[alsa-devel] ALSA C++ API

[Lasse Kärkkäinen]

Even though I got no replies to my original announcement, here is a
new version that wraps hw and sw params completely, has a macro for
checking ALSA C function return values (throws alsa::error) and uses
different naming style (similar to the C++ standard library). It is
better documented now, too.

The code is now largely generated with macros, so it isn't very readable
anymore :/

Next I'll be trying to figure out how the PCM API itself should be
wrapped, for C++ style callbacks, etc. I am using the test/pcm.c program
for my tests. Does it use good style for error recovery, etc? Mine will
base on it, so this is important.

Example of use (a port of what test/pcm.c does using a few separate
functions and 140 lines of code):

	alsa::pcm handle(device);
	unsigned int rrate = rate;
	alsa::hw_config(handle)
	  .rate_resample(resample)
	  .set(transfer_methods[method].access)
	  .set(format)
	  .channels(channels)
	  .rate_near(rrate)
	  .buffer_time_near(buffer_time)
	  .get_buffer_size(buffer_size)
	  .period_time_near(period_time)
	  .get_period_size(period_size)
	  .commit();
	if (rate != rrate) {
		std::cout << "Requested rate " << rate << " Hz, got "      		  <<
rrate << " Hz" << std::endl;
		rate = rrate;
	}
	alsa::sw_config(handle)
	  .start_threshold((buffer_size / period_size) * period_size)
	  .avail_min(period_size)
	  .xfer_align(1)
	  .commit();

I'd prefer to use the Boost libraries (boost::function,
boost::noncopyable, etc), but I am afraid that a dependency on them
might be problematic. What do you think?

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