Some parts of control API documentation are described with core-developer
friendly explanations. To usual developer such as me, they're quite hard
to understand.
This commit improves such comments for a part of APIs to handle data of
each element.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit adds a description about the design of ALSA control interface
for developers to understand a few components of low level.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Most of open functions in alsa-lib have the call pattern:
snd_config_update();
return snd_xxx_open(x, snd_config, ...);
This means that the toplevel config gets updated, and passed to a
local open function. Although snd_config_update() itself has a
pthread mutex to be thread safe, the whole procedure above isn't
thread safe. Namely, the global snd_config tree may be deleted and
recreated at any time while the open function is being processed.
This may lead to a data corruption and crash of the program.
For avoiding the corruption, this patch introduces a refcount to
config tree object. A few new helper functions are introduced as
well:
- snd_config_update_ref() does update and take the refcount of the
toplevel tree. The obtained config tree has to be freed via
snd_config_unref() below.
- snd_config_ref() and snd_config_unref() manage the refcount of the
config object. The latter eventually deletes the object when all
references are gone.
Along with these additions, the caller of snd_config_update() and
snd_config global tree in alsa-lib are replaced with the new helpers.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In most codes for control APIs, assertions are used to check given
arguments from applications. If the arguments are not expected, the
application is forced to abort. When NDEBUG is defined in the beginning
of the codes, no checks are performed.
Although, in snd_ctl_elem_set_bytes(), assertion is used with condition
statement. There's an intention to check the arguments regardless of
NDEBUG. However, this is not the same fashion in the codes.
This commit applies the same fashion to the function, to keep consistent
usage of assertion.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In ALSA control core, there're two ways to identify elements. One is by
numid. Another is by name/index. The former way is lighter than the latter
way.
In control API, after adding elements by snd_ctl_elem_add_integer() and
snd_ctl_elem_add_integer64(), these functions initialize value of each
channel. When executing this operation, used ID information is still given
by applications. Although, in this time, the element can be identified
according to numid.
This commit uses the numid instead of name/index pair.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In UAPI of asound.h, there're 6 types of control element; boolean, integer,
enumerated, bytes, iec958 and integer64 (The none type seems to be added to
start the value at non-zero). Although, current description in alsa-lib
has a lack of integer64 type.
This commit fulfil the type.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
When minus value is given as a parameter, the API returns whether
the caller has already subscribed or not.
This commit adds a comment about this so as better documentation.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Upon an interrupt, it is necessary to abort the wait loops with the EINTR
error code. Introduce snd_*_abort() functions to handle this case.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This allows us to build in environments that don't provide stpcpy().
This makes it necessary to traverse the string twice, but should not be
noticeable in clients since this function is very unlikely to be part of
a performance-critical path.
[coding style fixed by tiwai]
Signed-off-by: Arun Raghavan <arun.raghavan@collabora.co.uk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Handling of user control elements was implemented for all types except
BYTES and ENUMERATED. Enumerated user controls will be needed for the
device-specific mixers of upcoming FireWire drivers.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This patch adds new API functions, snd_ctl_open_fallback() and
snd_pcm_open_fallback(). These are just like snd_*_open_lconf() but
used to open a fallback PCM/control. The difference is that it replaces
the name string with the given original name, so that hctl and other
upper-layers will recognize it as an alias.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
- changed logic to get/put blocks
- added mutex locking of the symbol list
- added reference counting (do not free used dl handles)
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Only restore the old value if it differs from the requested
value, because if it has changed restoring the old value
overrides the change. Take for example, a voice modem with
a .conf that sets preserve off-hook. Start playback (on-hook
to off-hook), start record (off-hook to off-hook), stop
playback (off-hook to restore on-hook), stop record (on-hook
to restore off-hook), Clearly you don't want to leave the
modem "on the phone" now that there isn't any playback or
recording active.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Use "const char *const []" as type for string arrays, or convert to
"const char [][x]" when it makes sense.
Signed-off-by: Diego E. 'Flameeyes' Pettenò <flameeyes@gmail.com>
Added --with-configdir and --with-plugindir options to configure
which specify the directories for config files and plugin objects
respectively. The default paths when these options are not
specified are unchanged.
- add snd_device_name_hint() and snd_device_name_free_hint() functions
- add snd_ctl_iface_conf_name() functions
- do not accept parameters for the plugin definition without @args section
- add defaults.pcm.dmix.card/device and dsnoop.card/device definitions
- add hints for HDA-Intel.conf, pcm/dmix.conf, pcm/dsnoop.conf and alsa.conf
- add test/namehint test utility
- doxygen related cleanups
Check whether non-zero size TLV is really returned by comparing
with the pre-filled pattern. ALSA 1.0.12 driver doesn't notify
the error even if user TLV is empty, so the previous value is
passed bogusly.
