133 lines
3.8 KiB
C++
133 lines
3.8 KiB
C++
/*
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** Command & Conquer Generals Zero Hour(tm)
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** Copyright 2025 Electronic Arts Inc.
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**
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** This program is free software: you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation, either version 3 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "rand.h"
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#include <cmath>
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static const double theMultFactor = 1.0 / (pow(2, 8 * sizeof(unsigned int)) - 1.0);
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RandClass::RandClass(int start)
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{
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seed[0] = 0xf22d0e56L;
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seed[1] = 0x883126e9L;
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seed[2] = 0xc624dd2fL;
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seed[3] = 0x702c49cL;
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seed[4] = 0x9e353f7dL;
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seed[5] = 0x6fdf3b64L;
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unsigned int ax;
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ax = start; /* mov eax,SEED */
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ax += 0xf22d0e56; /* add eax,0f22d0e56h */
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seed[0] = ax; /* mov seed,eax */
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ax += 0x883126e9 - 0xf22d0e56; /* add eax,0883126e9h-0f22d0e56h */
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seed[1] = ax; /* mov seed+4,eax */
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ax += 0xc624dd2f - 0x883126e9; /* add eax,0c624dd2fh-0883126e9h */
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seed[2] = ax; /* mov seed+8,eax */
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ax += 0x0702c49c - 0xc624dd2f; /* add eax,00702c49ch-0c624dd2fh */
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seed[3] = ax; /* mov seed+12,eax */
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ax += 0x9e353f7d - 0x0702c49c; /* add eax,09e353f7dh-00702c49ch */
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seed[4] = ax; /* mov seed+16,eax */
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ax += 0x6fdf3b64 - 0x9e353f7d; /* add eax,06fdf3b64h-09e353f7dh */
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seed[5] = ax; /* mov seed+20,eax */
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}
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// Add with carry. SUM is replaced with A + B + C, C is replaced with 1 if there was a carry, 0 if there wasn't. A carry occurred if the sum is less than one of the inputs. This is addition, so carry can never be more than one.
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#define ADC(SUM, A, B, C) SUM = (A) + (B) + (C); C = ((SUM < (A)) || (SUM < (B)))
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unsigned int RandClass::randomValue( void )
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{
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unsigned int ax;
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unsigned int c = 0;
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ADC(ax, seed[5], seed[4], c); /* mov ax,seed+20 */
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/* add ax,seed+16 */
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seed[4] = ax; /* mov seed+8,ax */
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ADC(ax, ax, seed[3], c); /* adc ax,seed+12 */
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seed[3] = ax; /* mov seed+12,ax */
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ADC(ax, ax, seed[2], c); /* adc ax,seed+8 */
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seed[2] = ax; /* mov seed+8,ax */
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ADC(ax, ax, seed[1], c); /* adc ax,seed+4 */
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seed[1] = ax; /* mov seed+4,ax */
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ADC(ax, ax, seed[0], c); /* adc ax,seed+0 */
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seed[0] = ax; /* mov seed+0,ax */
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/* Increment seed array, bubbling up the carries. */
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if (!++seed[5])
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{
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if (!++seed[4])
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{
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if (!++seed[3])
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{
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if (!++seed[2])
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{
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if (!++seed[1])
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{
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++seed[0];
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++ax;
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}
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}
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}
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}
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}
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return(ax);
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}
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int RandClass::Int(void)
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{
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return (int)randomValue();
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}
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int RandClass::Int(int low, int high)
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{
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unsigned int delta = high - low + 1;
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int rval;
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if (delta == 0)
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return high;
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rval = ((int)(randomValue()%delta)) + low;
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return rval;
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}
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double RandClass::Double(void)
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{
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return Double(0.0, 1.0);
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}
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double RandClass::Double(double low, double high)
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{
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double delta = high - low;
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double rval;
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if (delta <= 0.0)
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return high;
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rval = ((double)(randomValue()) * theMultFactor) * delta + low;
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return rval;
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}
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