fnv1a

fnv1a_32.cpp

#include <iostream>
#include <cstdlib>

/***********************************************************************************/

constexpr std::uint32_t fnv1a_r(const char *s, std::uint32_t h = 0x811c9dc5) {
    return (*s == 0) ? h : fnv1a_r(s+1, ((h ^ (*s)) * 0x01000193));
}

constexpr std::uint32_t fnv1a_i(const char *s) {
    std::uint32_t seed = 0x811c9dc5;
    for ( ; *s; ++s ) {
        seed = ((seed ^ (*s)) * 0x01000193);
    }
    
    return seed;
}

/***********************************************************************************/

int main(int argc, char **argv) {
    constexpr char s0[] = "1234567890";
    enum { v0 = fnv1a_r(s0), v1 = fnv1a_i(s0) };
    
    std::cout << v0 << std::endl;
    std::cout << v1 << std::endl;
    std::cout << (v0 == v1 && v1 == fnv1a_i(argv[1])) << std::endl;
}

/***********************************************************************************/