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engines/ags/lib/allegro/fmaths.cpp

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+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "ags/lib/allegro/fmaths.h"
+
+namespace AGS3 {
+
+fixed fixsqrt(fixed x) {
+	if (x > 0)
+		return ftofix(sqrt(fixtof(x)));
+
+	if (x < 0)
+		*allegro_errno = EDOM;
+
+	return 0;
+}
+
+fixed fixhypot(fixed x, fixed y) {
+	return ftofix(hypot(fixtof(x), fixtof(y)));
+}
+
+fixed fixatan(fixed x) {
+	int a, b, c;            /* for binary search */
+	fixed d;                /* difference value for search */
+
+	if (x >= 0) {           /* search the first part of tan table */
+		a = 0;
+		b = 127;
+	} else {                  /* search the second half instead */
+		a = 128;
+		b = 255;
+	}
+
+	do {
+		c = (a + b) >> 1;
+		d = x - _tan_tbl[c];
+
+		if (d > 0)
+			a = c + 1;
+		else if (d < 0)
+			b = c - 1;
+
+	} while ((a <= b) && (d));
+
+	if (x >= 0)
+		return ((long)c) << 15;
+
+	return (-0x00800000L + (((long)c) << 15));
+}
+
+fixed fixatan2(fixed y, fixed x) {
+	fixed r;
+
+	if (x == 0) {
+		if (y == 0) {
+			*allegro_errno = EDOM;
+			return 0L;
+		} else
+			return ((y < 0) ? -0x00400000L : 0x00400000L);
+	}
+
+	*allegro_errno = 0;
+	r = fixdiv(y, x);
+
+	if (*allegro_errno) {
+		*allegro_errno = 0;
+		return ((y < 0) ? -0x00400000L : 0x00400000L);
+	}
+
+	r = fixatan(r);
+
+	if (x >= 0)
+		return r;
+
+	if (y >= 0)
+		return 0x00800000L + r;
+
+	return r - 0x00800000L;
+}
+
+} // namespace AGS3