Add a random number generator from glib

3 files changed, 517 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index abc5e53..e999729 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,6 +10,7 @@ libnul_la_SOURCES =	\
 	array.c		\
 	epoll.c		\
 	dbus-int.c	\
+	random.c	\
 	signal-handler.c \
 	file-utils.c	\
 	libnul.h
diff --git a/libnul.h b/libnul.h
index c266be4..b8c2f06 100644
--- a/libnul.h
+++ b/libnul.h
@@ -307,6 +307,20 @@ nul_bool_t nul_fd_is_watched            (int           fd);
  */
 char *nul_canonicalize_filename (const char *filename);
 
+
+/*
+ * Random numbers
+ */
+void     nul_random_set_seed     (uint32_t seed);
+uint32_t nul_random_int          (void);
+int32_t  nul_random_int_range    (int32_t  begin,
+				  int32_t  end);
+double   nul_random_double       (void);
+double   nul_random_double_range (double   begin,
+				  double   end);
+
+#define nul_random_boolean() ((nul_random_int () & (1 << 15)) != 0)
+
 /*
  * Unix signal handlers
  */
diff --git a/random.c b/random.c
new file mode 100644
index 0000000..cc84023
--- /dev/null
+++ b/random.c
@@ -0,0 +1,502 @@
+/* libnul - another utility library */
+
+/* Based on grand.c from GLib. GLib copyright:
+ *
+ * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * 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 "libnul.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
+
+typedef struct _rand_t rand_t;
+
+G_LOCK_DEFINE_STATIC (global_random);
+static rand_t* global_random = NULL;
+
+/* 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)
+
+struct _rand_t
+{
+    uint32_t mt[N]; /* the array for the state vector  */
+    guint mti;
+};
+
+/**
+ * nul_rand_set_seed:
+ * @rand_: a #rand_t.
+ * @seed: a value to reinitialize the random number generator.
+ *
+ * Sets the seed for the random number generator #rand_t to @seed.
+ **/
+static void
+nul_rand_set_seed (rand_t* rand, uint32_t seed)
+{
+    g_return_if_fail (rand != NULL);
+
+	/* 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;
+}
+
+/**
+ * nul_rand_set_seed_array:
+ * @rand_: a #rand_t.
+ * @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
+ **/
+static void
+nul_rand_set_seed_array (rand_t* rand, const uint32_t *seed, guint seed_length)
+{
+    int i, j, k;
+
+    g_return_if_fail (rand != NULL);
+    g_return_if_fail (seed_length >= 1);
+
+    nul_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 */
+}
+
+/**
+ * nul_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 #rand_t.
+ **/
+static rand_t*
+nul_rand_new_with_seed (uint32_t seed)
+{
+    rand_t *rand = g_new0 (rand_t, 1);
+    nul_rand_set_seed (rand, seed);
+    return rand;
+}
+
+/**
+ * nul_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 #rand_t.
+ *
+ * Since: 2.4
+ **/
+static rand_t*
+nul_rand_new_with_seed_array (const uint32_t *seed, guint seed_length)
+{
+    rand_t *rand = g_new0 (rand_t, 1);
+    nul_rand_set_seed_array (rand, seed, seed_length);
+    return rand;
+}
+
+/**
+ * nul_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 #rand_t.
+ **/
+static rand_t*
+nul_rand_new (void)
+{
+    uint32_t seed[4];
+    GTimeVal now;
+#ifdef G_OS_UNIX
+    static gboolean dev_urandom_exists = TRUE;
+
+    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
+    static gboolean dev_urandom_exists = FALSE;
+#endif
+
+    if (!dev_urandom_exists)
+    {
+	g_get_current_time (&now);
+	seed[0] = now.tv_sec;
+	seed[1] = now.tv_usec;
+	seed[2] = getpid ();
+#ifdef G_OS_UNIX
+	seed[3] = getppid ();
+#else
+	seed[3] = 0;
+#endif
+    }
+
+    return nul_rand_new_with_seed_array (seed, 4);
+}
+
+/**
+ * nul_rand_int:
+ * @rand_: a #rand_t.
+ *
+ * Returns the next random #uint32_t from @rand_ equally distributed over
+ * the range [0..2^32-1].
+ *
+ * Return value: A random number.
+ **/
+static uint32_t
+nul_rand_int (rand_t* rand)
+{
+    uint32_t y;
+    static const uint32_t 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 NUL_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
+
+/**
+ * nul_rand_int_range:
+ * @rand_: a #rand_t.
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
+ *
+ * Returns the next random #int32_t from @rand_ equally distributed over
+ * the range [@begin..@end-1].
+ *
+ * Return value: A random number.
+ **/
+static int32_t
+nul_rand_int_range (rand_t* rand, int32_t begin, int32_t end)
+{
+    uint32_t dist = end - begin;
+    uint32_t random;
+
+    g_return_val_if_fail (rand != NULL, begin);
+    g_return_val_if_fail (end > begin, begin);
+
+	if (dist == 0)
+	    random = 0;
+	else
+	{
+	    /* maxvalue is set to the predecessor of the greatest
+	     * multiple of dist less or equal 2^32. */
+	    uint32_t maxvalue;
+	    if (dist <= 0x80000000u) /* 2^31 */
+	    {
+		/* maxvalue = 2^32 - 1 - (2^32 % dist) */
+		uint32_t leftover = (0x80000000u % dist) * 2;
+		if (leftover >= dist) leftover -= dist;
+		maxvalue = 0xffffffffu - leftover;
+	    }
+	    else
+		maxvalue = dist - 1;
+
+	    do
+		random = nul_rand_int (rand);
+	    while (random > maxvalue);
+
+	    random %= dist;
+	}
+    return begin + random;
+}
+
+/**
+ * nul_rand_double:
+ * @rand_: a #rand_t.
+ *
+ * Returns the next random #double from @rand_ equally distributed over
+ * the range [0..1).
+ *
+ * Return value: A random number.
+ **/
+static double
+nul_rand_double (rand_t* rand)
+{
+    /* We set all 52 bits after the point for this, not only the first
+       32. Thats why we need two calls to nul_rand_int */
+    double retval = nul_rand_int (rand) * NUL_RAND_DOUBLE_TRANSFORM;
+    retval = (retval + nul_rand_int (rand)) * NUL_RAND_DOUBLE_TRANSFORM;
+
+    /* The following might happen due to very bad rounding luck, but
+     * actually this should be more than rare, we just try again then */
+    if (retval >= 1.0)
+	return nul_rand_double (rand);
+
+    return retval;
+}
+
+/**
+ * nul_rand_double_range:
+ * @rand_: a #rand_t.
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
+ *
+ * Returns the next random #double from @rand_ equally distributed over
+ * the range [@begin..@end).
+ *
+ * Return value: A random number.
+ **/
+static double
+nul_rand_double_range (rand_t* rand, double begin, double end)
+{
+    return nul_rand_double (rand) * (end - begin) + begin;
+}
+
+/**
+ * nul_random_int:
+ *
+ * Return a random #uint32_t equally distributed over the range
+ * [0..2^32-1].
+ *
+ * Return value: A random number.
+ **/
+uint32_t
+nul_random_int (void)
+{
+    uint32_t result;
+    G_LOCK (global_random);
+    if (!global_random)
+	global_random = nul_rand_new ();
+
+    result = nul_rand_int (global_random);
+    G_UNLOCK (global_random);
+    return result;
+}
+
+/**
+ * nul_random_int_range:
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
+ *
+ * Returns a random #int32_t equally distributed over the range
+ * [@begin..@end-1].
+ *
+ * Return value: A random number.
+ **/
+int32_t
+nul_random_int_range (int32_t begin, int32_t end)
+{
+    int32_t result;
+    G_LOCK (global_random);
+    if (!global_random)
+	global_random = nul_rand_new ();
+
+    result = nul_rand_int_range (global_random, begin, end);
+    G_UNLOCK (global_random);
+    return result;
+}
+
+/**
+ * nul_random_double:
+ *
+ * Returns a random #double equally distributed over the range [0..1).
+ *
+ * Return value: A random number.
+ **/
+double
+nul_random_double (void)
+{
+    double result;
+    G_LOCK (global_random);
+    if (!global_random)
+	global_random = nul_rand_new ();
+
+    result = nul_rand_double (global_random);
+    G_UNLOCK (global_random);
+    return result;
+}
+
+/**
+ * nul_random_double_range:
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
+ *
+ * Returns a random #double equally distributed over the range [@begin..@end).
+ *
+ * Return value: A random number.
+ **/
+double
+nul_random_double_range (double begin, double end)
+{
+    double result;
+    G_LOCK (global_random);
+    if (!global_random)
+	global_random = nul_rand_new ();
+
+    result = nul_rand_double_range (global_random, begin, end);
+    G_UNLOCK (global_random);
+    return result;
+}
+
+/**
+ * nul_random_set_seed:
+ * @seed: a value to reinitialize the global random number generator.
+ *
+ * Sets the seed for the global random number generator, which is used
+ * by the <function>nul_random_*</function> functions, to @seed.
+ **/
+void
+nul_random_set_seed (uint32_t seed)
+{
+    G_LOCK (global_random);
+    if (!global_random)
+	global_random = nul_rand_new_with_seed (seed);
+    else
+	nul_rand_set_seed (global_random, seed);
+    G_UNLOCK (global_random);
+}
+
+
+#define __NUL_RAND_C__