/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 * Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

 *

 * 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 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.

 */

/* Originally developed and coded by Makoto Matsumoto and Takuji

 * Nishimura.  Please mail <matumoto@math.keio.ac.jp>, if you're using

 * code from this file in your own programs or libraries.

 * Further information on the Mersenne Twister can be found at

 * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html

 * This code was adapted to glib by Sebastian Wilhelmi.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.  

 */

/* 

 * MT safe

 */

#include "config.h"

#include <math.h>

#include <errno.h>

#include <stdio.h>

#include <string.h>

#include <sys/types.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include "glib.h"

#include "gthreadinit.h"

#include "galias.h"

#ifdef __SYMBIAN32__

#include <glib_wsd.h>

#endif

#if EMULATOR

#define g_thread_functions_for_glib_use (*_g_thread_functions_for_glib_use())

#define g_thread_use_default_impl (*_g_thread_use_default_impl())

#endif /* EMULATOR */

#ifdef G_OS_WIN32

#include <process.h>		/* For getpid() */

#endif

#if EMULATOR

PLS_MACRO(global_random,grand,GStaticMutex)

PLS(global_random,grand,GRand *)

#define g__global_random_lock (*FUNCTION_NAME_MACRO(global_random,grand)())

#define global_random (*FUNCTION_NAME(global_random,grand)())

#else

G_LOCK_DEFINE_STATIC (global_random);

static GRand* global_random = NULL;

#endif /* EMULATOR */

/* Period parameters */  

#define N 624

#define M 397

#define MATRIX_A 0x9908b0df   /* constant vector a */

#define UPPER_MASK 0x80000000 /* most significant w-r bits */

#define LOWER_MASK 0x7fffffff /* least significant r bits */

/* Tempering parameters */   

#define TEMPERING_MASK_B 0x9d2c5680

#define TEMPERING_MASK_C 0xefc60000

#define TEMPERING_SHIFT_U(y)  (y >> 11)

#define TEMPERING_SHIFT_S(y)  (y << 7)

#define TEMPERING_SHIFT_T(y)  (y << 15)

#define TEMPERING_SHIFT_L(y)  (y >> 18)

#if EMULATOR

PLS(initialized ,get_random_version,gboolean)

PLS(random_version ,get_random_version,guint)

#define initialized (*FUNCTION_NAME(initialized,get_random_version)())

#define random_version (*FUNCTION_NAME(random_version,get_random_version)())

#endif /* EMULATOR */

static guint

get_random_version (void)

{

  #if !(EMULATOR)

  static gboolean initialized = FALSE;

  static guint random_version;

  #endif /* EMULATOR */

  if (!initialized)

    {

      const gchar *version_string = g_getenv ("G_RANDOM_VERSION");

      if (!version_string || version_string[0] == '\000' || 

	  strcmp (version_string, "2.2") == 0)

	random_version = 22;

      else if (strcmp (version_string, "2.0") == 0)

	random_version = 20;

      else

	{

	  g_warning ("Unknown G_RANDOM_VERSION \"%s\". Using version 2.2.",

		     version_string);

	  random_version = 22;

	}

      initialized = TRUE;

    }

  return random_version;

}

#if EMULATOR

#undef initialized

#undef random_version

#endif /* EMULATOR */

/* This is called from g_thread_init(). It's used to

 * initialize some static data in a threadsafe way.

 */

void 

_g_rand_thread_init (void)

{

  (void)get_random_version ();

}

struct _GRand

{

  guint32 mt[N]; /* the array for the state vector  */

  guint mti; 

};

/**

 * g_rand_new_with_seed:

 * @seed: a value to initialize the random number generator.

 * 

 * Creates a new random number generator initialized with @seed.

 * 

 * Return value: the new #GRand.

 **/

EXPORT_C GRand*

g_rand_new_with_seed (guint32 seed)

{

  GRand *rand = g_new0 (GRand, 1);

  g_rand_set_seed (rand, seed);

  return rand;

}

/**

 * g_rand_new_with_seed_array:

 * @seed: an array of seeds to initialize the random number generator.

 * @seed_length: an array of seeds to initialize the random number generator.

 * 

 * Creates a new random number generator initialized with @seed.

 * 

 * Return value: the new #GRand.

 *

 * Since: 2.4

 **/

EXPORT_C GRand*

g_rand_new_with_seed_array (const guint32 *seed, guint seed_length)

{

  GRand *rand = g_new0 (GRand, 1);

  g_rand_set_seed_array (rand, seed, seed_length);

  return rand;

}

/**

 * g_rand_new:

 * 

 * Creates a new random number generator initialized with a seed taken

 * either from <filename>/dev/urandom</filename> (if existing) or from 

 * the current time (as a fallback).

 * 

 * Return value: the new #GRand.

 **/

#if EMULATOR

PLS(dev_urandom_exists,g_rand_new ,gboolean)

#define dev_urandom_exists (*FUNCTION_NAME(dev_urandom_exists,g_rand_new )())

#endif /* EMULATOR */

EXPORT_C GRand* 

g_rand_new (void)

{

  guint32 seed[4];

  GTimeVal now;

#if defined(G_OS_UNIX) && !defined(__SYMBIAN32__)

  #if !(EMULATOR)

  static gboolean dev_urandom_exists = TRUE;

  #endif /* EMULATOR */

  if (dev_urandom_exists)

    {

      FILE* dev_urandom;

      do

        {

	  errno = 0;

	  dev_urandom = fopen("/dev/urandom", "rb");

	}

      while G_UNLIKELY (errno == EINTR);

      if (dev_urandom)

	{

	  int r;

	  do

	    {

	      errno = 0;

	      r = fread (seed, sizeof (seed), 1, dev_urandom);

	    }

	  while G_UNLIKELY (errno == EINTR);

	  if (r != 1)

	    dev_urandom_exists = FALSE;

	  fclose (dev_urandom);

	}	

      else

	dev_urandom_exists = FALSE;

    }

#else

  #if !(EMULATOR)

  static gboolean dev_urandom_exists = FALSE;

  #endif /* EMULATOR */

#endif

  if (!dev_urandom_exists)

    {  

      g_get_current_time (&now);

      seed[0] = now.tv_sec;

      seed[1] = now.tv_usec;

      seed[2] = getpid ();

#if defined G_OS_UNIX && !defined __SYMBIAN32__

      seed[3] = getppid ();

#else

      seed[3] = 0;

#endif

    }

  return g_rand_new_with_seed_array (seed, 4);

}

#if EMULATOR

#undef dev_urandom_exists 

#endif /* EMULATOR */

/**

 * g_rand_free:

 * @rand_: a #GRand.

 *

 * Frees the memory allocated for the #GRand.

 **/

EXPORT_C void

g_rand_free (GRand* rand)

{

  g_return_if_fail (rand != NULL);

  g_free (rand);

}

/**

 * g_rand_copy:

 * @rand_: a #GRand.

 *

 * Copies a #GRand into a new one with the same exact state as before.

 * This way you can take a snapshot of the random number generator for

 * replaying later.

 *

 * Return value: the new #GRand.

 *

 * Since: 2.4

 **/

EXPORT_C GRand *

g_rand_copy (GRand* rand)

{

  GRand* new_rand;

  g_return_val_if_fail (rand != NULL, NULL);

  new_rand = g_new0 (GRand, 1);

  memcpy (new_rand, rand, sizeof (GRand));

  return new_rand;

}

/**

 * g_rand_set_seed:

 * @rand_: a #GRand.

 * @seed: a value to reinitialize the random number generator.

 *

 * Sets the seed for the random number generator #GRand to @seed.

 **/

EXPORT_C void

g_rand_set_seed (GRand* rand, guint32 seed)

{

  g_return_if_fail (rand != NULL);

  switch (get_random_version ())

    {

    case 20:

      /* setting initial seeds to mt[N] using         */

      /* the generator Line 25 of Table 1 in          */

      /* [KNUTH 1981, The Art of Computer Programming */

      /*    Vol. 2 (2nd Ed.), pp102]                  */

      if (seed == 0) /* This would make the PRNG procude only zeros */

	seed = 0x6b842128; /* Just set it to another number */

      rand->mt[0]= seed;

      for (rand->mti=1; rand->mti<N; rand->mti++)

	rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]);

      break;

    case 22:

      /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */

      /* In the previous version (see above), MSBs of the    */

      /* seed affect only MSBs of the array mt[].            */

      rand->mt[0]= seed;

      for (rand->mti=1; rand->mti<N; rand->mti++)

	rand->mt[rand->mti] = 1812433253UL * 

	  (rand->mt[rand->mti-1] ^ (rand->mt[rand->mti-1] >> 30)) + rand->mti; 

      break;

    default:

      g_assert_not_reached ();

    }

}

/**

 * g_rand_set_seed_array:

 * @rand_: a #GRand.

 * @seed: array to initialize with

 * @seed_length: length of array

 *

 * Initializes the random number generator by an array of

 * longs.  Array can be of arbitrary size, though only the

 * first 624 values are taken.  This function is useful

 * if you have many low entropy seeds, or if you require more then

 * 32bits of actual entropy for your application.

 *

 * Since: 2.4

 **/

EXPORT_C void

g_rand_set_seed_array (GRand* rand, const guint32 *seed, guint seed_length)

{

  int i, j, k;

  g_return_if_fail (rand != NULL);

  g_return_if_fail (seed_length >= 1);

  g_rand_set_seed (rand, 19650218UL);

  i=1; j=0;

  k = (N>seed_length ? N : seed_length);

  for (; k; k--)

    {

      rand->mt[i] = (rand->mt[i] ^

		     ((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1664525UL))

	      + seed[j] + j; /* non linear */

      rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */

      i++; j++;

      if (i>=N)

        {

	  rand->mt[0] = rand->mt[N-1];

	  i=1;

	}

      if (j>=seed_length)

	j=0;

    }

  for (k=N-1; k; k--)

    {

      rand->mt[i] = (rand->mt[i] ^

		     ((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1566083941UL))

	      - i; /* non linear */

      rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */

      i++;

      if (i>=N)

        {

	  rand->mt[0] = rand->mt[N-1];

	  i=1;

	}

    }

  rand->mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 

}

/**

 * g_rand_int:

 * @rand_: a #GRand.

 *

 * Returns the next random #guint32 from @rand_ equally distributed over

 * the range [0..2^32-1].

 *

 * Return value: A random number.

 **/

EXPORT_C guint32

g_rand_int (GRand* rand)

{

  guint32 y;

  static const guint32 mag01[2]={0x0, MATRIX_A};

  /* mag01[x] = x * MATRIX_A  for x=0,1 */

  g_return_val_if_fail (rand != NULL, 0);

  if (rand->mti >= N) { /* generate N words at one time */

    int kk;

    for (kk=0;kk<N-M;kk++) {

      y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);

      rand->mt[kk] = rand->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];

    }

    for (;kk<N-1;kk++) {

      y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);

      rand->mt[kk] = rand->mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];

    }

    y = (rand->mt[N-1]&UPPER_MASK)|(rand->mt[0]&LOWER_MASK);

    rand->mt[N-1] = rand->mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];

    rand->mti = 0;

  }

  y = rand->mt[rand->mti++];

  y ^= TEMPERING_SHIFT_U(y);

  y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;

  y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;

  y ^= TEMPERING_SHIFT_L(y);

  return y; 

}

/* transform [0..2^32] -> [0..1] */

#define G_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10

/**

 * g_rand_int_range:

 * @rand_: a #GRand.

 * @begin: lower closed bound of the interval.

 * @end: upper open bound of the interval.

 *

 * Returns the next random #gint32 from @rand_ equally distributed over

 * the range [@begin..@end-1].

 *

 * Return value: A random number.

 **/

EXPORT_C gint32 

g_rand_int_range (GRand* rand, gint32 begin, gint32 end)

{

  guint32 dist = end - begin;

  guint32 random;

  g_return_val_if_fail (rand != NULL, begin);

  g_return_val_if_fail (end > begin, begin);

  switch (get_random_version ())

    {

    case 20:

      if (dist <= 0x10000L) /* 2^16 */

	{

	  /* This method, which only calls g_rand_int once is only good

	   * for (end - begin) <= 2^16, because we only have 32 bits set

	   * from the one call to g_rand_int (). */

	  /* we are using (trans + trans * trans), because g_rand_int only

	   * covers [0..2^32-1] and thus g_rand_int * trans only covers

	   * [0..1-2^-32], but the biggest double < 1 is 1-2^-52. 

	   */

	  gdouble double_rand = g_rand_int (rand) * 

	    (G_RAND_DOUBLE_TRANSFORM +

	     G_RAND_DOUBLE_TRANSFORM * G_RAND_DOUBLE_TRANSFORM);

	  random = (gint32) (double_rand * dist);

	}

      else

	{

	  /* Now we use g_rand_double_range (), which will set 52 bits for

	     us, so that it is safe to round and still get a decent

	     distribution */

	  random = (gint32) g_rand_double_range (rand, 0, dist);

	}

      break;

    case 22:

      if (dist == 0)

	random = 0;

      else 

	{

	  /* maxvalue is set to the predecessor of the greatest

	   * multiple of dist less or equal 2^32. */

	  guint32 maxvalue;

	  if (dist <= 0x80000000u) /* 2^31 */

	    {

	      /* maxvalue = 2^32 - 1 - (2^32 % dist) */

	      guint32 leftover = (0x80000000u % dist) * 2;

	      if (leftover >= dist) leftover -= dist;

	      maxvalue = 0xffffffffu - leftover;

	    }

	  else

	    maxvalue = dist - 1;

	  do

	    random = g_rand_int (rand);

	  while (random > maxvalue);