From 7a1152369227e81f4ec1c14c2c090fb02950b075 Mon Sep 17 00:00:00 2001
From: david <david>
Date: Wed, 31 Jul 2002 17:14:29 +0000
Subject: [PATCH] Random-number seed patch from Erik Hofman.

---
 configure.in             |  2 +-
 simgear/math/sg_random.c | 33 ++++++++++++++++-----------------
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/configure.in b/configure.in
index c2e2a326..aa443d51 100644
--- a/configure.in
+++ b/configure.in
@@ -322,7 +322,7 @@ dnl Checks for library functions.
 AC_TYPE_SIGNAL
 AC_FUNC_VPRINTF
 AC_CHECK_FUNCS( ftime gettimeofday timegm memcpy bcopy mktime strstr rand \
-	random setitimer getitimer signal GetLocalTime rint getrusage )
+	random drand48 setitimer getitimer signal GetLocalTime rint getrusage )
 
 AM_CONFIG_HEADER(simgear/simgear_config.h)
 
diff --git a/simgear/math/sg_random.c b/simgear/math/sg_random.c
index f67f1341..ec103f13 100644
--- a/simgear/math/sg_random.c
+++ b/simgear/math/sg_random.c
@@ -27,18 +27,11 @@
 #endif
 
 #include <stdio.h>
-#include <stdlib.h>         // for random(), srandom()
+#include <stdlib.h>         // for random(), srandom(), drand48()
 #include <time.h>           // for time() to seed srandom()        
 
 #include "sg_random.h"
 
-#ifndef HAVE_RAND
-#  ifdef sgi
-#    undef RAND_MAX
-#    define RAND_MAX 2147483647
-#  endif
-#endif
-
 #ifdef __SUNPRO_CC
     extern "C" {
 	long int random();
@@ -50,10 +43,12 @@
 // Seed the random number generater with time() so we don't see the
 // same sequence every time
 void sg_srandom_time() {
-#ifdef HAVE_RAND
-    srand(time(NULL));
-#else
+#ifdef HAVE_DRAND48
+    srand48(time(NULL) + getpid());
+#elif defined( HAVE_RANDOM )
     srandom(time(NULL));
+#else
+    srand(time(NULL));
 #endif                                       
 }
 
@@ -61,20 +56,24 @@ void sg_srandom_time() {
 // Seed the random number generater with your own seed so can set up
 // repeatable randomization.
 void sg_srandom( unsigned int seed ) {
-#ifdef HAVE_RAND
-    srand( seed );
-#else
+#ifdef HAVE_DRAND48
+    srand48( seed );
+#elif defined( HAVE_RANDOM )
     srandom( seed );
+#else
+    srand( seed );
 #endif                                       
 }
 
 
 // return a random number between [0.0, 1.0)
 double sg_random() {
-#ifdef HAVE_RAND
-    return(rand() / (double)RAND_MAX);
-#else
+#ifdef HAVE_DRAND48
+    return(drand48());
+#elif defined( HAVE_RANDOM )
     return(random() / (double)RAND_MAX);
+#else
+    return(rand() / (double)RAND_MAX);
 #endif
 }
 
-- 
2.39.5