teensy-cores/teensy3/WMath.cpp

/*
  Part of the Wiring project - http://wiring.org.co
  Copyright (c) 2004-06 Hernando Barragan
  Modified 13 August 2006, David A. Mellis for Arduino - http://www.arduino.cc/

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA
*/

#include <stdint.h>

static uint32_t seed;

void randomSeed(uint32_t newseed)
{
	if (newseed > 0) seed = newseed;
}

void srandom(uint32_t newseed)
{
	seed = newseed;
}

int32_t random(void)
{
	int32_t hi, lo, x;

	// the algorithm used in avr-libc 1.6.4
	x = seed;
	if (x == 0) x = 123459876;
	hi = x / 127773;
	lo = x % 127773;
	x = 16807 * lo - 2836 * hi;
	if (x < 0) x += 0x7FFFFFFF;
	seed = x;
	return x;
}

uint32_t random(uint32_t howbig)
{
	if (howbig == 0) return 0;
	return random() % howbig;
}

int32_t random(int32_t howsmall, int32_t howbig)
{
	if (howsmall >= howbig) return howsmall;
	int32_t diff = howbig - howsmall;
	return random(diff) + howsmall;
}

unsigned int makeWord(unsigned int w) { return w; }
unsigned int makeWord(unsigned char h, unsigned char l) { return (h << 8) | l; }