#include <stdint.h>
#include <stdio.h>

#include <x86intrin.h>

#define ISODD(n) (n) & 1

unsigned char max2(unsigned char * x, int n) {
    unsigned char m = *x++;
    for(int i = 0; i < n; i++, x++)
        if(m < *x)
            m = *x;
    return m;
}



unsigned char m1(const unsigned char* u8x, int n)
{
	const uint64_t* u64x = (u8x);
	int i, j;
	unsigned char max = 0;
	for(i = 0, j = 0; i < n; i += 8, j++)
	{
		//"or" and "bitor" are keywords, of course
		uint64_t oR = u64x[j];
		oR |= oR >> 32;
		oR |= oR >> 16;
		oR |= oR >> 8;
		if(oR > (uint64_t)max)
		{
			for(int off = 0; off < 8; off++)
				max = max > u8x[i + off] ? max : u8x[i + off];
		}
	}
	i -= 8;
	for(; i < n; i++)
		max = max > u8x[i] ? max : u8x[i];
	return max;
}


int main(void) {
    uint64_t a, b;
    unsigned char ret, array[4096];

    srand(time(NULL));

    for(int i = 0; i < 4096; i++)
        array[i] = rand();

    a = __rdtsc();
    ret = m1(array, 4096);
    printf("you: %llu ", __rdtsc() - a, ret);

    a = __rdtsc();
    ret = max2(array, 4096);
    printf("Hui: %llu", __rdtsc() - a, ret);
}