1 files changed, 132 insertions, 0 deletions
diff --git a/ext/standard/lcg.c b/ext/standard/lcg.c
new file mode 100644
index 0000000..8bbe603
--- /dev/null
+++ b/ext/standard/lcg.c
@@ -0,0 +1,132 @@
+/*
+   +----------------------------------------------------------------------+
+   | PHP Version 5                                                        |
+   +----------------------------------------------------------------------+
+   | Copyright (c) 1997-2013 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:           |
+   | http://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.               |
+   +----------------------------------------------------------------------+
+   | Author: Sascha Schumann <sascha@schumann.cx>                         |
+   +----------------------------------------------------------------------+
+*/
+
+/* $Id$ */
+
+#include "php.h"
+#include "php_lcg.h"
+
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef PHP_WIN32
+#include "win32/time.h"
+#else
+#include <sys/time.h>
+#endif
+
+#ifdef ZTS
+int lcg_globals_id;
+#else
+static php_lcg_globals lcg_globals;
+#endif
+
+#ifdef PHP_WIN32
+#include <process.h>
+#endif
+
+/*
+ * 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 lcg_seed(TSRMLS_D);
+
+PHPAPI double php_combined_lcg(TSRMLS_D) /* {{{ */
+{
+	php_int32 q;
+	php_int32 z;
+
+	if (!LCG(seeded)) {
+		lcg_seed(TSRMLS_C);
+	}
+
+	MODMULT(53668, 40014, 12211, 2147483563L, LCG(s1));
+	MODMULT(52774, 40692, 3791, 2147483399L, LCG(s2));
+
+	z = LCG(s1) - LCG(s2);
+	if (z < 1) {
+		z += 2147483562;
+	}
+
+	return z * 4.656613e-10;
+}
+/* }}} */
+
+static void lcg_seed(TSRMLS_D) /* {{{ */
+{
+	struct timeval tv;
+
+	if (gettimeofday(&tv, NULL) == 0) {
+		LCG(s1) = tv.tv_sec ^ (tv.tv_usec<<11);
+	} else {
+		LCG(s1) = 1;
+	}
+#ifdef ZTS
+	LCG(s2) = (long) tsrm_thread_id();
+#else
+	LCG(s2) = (long) getpid();
+#endif
+
+	/* Add entropy to s2 by calling gettimeofday() again */
+	if (gettimeofday(&tv, NULL) == 0) {
+		LCG(s2) ^= (tv.tv_usec<<11);
+	}
+
+	LCG(seeded) = 1;
+}
+/* }}} */
+
+static void lcg_init_globals(php_lcg_globals *lcg_globals_p TSRMLS_DC) /* {{{ */
+{
+	LCG(seeded) = 0;
+}
+/* }}} */
+
+PHP_MINIT_FUNCTION(lcg) /* {{{ */
+{
+#ifdef ZTS
+	ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
+#else
+	lcg_init_globals(&lcg_globals);
+#endif
+	return SUCCESS;
+}
+/* }}} */
+
+/* {{{ proto float lcg_value()
+   Returns a value from the combined linear congruential generator */
+PHP_FUNCTION(lcg_value)
+{
+	RETURN_DOUBLE(php_combined_lcg(TSRMLS_C));
+}
+/* }}} */
+
+/*
+ * Local variables:
+ * tab-width: 4
+ * c-basic-offset: 4
+ * End:
+ * vim600: sw=4 ts=4 fdm=marker
+ * vim<600: sw=4 ts=4
+ */