mirror of https://github.com/ArduPilot/ardupilot
61 lines
1.3 KiB
Plaintext
61 lines
1.3 KiB
Plaintext
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#if 0 // currently unused
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struct DataPoint {
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unsigned long x;
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long y;
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};
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DataPoint history[ALTITUDE_HISTORY_LENGTH]; // Collection of (x,y) points to regress a rate of change from
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unsigned char hindex; // Index in history for the current data point
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unsigned long xoffset;
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unsigned char n;
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// Intermediate variables for regression calculation
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long xi;
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long yi;
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long xiyi;
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unsigned long xi2;
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void add_altitude_data(unsigned long xl, long y)
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{
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//Reset the regression if our X variable overflowed
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if (xl < xoffset)
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n = 0;
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//To allow calculation of sum(xi*yi), make sure X hasn't exceeded 2^32/2^15/length
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if (xl - xoffset > 131072/ALTITUDE_HISTORY_LENGTH)
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n = 0;
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if (n == ALTITUDE_HISTORY_LENGTH) {
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xi -= history[hindex].x;
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yi -= history[hindex].y;
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xiyi -= (long)history[hindex].x * history[hindex].y;
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xi2 -= history[hindex].x * history[hindex].x;
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} else {
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if (n == 0) {
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xoffset = xl;
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xi = 0;
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yi = 0;
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xiyi = 0;
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xi2 = 0;
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}
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n++;
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}
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history[hindex].x = xl - xoffset;
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history[hindex].y = y;
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xi += history[hindex].x;
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yi += history[hindex].y;
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xiyi += (long)history[hindex].x * history[hindex].y;
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xi2 += history[hindex].x * history[hindex].x;
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if (++hindex >= ALTITUDE_HISTORY_LENGTH)
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hindex = 0;
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}
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#endif
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