id_us_a.c

/* Keen Dreams (SDL2/Steam Port) Source Code
 * Copyright (C) 2012 David Gow <david@davidgow.net>
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "id_heads.h"
#include <time.h>
// Random Number Generator from Omnispeak/id_us_a.asm

/*		This is just John Carmack's table
		driven pseudo-random number generator, and we put it in the User Mgr
		because we couldn't figure out where it should go
*/

/*============================================================================
 *
 *                           RANDOM ROUTINES
 *
 *============================================================================
 */



/*
 * This random number generator simply outputs these numbers, in order
 * from a random index. This makes behaviour predictable during demos, and
 * ensures a uniform (enough) distribution.
 */
uint8_t rndtable[256] ={
	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
};

static uint16_t rndindex; // Was 16-bit, even if storing just a 8-bit val

// Seed the random number generator.

void US_InitRndT(boolean randomize)
{
	if (randomize)
	{
		rndindex = time(0) & 0xFF;
	}
	else
	{
		rndindex = 0;
	}
}

// Get a random integer in the range 0-255

int US_RndT()
{
	rndindex++;
	rndindex &= 0xFF;
#ifdef CK_RAND_DEBUG
	CK_Cross_LogMessage(CK_LOG_MSG_NORMAL,"Returning random number %d, %d for:\n", rndindex, rndtable[rndindex]);
	CK_Cross_StackTrace();
#endif
	return rndtable[rndindex];
}

// Set the random seed (index)

void US_SetRndI(int index)
{
	rndindex = index;
}

// Get the random seed (index)

int US_GetRndI()
{
	return rndindex;
}