[PD] share-mem lib
Cyrille Henry
ch at chnry.net
Mon Feb 25 15:54:30 CET 2013
hello
looking at the thread, i was assuming that the question was about shmem, but it look more like a question about pix_share_write.
in shmem, the shmid is the id provide by the user so anyone can acces to the mem.
but shmem did share table, so you have to put the pix in a table before sharing it.
on the other hand, pix_share_read / pix_share_write are dedicated to share pix data.
but the id provide is not the shmid.
looking at the source, i think the shmid is computed with this code :
int hash_str2us(std::string s) {
int result=0;
int a=63689;
int b=378551;
if(s.length()<1)return -1;
unsigned int i=0;
for(i=0; i<s.length(); i++) {
result=result*a+s[i];
a *= b;
}
return ((unsigned short)(result) & 0x7FFFFFFF);
}
is that what you where looking for?
cheers
cyrille
Le 25/02/2013 15:13, Charles Goyard a écrit :
> Hi,
>
> Cyrille Henry wrote:
>> i just did a initial commit of share-mem, a lib dedicated to deal with
>> shared memory.
>
> Wow, great !
>
> I'd like to use this to share pixes with veejay (a vjing tool that runs
> on linux). Veejay wants YUV and can read/write from/to shm. So it looks
> like communication can be done pretty easily. (note there's also an OGRE
> plugin that uses shm).
>
> My question is: how can I map the shm id of pix_share_write to the
> output of ipcs ? Reading the source code left me clueless.
>
> For example:
> [ set 400 256 256 RGBA (
> creates this:
> ~$ ipcs
> key shmid size
> 0x0000798c 229379 charles 666 262164 1
>
> veejay want the shm id as shown in the second field.
>
> How course I can grep the pid and look for pd. But it won't work for
> several shms.
>
> Thanks for any hints,
>
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