X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;ds=sidebyside;f=simgear%2Fmath%2Fsg_random.h;h=aa084a6362439b50063ec9a94bd6ab8552bc8fb5;hb=6672a1212cfccb2a08be21ff5271eae9b6f91b2a;hp=1ff1b1de3162bd65a4dfd052301d11c9c6a7b459;hpb=a53faf45652d31d3f370884b37d21c86eae12115;p=simgear.git

diff --git a/simgear/math/sg_random.h b/simgear/math/sg_random.h
index 1ff1b1de..aa084a63 100644
--- a/simgear/math/sg_random.h
+++ b/simgear/math/sg_random.h
@@ -1,8 +1,11 @@
-// sg_random.h -- routines to handle random number generation
-//
+/**
+ * \file sg_random.h
+ * Routines to handle random number generation and hide platform differences.
+ */
+
 // Written by Curtis Olson, started July 1997.
 //
-// Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
+// Copyright (C) 1997  Curtis L. Olson  - http://www.flightgear.org/~curt
 //
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Library General Public
@@ -14,10 +17,9 @@
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 // Library General Public License for more details.
 //
-// You should have received a copy of the GNU Library General Public
-// License along with this library; if not, write to the
-// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-// Boston, MA  02111-1307, USA.
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 //
 // $Id$
 
@@ -31,16 +33,63 @@ extern "C" {
 #endif                                   
 
 
-// Seed the random number generater with time() so we don't see the
-// same sequence every time
-void sg_srandom_time(void);
+#define MT_N 624
+#define MT_M 397
+
+/**
+ * Structure to hold MT algorithm state to easily allow independant
+ * sets of random numbers with different seeds.
+ */
+typedef struct {unsigned int array[MT_N]; int index; } mt;
+
+/**
+ * Initialize a new MT state with a given seed.
+ */
+void mt_init(mt *mt, unsigned int seed);
+
+/**
+ * Initialize a new MT state with a seed that only
+ * changes every 10 minutes.  Used to synchronize
+ * multi-process deployments.
+ */
+void mt_init_time_10(mt *mt);
+
+/**
+ * Generate a new 32-bit random number based on the given MT state.
+ */
+unsigned int mt_rand32( mt *mt);
+
+/**
+ * Generate a new random number between [0.0, 1.0) based 
+ * on the given MT state.
+ */
+double mt_rand(mt *mt);
+ 
+/**
+ * Seed the random number generater with time() so we don't see the
+ * same sequence every time.
+ */
+void sg_srandom_time();
+
+/**
+ * Seed the random number generater with time() in 10 minute intervals
+ * so we get the same sequence within 10 minutes interval.
+ * This is useful for synchronizing two display systems.
+ */
+void sg_srandom_time_10();
 
-// Seed the random number generater with your own seed so can set up
-// repeatable randomization.
-void sg_srandom( unsigned int seed );
+/**
+ * Seed the random number generater with your own seed so can set up
+ * repeatable randomization.
+ * @param seed random number generator seed
+ */
+void sg_srandom(unsigned int seed );
 
-// return a random number between [0.0, 1.0)
-double sg_random(void);
+/**
+ * Return a random number between [0.0, 1.0)
+ * @return next "random" number in the "random" sequence
+ */
+double sg_random();
 
 
 #ifdef __cplusplus