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Diffstat (limited to 'winsup/cygwin/random.cc')
| -rw-r--r-- | winsup/cygwin/random.cc | 504 |
1 files changed, 0 insertions, 504 deletions
diff --git a/winsup/cygwin/random.cc b/winsup/cygwin/random.cc deleted file mode 100644 index fe1ac08fd..000000000 --- a/winsup/cygwin/random.cc +++ /dev/null @@ -1,504 +0,0 @@ -/* - * 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. - */ - -extern "C" { -#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 $"); - -#include <sys/time.h> /* for srandomdev() */ -#include <fcntl.h> /* for srandomdev() */ -#include <stdio.h> -#include <stdlib.h> -#include <unistd.h> /* for srandomdev() */ - -/* - * 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 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(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(); -} - -/* Avoid a compiler warning when we really want to get at the junk in - an uninitialized variable. */ -static unsigned long -dummy (unsigned volatile long *x) -{ - return *x; -} - -/* - * 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 ^ dummy(&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(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 (%lu bytes); ignored.\n", - (unsigned long) 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(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); -} -} |