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author | Lars-Peter Clausen <lars@metafoo.de> | 2012-09-14 15:21:00 (GMT) |
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committer | Jonathan Cameron <jic23@kernel.org> | 2012-09-15 09:12:22 (GMT) |
commit | 7985e7c1003bc5cdfa20755f8cfdada946ed8e18 (patch) | |
tree | 94adb3cf91ec3406361c2bc9d0c66485e1bf2436 /include/Kbuild | |
parent | ca7d1b32d2a0d4c62533b9401cf9ce4d14d183f7 (diff) | |
download | linux-fsl-qoriq-7985e7c1003bc5cdfa20755f8cfdada946ed8e18.tar.xz |
iio: Introduce a new fractional value type
Currently IIO uses a decimal fixed point representations for real type numbers.
This patch introduces a new representation for rational type numbers. The number
will be expressed by specifying a numerator and denominator. For converting a
raw value to a processed value multiply it by the numerator and divide it by the
denominator.
The reasoning for introducing this new type is that for a lot of devices the
scale can be represented easily by a fractional number, but it is not possible
to represent it as fixed point number without rounding. E.g. for a simple DAC
the scale is often the reference voltage divided by the number of possible
values (Usually 2**n_bits - 1). Each driver currently implements the conversion
of this fraction to a fixed point number on its own.
Also when it comes to the in-kernel interface this allows to directly use the
fractional factors to convert a raw value to a processed value. This should on
one hand require less instructions and on the other hand increase the
precision.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'include/Kbuild')
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