From: Craig Tatlor Date: Fri, 4 Dec 2020 02:54:56 +0000 (+0300) Subject: fixp-arith: add a linear interpolation function X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8d502ef682fdbe0ddf2274dae903b07baf1140e0;p=linux.git 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 Signed-off-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20201204025509.1075506-3-dmitry.baryshkov@linaro.org Signed-off-by: Jonathan Cameron --- diff --git a/include/linux/fixp-arith.h b/include/linux/fixp-arith.h index 8396013785efe..281cb4f83dbeb 100644 --- a/include/linux/fixp-arith.h +++ b/include/linux/fixp-arith.h @@ -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