Raised buffer size to 8 MiB for large cards.

Added experimental exFAT support.

Author: profi200

README.md

@@ -2,11 +2,12 @@
 Unfortunately SDFormatter isn't available for Linux so i made this. It is a tool to format your SD card the way the SD Association intended but under Linux.
 
 Multiple SD cards with different capacities have been tested and this tool formats them 1:1 the same as SDFormatter with the following exceptions:
-* SDFormatter does not set the jmp instruction offset in the boot sector. sdFormatLinux does.
-* sdFormatLinux does not support exFAT right now.
+* SDFormatter does not set the jmp instruction offset in the boot sector for FAT12/16/32. sdFormatLinux does.
+* For exFAT sdFormatLinux clears unused FAT entries SDFormatter leaves untouched and SDFormatter clears more areas after root directory cluster. As far as i can tell these differences don't matter.
+* sdFormatLinux currently does not preserve OEM flash parameters when reformatting in exFAT. It will recalculate the correct values instead.
 
 ## Examples
-Erase (TRIM) and format SD card (recommended). TRIM will not work with USB card readers and is ignored.  
+Erase (TRIM) and format SD card (recommended). TRIM will not work with USB card readers and is ignored if used with one.  
 `sudo sdFormatLinux -e trim /dev/mmcblkX` where X is a number.
 
 Erase and format with label.  

include/buffered_fs_writer.h

@@ -14,7 +14,7 @@
 //          Padding for alignment is filled with zeros (no read-modify-write).
 class BufferedFsWriter final : private BlockDev
 {
-	static constexpr u32 m_blkSize = 1024 * 1024 * 4; // Must be >=512 and power of 2.
+	static constexpr u32 m_blkSize = 1024 * 1024 * 8; // Must be >=512 and power of 2.
 	static constexpr u32 m_blkMask = m_blkSize - 1;
 	static_assert(m_blkSize > 512 && (m_blkSize & m_blkMask) == 0, "Invalid buffer size for BufferedFsWriter.");
 

include/exfat.h

@@ -5,9 +5,10 @@
 #include <cstddef>
 #include "types.h"
 #include "format.h"
+#include "buffered_fs_writer.h"
 
 // References:
-// exFAT: https://learn.microsoft.com/en-us/windows/win32/fileio/exfat-specification
+// https://learn.microsoft.com/en-us/windows/win32/fileio/exfat-specification
 
 
 // Boot Sector.
@@ -21,7 +22,7 @@ typedef struct
 	u32 fatOffset;                   // Minimum "24", maximum "ClusterHeapOffset - (FatLength * NumberOfFats)".
 	u32 fatLength;                   // Minimum "(ClusterCount + 2) * 2^2 / 2^BytesPerSectorShift" rounded up to nearest integer, maximum "(ClusterHeapOffset - FatOffset) / NumberOfFats" rounded down to nearest integer.
 	u32 clusterHeapOffset;           // Minimum "FatOffset + FatLength * NumberOfFats", maximum "2^32 - 1" or "VolumeLength - (ClusterCount * 2^SectorsPerClusterShift)" whichever is smaller.
-	u32 clusterCount;                // Shall be the lesser of "(VolumeLength - ClusterHeapOffset) / 2^SectorsPerClusterShiftrounded down to the nearest integer" or "2^32 - 11". Recommended no more than "2^24 - 2".
+	u32 clusterCount;                // Shall be the lesser of "(VolumeLength - ClusterHeapOffset) / 2^SectorsPerClusterShift rounded down to the nearest integer" or "2^32 - 11". Recommended no more than "2^24 - 2".
 	u32 firstClusterOfRootDirectory; // Minimum "2", maximum "ClusterCount + 1".
 	u32 volumeSerialNumber;          // Volume serial number generated from date and time.
 	u16 fileSystemRevision;          // versionHigh<<8 | (u8)versionLow. Version high 1-99, versionLow 0-99. Usually 1.00.
@@ -35,16 +36,99 @@ typedef struct
 	u8  bootCode[390];               // Bootstrapping code or 0xF4 filled (x86 halt).
 	u16 bootSignature;               // 0xAA55.
 	//u8 excessSpace[(1u<<bytesPerSectorShift) - 512];
-} BootSector;
-static_assert(offsetof(BootSector, bootSignature) == 510, "Member bootSignature of BootSector not at offsetof 510.");
+} ExfatBootSec;
+static_assert(offsetof(ExfatBootSec, bootSignature) == 510, "Member bootSignature of ExfatBootSec not at offsetof 510.");
 
-// Extended Boot Sector.
-/*typedef struct
+typedef struct
+{
+	u8  guid[16];         // {0A0C7E46-3399-4021-90C8-FA6D389C4BA2} (467E0C0A 9933 2140 90C8 FA6D389C4BA2 in memory).
+	u32 eraseBlockSize;
+	u32 pageSize;
+	u32 spareSectors;
+	u32 randomAccessTime;
+	u32 programmingTime;
+	u32 readCycle;
+	u32 writeCycle;
+	u32 reserved;
+} FlashParameters;
+static_assert(offsetof(FlashParameters, reserved) == 44, "Member reserved of FlashParameters not at offsetof 44.");
+
+typedef struct
 {
-	u8  extendedBootCode[(1u<<bytesPerSectorShift) - 4];
-	u32 extendedBootSignature;                          // 0xAA550000.
-} ExtendedBootSector;*/
+	u8 entryType;
+	union
+	{
+		struct __attribute__((packed))
+		{
+			u8  bitmapFlags;
+			u8  reserved[18];
+			u32 firstCluster;
+			u64 dataLength;
+		} bitmap;
+		struct __attribute__((packed))
+		{
+			u8  reserved1[3];
+			u32 tableChecksum;
+			u8  reserved2[12];
+			u32 firstCluster;
+			u64 dataLength;
+		} upCase;
+		struct __attribute__((packed))
+		{
+			u8  characterCount;
+			u16 volumeLabel[11];
+			u8  reserved[8];
+		} label;
+		// TODO: Other entry types.
+	};
+} ExfatDirEnt;
+static_assert(sizeof(ExfatDirEnt) == 32, "ExfatDirEnt is not 32 bytes.");
+
+
+// Boot Sector.
+#define BS_JUMP_BOOT           "\xEB\x76\x90"
+#define BS_FILE_SYS_NAME       "EXFAT   "
+#define BS_FILE_SYS_REV_1_00   (1u<<8 | 0) // 1.00.
+#define BS_DRIVE_SELECT        (0x80u)
+#define BS_BOOT_SIG            (0xAA55u)
+
+// Extended Boot Sectors.
+#define EBS_EXT_BOOT_SIG       (0xAA550000u)
+
+// OEM Parameters.
+#define OEM_FLASH_PARAMS_GUID  "\x46\x7E\x0C\x0A\x99\x33\x21\x40\x90\xC8\xFA\x6D\x38\x9C\x4B\xA2"
+
+// File Allocation Table.
+#define EXFAT_FIRST_ENT        (2u)          // Index 0 and 1 are reserved.
+#define EXFAT_MAX_CLUS         (0xFFFFFFF5u) // "2^32 - 11, which is the maximum number of clusters a FAT can describe"
+
+#define EXFAT_FREE             (0u)
+#define EXFAT_BAD              (0xFFFFFFF7u)
+#define EXFAT_RESERVED         (0xFFFFFFF8u)
+#define EXFAT_EOF              (0xFFFFFFFFu)
+
+// Directory Entry.
+// Bits 0-4 TypeCode.
+#define TYPE_IMPORTANCE_CRITICAL  (0u)
+#define TYPE_IMPORTANCE_BENIGN    (1u<<5)
+#define TYPE_CATEGORY_PRIMARY     (0u)
+#define TYPE_CATEGORY_SECONDARY   (1u<<6)
+#define TYPE_IN_USE               (1u<<7)
+
+#define TYPE_END_OF_DIR           (                TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 0u)
+#define TYPE_INVALID              (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 0u)
+#define TYPE_BITMAP               (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 1u)
+#define TYPE_UP_CASE              (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 2u)
+#define TYPE_VOL_LABEL            (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 3u)
+#define TYPE_FILE                 (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY | TYPE_IMPORTANCE_CRITICAL | 5u) // Or directory.
+#define TYPE_GUID                 (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY |   TYPE_IMPORTANCE_BENIGN | 0u)
+#define TYPE_TEXFAT_PADDING       (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY |   TYPE_IMPORTANCE_BENIGN | 1u)
+#define TYPE_WIN_CE_ACT           (TYPE_IN_USE |   TYPE_CATEGORY_PRIMARY |   TYPE_IMPORTANCE_BENIGN | 2u)
+#define TYPE_STREAM               (TYPE_IN_USE | TYPE_CATEGORY_SECONDARY | TYPE_IMPORTANCE_CRITICAL | 0u)
+#define TYPE_NAME                 (TYPE_IN_USE | TYPE_CATEGORY_SECONDARY | TYPE_IMPORTANCE_CRITICAL | 1u)
+#define TYPE_WIN_CE_AC            (TYPE_IN_USE | TYPE_CATEGORY_SECONDARY | TYPE_IMPORTANCE_CRITICAL | 2u)
 
 
 
 void calcFormatExFat(FormatParams &params);
+int makeFsExFat(const FormatParams &params, BufferedFsWriter &dev, const std::u16string &label);