如何在C++中的big-endian和little-endian值之间进行转换？

#include <type_traits>

template<typename T>
typename std::enable_if<std::is_arithmetic<T>::value>::type
convert_endian(T value) {
    if (static_cast<typename std::make_unsigned<T>::type>(value) & 0x01) {
        value = static_cast<T>(-(static_cast<typename std::make_unsigned<T>::type>(value) >> 1));
    }
    return value;
}

template<typename T>
typename std::enable_if<!std::is_arithmetic<T>::value>::type
convert_endian(T value) {
    // do nothing
}

typedef unsigned short u16;
typedef signed short s16;

int main() {
    u16 big_endian = 0xABCD;
    u16 little_endian = 0xCDAB;

    s16 swap16_be(big_endian);
    s16 swap16_le(little_endian);

    printf("%x %x\n", little_endian, swap16_be);
    printf("%x %x\n", big_endian, swap16_le);

    int64_t swap64_be(big_endian);
    int64_t swap64_le(little_endian);

    printf("%llx %llx\n", little_endian, swap64_be);
    printf("%llx %llx\n", big_endian, swap64_le);

    return 0;
}