wings/src/maths.c

#include "maths.h"

float fcos(unsigned char x)
{
    char n = 1;
    float cos[4] = {1.0, 0.707106, 0.0, -0.707106};

    while(x >= 4)
    {
        x -= 4;
        n = -n;
    }
    return (n*cos[x]);
}

float fsin(unsigned char x)
{
    return fcos(x - 2);
}


#define MAX_TURN 6

float cos(float x)
{
unsigned int a = 8 * MAX_TURN - 6;
unsigned int b = 2 * MAX_TURN * (2 * MAX_TURN - 1); // 2n(2n-1)
float s = 1;

unsigned short i;

x = x * x; // x²

for(i = 0; i < MAX_TURN; i++)
    {
    s = 1 - x * s / b;
    b -= a;
    a -= 8;
    }

return s;
}

float sin(float x)
{
    return cos(x - pi_2);
}