//Copyright Paul Reiche, Fred Ford. 1992-2002

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "units.h"
#include "libs/compiler.h"


SIZE sinetab[] =
{
	-FLT_ADJUST (1.000000),
	-FLT_ADJUST (0.995185),
	-FLT_ADJUST (0.980785),
	-FLT_ADJUST (0.956940),
	-FLT_ADJUST (0.923880),
	-FLT_ADJUST (0.881921),
	-FLT_ADJUST (0.831470),
	-FLT_ADJUST (0.773010),
	-FLT_ADJUST (0.707107),
	-FLT_ADJUST (0.634393),
	-FLT_ADJUST (0.555570),
	-FLT_ADJUST (0.471397),
	-FLT_ADJUST (0.382683),
	-FLT_ADJUST (0.290285),
	-FLT_ADJUST (0.195090),
	-FLT_ADJUST (0.098017),
	FLT_ADJUST (0.000000),
	FLT_ADJUST (0.098017),
	FLT_ADJUST (0.195090),
	FLT_ADJUST (0.290285),
	FLT_ADJUST (0.382683),
	FLT_ADJUST (0.471397),
	FLT_ADJUST (0.555570),
	FLT_ADJUST (0.634393),
	FLT_ADJUST (0.707107),
	FLT_ADJUST (0.773010),
	FLT_ADJUST (0.831470),
	FLT_ADJUST (0.881921),
	FLT_ADJUST (0.923880),
	FLT_ADJUST (0.956940),
	FLT_ADJUST (0.980785),
	FLT_ADJUST (0.995185),
	FLT_ADJUST (1.000000),
	FLT_ADJUST (0.995185),
	FLT_ADJUST (0.980785),
	FLT_ADJUST (0.956940),
	FLT_ADJUST (0.923880),
	FLT_ADJUST (0.881921),
	FLT_ADJUST (0.831470),
	FLT_ADJUST (0.773010),
	FLT_ADJUST (0.707107),
	FLT_ADJUST (0.634393),
	FLT_ADJUST (0.555570),
	FLT_ADJUST (0.471397),
	FLT_ADJUST (0.382683),
	FLT_ADJUST (0.290285),
	FLT_ADJUST (0.195090),
	FLT_ADJUST (0.098017),
	FLT_ADJUST (0.000000),
	-FLT_ADJUST (0.098017),
	-FLT_ADJUST (0.195090),
	-FLT_ADJUST (0.290285),
	-FLT_ADJUST (0.382683),
	-FLT_ADJUST (0.471397),
	-FLT_ADJUST (0.555570),
	-FLT_ADJUST (0.634393),
	-FLT_ADJUST (0.707107),
	-FLT_ADJUST (0.773010),
	-FLT_ADJUST (0.831470),
	-FLT_ADJUST (0.881921),
	-FLT_ADJUST (0.923880),
	-FLT_ADJUST (0.956940),
	-FLT_ADJUST (0.980785),
	-FLT_ADJUST (0.995185),
};

COUNT
ARCTAN (SIZE delta_x, SIZE delta_y)
{
	SIZE v1, v2;
	static COUNT atantab[] =
	{
		0,
		0,
		1,
		1,
		1,
		2,
		2,
		2,
		2,
		3,
		3,
		3,
		4,
		4,
		4,
		4,
		5,
		5,
		5,
		5,
		6,
		6,
		6,
		6,
		7,
		7,
		7,
		7,
		7,
		7,
		8,
		8,
		8,
	};

	v1 = delta_x;
	v2 = delta_y;
	if (v1 == 0 && v2 == 0)
		return (FULL_CIRCLE);

	if (v1 < 0)
		v1 = -v1;
	if (v2 < 0)
		v2 = -v2;
	if (v1 > v2)
		v1 = QUADRANT
				- atantab[(((DWORD)v2 << (CIRCLE_SHIFT - 1)) + (v1 >> 1)) / v1];
	else
		v1 = atantab[(((DWORD)v1 << (CIRCLE_SHIFT - 1)) + (v2 >> 1)) / v2];

	if (delta_x < 0)
		v1 = FULL_CIRCLE - v1;
	if (delta_y > 0)
		v1 = HALF_CIRCLE - v1;

	return (NORMALIZE_ANGLE (v1));
}