+++ /dev/null
-/*
- * Copyright (c) 1983, 1993
- * The 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.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)random.c 8.2 (Berkeley) 5/19/95";
-#endif /* LIBC_SCCS and not lint */
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD: src/lib/libc/stdlib/random.c,v 1.25 2007/01/09 00:28:10 imp Exp $");
-
-/*
- * We always compile with __DARWIN_UNIX03 set to one, relying on the fact that
- * (for non-LP64) sizeof(int) == sizeof(long) == sizeof(size_t), so that we
- * don't have to have two different versions of the prototypes. For LP64,
- * we only support the POSIX-compatible prototypes.
- */
-#undef __DARWIN_UNIX03
-#define __DARWIN_UNIX03 1
-#include "namespace.h"
-#include <sys/time.h> /* for srandomdev() */
-#include <fcntl.h> /* for srandomdev() */
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h> /* for srandomdev() */
-#include "un-namespace.h"
-
-/*
- * random.c:
- *
- * 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() routine with the same array as was initiallized
- * 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 uint32_t's; the
- * zeroeth 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 ints worth of
- * state information, which will allow a degree seven polynomial. (Note:
- * the zeroeth 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 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.
- *
- * Modified 28 December 1994 by Jacob S. Rosenberg.
- * The following changes have been made:
- * All references to the type u_int have been changed to unsigned long.
- * All references to type int have been changed to type long. Other
- * cleanups have been made as well. A warning for both initstate and
- * setstate has been inserted to the effect that on Sparc platforms
- * the 'arg_state' variable must be forced to begin on word boundaries.
- * This can be easily done by casting a long integer array to char *.
- * The overall logic has been left STRICTLY alone. This software was
- * tested on both a VAX and Sun SpacsStation with exactly the same
- * results. The new version and the original give IDENTICAL results.
- * The new version is somewhat faster than the original. As the
- * documentation says: "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." For a buffer of
- * 128 bytes, this new version runs about 19 percent faster and for a 16
- * byte buffer it is about 5 percent faster.
- */
-
-/*
- * 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
- * the separation between the two lower order coefficients of the trinomial.
- */
-#define TYPE_0 0 /* linear congruential */
-#define BREAK_0 8
-#define DEG_0 0
-#define SEP_0 0
-
-#define TYPE_1 1 /* x**7 + x**3 + 1 */
-#define BREAK_1 32
-#define DEG_1 7
-#define SEP_1 3
-
-#define TYPE_2 2 /* x**15 + x + 1 */
-#define BREAK_2 64
-#define DEG_2 15
-#define SEP_2 1
-
-#define TYPE_3 3 /* x**31 + x**3 + 1 */
-#define BREAK_3 128
-#define DEG_3 31
-#define SEP_3 3
-
-#define TYPE_4 4 /* x**63 + x + 1 */
-#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 */
-
-#ifdef USE_WEAK_SEEDING
-#define NSHUFF 0
-#else /* !USE_WEAK_SEEDING */
-#define NSHUFF 50 /* to drop some "seed -> 1st value" linearity */
-#endif /* !USE_WEAK_SEEDING */
-
-static const int degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 };
-static const int seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
-
-/*
- * 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 zeroeth
- * 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 uint32_t randtbl[DEG_3 + 1] = {
- TYPE_3,
-#ifdef USE_WEAK_SEEDING
-/* Historic implementation compatibility */
-/* The random sequences do not vary much with the seed */
- 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 0xde3b81e0, 0xdf0a6fb5,
- 0xf103bc02, 0x48f340fb, 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd,
- 0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88,
- 0xe369735d, 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
- 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, 0x8999220b,
- 0x27fb47b9,
-#else /* !USE_WEAK_SEEDING */
- 0x991539b1, 0x16a5bce3, 0x6774a4cd, 0x3e01511e, 0x4e508aaa, 0x61048c05,
- 0xf5500617, 0x846b7115, 0x6a19892c, 0x896a97af, 0xdb48f936, 0x14898454,
- 0x37ffd106, 0xb58bff9c, 0x59e17104, 0xcf918a49, 0x09378c83, 0x52c7a471,
- 0x8d293ea9, 0x1f4fc301, 0xc3db71be, 0x39b44e1c, 0xf8a44ef9, 0x4c8b80b1,
- 0x19edc328, 0x87bf4bdd, 0xc9b240e5, 0xe9ee4b1b, 0x4382aee7, 0x535b6b41,
- 0xf3bec5da
-#endif /* !USE_WEAK_SEEDING */
-};
-
-/*
- * fptr and rptr are two pointers into the state info, a front and a rear
- * pointer. These two pointers are always rand_sep places aparts, as they
- * cycle cyclically 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).
- */
-static uint32_t *fptr = &randtbl[SEP_3 + 1];
-static uint32_t *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 zeroeth. 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.
- */
-static uint32_t *state = &randtbl[1];
-static int rand_type = TYPE_3;
-static int rand_deg = DEG_3;
-static int rand_sep = SEP_3;
-static uint32_t *end_ptr = &randtbl[DEG_3 + 1];
-
-static inline uint32_t good_rand(int32_t) __attribute__((always_inline));
-
-static inline uint32_t good_rand (x)
- int32_t x;
-{
-#ifdef USE_WEAK_SEEDING
-/*
- * Historic implementation compatibility.
- * The random sequences do not vary much with the seed,
- * even with overflowing.
- */
- return (1103515245 * x + 12345);
-#else /* !USE_WEAK_SEEDING */
-/*
- * Compute x = (7^5 * x) mod (2^31 - 1)
- * wihout overflowing 31 bits:
- * (2^31 - 1) = 127773 * (7^5) + 2836
- * From "Random number generators: good ones are hard to find",
- * Park and Miller, Communications of the ACM, vol. 31, no. 10,
- * October 1988, p. 1195.
- */
- int32_t hi, lo;
-
- /* Can't be initialized with 0, so use another value. */
- if (x == 0)
- x = 123459876;
- hi = x / 127773;
- lo = x % 127773;
- x = 16807 * lo - 2836 * hi;
- if (x < 0)
- x += 0x7fffffff;
- return (x);
-#endif /* !USE_WEAK_SEEDING */
-}
-
-/*
- * srandom:
- *
- * 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(x)
- unsigned x;
-{
- int i, lim;
-
- state[0] = (uint32_t)x;
- if (rand_type == TYPE_0)
- lim = NSHUFF;
- else {
- for (i = 1; i < rand_deg; i++)
- state[i] = good_rand(state[i - 1]);
- fptr = &state[rand_sep];
- rptr = &state[0];
- lim = 10 * rand_deg;
- }
- for (i = 0; i < lim; i++)
- (void)random();
-}
-
-/*
- * srandomdev:
- *
- * Many programs choose the seed value in a totally predictable manner.
- * This often causes problems. We seed the generator using the much more
- * secure random(4) interface. Note that this particular seeding
- * procedure can generate states which are impossible to reproduce by
- * calling srandom() with any value, since the succeeding terms in the
- * state buffer are no longer derived from the LC algorithm applied to
- * a fixed seed.
- */
-void
-srandomdev()
-{
- int fd, done;
- size_t len;
-
- if (rand_type == TYPE_0)
- len = sizeof state[0];
- else
- len = rand_deg * sizeof state[0];
-
- done = 0;
- fd = _open("/dev/random", O_RDONLY, 0);
- if (fd >= 0) {
- if (_read(fd, (void *) state, len) == (ssize_t) len)
- done = 1;
- _close(fd);
- }
-
- if (!done) {
- struct timeval tv;
- unsigned long junk;
-
- gettimeofday(&tv, NULL);
- srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk);
- return;
- }
-
- if (rand_type != TYPE_0) {
- fptr = &state[rand_sep];
- rptr = &state[0];
- }
-}
-
-/*
- * initstate:
- *
- * 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.
- *
- * Note: The Sparc platform requires that arg_state begin on an int
- * word boundary; otherwise a bus error will occur. Even so, lint will
- * complain about mis-alignment, but you should disregard these messages.
- */
-char *
-initstate(seed, arg_state, n)
- unsigned seed; /* seed for R.N.G. */
- char *arg_state; /* pointer to state array */
- size_t n; /* # bytes of state info */
-{
- char *ostate = (char *)(&state[-1]);
- uint32_t *int_arg_state = (uint32_t *)arg_state;
-
- if (rand_type == TYPE_0)
- state[-1] = rand_type;
- else
- state[-1] = MAX_TYPES * (rptr - state) + rand_type;
- if (n < BREAK_0) {
- (void)fprintf(stderr,
- "random: not enough state (%ld bytes); ignored.\n", n);
- return(0);
- }
- if (n < BREAK_1) {
- rand_type = TYPE_0;
- rand_deg = DEG_0;
- rand_sep = SEP_0;
- } else if (n < BREAK_2) {
- rand_type = TYPE_1;
- rand_deg = DEG_1;
- rand_sep = SEP_1;
- } else if (n < BREAK_3) {
- rand_type = TYPE_2;
- rand_deg = DEG_2;
- rand_sep = SEP_2;
- } else if (n < BREAK_4) {
- rand_type = TYPE_3;
- rand_deg = DEG_3;
- rand_sep = SEP_3;
- } else {
- rand_type = TYPE_4;
- rand_deg = DEG_4;
- rand_sep = SEP_4;
- }
- state = int_arg_state + 1; /* first location */
- end_ptr = &state[rand_deg]; /* must set end_ptr before srandom */
- srandom(seed);
- if (rand_type == TYPE_0)
- int_arg_state[0] = rand_type;
- else
- int_arg_state[0] = MAX_TYPES * (rptr - state) + rand_type;
- return(ostate);
-}
-
-/*
- * setstate:
- *
- * 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 zeroeth 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.
- *
- * Note: The Sparc platform requires that arg_state begin on an int
- * word boundary; otherwise a bus error will occur. Even so, lint will
- * complain about mis-alignment, but you should disregard these messages.
- */
-char *
-setstate(arg_state)
- const char *arg_state; /* pointer to state array */
-{
- uint32_t *new_state = (uint32_t *)arg_state;
- uint32_t type = new_state[0] % MAX_TYPES;
- uint32_t rear = new_state[0] / MAX_TYPES;
- char *ostate = (char *)(&state[-1]);
-
- if (rand_type == TYPE_0)
- state[-1] = rand_type;
- else
- state[-1] = MAX_TYPES * (rptr - state) + rand_type;
- switch(type) {
- case TYPE_0:
- case TYPE_1:
- case TYPE_2:
- case TYPE_3:
- case TYPE_4:
- rand_type = type;
- rand_deg = degrees[type];
- rand_sep = seps[type];
- break;
- default:
- (void)fprintf(stderr,
- "random: state info corrupted; not changed.\n");
- }
- state = new_state + 1;
- if (rand_type != TYPE_0) {
- rptr = &state[rear];
- fptr = &state[(rear + rand_sep) % rand_deg];
- }
- end_ptr = &state[rand_deg]; /* set end_ptr too */
- return(ostate);
-}
-
-/*
- * random:
- *
- * 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
-random()
-{
- uint32_t i;
- uint32_t *f, *r;
-
- if (rand_type == TYPE_0) {
- i = state[0];
- state[0] = i = (good_rand(i)) & 0x7fffffff;
- } else {
- /*
- * Use local variables rather than static variables for speed.
- */
- f = fptr; r = rptr;
- *f += *r;
- i = (*f >> 1) & 0x7fffffff; /* chucking least random bit */
- if (++f >= end_ptr) {
- f = state;
- ++r;
- }
- else if (++r >= end_ptr) {
- r = state;
- }
-
- fptr = f; rptr = r;
- }
- return((long)i);
-}
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