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archived-php-src/ext/random/engine_combinedlcg.c
Tim Düsterhus 79133df156 random: Pass algorithm and state together as php_random_algo_with_state (#13350)
* random: Remove `php_random_status`

Since 162e1dce98, the `php_random_status` struct
contains just a single `void*`, resulting in needless indirection when
accessing the engine state and thus decreasing readability because of the
additional non-meaningful `->state` references / the local helper variables.

There is also a small, but measurable performance benefit:

    <?php
    $e = new Random\Engine\Xoshiro256StarStar(0);
    $r = new Random\Randomizer($e);

    for ($i = 0; $i < 15; $i++)
    	var_dump(strlen($r->getBytes(100000000)));

goes from roughly 3.85s down to 3.60s.

The names of the `status` variables have not yet been touched to keep the diff
small. They will be renamed to the more appropriate `state` in a follow-up
cleanup commit.

* Introduce `php_random_algo_with_state`
2024-02-25 20:48:58 +01:00

133 lines
3.6 KiB
C

/*
+----------------------------------------------------------------------+
| Copyright (c) The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 3.01 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| https://www.php.net/license/3_01.txt |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Sascha Schumann <sascha@schumann.cx> |
| Go Kudo <zeriyoshi@php.net> |
+----------------------------------------------------------------------+
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "php.h"
#include "php_random.h"
#include "Zend/zend_exceptions.h"
/*
* combinedLCG() returns a pseudo random number in the range of (0, 1).
* The function combines two CGs with periods of
* 2^31 - 85 and 2^31 - 249. The period of this function
* is equal to the product of both primes.
*/
#define MODMULT(a, b, c, m, s) q = s / a; s = b * (s - a * q) - c * q; if (s < 0) s += m
static void seed(void *status, uint64_t seed)
{
php_random_status_state_combinedlcg *s = status;
s->state[0] = seed & 0xffffffffU;
s->state[1] = seed >> 32;
}
static php_random_result generate(void *status)
{
php_random_status_state_combinedlcg *s = status;
int32_t q, z;
MODMULT(53668, 40014, 12211, 2147483563L, s->state[0]);
MODMULT(52774, 40692, 3791, 2147483399L, s->state[1]);
z = s->state[0] - s->state[1];
if (z < 1) {
z += 2147483562;
}
return (php_random_result){
.size = sizeof(uint32_t),
.result = (uint64_t) z,
};
}
static zend_long range(void *status, zend_long min, zend_long max)
{
return php_random_range((php_random_algo_with_state){
.algo = &php_random_algo_combinedlcg,
.status = status,
}, min, max);
}
static bool serialize(void *status, HashTable *data)
{
php_random_status_state_combinedlcg *s = status;
zval t;
for (uint32_t i = 0; i < 2; i++) {
ZVAL_STR(&t, php_random_bin2hex_le(&s->state[i], sizeof(uint32_t)));
zend_hash_next_index_insert(data, &t);
}
return true;
}
static bool unserialize(void *status, HashTable *data)
{
php_random_status_state_combinedlcg *s = status;
zval *t;
for (uint32_t i = 0; i < 2; i++) {
t = zend_hash_index_find(data, i);
if (!t || Z_TYPE_P(t) != IS_STRING || Z_STRLEN_P(t) != (2 * sizeof(uint32_t))) {
return false;
}
if (!php_random_hex2bin_le(Z_STR_P(t), &s->state[i])) {
return false;
}
}
return true;
}
const php_random_algo php_random_algo_combinedlcg = {
sizeof(php_random_status_state_combinedlcg),
seed,
generate,
range,
serialize,
unserialize
};
/* {{{ php_random_combinedlcg_seed_default */
PHPAPI void php_random_combinedlcg_seed_default(php_random_status_state_combinedlcg *state)
{
struct timeval tv;
if (gettimeofday(&tv, NULL) == 0) {
state->state[0] = tv.tv_usec ^ (tv.tv_usec << 11);
} else {
state->state[0] = 1;
}
#ifdef ZTS
state->state[1] = (zend_long) tsrm_thread_id();
#else
state->state[1] = (zend_long) getpid();
#endif
/* Add entropy to s2 by calling gettimeofday() again */
if (gettimeofday(&tv, NULL) == 0) {
state->state[1] ^= (tv.tv_usec << 11);
}
}
/* }}} */