#include	"type.h"

ushort	atntab[64+2];

Angle
iatan(long x, long y)
{
	Angle a, b;
	Fract f;
	int f1, f2, f3, i;
	long t;

	f1 = 0;
	if(x < 0) {
		x = -x;
		f1 = 1;
	}
	f2 = 0;
	if(y < 0) {
		y = -y;
		f2 = 1;
	}
	f3 = 0;
	if(x > y) {
		t = x;
		x = y;
		y = t;
		f3 = 1;
	}
	if(y <= 0)
		return 0;
	f = fdiv(x, y);
	i = f >> 9;
	a = atntab[i];
	b = atntab[i+1] - a;
	i = f & 0777;
	a += (b*i + 256) >> 9;
	if(a & 02)
		a += 04;
	a >>= 2;
	if(f3)
		a = PI/2 - a;
	if(f2)
		a = PI - a;
	if(f1)
		a = PI - a + PI;
	return a;
}

ushort	atntab[64+2] =
{
	0,	652,	1303,	1954,	2604,	3253,	3900,	4545,	5188,
	5829,	6467,	7101,	7733,	8361,	8985,	9605,	10221,	10832,
	11439,	12040,	12637,	13228,	13814,	14394,	14968,	15537,	16100,
	16656,	17206,	17750,	18288,	18819,	19344,	19862,	20374,	20879,
	21378,	21870,	22355,	22834,	23306,	23771,	24230,	24682,	25128,
	25568,	26001,	26427,	26848,	27262,	27670,	28072,	28467,	28857,
	29241,	29619,	29991,	30357,	30718,	31073,	31423,	31767,	32106,
	32439,	32767,	32767,
};