67 lines
1.7 KiB
C++
67 lines
1.7 KiB
C++
/*
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Part of the Wiring project - http://wiring.org.co
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Copyright (c) 2004-06 Hernando Barragan
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Modified 13 August 2006, David A. Mellis for Arduino - http://www.arduino.cc/
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General
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Public License along with this library; if not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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Boston, MA 02111-1307 USA
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*/
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#include <stdint.h>
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static uint32_t seed;
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void randomSeed(uint32_t newseed)
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{
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if (newseed > 0) seed = newseed;
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}
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void srandom(unsigned int newseed)
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{
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seed = newseed;
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}
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int32_t random(void)
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{
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int32_t hi, lo, x;
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// the algorithm used in avr-libc 1.6.4
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x = seed;
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if (x == 0) x = 123459876;
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hi = x / 127773;
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lo = x % 127773;
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x = 16807 * lo - 2836 * hi;
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if (x < 0) x += 0x7FFFFFFF;
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seed = x;
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return x;
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}
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uint32_t random(uint32_t howbig)
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{
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if (howbig == 0) return 0;
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return random() % howbig;
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}
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int32_t random(int32_t howsmall, int32_t howbig)
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{
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if (howsmall >= howbig) return howsmall;
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int32_t diff = howbig - howsmall;
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return random(diff) + howsmall;
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}
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unsigned int makeWord(unsigned int w) { return w; }
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unsigned int makeWord(unsigned char h, unsigned char l) { return (h << 8) | l; }
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