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rocrand_threefry2_impl.h
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52 
53 #ifndef ROCRAND_THREEFRY2_IMPL_H_
54 #define ROCRAND_THREEFRY2_IMPL_H_
55 
56 #include "rocrand/rocrand_common.h"
57 #include "rocrand/rocrand_threefry_common.h"
58 
59 #include <hip/hip_runtime.h>
60 
61 #ifndef THREEFRY2x32_DEFAULT_ROUNDS
62  #define THREEFRY2x32_DEFAULT_ROUNDS 20
63 #endif
64 
65 #ifndef THREEFRY2x64_DEFAULT_ROUNDS
66  #define THREEFRY2x64_DEFAULT_ROUNDS 20
67 #endif
68 
69 namespace rocrand_device
70 {
71 
72 template<class value>
73 __forceinline__ __device__ __host__ int threefry_rotation_array(int index) = delete;
74 
75 template<>
76 __forceinline__ __device__ __host__ int threefry_rotation_array<unsigned int>(int index)
77 {
78  // Output from skein_rot_search (srs32x2-X5000.out)
79  // Random seed = 1. BlockSize = 64 bits. sampleCnt = 1024. rounds = 8, minHW_or=28
80  // Start: Tue Jul 12 11:11:33 2011
81  // rMin = 0.334. #0206[*07] [CRC=1D9765C0. hw_OR=32. cnt=16384. blkSize= 64].format
82  static constexpr int THREEFRY_ROTATION_32_2[8] = {13, 15, 26, 6, 17, 29, 16, 24};
83  return THREEFRY_ROTATION_32_2[index];
84 }
85 
86 template<>
87 __forceinline__ __device__ __host__ int threefry_rotation_array<unsigned long long>(int index)
88 {
89  // Output from skein_rot_search: (srs64_B64-X1000)
90  // Random seed = 1. BlockSize = 128 bits. sampleCnt = 1024. rounds = 8, minHW_or=57
91  // Start: Tue Mar 1 10:07:48 2011
92  // rMin = 0.136. #0325[*15] [CRC=455A682F. hw_OR=64. cnt=16384. blkSize= 128].format
93  static constexpr int THREEFRY_ROTATION_64_2[8] = {16, 42, 12, 31, 16, 32, 24, 21};
94  return THREEFRY_ROTATION_64_2[index];
95 }
96 
97 template<typename state_value, typename value, unsigned int Nrounds>
98 class threefry_engine2_base
99 {
100 public:
101  struct threefry_state_2
102  {
103  state_value counter;
104  state_value key;
105  state_value result;
106  unsigned int substate;
107  };
108  using state_type = threefry_state_2;
109  using state_vector_type = state_value;
110 
111  __forceinline__ __device__ __host__ void discard(unsigned long long offset)
112  {
113  this->discard_impl(offset);
114  m_state.result = this->threefry_rounds(m_state.counter, m_state.key);
115  }
116 
117  __forceinline__ __device__ __host__ void discard()
118  {
119  m_state.result = this->threefry_rounds(m_state.counter, m_state.key);
120  }
121 
127  __forceinline__ __device__ __host__ void discard_subsequence(unsigned long long subsequence)
128  {
129  this->discard_subsequence_impl(subsequence);
130  m_state.result = this->threefry_rounds(m_state.counter, m_state.key);
131  }
132 
133  __forceinline__ __device__ __host__ value operator()()
134  {
135  return this->next();
136  }
137 
138  __forceinline__ __device__ __host__
139  value next()
140  {
141 #if defined(__HIP_PLATFORM_AMD__)
142  value ret = ROCRAND_HIPVEC_ACCESS(m_state.result)[m_state.substate];
143 #else
144  value ret = (&m_state.result.x)[m_state.substate];
145 #endif
146  m_state.substate++;
147  if(m_state.substate == 2)
148  {
149  m_state.substate = 0;
150  m_state.counter = this->bump_counter(m_state.counter);
151  m_state.result = this->threefry_rounds(m_state.counter, m_state.key);
152  }
153  return ret;
154  }
155 
156  __forceinline__ __device__ __host__ state_value next2()
157  {
158  state_value ret = m_state.result;
159  m_state.counter = this->bump_counter(m_state.counter);
160  m_state.result = this->threefry_rounds(m_state.counter, m_state.key);
161 
162  return this->interleave(ret, m_state.result);
163  }
164 
165 protected:
166  __forceinline__ __device__ __host__ static state_value threefry_rounds(state_value counter,
167  state_value key)
168  {
169  state_value X;
170  value ks[2 + 1];
171 
172  static_assert(Nrounds <= 32, "32 or less only supported in threefry rounds");
173 
174  ks[2] = skein_ks_parity<value>();
175 
176  ks[0] = key.x;
177  ks[1] = key.y;
178 
179  X.x = counter.x;
180  X.y = counter.y;
181 
182  ks[2] ^= key.x;
183  ks[2] ^= key.y;
184 
185  /* Insert initial key before round 0 */
186  X.x += ks[0];
187  X.y += ks[1];
188 
189  for(unsigned int round_idx = 0; round_idx < Nrounds; round_idx++)
190  {
191  X.x += X.y;
192  X.y = rotl<value>(X.y, threefry_rotation_array<value>(round_idx & 7u));
193  X.y ^= X.x;
194 
195  if((round_idx & 3u) == 3)
196  {
197  unsigned int inject_idx = round_idx / 4;
198  // InjectKey(r = 1 + inject_idx)
199  X.x += ks[(1 + inject_idx) % 3];
200  X.y += ks[(2 + inject_idx) % 3];
201  X.y += 1 + inject_idx;
202  }
203  }
204 
205  return X;
206  }
207 
210  __forceinline__ __device__ __host__ void discard_impl(unsigned long long offset)
211  {
212  // Adjust offset for subset
213  m_state.substate += offset & 1;
214  unsigned long long counter_offset = offset / 2;
215  counter_offset += m_state.substate < 2 ? 0 : 1;
216  m_state.substate += m_state.substate < 2 ? 0 : -2;
217  // Discard states
218  this->discard_state(counter_offset);
219  }
220 
222  __forceinline__ __device__ __host__ void
223  discard_subsequence_impl(unsigned long long subsequence)
224  {
225  m_state.counter.y += subsequence;
226  }
227 
230  __forceinline__ __device__ __host__ void discard_state(unsigned long long offset)
231  {
232  value lo, hi;
233  ::rocrand_device::detail::split_ull(lo, hi, offset);
234 
235  value old_counter = m_state.counter.x;
236  m_state.counter.x += lo;
237  m_state.counter.y += hi + (m_state.counter.x < old_counter ? 1 : 0);
238  }
239 
240  __forceinline__ __device__ __host__ static state_value bump_counter(state_value counter)
241  {
242  counter.x++;
243  value add = counter.x == 0 ? 1 : 0;
244  counter.y += add;
245  return counter;
246  }
247 
248  __forceinline__ __device__ __host__ state_value interleave(const state_value prev,
249  const state_value next) const
250  {
251  switch(m_state.substate)
252  {
253  case 0: return prev;
254  case 1: return state_value{prev.y, next.x};
255  }
256  __builtin_unreachable();
257  }
258 
259 protected:
260  threefry_state_2 m_state;
261 }; // threefry_engine2_base class
262 
263 } // end namespace rocrand_device
264 
265 #endif // ROCRAND_THREEFRY2_IMPL_H_