/*
      g++ test2.cpp -o test -O3 -lrt -ffast-math
 */

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <ctime>

#if defined _WIN32
#   include <windows.h>
#endif

static void version1(float h, float s, float v,
                     float &r, float &g, float &b)
{
    h *= 6.f;
    s *= v;

    float r2 = -2.f + fabs(h - 3.f);
    float g2 = 1.f - fabs(h - 2.f);
    float b2 = 1.f - fabs(h - 4.f);

    /* Minus 1 */
    r2 = std::min(std::max(r2, -1.f), 0.f);
    g2 = std::min(std::max(g2, -1.f), 0.f);
    b2 = std::min(std::max(b2, -1.f), 0.f);

    r = r2 * s + v;
    g = g2 * s + v;
    b = b2 * s + v;
}

static void version2(float h, float s, float v,
                     float &r, float &g, float &b)
{
    h *= 3.f;
    s *= v;

    float x = fabs(1.5f - fabs(h - 2.5f));
    float y = fabs(1.5f - fabs(h - 0.5f));
    float z = -0.5f - fabs(1.5f - h);

    /* Minus 1 */
    float r2 = x + y - 2.f;
    float g2 = y + z;
    float b2 = x + z;

    r = r2 * s + v;
    g = g2 * s + v;
    b = b2 * s + v;
}

static int const NCOLORS = 10000;
static int const NITERS = 5000;
static float data[NCOLORS * 2 * 3];

static void reset(int seed)
{
    srand(seed);

    for (int i = 0; i < NCOLORS; i++)
    {
        data[i * 6 + 0] = rand() % 131072 / 131071.f;
        data[i * 6 + 1] = rand() % 131072 / 131071.f;
        data[i * 6 + 2] = rand() % 131072 / 131071.f;
    }
}

static volatile long double gettime()
{
#if defined _WIN32
    static long double secs_per_cycle = 0.0L;
    LARGE_INTEGER cycles;
    if (!secs_per_cycle)
    {
        QueryPerformanceFrequency(&cycles);
        secs_per_cycle = 1.0L / cycles.QuadPart;
    }
    QueryPerformanceCounter(&cycles);
    return secs_per_cycle * cycles.QuadPart;
#else
    timespec t1;
    clock_gettime(CLOCK_MONOTONIC, &t1);
    return 1.e-9L * t1.tv_nsec + t1.tv_sec;
#endif
}

#define TEST(fn) \
    { \
        long double t = 0; \
        for (int n = 0; n < NITERS; n++) \
        { \
            reset(n); \
            t -= gettime(); \
            for (int i = 0; i < NCOLORS; i++) \
                fn(data[i * 6 + 0], data[i * 6 + 1], data[i * 6 + 2], \
                   data[i * 6 + 3], data[i * 6 + 4], data[i * 6 + 5]); \
            t += gettime(); \
        } \
        \
        for (int n = 0; n < 16; n++) \
            fprintf(stderr, #fn ": %f nanoseconds [%f %f %f]\n", \
                    (double)t / NITERS / NCOLORS * 1e9, \
                    data[n * 6 + 3], data[n * 6 + 4], data[n * 6 + 5]); \
    }

int main(void)
{
    TEST(version1);
    TEST(version2);
}