ra8_io_cache_demo Directory Reference

Directory dependency graph for ra8_io_cache_demo:

Directories
	src

Detailed Description

Drives the ra8_io caching block device (#160) with no external hardware.

The cache is a decorator: it wraps any other ra8_io_blockdev_t and keeps a fixed set of recently-used 512-byte sectors in a caller-owned buffer, so repeated reads of the same blocks – filesystem metadata, a re-read page – skip the slow medium. Reads are served on a hit and fill on a miss, writes are write-through, eviction is least-recently-used, and it allocates nothing. It is the layer that sits between the filesystem and the media.

Here it wraps an in-SRAM RAM block device (#156), the cached device is bridged to ra8_fs (#158) and formatted, mounted and registered in the VFS, so every FAT access flows through the cache. A file is written and then read back several times through its VFS path and byte-compared each pass: the first pass fills the cache and the re-reads touch the same metadata and data sectors, so the run requires a non-zero hit count from ra8_io_blockdev_cache_stats. The exact hit and miss numbers depend on FAT geometry and are not the assertion.