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RandSync.cpp
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1 /*
2  * Original work: Copyright (c) 2014, Oculus VR, Inc.
3  * All rights reserved.
4  *
5  * This source code is licensed under the BSD-style license found in the
6  * RakNet License.txt file in the licenses directory of this source tree. An additional grant
7  * of patent rights can be found in the RakNet Patents.txt file in the same directory.
8  *
9  *
10  * Modified work: Copyright (c) 2017, SLikeSoft UG (haftungsbeschränkt)
11  *
12  * This source code was modified by SLikeSoft. Modifications are licensed under the MIT-style
13  * license found in the license.txt file in the root directory of this source tree.
14  */
15 
16 #include "slikenet/RandSync.h"
17 #include "slikenet/BitStream.h"
18 #include <limits>
19 #include <limits.h>
20 
21 namespace SLNet
22 {
23 
24 RakNetRandomSync::RakNetRandomSync()
25 {
26  seed = (uint32_t) -1;
27  callCount = 0;
28  usedValueBufferCount = 0;
29 }
30 RakNetRandomSync::~RakNetRandomSync()
31 {
32 }
33 void RakNetRandomSync::SeedMT( uint32_t _seed )
34 {
35  seed = _seed;
36  rnr.SeedMT( seed );
37  callCount = 0;
38  usedValueBufferCount = 0;
39 }
40 void RakNetRandomSync::SeedMT( uint32_t _seed, uint32_t skipValues )
41 {
42  SeedMT(_seed);
43  Skip(skipValues);
44 }
45 float RakNetRandomSync::FrandomMT( void )
46 {
47  return ( float ) ( ( double ) RandomMT() / (double) UINT_MAX );
48 }
49 unsigned int RakNetRandomSync::RandomMT( void )
50 {
51  if (usedValueBufferCount > 0)
52  {
53  --usedValueBufferCount;
54  if (usedValueBufferCount < usedValues.Size())
55  {
56  // The remote system had less calls than the current system, so return values from the past
57  return usedValues[usedValues.Size()-usedValueBufferCount-1];
58  }
59  else
60  {
61  // Unknown past value, too far back
62  // Return true random
63  return rnr.RandomMT();
64  }
65  }
66  else
67  {
68  // Get random number and store what it is
69  usedValues.Push(rnr.RandomMT(), _FILE_AND_LINE_);
70  ++callCount;
71  while (usedValues.Size()>64)
72  usedValues.Pop();
73  return usedValues[usedValues.Size()-1];
74  }
75 }
76 uint32_t RakNetRandomSync::GetSeed( void ) const
77 {
78  return seed;
79 }
80 uint32_t RakNetRandomSync::GetCallCount( void ) const
81 {
82  return callCount;
83 }
84 void RakNetRandomSync::SetCallCount( uint32_t i )
85 {
86  callCount = i;
87 }
88 void RakNetRandomSync::SerializeConstruction(SLNet::BitStream *constructionBitstream)
89 {
90  constructionBitstream->Write(seed);
91  constructionBitstream->Write(callCount);
92 }
93 bool RakNetRandomSync::DeserializeConstruction(SLNet::BitStream *constructionBitstream)
94 {
95  uint32_t _seed;
96  uint32_t _skipValues;
97  constructionBitstream->Read(_seed);
98  bool success = constructionBitstream->Read(_skipValues);
99  if (success)
100  SeedMT(_seed, _skipValues);
101  return success;
102 }
103 void RakNetRandomSync::Serialize(SLNet::BitStream *outputBitstream)
104 {
105  outputBitstream->Write(callCount);
106 }
107 void RakNetRandomSync::Deserialize(SLNet::BitStream *outputBitstream)
108 {
109  uint32_t _callCount;
110  outputBitstream->Read(_callCount);
111  if (_callCount < callCount )
112  {
113  // We locally read more values than the remote system
114  // The next n calls should come from buffered values
115  usedValueBufferCount = callCount - _callCount;
116  }
117  else if (_callCount > callCount )
118  {
119  // Remote system read more values than us
120  uint32_t diff = _callCount - callCount;
121  if (diff <= usedValueBufferCount)
122  usedValueBufferCount -= diff;
123  if (diff > 0)
124  Skip(diff);
125  }
126 }
127 void RakNetRandomSync::Skip( uint32_t count )
128 {
129  for (uint32_t i = 0; i < count; i++)
130  rnr.RandomMT();
131  callCount+=count;
132 }
133 
134 } // namespace SLNet
135 
136 /*
137 RakNetRandomSync r1, r2;
138 BitStream bsTest;
139 r1.SeedMT(0);
140 r1.SerializeConstruction(&bsTest);
141 bsTest.SetReadOffset(0);
142 r2.DeserializeConstruction(&bsTest);
143 printf("1. (r1) %f\n", r1.FrandomMT());
144 printf("1. (r2) %f\n", r2.FrandomMT());
145 printf("2. (r1) %f\n", r1.FrandomMT());
146 printf("2. (r2) %f\n", r2.FrandomMT());
147 printf("3. (r1) %f\n", r1.FrandomMT());
148 printf("3. (r2) %f\n", r2.FrandomMT());
149 printf("4. (r1) %f\n", r1.FrandomMT());
150 printf("4. (r2) %f\n", r2.FrandomMT());
151 printf("5. (r2) %f\n", r2.FrandomMT());
152 printf("6. (r2) %f\n", r2.FrandomMT());
153 printf("7. (r2) %f\n", r2.FrandomMT());
154 bsTest.Reset();
155 r1.Serialize(&bsTest);
156 bsTest.SetReadOffset(0);
157 r2.Deserialize(&bsTest);
158 printf("Synched r2 to match r1\n");
159 printf("5. (r1) %f\n", r1.FrandomMT());
160 printf("5. (r2) %f --Should continue sequence from 5-\n", r2.FrandomMT());
161 printf("6. (r1) %f\n", r1.FrandomMT());
162 printf("6. (r2) %f\n", r2.FrandomMT());
163 printf("7. (r1) %f -- Extra call to r1, no r2 equivalent --\n", r1.FrandomMT());
164 printf("8. (r1) %f -- Extra call to r1, no r2 equivalent --\n", r1.FrandomMT());
165 bsTest.Reset();
166 r1.Serialize(&bsTest);
167 bsTest.SetReadOffset(0);
168 r2.Deserialize(&bsTest);
169 printf("Synched r2 to match r1\n");
170 printf("9. (r1) %f\n", r1.FrandomMT());
171 printf("9. (r2) %f --SKIPPED 7,8, SHOULD MATCH 9-\n", r2.FrandomMT());
172 */