From d6957aaa57c814a2d779874cd714c65ab9e321c3 Mon Sep 17 00:00:00 2001
From: Filip Gawin <filip.gawin@zoho.com>
Date: Mon, 1 Jul 2019 16:21:03 +0200
Subject: RandomDisplacement

---
 src/audio/AudioManager.cpp | 19 +++++++++++++++++++
 src/audio/AudioManager.h   |  2 ++
 2 files changed, 21 insertions(+)

diff --git a/src/audio/AudioManager.cpp b/src/audio/AudioManager.cpp
index d9b7fee2..0a7cd93a 100644
--- a/src/audio/AudioManager.cpp
+++ b/src/audio/AudioManager.cpp
@@ -12,6 +12,24 @@ cAudioManager &AudioManager = *(cAudioManager *)0x880FC0;
 
 constexpr int totalAudioEntitiesSlots = 200;
 
+int32
+cAudioManager::RandomDisplacement(uint32 seed)
+{
+	int32 value;
+
+	static bool bIsEven = true;
+	static uint8 base = 0;
+
+	if(!seed) return 0;
+
+	value = m_anRandomTable[(base + seed) % 5] % seed;
+	base += value;
+
+	if(value % 2) { bIsEven = !bIsEven; }
+	if(!bIsEven) value = -value;
+	return value;
+}
+
 void
 cAudioManager::ReleaseDigitalHandle()
 {
@@ -2814,6 +2832,7 @@ cAudioManager::Service()
 }
 
 STARTPATCHES
+InjectHook(0x57AF90, &cAudioManager::RandomDisplacement, PATCH_JUMP);
 
 InjectHook(0x57A9E0, &cAudioManager::ReleaseDigitalHandle, PATCH_JUMP);
 InjectHook(0x57A9F0, &cAudioManager::RequireDigitalHandle, PATCH_JUMP);
diff --git a/src/audio/AudioManager.h b/src/audio/AudioManager.h
index 6b320b60..95478922 100644
--- a/src/audio/AudioManager.h
+++ b/src/audio/AudioManager.h
@@ -216,6 +216,8 @@ public:
 	char field_19195;
 	int m_nTimeOfRecentCrime;
 
+	int32 RandomDisplacement(uint32 seed);
+
 	void ReleaseDigitalHandle();
 	void RequireDigitalHandle();
 	void SetDynamicAcousticModelingStatus(bool status);
-- 
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