The DOOM sources as originally released on December 23, 1997

linuxdoom-1.10/m_fixed.c

@@ -0,0 +1,87 @@
+// Emacs style mode select   -*- C++ -*- 
+//-----------------------------------------------------------------------------
+//
+// $Id:$
+//
+// Copyright (C) 1993-1996 by id Software, Inc.
+//
+// This source is available for distribution and/or modification
+// only under the terms of the DOOM Source Code License as
+// published by id Software. All rights reserved.
+//
+// The source is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
+// for more details.
+//
+// $Log:$
+//
+// DESCRIPTION:
+//	Fixed point implementation.
+//
+//-----------------------------------------------------------------------------
+
+
+static const char
+rcsid[] = "$Id: m_bbox.c,v 1.1 1997/02/03 22:45:10 b1 Exp $";
+
+#include "stdlib.h"
+
+#include "doomtype.h"
+#include "i_system.h"
+
+#ifdef __GNUG__
+#pragma implementation "m_fixed.h"
+#endif
+#include "m_fixed.h"
+
+
+
+
+// Fixme. __USE_C_FIXED__ or something.
+
+fixed_t
+FixedMul
+( fixed_t	a,
+  fixed_t	b )
+{
+    return ((long long) a * (long long) b) >> FRACBITS;
+}
+
+
+
+//
+// FixedDiv, C version.
+//
+
+fixed_t
+FixedDiv
+( fixed_t	a,
+  fixed_t	b )
+{
+    if ( (abs(a)>>14) >= abs(b))
+	return (a^b)<0 ? MININT : MAXINT;
+    return FixedDiv2 (a,b);
+}
+
+
+
+fixed_t
+FixedDiv2
+( fixed_t	a,
+  fixed_t	b )
+{
+#if 0
+    long long c;
+    c = ((long long)a<<16) / ((long long)b);
+    return (fixed_t) c;
+#endif
+
+    double c;
+
+    c = ((double)a) / ((double)b) * FRACUNIT;
+
+    if (c >= 2147483648.0 || c < -2147483648.0)
+	I_Error("FixedDiv: divide by zero");
+    return (fixed_t) c;
+}