emulate_gcc_builtin.h

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#ifndef ROUTING_KIT_EMULATE_GCC_BUILTIN_H
#define ROUTING_KIT_EMULATE_GCC_BUILTIN_H
#ifdef ROUTING_KIT_NO_GCC_EXTENSIONS
 
#include <mutex>
#include <atomic>
 
#define __builtin_expect(x, y) (x)
 
namespace RoutingKit{namespace detail{
    inline
    unsigned emulated_builtin_popcountll(unsigned long long x){
        int n=0;
        for(unsigned long long i=1; i!=0; i<<=1)
            if(x & i)
                ++n;
        return n;
    }
 
    inline
    unsigned emulated_builtin_popcount(unsigned x){
        return emulated_builtin_popcountll(x);
    }
 
    inline
    unsigned emulated_builtin_ffsll(unsigned long long x){
        int n=1;
        for(unsigned long long i=1; i!=0; i<<=1, ++n)
            if(x & i)
                return n;
        return 0;
    }
 
    template<class T>
    bool emulated_sync_bool_compare_and_swap(T*var, T comp_value, T new_value){
        static std::mutex m;
        std::lock_guard<std::mutex> lock(m);
 
        std::atomic_thread_fence(std::memory_order_seq_cst);
 
        if(*var == comp_value){
            *var = new_value;
 
            std::atomic_thread_fence(std::memory_order_seq_cst);
            return true;
        }else{
            return false;
        }
    }
 
}}
 
#define __builtin_popcount(x) ::RoutingKit::detail::emulated_builtin_popcount(x)
 
#define __builtin_popcountll(x) ::RoutingKit::detail::emulated_builtin_popcountll(x)
 
#define __builtin_ffsll(x) ::RoutingKit::detail::emulated_builtin_ffsll(x)
 
#define __sync_bool_compare_and_swap(x, y, z) ::RoutingKit::detail::emulated_sync_bool_compare_and_swap(x, y, z)
 
#endif
#endif