rng.h

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// This is the ``Mersenne Twister'' random number generator MT19937, which
// generates pseudorandom integers uniformly distributed in 0..(2^32 - 1)
// starting from any odd seed in 0..(2^32 - 1).  This version is a recode
// by Rafael Baptista, based on a recode by Shawn Cokus 
// ([e-mail]) on March 8, 1998 of a version by
// Takuji Nishimura (who had suggestions from Topher Cooper and Marc Rieffel in
// July-August 1997).
//
// According to the URL 
// (and paraphrasing a bit in places), the Mersenne Twister is ``designed
// with consideration of the flaws of various existing generators,'' has
// a period of 2^19937 - 1, gives a sequence that is 623-dimensionally
// equidistributed, and ``has passed many stringent tests, including the
// die-hard test of G. Marsaglia and the load test of P. Hellekalek and
// S. Wegenkittl.''  It is efficient in memory usage (typically using 2506
// to 5012 bytes of static data, depending on data type sizes, and the code
// is quite short as well).  It generates random numbers in batches of 624
// at a time, so the caching and pipelining of modern systems is exploited.
// It is also divide- and mod-free.
//
//
// The code as Shawn received it included the following notice:
//
//   Copyright (C) 1997 Makoto Matsumoto and Takuji Nishimura.  When
//   you use this, send an e-mail to  with
//   an appropriate reference to your work.
//
// It would be nice to CC:  when you write.
//


#define N              (624)                 // length of state vector
#define M              (397)                 // a period parameter
#define K              (0x9908B0DFU)         // a magic constant
#define hiBit(u)       ((u) & 0x80000000U)   // mask all but highest   bit of u
#define loBit(u)       ((u) & 0x00000001U)   // mask all but lowest    bit of u
#define loBits(u)      ((u) & 0x7FFFFFFFU)   // mask     the highest   bit of u
#define mixBits(u, v)  (hiBit(u)|loBits(v))  // move hi bit of u to hi bit of v

void seedMT( unsigned long  seed ) __attribute__ ((section(".ewram")));
unsigned long  reloadMT() __attribute__ ((section(".ewram")));
unsigned long  randomMT() __attribute__ ((section(".ewram")));
unsigned short  Rand( unsigned short  Range ) __attribute__ ((section(".ewram")));