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The cos table used at fixp-arith.h has only 8 bits of precision.
That causes problems if it is reused on other drivers.
As some media drivers require a higher precision sin/cos
implementation, replace the current implementation by one that
will provide 32 bits precision.
The values generated by the new implementation matches the
32 bit precision of glibc's sin for an angle measured in
integer degrees.
It also provides support for fractional angles via linear
interpolation. On experimental calculus, when used a table
with a 0.001 degree angle, the maximum error for sin is
0.000038, which is likely good enough for practical purposes.
There are some logic there that seems to be specific to the
usage inside ff-memless.c. Move those logic to there, as they're
not needed elsewhere.
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Prashant Laddha <prladdha@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
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Move drivers/input/fixp-arith.h to include/linux so that the functions
defined there can be used by other subsystems, for instance some video
devices ISPs can control the output HUE value by setting registers for
sin(HUE) and cos(HUE).
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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Changed email address of Johann Deneux (myself)
Also removed CVS tags in comments (no longer using cvs)
Signed-off-by: Johann Deneux <johann.deneux@gmail.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
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Move fixp-arith.h from drivers/usb/input to drivers/input, as the part of
force feedback support that requires trigonometric functions is being moved
there.
Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Add the value of cos(90) = 0 to the table. This also moves the results so
that sin(x) == sin(180-x) is true as expected.
Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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patch below marks various USB tables and variables as const so that they
end up in .rodata section and don't cacheline share with things that get
written to. For the non-array variables it also allows gcc to optimize
more.
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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