254 lines
8.8 KiB
C
254 lines
8.8 KiB
C
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/*++
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Copyright (c) 1991 Microsoft Corporation
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Module Name:
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cvf.hxx
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Abstract:
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This module contains basic declarations and definitions for
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the double-space file system format. Note that more extensive
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description of the file system structures may be found in
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ntos\fastfat\cvf.h
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Author:
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Bill McJohn [BillMc] 24-September-1993
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Revision History:
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Adapted from utils\ufat\inc\cvf.hxx
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--*/
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#if !defined( _CVF_DEFN_ )
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#define _CVF_DEFN_
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#include "bpb.h"
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// Manifest constants for fixed values on a Double Space drive:
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//
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CONST DoubleSpaceBytesPerSector = 512;
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CONST DoubleSpaceLog2BytesPerSector = 9;
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CONST DoubleSpaceSectorsPerCluster = 16;
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CONST DoubleSpaceLog2SectorsPerCluster = 4;
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CONST DoubleSpaceReservedSectors = 16;
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CONST DoubleSpaceFats = 1;
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CONST DoubleSpaceSectorsInRootDir = 32;
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CONST DoubleSpaceRootEntries = 512;
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CONST DoubleSpaceMediaByte = 0xf8;
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CONST DoubleSpaceSectorsPerTrack = 0x11;
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CONST DoubleSpaceHeads = 6;
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CONST DoubleSpaceHiddenSectors = 0;
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CONST DoubleSpaceReservedSectors2 = 31;
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CONST DSBytesPerBitmapPage = 2048;
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CONST DSSectorsPerBitmapPage = 4;
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CONST ULONG EIGHT_MEG = 8 * 1024L * 1024L;
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CONST DbSignatureLength = 4;
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CONST UCHAR FirstDbSignature[4 /* DbSignatureLength */] = { (UCHAR)0xf8, 'D', 'R', 0 };
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CONST UCHAR SecondDbSignature[4 /* DbSignatureLength */] = "MDR";
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#if 0
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// INLINE
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ULONG
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ComputeMaximumCapacity(
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IN ULONG HostDriveSize
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)
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/*++
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Routine Description:
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This function computes the maximum capacity for a compressed
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volume file on a host volume of a given size.
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Arguments:
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HostDriveSize -- Supplies the size in bytes of the host drive.
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Return Value:
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The appropriate Maximum Capacity.
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--*/
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{
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ULONG MaxCap;
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if( HostDriveSize < 20 * 1024L * 1024L ) {
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MaxCap = 16 * HostDriveSize;
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} else if ( HostDriveSize < 64 * 1024L * 1024L ) {
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MaxCap = 8 * HostDriveSize;
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} else {
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MaxCap = 4 * HostDriveSize;
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}
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if( MaxCap < 4 * 1024L * 1024L ) {
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MaxCap = 4 * 1024L * 1024L;
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} else if( MaxCap > 512 * 1024L * 1024L ) {
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MaxCap = 512 * 1024L * 1024L;
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}
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return MaxCap;
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}
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#endif
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typedef struct _PACKED_CVF_HEADER {
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//
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// First a typical start of a boot sector
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//
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UCHAR Jump[1]; // offset = 0x000 0
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UCHAR JmpOffset[2];
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UCHAR Oem[8]; // offset = 0x003 3
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PACKED_BIOS_PARAMETER_BLOCK PackedBpb; // offset = 0x00B 11
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//
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// Now the DblSpace extensions
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//
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UCHAR CvfFatExtensionsLbnMinus1[2]; // offset = 0x024 36
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UCHAR LogOfBytesPerSector[1]; // offset = 0x026 38
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UCHAR DosBootSectorLbn[2]; // offset = 0x027 39
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UCHAR DosRootDirectoryOffset[2]; // offset = 0x029 41
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UCHAR CvfHeapOffset[2]; // offset = 0x02B 43
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UCHAR CvfFatFirstDataEntry[2]; // offset = 0x02D 45
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UCHAR CvfBitmap2KSize[1]; // offset = 0x02F 47
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UCHAR Reserved1[2]; // offset = 0x030 48
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UCHAR LogOfSectorsPerCluster[1]; // offset = 0x032 50
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UCHAR Reserved2[2]; // offset = 0x033
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UCHAR MinFile[4]; // offset = 0x035
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UCHAR Reserved3[4]; // offset = 0x039
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UCHAR Is12BitFat[1]; // offset = 0x03D 61
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UCHAR CvfMaximumCapacity[2]; // offset = 0x03E 62
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UCHAR StartBootCode;
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} PACKED_CVF_HEADER; // sizeof = 0x040 64
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typedef PACKED_CVF_HEADER *PPACKED_CVF_HEADER;
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//
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// For the unpacked version we'll only define the necessary field and skip
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// the jump and oem fields.
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//
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typedef struct _CVF_HEADER {
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UCHAR Jump;
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USHORT JmpOffset;
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UCHAR Oem[8];
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BIOS_PARAMETER_BLOCK Bpb;
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USHORT CvfFatExtensionsLbnMinus1;
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UCHAR LogOfBytesPerSector;
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USHORT DosBootSectorLbn;
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USHORT DosRootDirectoryOffset;
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USHORT CvfHeapOffset;
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USHORT CvfFatFirstDataEntry;
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UCHAR CvfBitmap2KSize;
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UCHAR LogOfSectorsPerCluster;
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UCHAR Is12BitFat;
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ULONG MinFile;
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USHORT CvfMaximumCapacity;
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} CVF_HEADER;
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typedef CVF_HEADER *PCVF_HEADER;
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//
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// Here is NT's typical routine/macro to unpack the cvf header because DOS
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// doesn't bother to naturally align anything.
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//
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// VOID
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// CvfUnpackCvfHeader (
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// IN OUT PCVF_HEADER UnpackedHeader,
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// IN PPACKED_CVF_HEADER PackedHeader
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// );
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//
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#define CvfUnpackCvfHeader(UH,PH) { \
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\
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memcpy( &(UH)->Jump, &(PH)->Jump, 1 ); \
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memcpy( &(UH)->JmpOffset, &(PH)->JmpOffset, 2 ); \
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memcpy( &(UH)->Oem, &(PH)->Oem, 8 ); \
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UnpackBios( &(UH)->Bpb, &(PH)->PackedBpb ); \
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CopyUchar2( &(UH)->CvfFatExtensionsLbnMinus1, &(PH)->CvfFatExtensionsLbnMinus1[0] ); \
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CopyUchar1( &(UH)->LogOfBytesPerSector, &(PH)->LogOfBytesPerSector[0] ); \
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CopyUchar2( &(UH)->DosBootSectorLbn, &(PH)->DosBootSectorLbn[0] ); \
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CopyUchar2( &(UH)->DosRootDirectoryOffset, &(PH)->DosRootDirectoryOffset[0] ); \
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CopyUchar2( &(UH)->CvfHeapOffset, &(PH)->CvfHeapOffset[0] ); \
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CopyUchar2( &(UH)->CvfFatFirstDataEntry, &(PH)->CvfFatFirstDataEntry[0] ); \
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CopyUchar1( &(UH)->CvfBitmap2KSize, &(PH)->CvfBitmap2KSize[0] ); \
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CopyUchar1( &(UH)->LogOfSectorsPerCluster, &(PH)->LogOfSectorsPerCluster[0] ); \
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CopyUchar1( &(UH)->Is12BitFat, &(PH)->Is12BitFat[0] ); \
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CopyUchar4( &(UH)->MinFile, &(PH)->MinFile[0] ); \
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CopyUchar2( &(UH)->CvfMaximumCapacity, &(PH)->CvfMaximumCapacity[0] ); \
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}
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#define CvfPackCvfHeader(PH,UH) { \
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\
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memcpy( &(PH)->Jump, &(UH)->Jump, 1 ); \
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memcpy( &(PH)->JmpOffset, &(UH)->JmpOffset, 2 ); \
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memcpy( &(PH)->Oem, &(UH)->Oem, 8 ); \
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PackBios( &(UH)->Bpb, &(PH)->PackedBpb, ); \
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CopyUchar2( (PH)->CvfFatExtensionsLbnMinus1, &(UH)->CvfFatExtensionsLbnMinus1 ); \
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CopyUchar1( (PH)->LogOfBytesPerSector, &(UH)->LogOfBytesPerSector ); \
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CopyUchar2( (PH)->DosBootSectorLbn, &(UH)->DosBootSectorLbn ); \
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CopyUchar2( (PH)->DosRootDirectoryOffset, &(UH)->DosRootDirectoryOffset ); \
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CopyUchar2( (PH)->CvfHeapOffset, &(UH)->CvfHeapOffset ); \
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CopyUchar2( (PH)->CvfFatFirstDataEntry, &(UH)->CvfFatFirstDataEntry ); \
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CopyUchar1( (PH)->CvfBitmap2KSize, &(UH)->CvfBitmap2KSize ); \
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CopyUchar1( (PH)->LogOfSectorsPerCluster, &(UH)->LogOfSectorsPerCluster ); \
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CopyUchar1( (PH)->Is12BitFat, &(UH)->Is12BitFat ); \
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CopyUchar4( (PH)->MinFile, &(UH)->MinFile ); \
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CopyUchar2( (PH)->CvfMaximumCapacity, &(UH)->CvfMaximumCapacity ); \
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memset( (PH)->Reserved1, 0, 2 ); \
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memset( (PH)->Reserved2, 0, 2 ); \
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memset( (PH)->Reserved3, 0, 4 ); \
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}
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//
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// The CVF FAT EXTENSIONS is a table is ULONG entries. Each entry corresponds
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// to a FAT cluster. The entries describe where in the CVF_HEAP to locate
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// the data for the cluster. It indicates if the data is compressed and the
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// length of the compressed and uncompressed form.
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//
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typedef struct _CVF_FAT_EXTENSIONS {
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ULONG CvfHeapLbnMinus1 : 21;
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ULONG Reserved : 1;
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ULONG CompressedSectorLengthMinus1 : 4;
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ULONG UncompressedSectorLengthMinus1 : 4;
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ULONG IsDataUncompressed : 1;
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ULONG IsEntryInUse : 1;
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} CVF_FAT_EXTENSIONS;
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typedef CVF_FAT_EXTENSIONS *PCVF_FAT_EXTENSIONS;
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//
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// Some sizes are fixed so we'll declare them as manifest constants
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//
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#define CVF_MINIMUM_DISK_SIZE (512 * 1024L)
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#define CVF_FATFAILSAFE (1024L)
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#define CVF_MIN_HEAP_SECTORS (60)
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#define CVF_RESERVED_AREA_1_SECTOR_SIZE (1)
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#define CVF_RESERVED_AREA_2_SECTOR_SIZE (31)
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#define CVF_RESERVED_AREA_4_SECTOR_SIZE (2)
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#endif // _CVF_DEFN_
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