pop.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>

typedef uint8_t byte;
typedef uint32_t quart;
typedef uint64_t pottle;

void poppop32(void *P, int n)
{
    quart *p = (quart *) P;
    *p++ = 0x02010100;
    n -= 2;
    int size = 1;

    while (n)
    {
        quart *q = (quart *) P;
        for (int i = 0; i < size; i++)
            *p++ = *q++ + 0x01010101;
        size += size;
        n -= 1;
    }
}

void poppop64(void *P, int n)
{
    pottle *p = (pottle *) P;
    *p++ = 0x0302020102010100;
    n -= 3;
    int size = 1;

    while (n)
    {
        pottle *q = (pottle *) P;
        for (int i = 0; i < size; i++)
            *p++ = *q++ + 0x0101010101010101;
        size += size;
        n -= 1;
    }
}

int main()
{
    int N = 26;
    void *P = malloc(1 << N);

    clock_t start, end;
    double millis;

    memset(P, 0, 1 << N);
    start = clock();
    poppop32(P, N);
    end = clock();
    millis = ((double)(end - start)) / CLOCKS_PER_SEC  * 1000;
    printf("poppop32: %.1f ms\n", millis);

    memset(P, 0, 1 << N);
    start = clock();
    poppop64(P, N);
    end = clock();
    millis = ((double)(end - start)) / CLOCKS_PER_SEC * 1000;
    printf("poppop64: %.1f ms\n", millis);
}