44 lines
590 B
C
44 lines
590 B
C
#include "maths.h"
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//get the value of sin/cos(dir * pi_4)
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float fcos(unsigned char x)
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{
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float cos[4] = {1.0, 0.707106, 0.0, -0.707106};
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return (x < 4 ? cos[x] : - cos[x%4]);
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}
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float fsin(unsigned char x)
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{
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return fcos(x - 2);
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}
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#define MAX_TURN 6
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float cos(float x)
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{
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unsigned int a = 8 * MAX_TURN - 6;
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unsigned int b = 2 * MAX_TURN * (2 * MAX_TURN - 1); // 2n(2n-1)
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float s = 1;
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unsigned short i;
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x = x * x; // x²
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for(i = 0; i < MAX_TURN; i++)
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{
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s = 1 - x * s / b;
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b -= a;
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a -= 8;
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}
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return s;
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}
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float sin(float x)
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{
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return cos(x - pi_2);
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}
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