Utilities.H

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#ifndef UTILITIES_H
#define UTILITIES_H
 
#include <AMReX.H>
#include <AMReX_RealVect.H>
#include <AMReX_MultiFab.H>
#include <AMReX_MultiFabUtil.H>
#include <AMReX_Random.H>
#include "Constants.H"
 
namespace spades {
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Long
pairing_function(const amrex::Long k1, const amrex::Long k2)
{
    return (k1 + k2) * (k1 + k2 + 1) / 2 + k2;
}
 
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Real
random_exponential(const amrex::Real lambda, amrex::RandomEngine const& engine)
{
    return std::log(1 - amrex::Random(engine)) / (-lambda);
}
 
amrex::Real random_exponential(const amrex::Real lambda);
 
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE std::uint64_t
max_representation(const int nbits)
{
    AMREX_ASSERT(nbits < 64);
    std::uint64_t result = 2;
    for (int i = 0; i < nbits; i++) {
        result *= 2;
    }
    return result;
}
 
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE std::uint64_t bitmask(const int nbits)
{
    AMREX_ASSERT(nbits < 64);
    // Shift 1 by nbits (create power of 2)
    // Subtract 1 to fill all lower nbits with 1s
    // bitmask(16): 0xFFFF
    return (1ULL << nbits) - 1;
}
 
void goto_next_line(std::istream& is);
 
void read_file(
    const std::string& filename,
    amrex::Vector<char>& charBuf,
    bool bExitOnError);
 
} // namespace spades
#endif