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/* Emacs style mode select -*- C++ -*-
*-----------------------------------------------------------------------------
*
*
* PrBoom a Doom port merged with LxDoom and LSDLDoom
* based on BOOM, a modified and improved DOOM engine
* Copyright (C) 1999 by
* id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
* Copyright (C) 1999-2000 by
* Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
*
* 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., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*
* 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.
*
*-----------------------------------------------------------------------------*/
#include "doomstat.h"
#include "m_random.h"
//
// M_Random
// Returns a 0-255 number
//
static const unsigned char rndtable[256] = { // 1/19/98 killough -- made const
0, 8, 109, 220, 222, 241, 149, 107, 75, 248, 254, 140, 16, 66 ,
74, 21, 211, 47, 80, 242, 154, 27, 205, 128, 161, 89, 77, 36 ,
95, 110, 85, 48, 212, 140, 211, 249, 22, 79, 200, 50, 28, 188 ,
52, 140, 202, 120, 68, 145, 62, 70, 184, 190, 91, 197, 152, 224 ,
149, 104, 25, 178, 252, 182, 202, 182, 141, 197, 4, 81, 181, 242 ,
145, 42, 39, 227, 156, 198, 225, 193, 219, 93, 122, 175, 249, 0 ,
175, 143, 70, 239, 46, 246, 163, 53, 163, 109, 168, 135, 2, 235 ,
25, 92, 20, 145, 138, 77, 69, 166, 78, 176, 173, 212, 166, 113 ,
94, 161, 41, 50, 239, 49, 111, 164, 70, 60, 2, 37, 171, 75 ,
136, 156, 11, 56, 42, 146, 138, 229, 73, 146, 77, 61, 98, 196 ,
135, 106, 63, 197, 195, 86, 96, 203, 113, 101, 170, 247, 181, 113 ,
80, 250, 108, 7, 255, 237, 129, 226, 79, 107, 112, 166, 103, 241 ,
24, 223, 239, 120, 198, 58, 60, 82, 128, 3, 184, 66, 143, 224 ,
145, 224, 81, 206, 163, 45, 63, 90, 168, 114, 59, 33, 159, 95 ,
28, 139, 123, 98, 125, 196, 15, 70, 194, 253, 54, 14, 109, 226 ,
71, 17, 161, 93, 186, 87, 244, 138, 20, 52, 123, 251, 26, 36 ,
17, 46, 52, 231, 232, 76, 31, 221, 84, 37, 216, 165, 212, 106 ,
197, 242, 98, 43, 39, 175, 254, 145, 190, 84, 118, 222, 187, 136 ,
120, 163, 236, 249
};
rng_t rng; // the random number state
unsigned long rngseed = 1993; // killough 3/26/98: The seed
int P_Random(pr_class_t pr_class)
{
// killough 2/16/98: We always update both sets of random number
// generators, to ensure repeatability if the demo_compatibility
// flag is changed while the program is running. Changing the
// demo_compatibility flag does not change the sequences generated,
// only which one is selected from.
//
// All of this RNG stuff is tricky as far as demo sync goes --
// it's like playing with explosives :) Lee
int compat = pr_class == pr_misc ?
(rng.prndindex = (rng.prndindex + 1) & 255) :
(rng. rndindex = (rng. rndindex + 1) & 255) ;
unsigned long boom;
// killough 3/31/98:
// If demo sync insurance is not requested, use
// much more unstable method by putting everything
// except pr_misc into pr_all_in_one
if (pr_class != pr_misc && !demo_insurance) // killough 3/31/98
pr_class = pr_all_in_one;
boom = rng.seed[pr_class];
// killough 3/26/98: add pr_class*2 to addend
rng.seed[pr_class] = boom * 1664525ul + 221297ul + pr_class*2;
if (demo_compatibility)
return rndtable[compat];
boom >>= 20;
/* killough 3/30/98: use gametic-levelstarttic to shuffle RNG
* killough 3/31/98: but only if demo insurance requested,
* since it's unnecessary for random shuffling otherwise
* killough 9/29/98: but use basetic now instead of levelstarttic
* cph - DEMOSYNC - this change makes MBF demos work,
* but does it break Boom ones?
*/
if (demo_insurance)
boom += (gametic-basetic)*7;
return boom & 255;
}
// Initialize all the seeds
//
// This initialization method is critical to maintaining demo sync.
// Each seed is initialized according to its class, so if new classes
// are added they must be added to end of pr_class_t list. killough
//
void M_ClearRandom (void)
{
int i;
unsigned long seed = rngseed*2+1; // add 3/26/98: add rngseed
for (i=0; i<NUMPRCLASS; i++) // go through each pr_class and set
rng.seed[i] = seed *= 69069ul; // each starting seed differently
rng.prndindex = rng.rndindex = 0; // clear two compatibility indices
}
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