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author | Devtools Arcadia <arcadia-devtools@yandex-team.ru> | 2022-02-07 18:08:42 +0300 |
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committer | Devtools Arcadia <arcadia-devtools@mous.vla.yp-c.yandex.net> | 2022-02-07 18:08:42 +0300 |
commit | 1110808a9d39d4b808aef724c861a2e1a38d2a69 (patch) | |
tree | e26c9fed0de5d9873cce7e00bc214573dc2195b7 /contrib/libs/poco/Foundation/src/Random.cpp | |
download | ydb-1110808a9d39d4b808aef724c861a2e1a38d2a69.tar.gz |
intermediate changes
ref:cde9a383711a11544ce7e107a78147fb96cc4029
Diffstat (limited to 'contrib/libs/poco/Foundation/src/Random.cpp')
-rw-r--r-- | contrib/libs/poco/Foundation/src/Random.cpp | 364 |
1 files changed, 364 insertions, 0 deletions
diff --git a/contrib/libs/poco/Foundation/src/Random.cpp b/contrib/libs/poco/Foundation/src/Random.cpp new file mode 100644 index 0000000000..048eea0144 --- /dev/null +++ b/contrib/libs/poco/Foundation/src/Random.cpp @@ -0,0 +1,364 @@ +// +// Random.cpp +// +// Library: Foundation +// Package: Crypt +// Module: Random +// +// Definition of class Random. +// +// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH. +// and Contributors. +// +// SPDX-License-Identifier: BSL-1.0 +// +// +// Based on the FreeBSD random number generator. +// src/lib/libc/stdlib/random.c,v 1.25 +// +// 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. +// + + +#include "Poco/Random.h" +#include "Poco/RandomStream.h" +#include <ctime> +#if defined(_WIN32_WCE) && _WIN32_WCE < 0x800 +#error #include "wce_time.h" +#endif + + +/* + * 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 + + +namespace Poco { + + +Random::Random(int stateSize) +{ + poco_assert (BREAK_0 <= stateSize && stateSize <= BREAK_4); + + _pBuffer = new char[stateSize]; +#if defined(_WIN32_WCE) && _WIN32_WCE < 0x800 + initState((UInt32) wceex_time(NULL), _pBuffer, stateSize); +#else + initState((UInt32) std::time(NULL), _pBuffer, stateSize); +#endif +} + + +Random::~Random() +{ + delete [] _pBuffer; +} + + +/* + * 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. + */ +inline UInt32 Random::goodRand(Int32 x) +{ + Int32 hi, lo; + + if (x == 0) x = 123459876; + hi = x / 127773; + lo = x % 127773; + x = 16807 * lo - 2836 * hi; + if (x < 0) x += 0x7FFFFFFF; + + return x; +} + + +/* + * 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 Random::seed(UInt32 x) +{ + int i, lim; + + _state[0] = x; + if (_randType == TYPE_0) + lim = NSHUFF; + else + { + for (i = 1; i < _randDeg; i++) + _state[i] = goodRand(_state[i - 1]); + _fptr = &_state[_randSep]; + _rptr = &_state[0]; + lim = 10 * _randDeg; + } + for (i = 0; i < lim; i++) + next(); +} + + +/* + * 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 Random::seed() +{ + std::streamsize len; + + if (_randType == TYPE_0) + len = sizeof _state[0]; + else + len = _randDeg * sizeof _state[0]; + + RandomInputStream rstr; + rstr.read((char*) _state, len); +} + + +/* + * 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. + */ +void Random::initState(UInt32 s, char* argState, Int32 n) +{ + UInt32* intArgState = (UInt32*) argState; + + if (n < BREAK_0) + { + poco_bugcheck_msg("not enough state"); + return; + } + if (n < BREAK_1) + { + _randType = TYPE_0; + _randDeg = DEG_0; + _randSep = SEP_0; + } + else if (n < BREAK_2) + { + _randType = TYPE_1; + _randDeg = DEG_1; + _randSep = SEP_1; + } + else if (n < BREAK_3) + { + _randType = TYPE_2; + _randDeg = DEG_2; + _randSep = SEP_2; + } + else if (n < BREAK_4) + { + _randType = TYPE_3; + _randDeg = DEG_3; + _randSep = SEP_3; + } + else + { + _randType = TYPE_4; + _randDeg = DEG_4; + _randSep = SEP_4; + } + _state = intArgState + 1; /* first location */ + _endPtr = &_state[_randDeg]; /* must set end_ptr before seed */ + seed(s); + if (_randType == TYPE_0) + intArgState[0] = _randType; + else + intArgState[0] = MAX_TYPES * (int) (_rptr - _state) + _randType; +} + + +/* + * Next: + * + * 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. + */ +UInt32 Random::next() +{ + UInt32 i; + UInt32 *f, *r; + + if (_randType == TYPE_0) + { + i = _state[0]; + _state[0] = i = goodRand(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 >= _endPtr) { + f = _state; + ++r; + } + else if (++r >= _endPtr) { + r = _state; + } + + _fptr = f; _rptr = r; + } + return i; +} + + +} // namespace Poco |