/* bench3 - re-measure with min-of-many-short-windows (immune to interrupts) */
#include <stdio.h>
#include <stdlib.h>

#define UNROLL 128
extern long k_add(long, long, long), k_mullw(long, long, long), k_mullw2(long, long, long);
extern long k_chase(long, long);
extern unsigned long long k_tb(void);

/* min ticks per kernel instruction over `reps` calls of f(n, a, b) */
static double
minwin(long (*f)(long, long, long), long n, long a, long b, int reps)
{
    unsigned long long t0, t, best = ~0ULL;
    int r;
    for (r = 0; r < reps; r++) {
        t0 = k_tb(); f(n, a, b); t = k_tb() - t0;
        if (t < best) best = t;
    }
    return (double)best / (n * (double)UNROLL);
}

int
main(void)
{
    double ref;
    int i;

    ref = minwin(k_add, 40, 1, 1, 5000);
    printf("ref add %.5f ticks -> core/TB %.3f\n", ref, 1 / ref);
    for (i = 0; i < 3; i++) {
        printf("k_mullw  x1 %5.2f | k_mullw2 x1 %5.2f | x0x7fff %5.2f | x0x12345 %5.2f | x-1 %5.2f\n",
               minwin(k_mullw, 40, 3, 1, 3000) / ref,
               minwin(k_mullw2, 40, 3, 1, 3000) / ref,
               minwin(k_mullw2, 40, 3, 0x7fff, 3000) / ref,
               minwin(k_mullw2, 40, 3, 0x12345, 3000) / ref,
               minwin(k_mullw2, 40, 3, -1, 3000) / ref);
    }
    printf("k_mullw2 x1 with r4=0x12345: %5.2f   r4=-1: %5.2f\n",
           minwin(k_mullw2, 40, 0x12345, 1, 3000) / ref,
           minwin(k_mullw2, 40, -1, 1, 3000) / ref);
    return 0;
}