cputime.h

包含哈希,对称以及非对称的经典算法 包含经典事例

#ifndef CPUTIME_H
#define CPUTIME_H

/*
 * Figure out what clock to use.  Each possibility can be specifically
 * enabled or disabled by predefining USE_XXX to 1 or 0.  For some,
 * the code attempts to detect availability automatically.  If the
 * Symbols HAVE_XXX are defined, they are used.  If not, they are
 * set to reasonable default assumptions while further conditions
 * are checked.  The choices, and the ways they are auto-detected are:
 * - gethrvtime(), if HAVE_GETHRVTIME is set to 1.
 * - clock_gettime(CLOCK_VIRTUAL,...), if CLOCK_VIRTUAL is defined in <time.h>
 * - getrusage(RUSAGE_SELF,...), if RUSAGE_SELF is defined in <sys/resource.h>
 * - clock(), if CLOCKS_PER_SEC or CLK_TCK are defined in <time.h>
 * - time(), unless specifically disabled.
 *
 * The symbol CLOCK_AVAIL is given a value of 1 if a clock is found.
 * The following are then available:
 * timetype (typedef): the type needed to hold a clock value.
 * gettime(t) (macro): A function that gets passed a timetype *.
 * subtime(d,s) (macro): Sets d -= s, essentially.
 * msec(t) (macro): Given a timetype, return the number of milliseconds
 *	in it, as an unsigned integer between 0 and 999.
 * sec(t) (macro): Given a timetype, return the number of seconds in it,
 *	as an unsigned long integer.
 */

#ifdef UNIX
/* Nothing */
#elif unix
#define UNIX 1
#elif __unix
#define UNIX 1
#elif __unix__
#define UNIX 1
#endif

#ifndef TIME_WITH_SYS_TIME
#define TIME_WITH_SYS_TIME 1	/* Assume true if not told */
#endif

/*
 * Include <time.h> unless that would prevent us from later including
 * <sys/time.h>, in which case include *that* immediately.
 */
#if TIME_WITH_SYS_TIME
#include <time.h>
#elif HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <time.h>
#endif

#ifndef USE_GETHRVTIME
#define USE_GETHRVTIME HAVE_GETHRVTIME
#endif

#if USE_GETHRVTIME
#define CLOCK_AVAIL 1
typedef hrtime_t timetype;
#define gettime(t) *(t) = gethrvtime()
#define subtime(d,s) d -= s
#define msec(t) (unsigned)((t/1000000)%1000)
#define sec(t) (unsigned long)(t/1000000000)

#else
#ifndef USE_CLOCK_GETTIME
#ifndef HAVE_CLOCK_GETTIME
#define HAVE_CLOCK_GETTIME 1	/* Assume the CLOCK_VIRTUAL test will catch */
#endif
/*
 * It breaks the DEC Alpha compiler to use the simpler construct
 * "#define USE_CLOCK_GETTIME defined(CLOCK_VIRTUAL)".
 */
#if HAVE_CLOCK_GETTIME
#ifdef CLOCK_VIRTUAL
#define USE_CLOCK_GETTIME 1
#endif
#endif
#endif

#if USE_CLOCK_GETTIME
#define CLOCK_AVAIL 1
typedef struct timespec timetype;
#define gettime(t) clock_gettime(CLOCK_VIRTUAL, t)
#define subtime(d,s) \
	d.tv_sec -= s.tv_sec + (d.tv_nsec >= s.tv_nsec ? \
	                        (d.tv_nsec -= s.tv_nsec, 0) : \
	                        (d.tv_nsec += 1000000000-s.tv_nsec, 1))
#define msec(t) (unsigned)(t.tv_nsec/1000000)
#define sec(t) (unsigned long)(t.tv_sec)

#else
#if UNIX
#ifndef HAVE_GETRUSAGE
#define HAVE_GETRUSAGE 1
#endif
#endif /* UNIX */

#if HAVE_GETRUSAGE
#if TIME_WITH_SYS_TIME
#ifndef HAVE_SYS_TIME_H
#include <sys/time.h>
#elif HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#endif /* TIME_WITH_SYS_TIME */
#include <sys/resource.h>

#ifdef RUSAGE_SELF
#define USE_GETRUSAGE 1
#endif
#endif /* HAVE_GETRUSAGE */

#if USE_GETRUSAGE
#define CLOCK_AVAIL 1
typedef struct rusage timetype;
#define gettime(t) getrusage(RUSAGE_SELF, t);
#define subtime(d, s) \
	d.ru_utime.tv_sec -= s.ru_utime.tv_sec + \
	             (d.ru_utime.tv_usec >= s.ru_utime.tv_usec ? \
	              (d.ru_utime.tv_usec -= s.ru_utime.tv_usec, 0) : \
	              (d.ru_utime.tv_usec += 1000000-s.ru_utime.tv_usec, 1))
#define msec(t) (unsigned)(t.ru_utime.tv_usec/1000)
#define sec(t) (unsigned long)(t.ru_utime.tv_sec)

#else

#ifndef HAVE_CLOCK
#define HAVE_CLOCK 1
#endif

#if HAVE_CLOCK
#ifndef CLOCKS_PER_SEC
#ifdef CLK_TCK
#define CLOCKS_PER_SEC CLK_TCK
#endif
#endif /* !defined(CLOCKS_PER_SEC) */

#ifndef USE_CLOCK
#ifdef CLOCKS_PER_SEC
#define USE_CLOCK 1
#endif
#endif /* !defined(USE_CLOCK) */
#endif /* HAVE_CLOCK */

#if USE_CLOCK
#define CLOCK_AVAIL 1
typedef clock_t timetype;
#define gettime(t) *(t) = clock()
#define subtime(d, s) d -= s
#define msec(t) (unsigned)(t % CLOCKS_PER_SEC * 1000 / CLOCKS_PER_SEC)
#define sec(t) (unsigned long)(t/CLOCKS_PER_SEC)

#else

#ifndef HAVE_TIME
#define HAVE_TIME 1
#endif

#if HAVE_TIME
#ifndef USE_TIME
#define USE_TIME 1
#endif
#endif

#if USE_TIME
#define CLOCK_AVAIL 1
typedef time_t timetype;
#define gettime(t) time(t)
#define subtime(d, s) d -= s
#define msec(t) (unsigned)0
#define sec(t) (unsigned long)t

#endif /* USE_TIME */
#endif /* USE_CLOCK */
#endif /* USE_GETRUSAGE */
#endif /* USE_CLOCK_GETTIME */
#endif /* USE_GETHRVTIME */

#endif CPUTIME_H