56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
#ifndef MATH_H
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#define MATH_H
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//Replace the standard arduino map() function to use the div function instead
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int fastMap(int x, int in_min, int in_max, int out_min, int out_max)
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{
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return div( ((x - in_min) * (out_max - out_min)) , (in_max - in_min) ).quot + 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: http://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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unsigned int 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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// return q + (r > 9);
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}
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//Signed divide by 10
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int divs10(int n) {
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int q, r;
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n = n + (n>>31 & 9);
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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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// return q + (r > 9);
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}
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//Signed divide by 100
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int divs100(int n) {
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int 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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// return q + (r > 99);
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}
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#endif // MATH_H
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