From b93bf95f2e76eca8be12ba07828387ab8529c050 Mon Sep 17 00:00:00 2001
From: Shauren <shauren.trinity@gmail.com>
Date: Sat, 9 Nov 2019 13:32:58 +0100
Subject: Core/Random: Refactor random number generation to use
 std::uniform_*_distribution to restrict result range instead of doing that
 ourselves

* Seed SFMTRand with more values for its state

(cherry picked from commit 73bc3d8ea49a4793b14976e86010a36f19c1d18b)
---
 src/common/Utilities/Random.cpp | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

(limited to 'src/common/Utilities/Random.cpp')

diff --git a/src/common/Utilities/Random.cpp b/src/common/Utilities/Random.cpp
index 974f13db0be..5a4004b41bd 100644
--- a/src/common/Utilities/Random.cpp
+++ b/src/common/Utilities/Random.cpp
@@ -22,7 +22,7 @@
 #include <random>
 
 static boost::thread_specific_ptr<SFMTRand> sfmtRand;
-static SFMTEngine engine;
+static RandomEngine engine;
 
 static SFMTRand* GetRng()
 {
@@ -40,26 +40,28 @@ static SFMTRand* GetRng()
 int32 irand(int32 min, int32 max)
 {
     ASSERT(max >= min);
-    return int32(GetRng()->IRandom(min, max));
+    std::uniform_int_distribution<int32> uid(min, max);
+    return uid(engine);
 }
 
 uint32 urand(uint32 min, uint32 max)
 {
     ASSERT(max >= min);
-    return GetRng()->URandom(min, max);
+    std::uniform_int_distribution<uint32> uid(min, max);
+    return uid(engine);
 }
 
 uint32 urandms(uint32 min, uint32 max)
 {
-    ASSERT(max >= min);
     ASSERT(std::numeric_limits<uint32>::max() / Milliseconds::period::den >= max);
-    return GetRng()->URandom(min * Milliseconds::period::den, max * Milliseconds::period::den);
+    return urand(min * Milliseconds::period::den, max * Milliseconds::period::den);
 }
 
 float frand(float min, float max)
 {
     ASSERT(max >= min);
-    return float(GetRng()->Random() * (max - min) + min);
+    std::uniform_real_distribution<float> urd(min, max);
+    return urd(engine);
 }
 
 Milliseconds randtime(Milliseconds min, Milliseconds max)
@@ -72,26 +74,28 @@ Milliseconds randtime(Milliseconds min, Milliseconds max)
 
 uint32 rand32()
 {
-    return GetRng()->BRandom();
+    return GetRng()->RandomUInt32();
 }
 
 double rand_norm()
 {
-    return GetRng()->Random();
+    std::uniform_real_distribution<double> urd;
+    return urd(engine);
 }
 
 double rand_chance()
 {
-    return GetRng()->Random() * 100.0;
+    std::uniform_real_distribution<double> urd(0.0, 100.0);
+    return urd(engine);
 }
 
 uint32 urandweighted(size_t count, double const* chances)
 {
     std::discrete_distribution<uint32> dd(chances, chances + count);
-    return dd(SFMTEngine::Instance());
+    return dd(engine);
 }
 
-SFMTEngine& SFMTEngine::Instance()
+RandomEngine& RandomEngine::Instance()
 {
     return engine;
 }
-- 
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