这是一个本人学习 csapp 的 learning 库
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/****************************
* High-level timing wrappers
****************************/
#include <stdio.h>
#include "fsecs.h"
#include "fcyc.h"
#include "clock.h"
#include "ftimer.h"
#include "config.h"
static double Mhz; /* estimated CPU clock frequency */
extern int verbose; /* -v option in mdriver.c */
/*
* init_fsecs - initialize the timing package
*/
void init_fsecs(void)
{
Mhz = 0; /* keep gcc -Wall happy */
#if USE_FCYC
if (verbose)
printf("Measuring performance with a cycle counter.\n");
/* set key parameters for the fcyc package */
set_fcyc_maxsamples(20);
set_fcyc_clear_cache(1);
set_fcyc_compensate(1);
set_fcyc_epsilon(0.01);
set_fcyc_k(3);
Mhz = mhz(verbose > 0);
#elif USE_ITIMER
if (verbose)
printf("Measuring performance with the interval timer.\n");
#elif USE_GETTOD
if (verbose)
printf("Measuring performance with gettimeofday().\n");
#endif
}
/*
* fsecs - Return the running time of a function f (in seconds)
*/
double fsecs(fsecs_test_funct f, void *argp)
{
#if USE_FCYC
double cycles = fcyc(f, argp);
return cycles/(Mhz*1e6);
#elif USE_ITIMER
return ftimer_itimer(f, argp, 10);
#elif USE_GETTOD
return ftimer_gettod(f, argp, 10);
#endif
}