arch/SSE/RandUtils.h

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#ifndef EIGENRAND_RAND_UTILS_SSE_H
#define EIGENRAND_RAND_UTILS_SSE_H
 
#include <xmmintrin.h>
 
namespace Eigen
{
    namespace internal
    {
        template<typename Rng, typename RngResult>
        struct RawbitsMaker<Packet4i, Rng, RngResult, Rand::RandomEngineType::scalar>
        {
            EIGEN_STRONG_INLINE Packet4i rawbits(Rng& rng)
            {
                if (sizeof(RngResult) == 8)
                {
                    return _mm_set_epi64x(rng(), rng());
                }
                else
                {
                    return _mm_set_epi32(rng(), rng(), rng(), rng());
                }
            }
 
            EIGEN_STRONG_INLINE Packet4i rawbits_34(Rng& rng)
            {
                if (sizeof(RngResult) == 8)
                {
                    return _mm_set_epi64x(rng(), rng());
                }
                else
                {
#ifdef EIGEN_VECTORIZE_SSSE3
                    Packet4i p = _mm_setr_epi32(rng(), rng(), rng(), 0);
                    return _mm_shuffle_epi8(p, _mm_setr_epi8(
                        0, 1, 2, 3,
                        4, 5, 6, 7,
                        8, 9, 10, 11,
                        3, 7, 11, 11));
#else
                    return _mm_set_epi32(rng(), rng(), rng(), rng());
#endif
                }
            }
 
            EIGEN_STRONG_INLINE Packet4i rawbits_half(Rng& rng)
            {
                if (sizeof(decltype(rng())) == 8)
                {
                    return _mm_set_epi64x(0, rng());
                }
                else
                {
                    return _mm_setr_epi32(rng(), rng(), 0, 0);
                }
            }
        };
 
        template<typename Rng>
        struct RawbitsMaker<Packet4i, Rng, Packet4i, Rand::RandomEngineType::packet>
        {
            EIGEN_STRONG_INLINE Packet4i rawbits(Rng& rng)
            {
                return rng();
            }
 
            EIGEN_STRONG_INLINE Packet4i rawbits_34(Rng& rng)
            {
                return rng();
            }
 
            EIGEN_STRONG_INLINE Packet4i rawbits_half(Rng& rng)
            {
                return rng();
            }
        };
 
        template<typename Rng>
        struct UniformRealUtils<Packet4f, Rng> : public RawbitsMaker<Packet4i, Rng>
        {
            EIGEN_STRONG_INLINE Packet4f zero_to_one(Rng& rng)
            {
                return pdiv((Packet4f)_mm_cvtepi32_ps(pand(this->rawbits(rng), pset1<Packet4i>(0x7FFFFFFF))),
                    pset1<Packet4f>(0x7FFFFFFF));
            }
 
            EIGEN_STRONG_INLINE Packet4f uniform_real(Rng& rng)
            {
                return bit_to_ur_float(this->rawbits_34(rng));
            }
        };
 
        template<typename Rng>
        struct UniformRealUtils<Packet2d, Rng> : public RawbitsMaker<Packet4i, Rng>
        {
            EIGEN_STRONG_INLINE Packet2d zero_to_one(Rng& rng)
            {
                return pdiv((Packet2d)_mm_cvtepi32_pd(pand(this->rawbits_half(rng), pset1<Packet4i>(0x7FFFFFFF))),
                    pset1<Packet2d>(0x7FFFFFFF));
            }
 
            EIGEN_STRONG_INLINE Packet2d uniform_real(Rng& rng)
            {
                return bit_to_ur_double(this->rawbits(rng));
            }
        };
    }
}
#endif