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fixp-arith: add a linear interpolation function 

Adds a function to interpolate against two points,
this is carried arount as a helper function by tons of drivers.

Signed-off-by: Craig Tatlor <ctatlor97@gmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201204025509.1075506-3-dmitry.baryshkov@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Craig Tatlor 2020-12-04 05:54:56 +03:00 committed by Jonathan Cameron
parent 5c8fe583cc
commit 8d502ef682
1 changed files with 19 additions and 0 deletions
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19
include/linux/fixp-arith.h
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@ -141,4 +141,23 @@ static inline s32 fixp_sin32_rad(u32 radians, u32 twopi)
#define fixp_cos32_rad(rad, twopi) \
fixp_sin32_rad(rad + twopi / 4, twopi)
/**
* fixp_linear_interpolate() - interpolates a value from two known points
*
* @x0: x value of point 0
* @y0: y value of point 0
* @x1: x value of point 1
* @y1: y value of point 1
* @x: the linear interpolant
*/
static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x)
{
if (y0 == y1 || x == x0)
return y0;
if (x1 == x0 || x == x1)
return y1;
return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
}
#endif