/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#define LINEMACRO(startx, starty, deltalinear, deltanonlinear, linearvar, nonlinearvar, \
                  linearend, nonlinearstart, linearmod, nonlinearmod) \
   x = (startx); y = (starty); \
   incrNE = ((deltalinear) > 0)? (deltalinear) : -(deltalinear); \
   incrNE <<= 1; \
   deltanonlinear <<= 1; \
   incrE = ((deltanonlinear) > 0) ? -(deltanonlinear) : (deltanonlinear);  \
   d = nonlinearstart-1;  \
   while (linearvar != (linearend)) { \
     memcpy(buffer + linewidth * y + x, &color, PIXELWIDTH); \
     linearvar += linearmod; \
     if ((d+=incrE) < 0) { \
       d += incrNE; \
       nonlinearvar += nonlinearmod; \
     }; \
   }; \
   memcpy(buffer + linewidth * y + x, &color, PIXELWIDTH);


static inline
void DRAWLINE_FUNC(byte *buffer, int linewidth, point_t start, point_t end, unsigned int color) {
	int dx, dy, incrE, incrNE, d, finalx, finaly;
	int x = start.x;
	int y = start.y;
	dx = end.x - start.x;
	dy = end.y - start.y;
	finalx = end.x;
	finaly = end.y;
#ifdef WORDS_BIGENDIAN
	color = GUINT32_SWAP_LE_BE_CONSTANT(color);
#endif
	dx = abs(dx);
	dy = abs(dy);

	if (dx > dy) {
		if (finalx < x) {
			if (finaly < y) { /* llu == left-left-up */
				LINEMACRO(x, y, dx, dy, x, y, finalx, dx, -PIXELWIDTH, -1);
			} else {         /* lld */
				LINEMACRO(x, y, dx, dy, x, y, finalx, dx, -PIXELWIDTH, 1);
			}
		} else { /* x1 >= x */
			if (finaly < y) { /* rru */
				LINEMACRO(x, y, dx, dy, x, y, finalx, dx, PIXELWIDTH, -1);
			} else {         /* rrd */
				LINEMACRO(x, y, dx, dy, x, y, finalx, dx, PIXELWIDTH, 1);
			}
		}
	} else { /* dx <= dy */
		if (finaly < y) {
			if (finalx < x) { /* luu */
				LINEMACRO(x, y, dy, dx, y, x, finaly, dy, -1, -PIXELWIDTH);
			} else {         /* ruu */
				LINEMACRO(x, y, dy, dx, y, x, finaly, dy, -1, PIXELWIDTH);
			}
		} else { /* y1 >= y */
			if (finalx < x) { /* ldd */
				LINEMACRO(x, y, dy, dx, y, x, finaly, dy, 1, -PIXELWIDTH);
			} else {         /* rdd */
				LINEMACRO(x, y, dy, dx, y, x, finaly, dy, 1, PIXELWIDTH);
			}
		}
	}
}



#undef LINEMACRO