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Unify SSE and AVX implementation of pexp

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Gael Guennebaud
2018-11-26 16:36:19 +01:00
parent c2f35b1b47
commit cf8b85d5c5
6 changed files with 126 additions and 122 deletions
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23
Eigen/src/Core/GenericPacketMath.h
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@@ -220,6 +220,12 @@ pandnot(const Packet& a, const Packet& b) { return a & (!b); }
template<typename Packet> EIGEN_DEVICE_FUNC inline Packet
pfrexp(const Packet &a, Packet &exponent) { return std::frexp(a,&exponent); }
/** \internal \returns a * 2^exponent
* See https://en.cppreference.com/w/cpp/numeric/math/ldexp
*/
template<typename Packet> EIGEN_DEVICE_FUNC inline Packet
pldexp(const Packet &a, const Packet &exponent) { return std::ldexp(a,exponent); }
/** \internal \returns zeros */
template<typename Packet> EIGEN_DEVICE_FUNC inline Packet
pzero(const Packet& a) { return pxor(a,a); }
@@ -656,6 +662,23 @@ pfrexp_float(const Packet& a, Packet& exponent) {
return por(pand(a, cst_inv_mant_mask), cst_half);
}
/** \internal shift the bits by n and cast the result to the initial type, i.e.:
* return reinterpret_cast<float>(int(a) >> n)
*/
template<typename Packet> EIGEN_DEVICE_FUNC inline Packet
pcast_and_shiftleft(Packet a, int n);
/** Default implementation of pldexp for float.
* It is expected to be called by implementers of template<> pldexp,
* and the above pcast_and_shiftleft function must be implemented.
*/
template<typename Packet> EIGEN_STRONG_INLINE Packet
pldexp_float(Packet a, Packet exponent) {
const Packet cst_127 = pset1<Packet>(127.f);
// return a * 2^exponent
return pmul(a, pcast_and_shiftleft(padd(exponent, cst_127), 23));
}
} // end namespace internal
} // end namespace Eigen