From 167ac704c8387c531630949860e33fb5a59789a8 Mon Sep 17 00:00:00 2001
From: Nat Goodspeed <nat@lindenlab.com>
Date: Mon, 17 Jul 2023 16:20:59 -0400
Subject: SL-18837: Clean up some redundancy in llrand.cpp.
---
indra/llcommon/llrand.cpp | 96 +++++++++++++++++++++++++++--------------------
1 file changed, 55 insertions(+), 41 deletions(-)
diff --git a/indra/llcommon/llrand.cpp b/indra/llcommon/llrand.cpp
index cb28a8f5c3..4e4345f37a 100644
--- a/indra/llcommon/llrand.cpp
+++ b/indra/llcommon/llrand.cpp
@@ -58,14 +58,18 @@
* to restore uniform distribution.
*/
+template <typename REAL>
+inline REAL ll_internal_random();
+
// *NOTE: The system rand implementation is probably not correct.
#define LL_USE_SYSTEM_RAND 0
+/*****************************************************************************
+* The LL_USE_SYSTEM_RAND implementation has been disabled since June 2008.
+*****************************************************************************/
#if LL_USE_SYSTEM_RAND
#include <cstdlib>
-#endif
-#if LL_USE_SYSTEM_RAND
class LLSeedRand
{
public:
@@ -79,25 +83,25 @@ public:
}
};
static LLSeedRand sRandomSeeder;
-inline F64 ll_internal_random_double()
+
+template <>
+inline F64 ll_internal_random<F64>()
{
#if LL_WINDOWS
- return (F64)rand() / (F64)RAND_MAX;
+ return (F64)rand() / (F64)(RAND_MAX+1);
#else
return drand48();
#endif
}
-inline F32 ll_internal_random_float()
-{
-#if LL_WINDOWS
- return (F32)rand() / (F32)RAND_MAX;
-#else
- return (F32)drand48();
-#endif
-}
-#else
+
+/*****************************************************************************
+* This is the implementation we've been using.
+*****************************************************************************/
+#else // LL_USE_SYSTEM_RAND
static LLRandLagFib2281 gRandomGenerator(LLUUID::getRandomSeed());
-inline F64 ll_internal_random_double()
+
+template <>
+inline F64 ll_internal_random<F64>()
{
// *HACK: Through experimentation, we have found that dual core
// CPUs (or at least multi-threaded processes) seem to
@@ -107,16 +111,40 @@ inline F64 ll_internal_random_double()
if(!((rv >= 0.0) && (rv < 1.0))) return fmod(rv, 1.0);
return rv;
}
+#endif // LL_USE_SYSTEM_RAND
+
+/*****************************************************************************
+* Functions common to both implementations
+*****************************************************************************/
+template <>
+inline F32 ll_internal_random<F32>()
+{
+ return F32(ll_internal_random<F64>());
+}
+
+/*------------------------------ F64 aliases -------------------------------*/
+inline F64 ll_internal_random_double()
+{
+ return ll_internal_random<F64>();
+}
+
+F64 ll_drand()
+{
+ return ll_internal_random_double();
+}
+/*------------------------------ F32 aliases -------------------------------*/
inline F32 ll_internal_random_float()
{
- // The clamping rules are described above.
- F32 rv = (F32)gRandomGenerator();
- if(!((rv >= 0.0f) && (rv < 1.0f))) return fmod(rv, 1.f);
- return rv;
+ return ll_internal_random<F32>();
}
-#endif
+F32 ll_frand()
+{
+ return ll_internal_random_float();
+}
+
+/*-------------------------- clamped random range --------------------------*/
S32 ll_rand()
{
return ll_rand(RAND_MAX);
@@ -130,42 +158,28 @@ S32 ll_rand(S32 val)
return rv;
}
-F32 ll_frand()
-{
- return ll_internal_random_float();
-}
-
-F32 ll_frand(F32 val)
+template <typename REAL>
+REAL ll_grand(REAL val)
{
// The clamping rules are described above.
- F32 rv = ll_internal_random_float() * val;
+ REAL rv = ll_internal_random<REAL>() * val;
if(val > 0)
{
- if(rv >= val) return 0.0f;
+ if(rv >= val) return REAL();
}
else
{
- if(rv <= val) return 0.0f;
+ if(rv <= val) return REAL();
}
return rv;
}
-F64 ll_drand()
+F32 ll_frand(F32 val)
{
- return ll_internal_random_double();
+ return ll_grand<F32>(val);
}
F64 ll_drand(F64 val)
{
- // The clamping rules are described above.
- F64 rv = ll_internal_random_double() * val;
- if(val > 0)
- {
- if(rv >= val) return 0.0;
- }
- else
- {
- if(rv <= val) return 0.0;
- }
- return rv;
+ return ll_grand<F64>(val);
}
--
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