something like this?
uint8_t isinTable8[] = {
0, 4, 9, 13, 18, 22, 27, 31, 35, 40, 44,
49, 53, 57, 62, 66, 70, 75, 79, 83, 87,
91, 96, 100, 104, 108, 112, 116, 120, 124, 128,
131, 135, 139, 143, 146, 150, 153, 157, 160, 164,
167, 171, 174, 177, 180, 183, 186, 190, 192, 195,
198, 201, 204, 206, 209, 211, 214, 216, 219, 221,
223, 225, 227, 229, 231, 233, 235, 236, 238, 240,
241, 243, 244, 245, 246, 247, 248, 249, 250, 251,
252, 253, 253, 254, 254, 254, 255, 255, 255, 255,
};
int isin(long x)
{
boolean pos = true; // positive - keeps an eye on the sign.
if (x < 0)
{
x = -x;
pos = !pos;
}
if (x >= 360) x %= 360;
if (x > 180)
{
x -= 180;
pos = !pos;
}
if (x > 90) x = 180 - x;
if (pos) return isinTable8[x]/2 ;
return -isinTable8[x]/2 ;
}
returns a val between -127and 127