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authorJörg Frings-Fürst <debian@jff.email>2024-03-24 08:54:48 +0100
committerJörg Frings-Fürst <debian@jff.email>2024-03-24 08:54:48 +0100
commit163a663518f33bab48b28431972e580b366b4d49 (patch)
treef518ffabaca4a0b93f0103d617e803792d3b0b43 /tests/random.c
parent1b3a8d5ad2ea2f099d514d9dd51ebf926a628076 (diff)
parentdd0000f7e25abe6c28d4329d324fd7fcab54094f (diff)
Merge branch 'release/debian/1.2-1'HEADdebian/1.2-1master
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+/* Copyright (C) 1995-2024 Free Software Foundation, Inc.
+
+ This file 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 3 of the
+ License, or (at your option) any later version.
+
+ This file 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 program. If not, see <https://www.gnu.org/licenses/>. */
+
+/*
+ * This is derived from the Berkeley source:
+ * @(#)random.c 5.5 (Berkeley) 7/6/88
+ * It was reworked for the GNU C Library by Roland McGrath.
+ * Rewritten to use reentrant functions by Ulrich Drepper, 1995.
+ */
+
+/*
+ Copyright (C) 1983 Regents of the University of California.
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ 4. Neither the name of the University nor the names of its contributors
+ may be used to endorse or promote products derived from this software
+ without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ SUCH DAMAGE.*/
+
+#ifndef _LIBC
+# include <libc-config.h>
+# define __srandom srandom
+# define __initstate initstate
+# define __setstate setstate
+# define __random random
+# define __srandom_r srandom_r
+# define __initstate_r initstate_r
+# define __setstate_r setstate_r
+# define __random_r random_r
+#endif
+
+/* Specification. */
+#include <stdlib.h>
+
+#ifdef _LIBC
+# include <libc-lock.h>
+#else
+# include "glthread/lock.h"
+# define __libc_lock_define_initialized gl_lock_define_initialized
+# define __libc_lock_lock gl_lock_lock
+# define __libc_lock_unlock gl_lock_unlock
+#endif
+
+/* An improved random number generation package. In addition to the standard
+ rand()/srand() like interface, this package also has a special state info
+ interface. The initstate() routine is called with a seed, an array of
+ bytes, and a count of how many bytes are being passed in; this array is
+ then initialized to contain information for random number generation with
+ that much state information. Good sizes for the amount of state
+ information are 32, 64, 128, and 256 bytes. The state can be switched by
+ calling the setstate() function with the same array as was initialized
+ with initstate(). By default, the package runs with 128 bytes of state
+ information and generates far better random numbers than a linear
+ congruential generator. If the amount of state information is less than
+ 32 bytes, a simple linear congruential R.N.G. is used. Internally, the
+ state information is treated as an array of longs; the zeroth element of
+ the array is the type of R.N.G. being used (small integer); the remainder
+ of the array is the state information for the R.N.G. Thus, 32 bytes of
+ state information will give 7 longs worth of state information, which will
+ allow a degree seven polynomial. (Note: The zeroth word of state
+ information also has some other information stored in it; see setstate
+ for details). The random number generation technique is a linear feedback
+ shift register approach, employing trinomials (since there are fewer terms
+ to sum up that way). In this approach, the least significant bit of all
+ the numbers in the state table will act as a linear feedback shift register,
+ and will have period 2^deg - 1 (where deg is the degree of the polynomial
+ being used, assuming that the polynomial is irreducible and primitive).
+ The higher order bits will have longer periods, since their values are
+ also influenced by pseudo-random carries out of the lower bits. The
+ total period of the generator is approximately deg*(2**deg - 1); thus
+ doubling the amount of state information has a vast influence on the
+ period of the generator. Note: The deg*(2**deg - 1) is an approximation
+ only good for large deg, when the period of the shift register is the
+ dominant factor. With deg equal to seven, the period is actually much
+ longer than the 7*(2**7 - 1) predicted by this formula. */
+
+
+
+/* For each of the currently supported random number generators, we have a
+ break value on the amount of state information (you need at least this many
+ bytes of state info to support this random number generator), a degree for
+ the polynomial (actually a trinomial) that the R.N.G. is based on, and
+ separation between the two lower order coefficients of the trinomial. */
+
+/* Linear congruential. */
+#define TYPE_0 0
+#define BREAK_0 8
+#define DEG_0 0
+#define SEP_0 0
+
+/* x**7 + x**3 + 1. */
+#define TYPE_1 1
+#define BREAK_1 32
+#define DEG_1 7
+#define SEP_1 3
+
+/* x**15 + x + 1. */
+#define TYPE_2 2
+#define BREAK_2 64
+#define DEG_2 15
+#define SEP_2 1
+
+/* x**31 + x**3 + 1. */
+#define TYPE_3 3
+#define BREAK_3 128
+#define DEG_3 31
+#define SEP_3 3
+
+/* x**63 + x + 1. */
+#define TYPE_4 4
+#define BREAK_4 256
+#define DEG_4 63
+#define SEP_4 1
+
+
+/* Array versions of the above information to make code run faster.
+ Relies on fact that TYPE_i == i. */
+
+#define MAX_TYPES 5 /* Max number of types above. */
+
+
+/* Initially, everything is set up as if from:
+ initstate(1, randtbl, 128);
+ Note that this initialization takes advantage of the fact that srandom
+ advances the front and rear pointers 10*rand_deg times, and hence the
+ rear pointer which starts at 0 will also end up at zero; thus the zeroth
+ element of the state information, which contains info about the current
+ position of the rear pointer is just
+ (MAX_TYPES * (rptr - state)) + TYPE_3 == TYPE_3. */
+
+static int32_t randtbl[DEG_3 + 1] =
+ {
+ TYPE_3,
+
+ -1726662223, 379960547, 1735697613, 1040273694, 1313901226,
+ 1627687941, -179304937, -2073333483, 1780058412, -1989503057,
+ -615974602, 344556628, 939512070, -1249116260, 1507946756,
+ -812545463, 154635395, 1388815473, -1926676823, 525320961,
+ -1009028674, 968117788, -123449607, 1284210865, 435012392,
+ -2017506339, -911064859, -370259173, 1132637927, 1398500161,
+ -205601318,
+ };
+
+
+static struct random_data unsafe_state =
+ {
+/* FPTR and RPTR are two pointers into the state info, a front and a rear
+ pointer. These two pointers are always rand_sep places apart, as they
+ cycle through the state information. (Yes, this does mean we could get
+ away with just one pointer, but the code for random is more efficient
+ this way). The pointers are left positioned as they would be from the call:
+ initstate(1, randtbl, 128);
+ (The position of the rear pointer, rptr, is really 0 (as explained above
+ in the initialization of randtbl) because the state table pointer is set
+ to point to randtbl[1] (as explained below).) */
+
+ .fptr = &randtbl[SEP_3 + 1],
+ .rptr = &randtbl[1],
+
+/* The following things are the pointer to the state information table,
+ the type of the current generator, the degree of the current polynomial
+ being used, and the separation between the two pointers.
+ Note that for efficiency of random, we remember the first location of
+ the state information, not the zeroth. Hence it is valid to access
+ state[-1], which is used to store the type of the R.N.G.
+ Also, we remember the last location, since this is more efficient than
+ indexing every time to find the address of the last element to see if
+ the front and rear pointers have wrapped. */
+
+ .state = &randtbl[1],
+
+ .rand_type = TYPE_3,
+ .rand_deg = DEG_3,
+ .rand_sep = SEP_3,
+
+ .end_ptr = &randtbl[sizeof (randtbl) / sizeof (randtbl[0])]
+};
+
+/* POSIX.1c requires that there is mutual exclusion for the 'rand' and
+ 'srand' functions to prevent concurrent calls from modifying common
+ data. */
+__libc_lock_define_initialized (static, lock)
+
+/* Initialize the random number generator based on the given seed. If the
+ type is the trivial no-state-information type, just remember the seed.
+ Otherwise, initializes state[] based on the given "seed" via a linear
+ congruential generator. Then, the pointers are set to known locations
+ that are exactly rand_sep places apart. Lastly, it cycles the state
+ information a given number of times to get rid of any initial dependencies
+ introduced by the L.C.R.N.G. Note that the initialization of randtbl[]
+ for default usage relies on values produced by this routine. */
+void
+__srandom (unsigned int x)
+{
+ __libc_lock_lock (lock);
+ (void) __srandom_r (x, &unsafe_state);
+ __libc_lock_unlock (lock);
+}
+
+weak_alias (__srandom, srandom)
+weak_alias (__srandom, srand)
+
+/* Initialize the state information in the given array of N bytes for
+ future random number generation. Based on the number of bytes we
+ are given, and the break values for the different R.N.G.'s, we choose
+ the best (largest) one we can and set things up for it. srandom is
+ then called to initialize the state information. Note that on return
+ from srandom, we set state[-1] to be the type multiplexed with the current
+ value of the rear pointer; this is so successive calls to initstate won't
+ lose this information and will be able to restart with setstate.
+ Note: The first thing we do is save the current state, if any, just like
+ setstate so that it doesn't matter when initstate is called.
+ Returns a pointer to the old state. */
+char *
+__initstate (unsigned int seed, char *arg_state, size_t n)
+{
+ int32_t *ostate;
+ int ret;
+
+ __libc_lock_lock (lock);
+
+ ostate = &unsafe_state.state[-1];
+
+ ret = __initstate_r (seed, arg_state, n, &unsafe_state);
+
+ __libc_lock_unlock (lock);
+
+ return ret == -1 ? NULL : (char *) ostate;
+}
+
+weak_alias (__initstate, initstate)
+
+/* Restore the state from the given state array.
+ Note: It is important that we also remember the locations of the pointers
+ in the current state information, and restore the locations of the pointers
+ from the old state information. This is done by multiplexing the pointer
+ location into the zeroth word of the state information. Note that due
+ to the order in which things are done, it is OK to call setstate with the
+ same state as the current state
+ Returns a pointer to the old state information. */
+char *
+__setstate (char *arg_state)
+{
+ int32_t *ostate;
+
+ __libc_lock_lock (lock);
+
+ ostate = &unsafe_state.state[-1];
+
+ if (__setstate_r (arg_state, &unsafe_state) < 0)
+ ostate = NULL;
+
+ __libc_lock_unlock (lock);
+
+ return (char *) ostate;
+}
+
+weak_alias (__setstate, setstate)
+
+/* If we are using the trivial TYPE_0 R.N.G., just do the old linear
+ congruential bit. Otherwise, we do our fancy trinomial stuff, which is the
+ same in all the other cases due to all the global variables that have been
+ set up. The basic operation is to add the number at the rear pointer into
+ the one at the front pointer. Then both pointers are advanced to the next
+ location cyclically in the table. The value returned is the sum generated,
+ reduced to 31 bits by throwing away the "least random" low bit.
+ Note: The code takes advantage of the fact that both the front and
+ rear pointers can't wrap on the same call by not testing the rear
+ pointer if the front one has wrapped. Returns a 31-bit random number. */
+
+long int
+__random (void)
+{
+ int32_t retval;
+
+ __libc_lock_lock (lock);
+
+ (void) __random_r (&unsafe_state, &retval);
+
+ __libc_lock_unlock (lock);
+
+ return retval;
+}
+
+weak_alias (__random, random)