81 lines
2.0 KiB
C++
81 lines
2.0 KiB
C++
#include "maths.h"
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#include "globals.h"
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//Replace the standard arduino map() function to use the div function instead
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int fastMap(unsigned long x, int in_min, int in_max, int out_min, int out_max)
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{
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unsigned long a = (x - (unsigned long)in_min);
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int b = (out_max - out_min);
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int c = (in_max - in_min);
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int d = (ldiv( (a * (long)b) , (long)c ).quot);
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return d + out_min;
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//return ldiv( ((x - in_min) * (out_max - out_min)) , (in_max - in_min) ).quot + out_min;
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//return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
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}
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/*
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The following are all fast versions of specific divisions
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Ref: www.hackersdelight.org/divcMore.pdf
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*/
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//Unsigned divide by 10
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unsigned int divu10(unsigned int n)
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{
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unsigned long q, r;
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q = (n >> 1) + (n >> 2);
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q = q + (q >> 4);
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q = q + (q >> 8);
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q = q + (q >> 16);
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q = q >> 3;
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r = n - (q * 10);
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return q + ((r + 6) >> 4);
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}
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//Signed divide by 100
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int divs100(long n)
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{
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return (n / 100); // Amazingly, gcc is producing a better /divide by 100 function than this
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/*
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long q, r;
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n = n + (n>>31 & 99);
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q = (n >> 1) + (n >> 3) + (n >> 6) - (n >> 10) +
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(n >> 12) + (n >> 13) - (n >> 16);
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q = q + (q >> 20);
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q = q >> 6;
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r = n - q*100;
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return q + ((r + 28) >> 7);
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*/
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}
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//Unsigned divide by 100
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unsigned long divu100(unsigned long n)
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{
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//return (n / 100);
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unsigned long q, r;
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q = (n >> 1) + (n >> 3) + (n >> 6) - (n >> 10) +
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(n >> 12) + (n >> 13) - (n >> 16);
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q = q + (q >> 20);
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q = q >> 6;
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r = n - (q * 100);
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return q + ((r + 28) >> 7);
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}
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//Return x percent of y
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//This is a relatively fast approximation of a percentage value.
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unsigned long percentage(byte x, unsigned long y)
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{
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return (y * x) / 100; //For some reason this is faster
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//return divu100(y * x);
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}
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/*
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* Calculates integer power values. Same as pow() but with ints
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*/
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inline long powint(int factor, unsigned int exponent)
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{
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long product = 1;
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unsigned int counter = exponent;
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while ( (counter--) > 0) { product *= factor; }
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return product;
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}
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