Add option to use libdivide in maths.h functions
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@ -1,6 +1,8 @@
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#ifndef MATH_H
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#define MATH_H
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#define USE_LIBDIVIDE
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int fastMap1023toX(int, int);
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unsigned long percentage(byte, unsigned long);
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unsigned long halfPercentage(byte, unsigned long);
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@ -16,4 +18,6 @@ unsigned long divu100(unsigned long);
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//This is a new version that allows for out_min
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#define fastMap10Bit(x, out_min, out_max) ( ( ((unsigned long)x * (out_max-out_min)) >> 10 ) + out_min)
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#endif
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@ -1,5 +1,14 @@
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#include "maths.h"
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#include "globals.h"
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#include "src/libdivide/libdivide.h"
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#ifdef USE_LIBDIVIDE
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//Constants used for libdivide
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struct libdivide::libdivide_u32_t libdiv_u32_10 = libdivide::libdivide_u32_gen(10);
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struct libdivide::libdivide_u32_t libdiv_u32_100 = libdivide::libdivide_u32_gen(100);
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struct libdivide::libdivide_s32_t libdiv_s32_100 = libdivide::libdivide_s32_gen(100);
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struct libdivide::libdivide_u32_t libdiv_u32_200 = libdivide::libdivide_u32_gen(200);
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#endif
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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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@ -13,65 +22,56 @@ int fastMap(unsigned long x, int in_min, int in_max, int out_min, int out_max)
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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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#ifdef USE_LIBDIVIDE
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return libdivide::libdivide_u32_do(n, &libdiv_u32_10);
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#else
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return (n / 10);
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#endif
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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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#ifdef USE_LIBDIVIDE
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return libdivide::libdivide_s32_do(n, &libdiv_s32_100);
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#else
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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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#endif
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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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#ifdef USE_LIBDIVIDE
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return libdivide::libdivide_u32_do(n, &libdiv_u32_100);
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#else
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return (n / 100);
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#endif
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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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#ifdef USE_LIBDIVIDE
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return libdivide::libdivide_u32_do((y * x), &libdiv_u32_100);
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#else
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return (y * x) / 100;
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#endif
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}
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//Same as above, but 0.5% accuracy
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unsigned long halfPercentage(byte x, unsigned long y)
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{
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#ifdef USE_LIBDIVIDE
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return libdivide::libdivide_u32_do((y * x), &libdiv_u32_200);
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#else
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return (y * x) / 200;
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#endif
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}
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/*
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