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Structure of an RTFiles-32 Program

Unlike file systems of most operating systems, RTFiles-32 is linked as a library into embedded systems application programs. This approach has several advantages: only those parts of the file system actually used will be linked and the file system can be accessed using function calls as opposed to software interrupts, dynamically linked entrypoints, or some other complicated access method.

RTFiles-32 consists of the following components:

• Portable File System Core
  The file system core is contained in the RTFiles-32 library. It is completely written in ANSI C. Its source code is available as a separate add-on product and contains no device specific code.
• RTFiles-32 Data Tables
  A default set of the data tables is contained in the RTFiles-32 library, but it can be replaced by the application (see section Configuring RTFiles-32, RTFiles-32 Data Tables). The configuration of these tables determines how many logical drives, simultaneously open files, and cache buffers RTFiles-32 can maintain.
• Device List
  RTFiles-32 can use one or more devices with one or more device drivers. Most device drivers are capable of handling several physical devices. The RTFiles-32 library contains all device drivers shipped with RTFiles-32 as well as a default configuration of these drivers to be linked into an application. An application can override the default (e.g., to add a custom driver or to remove an unneeded driver) by defining a suitable data structure (see section Configuring RTFiles-32, Device List.
• System Driver
  The system driver enables RTFiles-32 and the device drivers to access system dependent services such as installing interrupt handlers, obtaining DMA buffers, etc. There is no default system driver in the RTFiles-32 library. Instead, each system driver is supplied as an additional library file, which must also be linked to the application. Further details are given in section Configuring RTFiles-32, The System Driver.

When RTFiles-32's default configuration is used, no source code modifications are required in existing programs using files. Existing file I/O operations using one or more of RTFiles-32's alternate APIs work unmodified. Thus, it is very easy to port existing programs with file I/O to RTFiles-32.

RTFiles-32 in Embedded Applications

RTFiles-32 APIs