpreting the data in a
//    specific way (this could in theory cause alignment problems).
//  - This type has a stricter alignment, so memcpy() and memset() can work
//    faster compared to using a raw byte array.
union SectorBuffer {
        byte raw[512];            // raw byte data
        MSXBootSector bootSector; // interpreted as bootSector
        MSXDirEntry dirEntry[16]; // interpreted as 16 dir entries
        PartitionTable pt;        // interpreted as Sunrise-IDE partition table
        AlignedBuffer aligned;    // force big alignment (for faster memcpy)
};
static_assert(sizeof(SectorBuffer) == 512);
 
 
namespace DiskImageUtils {
 
        void checkValidPartition(SectorAccessibleDisk& disk, unsigned partition);
 
        void checkFAT12Partition(SectorAccessibleDisk& disk, unsigned partition);
 
        [[nodiscard]] bool hasPartitionTable(SectorAccessibleDisk& disk);
 
        void format(SectorAccessibleDisk& disk, bool dos1 = false);
 
        void partition(SectorAccessibleDisk& disk,
                       std::span<const unsigned> sizes);
};
 
} // namespace openmsx
 
#endif