Annotation of embedaddon/php/ext/standard/rand.c, revision 1.1.1.4
1.1 misho 1: /*
2: +----------------------------------------------------------------------+
3: | PHP Version 5 |
4: +----------------------------------------------------------------------+
1.1.1.4 ! misho 5: | Copyright (c) 1997-2014 The PHP Group |
1.1 misho 6: +----------------------------------------------------------------------+
7: | This source file is subject to version 3.01 of the PHP license, |
8: | that is bundled with this package in the file LICENSE, and is |
9: | available through the world-wide-web at the following url: |
10: | http://www.php.net/license/3_01.txt |
11: | If you did not receive a copy of the PHP license and are unable to |
12: | obtain it through the world-wide-web, please send a note to |
13: | license@php.net so we can mail you a copy immediately. |
14: +----------------------------------------------------------------------+
15: | Authors: Rasmus Lerdorf <rasmus@php.net> |
16: | Zeev Suraski <zeev@zend.com> |
17: | Pedro Melo <melo@ip.pt> |
18: | Sterling Hughes <sterling@php.net> |
19: | |
20: | Based on code from: Richard J. Wagner <rjwagner@writeme.com> |
21: | Makoto Matsumoto <matumoto@math.keio.ac.jp> |
22: | Takuji Nishimura |
23: | Shawn Cokus <Cokus@math.washington.edu> |
24: +----------------------------------------------------------------------+
25: */
1.1.1.2 misho 26: /* $Id$ */
1.1 misho 27:
28: #include <stdlib.h>
29:
30: #include "php.h"
31: #include "php_math.h"
32: #include "php_rand.h"
33:
34: #include "basic_functions.h"
35:
36:
37: /* SYSTEM RAND FUNCTIONS */
38:
39: /* {{{ php_srand
40: */
41: PHPAPI void php_srand(long seed TSRMLS_DC)
42: {
43: #ifdef ZTS
44: BG(rand_seed) = (unsigned int) seed;
45: #else
46: # if defined(HAVE_SRANDOM)
47: srandom((unsigned int) seed);
48: # elif defined(HAVE_SRAND48)
49: srand48(seed);
50: # else
51: srand((unsigned int) seed);
52: # endif
53: #endif
54:
55: /* Seed only once */
56: BG(rand_is_seeded) = 1;
57: }
58: /* }}} */
59:
60: /* {{{ php_rand
61: */
62: PHPAPI long php_rand(TSRMLS_D)
63: {
64: long ret;
65:
66: if (!BG(rand_is_seeded)) {
67: php_srand(GENERATE_SEED() TSRMLS_CC);
68: }
69:
70: #ifdef ZTS
71: ret = php_rand_r(&BG(rand_seed));
72: #else
73: # if defined(HAVE_RANDOM)
74: ret = random();
75: # elif defined(HAVE_LRAND48)
76: ret = lrand48();
77: # else
78: ret = rand();
79: # endif
80: #endif
81:
82: return ret;
83: }
84: /* }}} */
85:
86:
87: /* MT RAND FUNCTIONS */
88:
89: /*
90: The following php_mt_...() functions are based on a C++ class MTRand by
91: Richard J. Wagner. For more information see the web page at
92: http://www-personal.engin.umich.edu/~wagnerr/MersenneTwister.html
93:
94: Mersenne Twister random number generator -- a C++ class MTRand
95: Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus
96: Richard J. Wagner v1.0 15 May 2003 rjwagner@writeme.com
97:
98: The Mersenne Twister is an algorithm for generating random numbers. It
99: was designed with consideration of the flaws in various other generators.
100: The period, 2^19937-1, and the order of equidistribution, 623 dimensions,
101: are far greater. The generator is also fast; it avoids multiplication and
102: division, and it benefits from caches and pipelines. For more information
103: see the inventors' web page at http://www.math.keio.ac.jp/~matumoto/emt.html
104:
105: Reference
106: M. Matsumoto and T. Nishimura, "Mersenne Twister: A 623-Dimensionally
107: Equidistributed Uniform Pseudo-Random Number Generator", ACM Transactions on
108: Modeling and Computer Simulation, Vol. 8, No. 1, January 1998, pp 3-30.
109:
110: Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
111: Copyright (C) 2000 - 2003, Richard J. Wagner
112: All rights reserved.
113:
114: Redistribution and use in source and binary forms, with or without
115: modification, are permitted provided that the following conditions
116: are met:
117:
118: 1. Redistributions of source code must retain the above copyright
119: notice, this list of conditions and the following disclaimer.
120:
121: 2. Redistributions in binary form must reproduce the above copyright
122: notice, this list of conditions and the following disclaimer in the
123: documentation and/or other materials provided with the distribution.
124:
125: 3. The names of its contributors may not be used to endorse or promote
126: products derived from this software without specific prior written
127: permission.
128:
129: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
130: "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
131: LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
132: A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
133: CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
134: EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
135: PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
136: PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
137: LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
138: NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
139: SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
140: */
141:
142: #define N MT_N /* length of state vector */
143: #define M (397) /* a period parameter */
144: #define hiBit(u) ((u) & 0x80000000U) /* mask all but highest bit of u */
145: #define loBit(u) ((u) & 0x00000001U) /* mask all but lowest bit of u */
146: #define loBits(u) ((u) & 0x7FFFFFFFU) /* mask the highest bit of u */
147: #define mixBits(u, v) (hiBit(u)|loBits(v)) /* move hi bit of u to hi bit of v */
148:
149: #define twist(m,u,v) (m ^ (mixBits(u,v)>>1) ^ ((php_uint32)(-(php_int32)(loBit(u))) & 0x9908b0dfU))
150:
151: /* {{{ php_mt_initialize
152: */
153: static inline void php_mt_initialize(php_uint32 seed, php_uint32 *state)
154: {
155: /* Initialize generator state with seed
156: See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
157: In previous versions, most significant bits (MSBs) of the seed affect
158: only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto. */
159:
160: register php_uint32 *s = state;
161: register php_uint32 *r = state;
162: register int i = 1;
163:
164: *s++ = seed & 0xffffffffU;
165: for( ; i < N; ++i ) {
166: *s++ = ( 1812433253U * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffU;
167: r++;
168: }
169: }
170: /* }}} */
171:
172: /* {{{ php_mt_reload
173: */
174: static inline void php_mt_reload(TSRMLS_D)
175: {
176: /* Generate N new values in state
177: Made clearer and faster by Matthew Bellew (matthew.bellew@home.com) */
178:
179: register php_uint32 *state = BG(state);
180: register php_uint32 *p = state;
181: register int i;
182:
183: for (i = N - M; i--; ++p)
184: *p = twist(p[M], p[0], p[1]);
185: for (i = M; --i; ++p)
186: *p = twist(p[M-N], p[0], p[1]);
187: *p = twist(p[M-N], p[0], state[0]);
188: BG(left) = N;
189: BG(next) = state;
190: }
191: /* }}} */
192:
193: /* {{{ php_mt_srand
194: */
195: PHPAPI void php_mt_srand(php_uint32 seed TSRMLS_DC)
196: {
197: /* Seed the generator with a simple uint32 */
198: php_mt_initialize(seed, BG(state));
199: php_mt_reload(TSRMLS_C);
200:
201: /* Seed only once */
202: BG(mt_rand_is_seeded) = 1;
203: }
204: /* }}} */
205:
206: /* {{{ php_mt_rand
207: */
208: PHPAPI php_uint32 php_mt_rand(TSRMLS_D)
209: {
210: /* Pull a 32-bit integer from the generator state
211: Every other access function simply transforms the numbers extracted here */
212:
213: register php_uint32 s1;
214:
215: if (BG(left) == 0) {
216: php_mt_reload(TSRMLS_C);
217: }
218: --BG(left);
219:
220: s1 = *BG(next)++;
221: s1 ^= (s1 >> 11);
222: s1 ^= (s1 << 7) & 0x9d2c5680U;
223: s1 ^= (s1 << 15) & 0xefc60000U;
224: return ( s1 ^ (s1 >> 18) );
225: }
226: /* }}} */
227:
228: /* {{{ proto void srand([int seed])
229: Seeds random number generator */
230: PHP_FUNCTION(srand)
231: {
232: long seed = 0;
233:
234: if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &seed) == FAILURE)
235: return;
236:
237: if (ZEND_NUM_ARGS() == 0)
238: seed = GENERATE_SEED();
239:
240: php_srand(seed TSRMLS_CC);
241: }
242: /* }}} */
243:
244: /* {{{ proto void mt_srand([int seed])
245: Seeds Mersenne Twister random number generator */
246: PHP_FUNCTION(mt_srand)
247: {
248: long seed = 0;
249:
250: if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &seed) == FAILURE)
251: return;
252:
253: if (ZEND_NUM_ARGS() == 0)
254: seed = GENERATE_SEED();
255:
256: php_mt_srand(seed TSRMLS_CC);
257: }
258: /* }}} */
259:
260:
261: /*
262: * A bit of tricky math here. We want to avoid using a modulus because
263: * that simply tosses the high-order bits and might skew the distribution
264: * of random values over the range. Instead we map the range directly.
265: *
266: * We need to map the range from 0...M evenly to the range a...b
267: * Let n = the random number and n' = the mapped random number
268: *
269: * Then we have: n' = a + n(b-a)/M
270: *
271: * We have a problem here in that only n==M will get mapped to b which
272: # means the chances of getting b is much much less than getting any of
273: # the other values in the range. We can fix this by increasing our range
274: # artifically and using:
275: #
276: # n' = a + n(b-a+1)/M
277: *
278: # Now we only have a problem if n==M which would cause us to produce a
279: # number of b+1 which would be bad. So we bump M up by one to make sure
280: # this will never happen, and the final algorithm looks like this:
281: #
282: # n' = a + n(b-a+1)/(M+1)
283: *
284: * -RL
285: */
286:
287: /* {{{ proto int rand([int min, int max])
288: Returns a random number */
289: PHP_FUNCTION(rand)
290: {
291: long min;
292: long max;
293: long number;
294: int argc = ZEND_NUM_ARGS();
295:
296: if (argc != 0 && zend_parse_parameters(argc TSRMLS_CC, "ll", &min, &max) == FAILURE)
297: return;
298:
299: number = php_rand(TSRMLS_C);
300: if (argc == 2) {
301: RAND_RANGE(number, min, max, PHP_RAND_MAX);
302: }
303:
304: RETURN_LONG(number);
305: }
306: /* }}} */
307:
308: /* {{{ proto int mt_rand([int min, int max])
309: Returns a random number from Mersenne Twister */
310: PHP_FUNCTION(mt_rand)
311: {
312: long min;
313: long max;
314: long number;
315: int argc = ZEND_NUM_ARGS();
316:
317: if (argc != 0) {
318: if (zend_parse_parameters(argc TSRMLS_CC, "ll", &min, &max) == FAILURE) {
319: return;
320: } else if (max < min) {
321: php_error_docref(NULL TSRMLS_CC, E_WARNING, "max(%ld) is smaller than min(%ld)", max, min);
322: RETURN_FALSE;
323: }
324: }
325:
326: if (!BG(mt_rand_is_seeded)) {
327: php_mt_srand(GENERATE_SEED() TSRMLS_CC);
328: }
329:
330: /*
331: * Melo: hmms.. randomMT() returns 32 random bits...
332: * Yet, the previous php_rand only returns 31 at most.
333: * So I put a right shift to loose the lsb. It *seems*
334: * better than clearing the msb.
335: * Update:
336: * I talked with Cokus via email and it won't ruin the algorithm
337: */
338: number = (long) (php_mt_rand(TSRMLS_C) >> 1);
339: if (argc == 2) {
340: RAND_RANGE(number, min, max, PHP_MT_RAND_MAX);
341: }
342:
343: RETURN_LONG(number);
344: }
345: /* }}} */
346:
347: /* {{{ proto int getrandmax(void)
348: Returns the maximum value a random number can have */
349: PHP_FUNCTION(getrandmax)
350: {
351: if (zend_parse_parameters_none() == FAILURE) {
352: return;
353: }
354:
355: RETURN_LONG(PHP_RAND_MAX);
356: }
357: /* }}} */
358:
359: /* {{{ proto int mt_getrandmax(void)
360: Returns the maximum value a random number from Mersenne Twister can have */
361: PHP_FUNCTION(mt_getrandmax)
362: {
363: if (zend_parse_parameters_none() == FAILURE) {
364: return;
365: }
366:
367: /*
368: * Melo: it could be 2^^32 but we only use 2^^31 to maintain
369: * compatibility with the previous php_rand
370: */
371: RETURN_LONG(PHP_MT_RAND_MAX); /* 2^^31 */
372: }
373: /* }}} */
374:
375: /*
376: * Local variables:
377: * tab-width: 4
378: * c-basic-offset: 4
379: * End:
380: * vim600: noet sw=4 ts=4 fdm=marker
381: * vim<600: noet sw=4 ts=4
382: */
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