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 // Copyright (c) 2017-2026 Advanced Micro Devices, Inc. All rights reserved.
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 /*
 Copyright 2010-2011, D. E. Shaw Research.
 All rights reserved.
  
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
 met:
  
 * Redistributions of source code must retain the above copyright
   notice, this list of conditions, and the following disclaimer.
  
 * Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions, and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
  
 * Neither the name of D. E. Shaw Research nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.
  
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
  
 #ifndef ROCRAND_PHILOX4X32_10_H_
 #define ROCRAND_PHILOX4X32_10_H_
  
 #include "rocrand/rocrand_common.h"
  
 #include <hip/hip_runtime.h>
  
 // Constants from Random123
 // See https://www.deshawresearch.com/resources_random123.html
 #define ROCRAND_PHILOX_M4x32_0 0xD2511F53U
 #define ROCRAND_PHILOX_M4x32_1 0xCD9E8D57U
 #define ROCRAND_PHILOX_W32_0 0x9E3779B9U
 #define ROCRAND_PHILOX_W32_1 0xBB67AE85U
  
 #if defined(__HIP_DEVICE_COMPILE__) && defined(__AMDGCN__)
     #define ROCRAND_BUILTIN_ADDC(a, b, carry_in, carry_out) \
         __builtin_addc(a, b, carry_in, carry_out)
 #else
     #define ROCRAND_BUILTIN_ADDC(a, b, carry_in, carry_out)                           \
         (                                                                             \
             [&]()                                                                     \
             {                                                                         \
                 unsigned int sum = (a) + (b) + (carry_in);                            \
                 *carry_out       = (sum < (a) || ((carry_in) && sum <= (b))) ? 1 : 0; \
                 return sum;                                                           \
             }())
 #endif
  
 #define ROCRAND_PHILOX4x32_DEFAULT_SEED 0xdeadbeefdeadbeefULL // end of group rocranddevice
  
 namespace rocrand_device
 {
  
 class philox4x32_10_engine
 {
 public:
     struct philox4x32_10_state
     {
         uint4        counter;
         uint4        result;
         uint2        key;
         unsigned int substate;
  
 #ifndef ROCRAND_DETAIL_BM_NOT_IN_STATE
         // The Box–Muller transform requires two inputs to convert uniformly
         // distributed real values [0; 1] to normally distributed real values
         // (with mean = 0, and stddev = 1). Often user wants only one
         // normally distributed number, to save performance and random
         // numbers the 2nd value is saved for future requests.
         float  boxmuller_float; // normally distributed float
         double boxmuller_double; // normally distributed double
 #endif
     };
  
     __forceinline__ __device__ __host__
     philox4x32_10_engine()
     {
         this->seed(ROCRAND_PHILOX4x32_DEFAULT_SEED, 0, 0);
     }
  
     __forceinline__ __device__ __host__
     philox4x32_10_engine(const unsigned long long seed,
                          const unsigned long long subsequence,
                          const unsigned long long offset)
     {
         this->seed(seed, subsequence, offset);
     }
  
     __forceinline__ __device__ __host__
     void seed(unsigned long long       seed_value,
               const unsigned long long subsequence,
               const unsigned long long offset)
     {
         m_state.key.x = static_cast<unsigned int>(seed_value);
         m_state.key.y = static_cast<unsigned int>(seed_value >> 32);
         this->restart(subsequence, offset);
     }
  
     __forceinline__ __device__ __host__
     void discard(unsigned long long offset)
     {
         this->discard_impl(offset);
         this->m_state.result = this->ten_rounds(m_state.counter, m_state.key);
     }
  
     __forceinline__ __device__ __host__
     void discard_subsequence(unsigned long long subsequence)
     {
         this->discard_subsequence_impl(subsequence);
         m_state.result = this->ten_rounds(m_state.counter, m_state.key);
     }
  
     __forceinline__ __device__ __host__
     void restart(const unsigned long long subsequence, const unsigned long long offset)
     {
         m_state.counter  = {0, 0, 0, 0};
         m_state.result   = {0, 0, 0, 0};
         m_state.substate = 0;
 #ifndef ROCRAND_DETAIL_BM_NOT_IN_STATE
         m_state.boxmuller_float  = ROCRAND_NAN_FLOAT;
         m_state.boxmuller_double = ROCRAND_NAN_DOUBLE;
 #endif
         this->discard_subsequence_impl(subsequence);
         this->discard_impl(offset);
         m_state.result = this->ten_rounds(m_state.counter, m_state.key);
     }
  
     __forceinline__ __device__ __host__
     unsigned int operator()()
     {
         return this->next();
     }
  
     __forceinline__ __device__ __host__
     unsigned int next()
     {
         unsigned int s = m_state.substate;
         unsigned int vs[4]
             = {m_state.result.x, m_state.result.y, m_state.result.z, m_state.result.w};
         unsigned int ret = vs[s];
  
         s++;
         if(s == 4)
         {
             s = 0;
             this->discard_state();
             m_state.result = this->ten_rounds(m_state.counter, m_state.key);
         }
         m_state.substate = s;
         return ret;
     }
  
     __forceinline__ __device__ __host__
     uint4 next4()
     {
         uint4 ret = m_state.result;
         this->discard_state();
         m_state.result = this->ten_rounds(m_state.counter, m_state.key);
         return this->interleave(ret, m_state.result);
     }
  
 protected:
     // Advances the internal state to skip \p offset numbers.
     // DOES NOT CALCULATE NEW 4 UINTs (m_state.result)
     __forceinline__ __device__ __host__
     void discard_impl(unsigned long long offset)
     {
         // Adjust offset for subset
         m_state.substate += offset & 3;
         unsigned long long counter_offset = offset / 4;
         counter_offset += m_state.substate < 4 ? 0 : 1;
         m_state.substate += m_state.substate < 4 ? 0 : -4;
         // Discard states
         this->discard_state(counter_offset);
     }
  
     // DOES NOT CALCULATE NEW 4 UINTs (m_state.result)
     __forceinline__ __device__ __host__
     void discard_subsequence_impl(unsigned long long subsequence)
     {
         const unsigned int lo    = static_cast<unsigned int>(subsequence);
         const unsigned int hi    = static_cast<unsigned int>(subsequence >> 32);
         unsigned int       carry = 0;
  
         m_state.counter.z = ROCRAND_BUILTIN_ADDC(m_state.counter.z, lo, 0, &carry);
         m_state.counter.w = ROCRAND_BUILTIN_ADDC(m_state.counter.w, hi, carry, &carry);
     }
  
     // Advances the internal state by offset times.
     // DOES NOT CALCULATE NEW 4 UINTs (m_state.result)
     __forceinline__ __device__ __host__
     void discard_state(unsigned long long offset)
     {
         const unsigned int lo    = static_cast<unsigned int>(offset);
         const unsigned int hi    = static_cast<unsigned int>(offset >> 32);
         unsigned int       carry = 0;
  
         m_state.counter.x = ROCRAND_BUILTIN_ADDC(m_state.counter.x, lo, 0, &carry);
         m_state.counter.y = ROCRAND_BUILTIN_ADDC(m_state.counter.y, hi, carry, &carry);
         m_state.counter.z = ROCRAND_BUILTIN_ADDC(m_state.counter.z, 0, carry, &carry);
         m_state.counter.w = ROCRAND_BUILTIN_ADDC(m_state.counter.w, 0, carry, &carry);
     }
  
     // Advances the internal state to the next state
     // DOES NOT CALCULATE NEW 4 UINTs (m_state.result)
     __forceinline__ __device__ __host__
     void discard_state()
     {
         m_state.counter = this->bump_counter(m_state.counter);
     }
  
     __forceinline__ __device__ __host__
     static uint4 bump_counter(uint4 counter)
     {
         unsigned int carry = 0;
         counter.x          = ROCRAND_BUILTIN_ADDC(counter.x, 1, 0, &carry);
         counter.y          = ROCRAND_BUILTIN_ADDC(counter.y, 0, carry, &carry);
         counter.z          = ROCRAND_BUILTIN_ADDC(counter.z, 0, carry, &carry);
         counter.w          = ROCRAND_BUILTIN_ADDC(counter.w, 0, carry, &carry);
         return counter;
     }
  
     __forceinline__ __device__ __host__
     uint4 interleave(const uint4 prev, const uint4 next) const
     {
         switch(m_state.substate)
         {
             case 0: return prev;
             case 1: return uint4{prev.y, prev.z, prev.w, next.x};
             case 2: return uint4{prev.z, prev.w, next.x, next.y};
             case 3: return uint4{prev.w, next.x, next.y, next.z};
         }
         __builtin_unreachable();
     }
  
     // 10 Philox4x32 rounds
     __forceinline__ __device__ __host__
     uint4 ten_rounds(uint4 counter, uint2 key)
     {
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 1
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 2
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 3
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 4
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 5
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 6
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 7
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 8
         counter = this->single_round(counter, key);
         key     = this->bumpkey(key); // 9
         return this->single_round(counter, key); // 10
     }
  
 private:
     // Single Philox4x32 round
     __forceinline__ __device__ __host__
     static uint4 single_round(uint4 counter, uint2 key)
     {
         // Source: Random123
         unsigned long long mul0 = detail::mul_u64_u32(ROCRAND_PHILOX_M4x32_0, counter.x);
         unsigned int       hi0  = static_cast<unsigned int>(mul0 >> 32);
         unsigned int       lo0  = static_cast<unsigned int>(mul0);
         unsigned long long mul1 = detail::mul_u64_u32(ROCRAND_PHILOX_M4x32_1, counter.z);
         unsigned int       hi1  = static_cast<unsigned int>(mul1 >> 32);
         unsigned int       lo1  = static_cast<unsigned int>(mul1);
         return uint4{hi1 ^ counter.y ^ key.x, lo1, hi0 ^ counter.w ^ key.y, lo0};
     }
  
     __forceinline__ __device__ __host__
     static uint2 bumpkey(uint2 key)
     {
         key.x += ROCRAND_PHILOX_W32_0;
         key.y += ROCRAND_PHILOX_W32_1;
         return key;
     }
  
 protected:
     // State
     philox4x32_10_state m_state;
  
 #ifndef ROCRAND_DETAIL_BM_NOT_IN_STATE
     friend struct detail::engine_boxmuller_helper<philox4x32_10_engine>;
 #endif
  
 }; // philox4x32_10_engine class
  
 } // end namespace rocrand_device
  
 typedef rocrand_device::philox4x32_10_engine rocrand_state_philox4x32_10;
  
 __forceinline__ __device__ __host__
 void rocrand_init(const unsigned long long     seed,
                   const unsigned long long     subsequence,
                   const unsigned long long     offset,
                   rocrand_state_philox4x32_10* state)
 {
     *state = rocrand_state_philox4x32_10(seed, subsequence, offset);
 }
  
 __forceinline__ __device__ __host__
 unsigned int rocrand(rocrand_state_philox4x32_10* state)
 {
     return state->next();
 }
  
 __forceinline__ __device__ __host__
 uint4 rocrand4(rocrand_state_philox4x32_10* state)
 {
     return state->next4();
 }
  
 __forceinline__ __device__ __host__
 void skipahead(unsigned long long offset, rocrand_state_philox4x32_10* state)
 {
     return state->discard(offset);
 }
  
 __forceinline__ __device__ __host__
 void skipahead_subsequence(unsigned long long subsequence, rocrand_state_philox4x32_10* state)
 {
     return state->discard_subsequence(subsequence);
 }
  
 __forceinline__ __device__ __host__
 void skipahead_sequence(unsigned long long sequence, rocrand_state_philox4x32_10* state)
 {
     return state->discard_subsequence(sequence);
 }
  // end of group rocranddevice
  
 #endif // ROCRAND_PHILOX4X32_10_H_