RTFiles-32 - Embedded FAT, exFAT, and ISO 9660 File System

RTFiles-32 is a portable royalty-free FAT-12/16/32, exFAT, and ISO 9660 file system for embedded systems. RTFiles-32 is a library containing the core file handling functions as well as the required device drivers. Several different APIs are provided for compatibility with other systems. No source code modifications of existing programs are required to use RTFiles-32.

Features

• Unlimited Number of Files
  RTFiles-32 can handle an unlimited number of open files as required by the application. Only about 300 bytes of RAM are required for each open file.
• Up to 32 Logical Drives
  RTFiles-32 easily handles many physical and logical drives.
• FAT-12, FAT-16, and FAT-32
  RTFiles-32 supports the same FAT (File Allocation Table) formats as DOS and Windows. Storage media can be shared between RTFiles-32 and other operating systems to exchange data.
• Supports exFAT
  RTFiles-32 supports the improved variation of the FAT file systems to support larger disks and files.
• Supports ISO 9660 File Systems
  RTFiles-32 supports the standard format used for data CD-ROMs and DVDs. Extensions to the ISO 9660 standard such as 9660-Relaxed or Joliet are supported. Most UDF volumes also contain an ISO 9660 directory tree and can thus be read by RTFiles-32.
• Long File Name Support
  On all three FAT types, exFAT, and ISO 9660, file names with up to 255 characters are allowed.
• Code Page and UTF-8 Support
  Through UTF-8 encoded file names, RTFiles-32 supports all 16-bit Unicode characters in file names, including Cyrillic, Japanese, Chinese, and other Asian languages.
• Supports Diskettes, Hard Disks, Flash Disks, SRAM Cards, USB Disks, CD-ROM, and DVD Drives
  RTFiles-32 supports the following device types: diskette drives and media with 360k, 1.2M, 720k, 1.44M, and 2.88M capacity, IDE and flash disks with CHS (Cylinder, Head, Sector) or LBA (Logical Block Addressing) interface, Serial ATA disk and CD/DVD drives, M-Systems DiskOnChip flash disks, linear flash, PCMCIA SRAM/CompactFlash/ATA cards, IDE-ATAPI CD-ROM/DVD drives, AHCI controller attached disks, RAM disks, USB sticks and USB disk/CD/DVD drives (RTUSB-32 required).
• Supports Removable Devices and Hot Swapping
  Floppy disks, removable hard disks (e.g., disks in PCMCIA sockets), USB devices, and CD-ROM/DVD media can be removed and reinserted while an application is running. Devices are automatically remounted as needed. Critical error handling support is available to handle disk removal of devices currently in use.
• Multiword DMA and UDMA Transfer Mode
  IDE, SATA, and AHCI disks are operated in Multiword DMA or Ultra DMA mode, if supported by the disk and host controller. The IDE disk driver automatically selects the best transfer mode supported by the hardware. The AHCI driver always uses UDMA mode.
• Hard Disks up to 2 Terabytes
  The latest standards such as LBA-48-bit for extended sector addressing are supported, if also supported by the disk controller. There is no limit on partition sizes.
• Extended File and Cluster Sizes
  Unlike DOS and Windows, RTFiles-32 supports extended cluster sizes up to 16 megabytes and file sizes up to 1 terabyte.
• Partitioning and Formatting
  RTFiles-32 provides functions to partition and format storage devices. Embedded systems assembled with virgin disks can automatically format their disks when first powered on.
• Efficient Cache Support
  RTFiles-32 will cache frequently accessed data such as a volume's FAT or directories. The application has full control over the size of the cache. Large data blocks that are read or written contiguously are not cached to avoid cache thrashing.
• Contiguous Files
  RTFiles-32 can preallocate files to reside in a single contiguous chain of sectors. In this way, it can guarantee that no extra seek operations are required for contiguous read or write operations.
• Committed and Lazy Write Files
  RTFiles-32's behavior can be fine-tuned for best data security (e.g. always commit all file write operations to disk immediately) or best throughput (e.g. data is kept in cache as long as possible to eliminate redundant write operations).
• Extensive Diagnostics Support
  RTFiles-32 provides functions to query the state of its cache in great detail. For each file or even a complete volume, the degree of fragmentation can be determined.
• File System Analysis and Repair
  RTFiles-32's function RTFCheckDisk can detect and automatically repair common file system errors, such as file chain crosslinks, lost clusters, invalid directory entries, etc.
• Customizable Critical Error Handler
  Applications have full control over how RTFiles-32 handles disk I/O errors. All errors can be passed back to the calling application using standard error codes, or RTFiles-32 can call custom error handlers of the application, which in turn can decide whether the operation should be failed or retried (possibly after prompting the user).
• Native API
  RTFiles-32 has its own API consisting of about 50 functions. While many of these functions appear in all file systems (e.g. open, read, write, etc.), some address advanced features tailored to the needs of embedded systems. For example, function RTFExtend can create contiguous (unfragmented) files and RTFBufferInfo returns detailed statistics about RTFiles-32's internal sector buffer cache.
• Raw I/O Functions
  RTFiles-32 allows the application to call device driver functions directly. Applications can completely bypass the high-level file system and perform sector-level I/O.
• Win32 Compatible API
  If used with RTTarget-32, RTFiles-32 emulates about 30 file I/O related Win32 functions. Existing Win32 programs that access files are supported without source code modifications.
• C/C++ and Pascal Run-Time System Support
  Through RTFiles-32's Win32 API emulation, all of the run-time systems' file I/O functions are fully supported. C functions such as fopen, fread, etc., work unmodified with RTFiles-32. The same is true for C++ classes such as iostream.
• Multitasking Support
  When RTFiles-32 is used with RTKernel-32 or another multi-tasking kernel, all RTFiles-32 operations perform appropriate locking to support simultaneous calls from several tasks. Simultaneous access to different devices is fully supported. I/O wait times are made available to other tasks by blocking the waiting tasks at a semaphore until the device signals I/O completion with an interrupt.
• Low Interrupt Latencies
  Although RTFiles-32's device drivers are interrupt-driven, they never disable interrupts and do not process data transfers in interrupt handlers.
• Installable Device Drivers
  RTFiles-32's device driver interface is very simple. Only three functions are required to access a device: MountDevice, ReadSectors, and WriteSectors. All drivers (except for the M-Systems DiskOnChip driver available free of charge from M-Systems/SanDisk) included with RTFiles-32 come with complete source code, which can be used as examples for implementing custom drivers.
• Portable
  RTFiles-32 is written in ANSI C and does not contain any system or hardware dependencies. All device-specific code is encapsulated in device drivers which are always delivered with full source code. The portable file system's source code is available as an option. By supplying an alternate System Driver, RTFiles-32 can easily be ported to other operating systems or CPUs. Compile-time options are available to support little-endian and big-endian CPUs or for packing/unpacking data in misaligned FAT data structures.

Structure of RTFiles-32