llrand.cpp File Reference

Global random generator. More...

#include "linden_common.h"
#include "llrand.h"
#include "lluuid.h"

Include dependency graph for llrand.cpp:

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#define LL_USE_SYSTEM_RAND   0


static LLRandLagFib2281 gRandomGenerator (LLUUID::getRandomSeed())
F64 ll_internal_random_double ()
F32 ll_internal_random_float ()
S32 ll_rand ()
 Generate a float from [0, RAND_MAX).
S32 ll_rand (S32 val)
 Generate a float from [0, val) or (val, 0].
F32 ll_frand ()
 Generate a float from [0, 1.0).
F32 ll_frand (F32 val)
 Generate a float from [0, val) or (val, 0].
F64 ll_drand ()
 Generate a double from [0, 1.0).
F64 ll_drand (F64 val)
 Generate a double from [0, val) or (val, 0].

Detailed Description

Global random generator.


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Definition in file llrand.cpp.

Define Documentation

#define LL_USE_SYSTEM_RAND   0

Through analysis, we have decided that we want to take values which are close enough to 1.0 to map back to 0.0. We came to this conclusion from noting that:

[0.0, 1.0)

when scaled to the integer set:

[0, 4)

there is some value close enough to 1.0 that when multiplying by 4, gets truncated to 4. Therefore:

[0,1-eps] => 0 [1,2-eps] => 1 [2,3-eps] => 2 [3,4-eps] => 3

So 0 gets uneven distribution if we simply clamp. The actual clamp utilized in this file is to map values out of range back to 0 to restore uniform distribution.

Also, for clamping floats when asking for a distribution from [0.0,g) we have determined that for values of g < 0.5, then rand*g=g, which is not the desired result. As above, we clamp to 0 to restore uniform distribution.

Definition at line 67 of file llrand.cpp.

Function Documentation

static LLRandLagFib2281 gRandomGenerator ( LLUUID::  getRandomSeed()  )  [static]

Referenced by ll_internal_random_double(), and ll_internal_random_float().

F64 ll_drand ( F64  val  ) 

Generate a double from [0, val) or (val, 0].

Definition at line 163 of file llrand.cpp.

References ll_internal_random_double().

F64 ll_drand (  ) 

Generate a double from [0, 1.0).

Definition at line 158 of file llrand.cpp.

F32 ll_frand ( F32  val  ) 

Generate a float from [0, val) or (val, 0].

Definition at line 143 of file llrand.cpp.

References ll_internal_random_float().

F32 ll_frand (  ) 

Generate a float from [0, 1.0).

Definition at line 138 of file llrand.cpp.

Referenced by add_object(), continue_file_receive(), LLAgent::fidget(), LLCacheName::getName(), LLVOGrass::initClass(), LLVOStars::initStars(), LLCircuitData::LLCircuitData(), LLVOTreeNew::llfrand_signed(), LLVOTreeNew::llfrand_unsigned(), LLVOPartGroup::LLVOPartGroup(), LLEyeMotion::onUpdate(), LLPacketRing::receivePacket(), LLHUDEffectBeam::setupParticle(), LLViewerPartSim::shouldAddPart(), trigger_hippo_bug(), LLViewerPartSourceChat::update(), LLViewerPartSourceSpiral::update(), LLViewerPartSourceScript::update(), LLCloudGroup::updatePuffCount(), LLViewerPartSim::updateSimulation(), LLVOStars::updateStarColors(), LLCircuit::updateWatchDogTimers(), and windCallback().

F64 ll_internal_random_double (  )  [inline]

Definition at line 105 of file llrand.cpp.

References gRandomGenerator().

Referenced by ll_drand(), and ll_rand().

F32 ll_internal_random_float (  )  [inline]

Definition at line 116 of file llrand.cpp.

References f, and gRandomGenerator().

Referenced by ll_frand().

S32 ll_rand ( S32  val  ) 

Generate a float from [0, val) or (val, 0].

Definition at line 130 of file llrand.cpp.

References ll_internal_random_double(), and S32.

S32 ll_rand (  ) 

Generate a float from [0, RAND_MAX).

Definition at line 125 of file llrand.cpp.

Referenced by LLFetchInWelcomeArea::done(), encode_vorbis_file_at(), LLAgent::fidget(), LLUUID::generate(), get_random_bytes(), LLDir_Solaris::getRandomFileInDir(), LLDir_Linux::getRandomFileInDir(), LLAgent::heardChat(), ll_rand(), LLVOTreeNew::llrand_signed(), lsa_randomize(), LLDoubleLinkedList< DATA_TYPE >::scramble(), LLGestureManager::triggerAndReviseString(), and LLGestureManager::triggerGesture().

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