/build/rocrand-sFFtDi/rocrand-10.0/library/include/rocrand/rocrand_sobol64.h Source File

/build/rocrand-sFFtDi/rocrand-10.0/library/include/rocrand/rocrand_sobol64.h Source File#

API library: /build/rocrand-sFFtDi/rocrand-10.0/library/include/rocrand/rocrand_sobol64.h Source File
library
include
rocrand
// Copyright (c) 2021-2026 Advanced Micro Devices, Inc. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
 
#ifndef ROCRAND_SOBOL64_H_
#define ROCRAND_SOBOL64_H_
 
#include <hip/hip_runtime.h>
 
namespace rocrand_device
{
 
template<bool UseSharedVectors>
struct sobol64_state
{
    unsigned long long int d;
    unsigned long long int i;
    unsigned long long int vectors[64];
 
    __forceinline__ __device__ __host__
    sobol64_state()
        : d(), i(), vectors()
    {}
 
    __forceinline__ __device__ __host__
    sobol64_state(const unsigned long long int  d,
                  const unsigned long long int  i,
                  const unsigned long long int* vectors)
        : d(d), i(i)
    {
        for(int k = 0; k < 64; k++)
        {
            this->vectors[k] = vectors[k];
        }
    }
};
 
template<>
struct sobol64_state<true>
{
    unsigned long long int        d;
    unsigned long long int        i;
    const unsigned long long int* vectors;
 
    __forceinline__ __device__ __host__
    sobol64_state()
        : d(), i(), vectors()
    {}
 
    __forceinline__ __device__ __host__
    sobol64_state(const unsigned long long int  d,
                  const unsigned long long int  i,
                  const unsigned long long int* vectors)
        : d(d), i(i), vectors(vectors)
    {}
};
 
template<bool UseSharedVectors>
class sobol64_engine
{
public:
    typedef struct sobol64_state<UseSharedVectors> sobol64_state;
 
    __forceinline__ __device__ __host__
    sobol64_engine()
    {}
 
    __forceinline__ __device__ __host__
    sobol64_engine(const unsigned long long int* vectors, const unsigned long long int offset)
        : m_state(0, 0, vectors)
    {
        discard_state(offset);
    }
    __forceinline__ __device__ __host__
    void discard(unsigned long long int offset)
    {
        discard_state(offset);
    }
 
    __forceinline__ __device__ __host__
    void discard()
    {
        discard_state();
    }
    __forceinline__ __device__ __host__
    void discard_stride(unsigned long long int stride)
    {
        discard_state_power2(stride);
    }
 
    __forceinline__ __device__ __host__
    unsigned long long int operator()()
    {
        return this->next();
    }
 
    __forceinline__ __device__ __host__
    unsigned long long int next()
    {
        unsigned long long int p = m_state.d;
        discard_state();
        return p;
    }
 
    __forceinline__ __device__ __host__
    unsigned long long int current() const
    {
        return m_state.d;
    }
 
    __forceinline__ __device__ __host__
    static constexpr bool uses_shared_vectors()
    {
        return UseSharedVectors;
    }
 
protected:
    // Advances the internal state by offset times.
    __forceinline__ __device__ __host__
    void discard_state(unsigned long long int offset)
    {
        m_state.i += offset;
        const unsigned long long int g = m_state.i ^ (m_state.i >> 1ull);
        m_state.d                      = 0;
        for(int i = 0; i < 64; i++)
        {
            m_state.d ^= (g & (1ull << i) ? m_state.vectors[i] : 0ull);
        }
    }
 
    // Advances the internal state to the next state
    __forceinline__ __device__ __host__
    void discard_state()
    {
        m_state.d ^= m_state.vectors[rightmost_zero_bit(m_state.i)];
        m_state.i++;
    }
 
    __forceinline__ __device__ __host__
    void discard_state_power2(unsigned long long int stride)
    {
        // Leap frog
        //
        // T Bradley, J Toit, M Giles, R Tong, P Woodhams
        // Parallelisation Techniques for Random Number Generators
        // GPU Computing Gems, 2011
        //
        // For power of 2 jumps only 2 bits in Gray code change values
        // All bits lower than log2(stride) flip 2, 4... times, i.e.
        // do not change their values.
 
        // log2(stride) bit
        m_state.d ^= m_state.vectors[rightmost_zero_bit(~stride) - 1];
        // the rightmost zero bit of i, not including the lower log2(stride) bits
        m_state.d ^= m_state.vectors[rightmost_zero_bit(m_state.i | (stride - 1))];
        m_state.i += stride;
    }
 
    // Returns the index of the rightmost zero bit in the binary expansion of
    // x (Gray code of the current element's index)
    // NOTE changing unsigned long long int to unit64_t will cause compile failure on device
    __forceinline__ __device__ __host__
    unsigned int rightmost_zero_bit(unsigned long long int x)
    {
#if defined(__HIP_DEVICE_COMPILE__)
        unsigned int z = __ffsll(~x);
        return z ? z - 1 : 0;
#else
        if(x == 0)
            return 0;
        unsigned long long int y = x;
        unsigned long long int z = 1;
        while(y & 1)
        {
            y >>= 1;
            z++;
        }
        return z - 1;
#endif
    }
 
protected:
    // State
    sobol64_state m_state;
 
}; // sobol64_engine class
 
} // end namespace rocrand_device
typedef rocrand_device::sobol64_engine<false> rocrand_state_sobol64;
__forceinline__ __device__ __host__
void rocrand_init(const unsigned long long int* vectors,
                  const unsigned long long int  offset,
                  rocrand_state_sobol64*        state)
{
    *state = rocrand_state_sobol64(vectors, offset);
}
__forceinline__ __device__ __host__
unsigned long long int rocrand(rocrand_state_sobol64* state)
{
    return state->next();
}
__forceinline__ __device__ __host__
void skipahead(unsigned long long int offset, rocrand_state_sobol64* state)
{
    return state->discard(offset);
}
 // end of group rocranddevice
 
#endif // ROCRAND_sobol64_H_