File Systems (Windows CE 5.0)
Windows CE offers three types of file systems:
- A ROM-based file system
- A RAM-based file system
- A FAT file system for Advanced Technology Attachment (ATA) devices, such as flash memory
In addition, embedded systems developers can create and register proprietary file systems.
Regardless of the type of storage, all of the file systems are accessed through the Microsoft Win32® file-system application programming interface (API).
Windows CE uses handles for file access. The CreateFile function returns a handle that references the created or opened file. Subsequent read, write, and information functions all use that handle to determine the file on which to act. File read and write functions use a file pointer to specify the location within a file in which the read or write operation takes place.
Windows CE does not use the current directory concept. Instead, all of the references to an object are given in the full path. Also, Windows CE automatically compresses all of the files in the object store, based on an OEM option, and the FILE_ATTRIBUTE_COMPRESSION attribute indicates compression. Of course, a flag does exist that distinguishes between a file in ROM and a file in RAM.
A file in the object store can be up to 4 GB. An installed file system such as the FAT file system can also be implemented in addition to the object store. File size limitations on installed file systems are implementation-dependent.
An installed file system can provide access to a PC Card or to other external storage devices. You can divide an external storage device into multiple volumes, one volume per partition, each of which is mounted separately. Each mounted volume is visible to the user as a folder in the root directory of the installed file system. While you can back up data to an external storage device, the working registry and RAM file system can exist only in the object store.
Note For programming purposes, Windows CE considers the object store to be a special type of volume that is always mounted.
File Systems and Data Store OS Design Development | Selecting the Internal File System for your Target Device | Filesys.exe Boot Process | File System Operations | FAT File System | Binary Rom Image File System (BinFS) | CD/UDFS File System | Installable File System | File System Filters
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