Directory restructuring to make it easier to version projects that don't build zdoom.exe.

SVN r4 (trunk)

src/m_random.cpp

@@ -0,0 +1,253 @@
+// Emacs style mode select   -*- C++ -*-
+//-----------------------------------------------------------------------------
+//
+// $Id: m_random.c,v 1.6 1998/05/03 23:13:18 killough Exp $
+//
+// 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.
+//
+//
+// DESCRIPTION:
+//      Random number LUT.
+//
+// 1/19/98 killough: Rewrote random number generator for better randomness,
+// while at the same time maintaining demo sync and backward compatibility.
+//
+// 2/16/98 killough: Made each RNG local to each control-equivalent block,
+// to reduce the chances of demo sync problems.
+//
+// [RH] Changed to use different class instances for different RNGs. Be
+// sure to compile with _DEBUG if you want to catch bad RNG names.
+//
+//-----------------------------------------------------------------------------
+
+#include <assert.h>
+
+#include "doomstat.h"
+#include "m_random.h"
+#include "farchive.h"
+#include "b_bot.h"
+#include "m_png.h"
+#include "m_crc32.h"
+#include "i_system.h"
+#include "c_dispatch.h"
+#include "files.h"
+
+#define RAND_ID MAKE_ID('r','a','N','d')
+
+FRandom M_Random;
+
+inline int UpdateSeed (DWORD &seed)
+{
+	DWORD oldseed = seed;
+	seed = oldseed * 1664525ul + 221297ul;
+	return (int)oldseed;
+}
+
+DWORD rngseed = 1993;   // killough 3/26/98: The seed
+
+FRandom *FRandom::RNGList;
+
+FRandom::FRandom ()
+: Seed (0), Next (NULL), NameCRC (0)
+{
+#ifdef _DEBUG
+	Name = NULL;
+#endif
+	Next = RNGList;
+	RNGList = this;
+}
+
+FRandom::FRandom (const char *name)
+: Seed (0)
+{
+	NameCRC = CalcCRC32 ((const BYTE *)name, (unsigned int)strlen (name));
+#ifdef _DEBUG
+	Name = name;
+	// A CRC of 0 is reserved for nameless RNGs that don't get stored
+	// in savegames. The chance is very low that you would get a CRC of 0,
+	// but it's still possible.
+	assert (NameCRC != 0);
+#endif
+
+	// Insert the RNG in the list, sorted by CRC
+	FRandom **prev = &RNGList, *probe = RNGList;
+
+	while (probe != NULL && probe->NameCRC < NameCRC)
+	{
+		prev = &probe->Next;
+		probe = probe->Next;
+	}
+
+#ifdef _DEBUG
+	if (probe != NULL)
+	{
+		// Because RNGs are identified by their CRCs in save games,
+		// no two RNGs can have names that hash to the same CRC.
+		// Obviously, this means every RNG must have a unique name.
+		assert (probe->NameCRC != NameCRC);
+	}
+#endif
+
+	Next = probe;
+	*prev = this;
+}
+
+FRandom::~FRandom ()
+{
+	FRandom *rng, **prev;
+
+	FRandom *last = NULL;
+
+	prev = &RNGList;
+	rng = RNGList;
+
+	while (rng != NULL && rng != this)
+	{
+		last = rng;
+		rng = rng->Next;
+	}
+
+	if (rng != NULL)
+	{
+		*prev = rng->Next;
+	}
+}
+
+int FRandom::operator() ()
+{
+	return (UpdateSeed (Seed) >> 20) & 255;
+}
+
+int FRandom::Random2 ()
+{
+	int t = (UpdateSeed (Seed) >> 20) & 255;
+	int u = (UpdateSeed (Seed) >> 20) & 255;
+	return t - u;
+}
+
+int FRandom::Random2 (int mask)
+{
+	int t = (UpdateSeed (Seed) >> 20) & mask;
+	int u = (UpdateSeed (Seed) >> 20) & mask;
+	return t - u;
+}
+
+int FRandom::HitDice (int count)
+{
+	return (1 + ((UpdateSeed (Seed) >> 20) & 7)) * count;
+}
+
+// Initialize all the seeds
+//
+// This initialization method is critical to maintaining demo sync.
+// Each seed is initialized according to its class. killough
+//
+
+void FRandom::StaticClearRandom ()
+{
+	const DWORD seed = rngseed*2+1;	// add 3/26/98: add rngseed
+	FRandom *rng = FRandom::RNGList;
+
+	// go through each RNG and set each starting seed differently
+	while (rng != NULL)
+	{
+		// [RH] Use the RNG's name's CRC to modify the original seed.
+		// This way, new RNGs can be added later, and it doesn't matter
+		// which order they get initialized in.
+		rng->Seed = seed * rng->NameCRC;
+		rng = rng->Next;
+	}
+}
+
+// This function produces a DWORD that can be used to check the consistancy
+// of network games between different machines. Only a select few RNGs are
+// used for the sum, because not all RNGs are important to network sync.
+
+extern FRandom pr_spawnmobj;
+extern FRandom pr_acs;
+extern FRandom pr_chase;
+extern FRandom pr_lost;
+extern FRandom pr_slam;
+
+DWORD FRandom::StaticSumSeeds ()
+{
+	return pr_spawnmobj.Seed + pr_acs.Seed + pr_chase.Seed + pr_lost.Seed + pr_slam.Seed;
+}
+
+void P_WriteRNGState (FILE *file)
+{
+	FRandom *rng;
+	const DWORD seed = rngseed*2+1;
+	FPNGChunkArchive arc (file, RAND_ID);
+
+	arc << rngseed;
+
+	// Only write those RNGs that have been used
+	for (rng = FRandom::RNGList; rng != NULL; rng = rng->Next)
+	{
+		if (rng->NameCRC != 0 && rng->Seed != seed + rng->NameCRC)
+		{
+			arc << rng->NameCRC << rng->Seed;
+		}
+	}
+}
+
+void P_ReadRNGState (PNGHandle *png)
+{
+	FRandom *rng;
+
+	size_t len = M_FindPNGChunk (png, RAND_ID);
+
+	if (len != 0)
+	{
+		const int rngcount = (int)((len-4) / 8);
+		int i;
+		DWORD crc;
+
+		FPNGChunkArchive arc (png->File->GetFile(), RAND_ID, len);
+
+		arc << rngseed;
+		FRandom::StaticClearRandom ();
+
+		for (i = rngcount; i; --i)
+		{
+			arc << crc;
+			for (rng = FRandom::RNGList; rng != NULL; rng = rng->Next)
+			{
+				if (rng->NameCRC == crc)
+				{
+					arc << rng->Seed;
+					break;
+				}
+			}
+		}
+		png->File->ResetFilePtr();
+	}
+}
+
+#ifdef _DEBUG
+void FRandom::StaticPrintSeeds ()
+{
+	FRandom *rng = RNGList;
+
+	while (rng != NULL)
+	{
+		Printf ("%s: %08lx\n", rng->Name, rng->Seed);
+		rng = rng->Next;
+	}
+}
+
+CCMD (showrngs)
+{
+	FRandom::StaticPrintSeeds ();
+}
+#endif