[alsa-devel] code improvements in /sound/usb/mixer.c

Daniel Schürmann daschuer at mixxx.org
Thu Apr 25 08:23:28 CEST 2013

Hi Takashi, Hi alsa-devel.

in my last mail I had supposed scaling issues with mixer.c, but finally it
turns out that was just a debugging problem of myself.
I was struggled how types are handled in the code. I have some ideas for
improvement but I am not sure if it its worth the work since nothing is

1. get rid of convert_bytes_value(cval, value_set):
This function return any type in a integer container, which is confusing.

2. use type casts in convert_signed_value():
gcc knows perfecly how to convert types.

3. merge convert_signed_value() and snd_usb_combine_bytes() to get rid of
the intermediate integer variant.


I am currently working on a patch that introduces a get_ctl_value_range_v2.
I want to get rid of the three single queries for min max and rate.
Also here, nothing broken. Is it worth to do the work?

Kind regards


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