This is a utility library providing access to the mmap family of functions in a portable way. It should work on Posix and Windows systems. mmap allows you to directly map a file into the address space of your process without having to manually read it into memory sequentially. Typically this is much more efficient for files that are larger than a few Kb.
The library offers access to the following functions:
mmapmunmapmsyncmprotect
It also provides a convenience macro called with-mmap to perform safe, local mappings of files.
(mmap:with-mmap (addr fd size #p"/etc/lsb-release")
(with-output-to-string (out)
(loop for i from 0 below size
for char = (code-char (cffi:mem-aref addr :char i))
do (write-char char out))))
If you're on a system where mmap is supported, :mmap will be in *features*.