Kari Argillander
f806c5829b
* pre-commit: Update and enable clang-format check There is newer version from clang-format so use that. We do not yet want 18 as that is little bit too new. * Format some thing by hand which clang-format "breaks" Clang-format will format some things little bit off in some cases. Format some things by hand so we get cleaner end result. * Run clang-format with ``` pre-commit run --all-files clang-format ``` We have already in previously checked places where clang-format does not make good format and ignored those (hopefully most of the things). --------- Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>
90 lines
3.0 KiB
C
90 lines
3.0 KiB
C
/**
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* @file
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* @brief Performs linear interpolation using single precision floating
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* point math or integer math, or a mixture of both. Linear interpolation
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* is a method of constructing new data points within the range of a discrete
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* set of known data points.
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* @author Steve Karg <skarg@users.sourceforge.net>
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* @date 2011
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* @copyright SPDX-License-Identifier: MIT
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "bacnet/basic/sys/linear.h"
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/**
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* Linearly Interpolate the values between y1 and y3 based on x.
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*
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* @param x1 - first x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x2 - intermediate x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x3 - last x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param y1 - first y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @param y3 - last y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @return y2 - an intermediate y value y1 <= y2 <= y3 or y1 >= y2 >= y3
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* and the y value is linearly proportional to x1, x2, and x2.
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*/
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float linear_interpolate(float x1, float x2, float x3, float y1, float y3)
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{
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float y2;
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if (y3 > y1) {
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y2 = y1 + (((x2 - x1) * (y3 - y1)) / (x3 - x1));
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} else {
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y2 = y1 - (((x2 - x1) * (y1 - y3)) / (x3 - x1));
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}
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return y2;
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}
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/**
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* Linearly Interpolate the values between y1 and y3 based on x
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* and round up the result. Useful for integer interpolation.
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*
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* @param x1 - first x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x2 - intermediate x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x3 - last x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param y1 - first y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @param y3 - last y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @return y2 - an intermediate y value y1 <= y2 <= y3 or y1 >= y2 >= y3
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* and the y value is linearly proportional to x1, x2, and x2.
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*/
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float linear_interpolate_round(float x1, float x2, float x3, float y1, float y3)
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{
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float y2;
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y2 = linear_interpolate(x1, x2, x3, y1, y3);
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/* round away from zero */
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if (y2 > 0.0f) {
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y2 += 0.5f;
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} else if (y2 < 0.0f) {
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y2 -= 0.5f;
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}
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return y2;
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}
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/**
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* Linearly Interpolate the values between y1 and y3 based on x
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* using integer math.
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*
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* @param x1 - first x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x2 - intermediate x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param x3 - last x value, where x1 <= x2 <= x3 or x1 >= x2 >= x3
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* @param y1 - first y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @param y3 - last y value, where y1 <= y2 <= y3 or y1 >= y2 >= y3
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* @return y2 - an intermediate y value y1 <= y2 <= y3 or y1 >= y2 >= y3
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* and the y value is linearly proportional to x1, x2, and x2.
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*/
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long linear_interpolate_int(long x1, long x2, long x3, long y1, long y3)
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{
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long y2;
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if (y3 > y1) {
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y2 = y1 + (((x2 - x1) * (y3 - y1)) / (x3 - x1));
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} else {
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y2 = y1 - (((x2 - x1) * (y1 - y3)) / (x3 - x1));
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}
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return y2;
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}
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