Since we are using the 'hw' interface of ALSA, we don't have the luxury of
samplerate conversion, given by the 'plughw' interface. If we try to set a
samplerate that is not supported, ALSA will just throw an error.
We can test for the supported samplerates, and create a list of supported
samplerates, then limit the selection to only those values. The frontend can
query the list of supported samplerates.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
The alsa driver requested signed 16-bit integers from ALSA, but casted them to
to an unsigned 16bit before finally casting them to a float. The end result was
that half of the wave would be clipped off.
We also requested data in little endian format. ALSA can be instructed to send
data with the correct endianness for the platform, without needing to worry
about what that is.
This patch attempts three points, which, together, fix the acquisition:
1) Request data from ALSA without specifying endianness; ALSA will handle the
endianness.
2) Simplify the int16_t to float loop by using straightforward indexes.
3) Normalize every value before sending it on the session bus.
NOTE: If testing with PulseView, it will appear as if sigrok is sending all
zeroes. sigrok is sending correct data, but since the data is normalized,
PulseView will incorrectly plot it as a straight line.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
The alsa driver only works with device "default". This limits the driver's
scope to whatever device ALSA deems to be "default". It is desirable to have
access to all ALSA devices from sigrok.
Change the alsa device scan so that:
Each alsa device (not alsa card) gets its own sigrok device
For example,
hw:1,0 == sigrok device 0
hw:1,1 == sigrok device 1
hw:2,0 == sigrok device 2
hw:2,1 == sigrok device 3
hw:2,2 == sigrok device 4
[...]
We don't currently look at alsa subdevices. We only use subdevice 0.
Every input device will have its own channels (left, right, etc). Each of
those channels gets mapped to a different sigrok probe. A device with 4
channels will have 4 probes from sigrok's perspective.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
snd_pcm_hw_params_set_rate_near() will try to use the samplerate closest to the
given value, potentially starting the acquisition with a different samplerate
than the one specified.
Instead, use snd_pcm_hw_params_set_rate(). It will return an error if the
samplerate is not supported by the hardware, which is arguably better than
collecting data with a different samplerate than the one specified.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Check whether a sample limit was actually set (> 0) before checking if
that sample limit is reached. This also fixes continuous acquisition mode
for drivers which have that.
This is the driver model agreed upon for all drivers.
As a result of the split, a devc->num_probes field had to be added in order to
reduce the interdependence between api.c and protocol.c .
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
The alsa driver was out of date wrt APIs and libsigrok conventions in
general, and wasn't compiling.
This fixes the compile and updates it to _basically_ work with the current
state of analog support in libsigrok.
This is not finished/full support for ALSA analog sampling yet, though,
various TODOs remain that will be addressed later.
All frontends will have to include <libsigrok/libsigrok.h> from now on.
This header includes proto.h and version.h, both installed from the
distribution into $INCLUDE/libsigrok/ as well.
The only dynamically changed header is now version.h, which has both
libsigrok and libtool compile-time versions in it.
Start/stop acquisition callbacks: Consistently name the 'void *' parameter
cb_data for now. The per-device-instance device pointer is called
'session_dev_id' everywhere for now, but this should be renamed to
something more clear.
Avoid plain malloc()/free() in sr/srd, especially in the API calls.
Also avoid g_malloc*() in favor of g_try_malloc*().
Use g_strdup() instead of strdup() so that we can use g_free()
consistently everywhere.
Exceptions: Stuff that is allocated via other libs (not using glib),
should also be properly free'd using the respective free-ing function
(instead of g_free()). Examples: Stuff allocated by libusb, libftdi, etc.
Also, use sr_err() instead of sr_warn() for actual errors. sr_warn() is
meant for non-fatal/uncritical warnings.
Use SR_API to mark public API symbols, and SR_PRIV for private symbols.
Variables and functions marked 'static' are private already and don't
need SR_PRIV. However, functions which are not static (because they need
to be used in other libsigrok-internal files) but are also not meant to
be part of the public libsigrok API, must use SR_PRIV.
This uses the 'visibility' feature of gcc (requires gcc >= 4.0).
Details: http://gcc.gnu.org/wiki/Visibility
For now, there's no analog/scope support in sigrok yet (will be added
later), so remove any such items from the public API (sigrok.h).
Having '#if defined(HAVE_LA_ALSA)' in sigrok.h is a bug anyway, the API
must not have anything device-dependent in general, and sigrok.h
specifically must not have any #ifdefs for specific hardware.
Uwe Hermann
Alexandru Gagniuc
Peter Stuge
Bert Vermeulen
Joel Holdsworth