Initial commit

engines/ags/lib/allegro/fixed.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/fixed.h"
+#include "ags/lib/allegro/error.h"
+#include "ags/globals.h"
+
+namespace AGS3 {
+
+fixed ftofix(double x) {
+	if (x > 32767.0) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return 0x7FFFFFFF;
+	}
+
+	if (x < -32767.0) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return (fixed) - 0x7FFFFFFF;
+	}
+
+	return (fixed)(x * 65536.0 + (x < 0 ? -0.5 : 0.5));
+}
+
+double fixtof(fixed x) {
+	return (double)x / 65536.0;
+}
+
+fixed fixadd(fixed x, fixed y) {
+	fixed result = x + y;
+
+	if (result >= 0) {
+		if ((x < 0) && (y < 0)) {
+			*_G(allegro_errno) = AL_ERANGE;
+			return (fixed) - 0x7FFFFFFF;
+		} else
+			return result;
+	} else {
+		if ((x > 0) && (y > 0)) {
+			*_G(allegro_errno) = AL_ERANGE;
+			return 0x7FFFFFFF;
+		} else
+			return result;
+	}
+}
+
+fixed fixsub(fixed x, fixed y) {
+	fixed result = x - y;
+
+	if (result >= 0) {
+		if ((x < 0) && (y > 0)) {
+			*_G(allegro_errno) = AL_ERANGE;
+			return (fixed) - 0x7FFFFFFF;
+		} else
+			return result;
+	} else {
+		if ((x > 0) && (y < 0)) {
+			*_G(allegro_errno) = AL_ERANGE;
+			return 0x7FFFFFFF;
+		} else
+			return result;
+	}
+}
+
+fixed fixmul(fixed x, fixed y) {
+	int64 lx = x;
+	int64 ly = y;
+	int64 lres = (lx * ly);
+
+	if (lres > 0x7FFFFFFF0000LL) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return 0x7FFFFFFF;
+	} else if (lres < -0x7FFFFFFF0000LL) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return 0x80000000;
+	} else {
+		int res = lres >> 16;
+		return res;
+	}
+}
+
+fixed fixdiv(fixed x, fixed y) {
+	if (y == 0) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return (fixed)(x < 0) ? -0x7FFFFFFF : 0x7FFFFFFF;
+	} else
+		return ftofix(fixtof(x) / fixtof(y));
+}
+
+int fixfloor(fixed x) {
+	// FIXME: GCC warning "this condition has identical branches [-Wduplicated-branches]" on this code i.e. both branches are functionally identical. Remove?
+#if 0
+	/* (x >> 16) is not portable */
+	if (x >= 0)
+		return (x >> 16);
+	else
+		return ~((~x) >> 16);
+#else
+	return (x >> 16);
+#endif
+}
+
+
+int fixceil(fixed x) {
+	if (x > 0x7FFF0000) {
+		*_G(allegro_errno) = AL_ERANGE;
+		return 0x7FFF;
+	}
+
+	return fixfloor(x + 0xFFFF);
+}
+
+fixed itofix(int x) {
+	return x << 16;
+}
+
+
+int fixtoi(fixed x) {
+	return fixfloor(x) + ((x & 0x8000) >> 15);
+}
+
+
+fixed fixcos(fixed x) {
+	return _cos_tbl[((x + 0x4000) >> 15) & 0x1FF];
+}
+
+
+fixed fixsin(fixed x) {
+	return _cos_tbl[((x - 0x400000 + 0x4000) >> 15) & 0x1FF];
+}
+
+
+fixed fixtan(fixed x) {
+	return _tan_tbl[((x + 0x4000) >> 15) & 0xFF];
+}
+
+
+fixed fixacos(fixed x) {
+	if ((x < -65536) || (x > 65536)) {
+		*_G(allegro_errno) = AL_EDOM;
+		return 0;
+	}
+
+	return _acos_tbl[(x + 65536 + 127) >> 8];
+}
+
+
+fixed fixasin(fixed x) {
+	if ((x < -65536) || (x > 65536)) {
+		*_G(allegro_errno) = AL_EDOM;
+		return 0;
+	}
+
+	return 0x00400000 - _acos_tbl[(x + 65536 + 127) >> 8];
+}
+
+} // namespace AGS3