Re: [Feature Request] Some ideas on 'mmap'

[Daniel Hartwig]

On 30 April 2013 17:27, Nala Ginrut <address@hidden> wrote:
> hi guys!
> A discussion on IRC about adding 'mmap' raised, and I will share some
> ideas on this topic:
>
> 1. Complex one or simple one?
> The simple one is just a simple wrapper taking advantage of (system
> foreign).
> The complex one is more alike Python's mmap module. Contains a special
> type of <mmap>, and a bunch of functions to handle it.
>
> 2. If simple one, just leave the rest of the mail alone.
> But if complex one was chosen, we need (ice-9 mmap).
>
> 3. I'll choose Python alike interface for mmap:
> (mmap port #:optional length prog flags offset)
> And if port is #f, it works as anonymous-mapping.
>
> 4. mmap returns a new type <mmap>, and it may work like 'array':
> (define m (mmap port))
> (mmap-ref m 10 20)
> (mmap-set! m 0 0 1024)
> The interfaces maybe:
> (mmap-ref <mmap> from to) ==> return u8 bytevector
> (mmap-set! <mmap> byte from to) ==> return unspecified
>

You may as well just have mmap return a bytevector or pointer to the
start, and forget about these redundant procedures.  mmaped data is a
bytevector, so no need to reimplement that interface with different
names.

> 5. use munmap to release it
> (munmap <mmap>)
>

> 6. other helper functions also available:

If you want a port, use a port.  Likewise for strings, bytevectors.

> (mmap-find <mmap> string #:optional start end)
> (mmap-flush <mmap> #:optional offset size)
> (mmap-move <mmap> dest src count)
> (mmap-read <mmap> num)
> (mmap-readbyte <mmap>)
> (mmap-readline <mmap>)
> (mmap-resize <mmap> newsize)
> (mmap-rfind <mmap> string #:optional start end)
> (mmap-seek <mmap> pos #:optional whence)
> (mmap-size <mmap>)
> (mmap-tell <mmap>) ; Returns the current position of the file pointer.
> (mmap-write <mmap> str/bv)
> (mmap-writebyte <mmap> byte)
>
> Comments?
> Thanks!
>
>
>