On Fri, Nov 27, 2015 at 9:16 AM, barret rhoden <[email protected]> wrote:
> > Question. Should I force the payloads to be strings, or should I use
> > binary? Example:
> >
> > struct req1 {
> > uint32_t size;
> > uint32_t req;
> > uint32_t cnt;
> > uint64_t something[NMAX];
> > };
>
> You could also use a binary, arch-independent format. That struct has
> endianness assumptions. But you can still use a binary format of your
> choosing.
>
> For another example, in Plan 9 (and Akaros), when we read() a
> directory, we get a byte stream of format 'M'. In Akaros, we convert
> those to structs for our own processing (e.g. convM2kdirent(), which
> you can see in a few places in kern/src/ns/sysfile.c). There are
> similar ones, e.g. convM2D().
>
> There's a bunch of helpers to convert from bytes to fields, e.g.
> GBIT8() and write fields as bytes (PBIT8()).
>
> What I'd do is come up with what you want the structs to look like,
> then write little conv() helpers. For example:
>
> conv_req1_to_X(struct req1 *req1, uint8_t *buf, size_t len)
> {
> PBIT32(buf, req1->size);
> buf += BIT32SZ;
> PBIT32(buf, req1->req);
> buf += BIT32SZ;
> PBIT32(buf, req1->cnt);
> buf += BIT32SZ;
> for (int i = 0; i < NMAX; i++) {
> PBIT64(buf, req1->something);
> buf += BIT64SZ;
> }
> }
>
> (written hastily, checkout convD2M for a better example).
>
These interfaces though, are not exposed to userspace, so I will have to
move them into a dedicated ros/ file, I guess?
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