/**
 * Code max/min/avg time spend counting
 *
 * @file	platon/misc/rdtsc.h
 * @author	Tomas Corej <lynx@platon.sk>
 * @author	Lubomir Host <rajo@platon.sk>
 * @author	Ondrej Jombik <nepto@platon.sk>
 * @version	\$Platon: libplaton/platon/misc/rdtsc.h,v 1.13 2003/04/23 19:01:37 nepto Exp $
 * @date	2002-2003
 *
 * This set of macros are very useful in particular code parts time spend
 * counting. They can be also used for benchmarking. Note, that result depens
 * on many factors such as architecture, operating system, machine load, etc.
 *
 * Here is simple example of usage:
 *
 * @code
 *   double result_avg;
 *   rdtsc_avg(time(NULL), 500000, result_avg);
 *   printf("time(NULL): avg:%g\n", result_avg);
 * @endcode
 */

#ifndef _PLATON_MISC_RDTSC_H
#define _PLATON_MISC_RDTSC_H

#ifndef PLATON_DOXYGEN_SKIP /* Skipped parts of code by Doxygen are already
							   documented. It can be usuable when generating
							   private documentation for libplaton developers,
							   not for public usage. */
/**
 * @name	Result types
 * @internal dummy text to make Doxygen happy
 */
/*@{*/
#define RDTSC_FIRST	0 /**< First result; default behaviour */
#define RDTSC_MIN	1 /**< Shortest result */
#define RDTSC_MAX	2 /**< Longest result */
#define RDTSC_AVG	3 /**< Average result */
/*@}*/
#endif /* #ifndef PLATON_DOXYGEN_SKIP */

/**
 * Get first time result of code execution
 *
 * @param	code	code to execute
 * @param	count	number of repetition
 * @retval	result	pointer to double where time result will be stored
 */
#define rdtsc_first(code, count, result) \
		rdtsc_core(RDTSC_FIRST, code, count, result)

/**
 * Get shortest time result from code executions
 *
 * @param	code	code to execute
 * @param	count	number of repetition
 * @retval	result	pointer to double where time result will be stored
 */
#define rdtsc_min(code, count, result) \
		rdtsc_core(RDTSC_MIN, code, count, result)

/**
 * Get longest time result from code executions
 *
 * @param	code	code to execute
 * @param	count	number of repetition
 * @retval	result	pointer to double where time result will be stored
 */
#define rdtsc_max(code, count, result) \
		rdtsc_core(RDTSC_MAX, code, count, result)

/**
 * Get average time result from code executions
 *
 * @param	code	code to execute
 * @param	count	number of repetition
 * @retval	result	pointer to double where time result will be stored
 */
#define rdtsc_avg(code, count, result) \
		rdtsc_core(RDTSC_AVG, code, count, result)

#ifndef PLATON_DOXYGEN_SKIP

/**
 * Time spend counting core function
 *
 * @internal	dummy text to make Doxygen happy
 *				this must be at the beginning, else Doxygen will f*ck this up
 * @param	type	type of result, see Result types
 *					(@ref RDTSC_FIRST and similar)
 * @param	code	code to execute
 * @param	count	number of repetition
 * @retval	result	pointer to double where time result will be stored
 */
#define rdtsc_core(type, code, count, result) \
	do { \
		unsigned long __start, __end, __i; \
			double __result; \
			for (__i = 0; __i < (count); __i++) { \
				__asm__ __volatile__("rdtsc" : "=a" (__start) : : "edx"); \
				code \
				__asm__ __volatile__("rdtsc" : "=a" (__end) : : "edx"); \
				__end -= __start; \
				if ((type) == RDTSC_AVG) { \
					/* compute average value on the fly */ \
					/* can't be optimized due overflow  */ \
					__result = (__result * ((double) __i / ((double) __i + 1)) \
							+ (double) __end / ((double) __i + 1)); \
				} \
				else { \
					if (! __i \
							|| ((type) == RDTSC_MIN && __end < __result) \
							|| ((type) == RDTSC_MAX && __end > __result)) \
						__result = __end; \
				} \
			} \
		(result) = __result; \
	} while(0)
#endif /* #ifndef PLATON_DOXYGEN_SKIP */

#endif				/* #ifndef _PLATON_MISC_RDTSC_H */