adam at os.inf.tu-dresden.de
Mon Mar 24 18:23:52 CET 2008
On Fri Mar 21, 2008 at 04:12:57 +0000, muhammad saufy wrote:
> im using register based IPC operation to transfer
> string of more than two double word. (32 bit x 2). how
> IPC handle this? it's the register copy is loop twice
> to transfer the data or fiasco automatically copy that
> data to memory and send to the receiver?
There are two ways: short IPC with UTCB and so-called long IPC.
Transfer with UTCBs basically works like this:
l4_msgtag_t tag = l4_msgtag(0, size, 0, 0); // max size is L4_UTCB_GENERIC_DATA_SIZE
memcpy(l4_utcb_get()->values, data, size * sizeof(long));
l4_ipc_send_tag(receiver_id, L4_IPC_SHORT_MSG, dw0, dw1, tag, L4_IPC_NEVER, &dope);
&d0, &d1, L4_IPC_NEVER, &dope, &tag);
memcpy(store, l4_utcb_get()->values, size); // at most sizeof(utcb)
Doing long-IPC needs a few more lines but also lets you transfer up to a
super-page data with one IPC. You can look up plenty of examples by
looking in IDL generated code.
Adam adam at os.inf.tu-dresden.de
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