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The Advanced Linux Sound Architecture (ALSA) - library
Both, min_dB and max_dB, are floating type whereas the TLV is (always)
unsigned.
The problem with the conversion of a negative floating-point number into an
unsigned integer is, that the behavior is undefined. This may, depending on
the platform, result in a wrong TLV, i.e. for the default values of min_dB
(-51dB) and max_dB (0dB), alsactl generates the following state on an ARM
cpu build with GCC:
control.1 {
iface MIXER
name Master
value.0 255
value.1 255
comment {
access 'read write user'
type INTEGER
count 2
range '0 - 255'
tlv '00000001000000080000000000000014'
dbmin 0
dbmax 5100
dbvalue.0 5100
dbvalue.1 5100
}
}
With the fix applied, alsactl stores the correct TLV:
control.1 {
iface MIXER
name Master
value.0 255
value.1 255
comment {
access 'read write user'
type INTEGER
count 2
range '0 - 255'
tlv '0000000100000008ffffec1400000014'
dbmin -5100
dbmax 0
dbvalue.0 0
dbvalue.1 0
}
}
Also tested for different combinations of min_dB and max_dB other than the
default values.
Replaces:
http://mailman.alsa-project.org/pipermail/alsa-devel/2016-May/107733.html
Fixes:
http://mailman.alsa-project.org/pipermail/alsa-devel/2016-May/107628.html
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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