On 22. 05. 23 12:31, Takashi Iwai wrote:
On Mon, 22 May 2023 10:00:40 +0200,
Takashi Iwai wrote:
On Mon, 22 May 2023 09:34:45 +0200,
Jaroslav Kysela wrote:
On 19. 05. 23 11:31, Takashi Iwai wrote:
Starting from this commit, we add the basic support of UMP (Universal
MIDI Packet) events on ALSA sequencer infrastructure. The biggest
change here is that, for transferring UMP packets that are up to 128
bits, we extend the data payload of ALSA sequencer event record when
the client is declared to support for the new UMP events.
A new event flag bit, SNDRV_SEQ_EVENT_UMP, is defined and it shall be
set for the UMP packet events that have the larger payload of 128
bits, defined as struct snd_seq_ump_event.
For applications that want to access the UMP packets, first of all, a
sequencer client has to declare the user-protocol to match with the
latest one via the new SNDRV_SEQ_IOCTL_USER_PVERSION; otherwise it's
treated as if a legacy client without UMP support.
Then the client can switch to the new UMP mode (MIDI 1.0 or MIDI 2.0)
with a new field, midi_version, in snd_seq_client_info. When switched
to UMP mode (midi_version = 1 or 2), the client can write the UMP
events with SNDRV_SEQ_EVENT_UMP flag. For reads, the alignment size
is changed from snd_seq_event (28 bytes) to snd_seq_ump_event (32
bytes). When a UMP sequencer event is delivered to a legacy sequencer
client, it's ignored or handled as an error.
The internal struct snd_seq_event_cell is also extended by 4 bytes. I
think that it is worth to note this in this commit (the memory
footprint is slightly growing).
Yes, will do that. But note that the size growth of
snd_seq_event_cell happens only for 32bit archs (there was already
padding on 64bit archs).
Maybe handle !SND_UMP here, but we can
wait, if someone really requires this optimization.
Right, I began with that, but I threw it away in the end as it becomes
unnecessarily complex.
Actually the optimization with CONFIG_SND_SEQ_UMP was already done;
unless CONFIG_SND_SEQ_UMP is set, the old size of snd_seq_event_cell
is still kept. The definition of union __snd_seq_event in
seq_memory.c takes care of the conditional builds.
I see now. All is fine. Thanks for the clarification.
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
