/* --------------------------------------------------------------------------
 * timer.c:     Copyright (c) Mark P Jones 1991-1998.   All rights reserved.
 *              See NOTICE for details and conditions of use etc...
 *              Hugs version 1.3b, January 1998
 *
 * This file provides a simple mechanism for measuring elapsed time on Unix
 * machines (more precisely, on any machine with an rusage() function).
 * A somewhat limited version for other systems is also included, believed
 * to be ANSI compatible, but not guaranteed ...
 *
 * It is included in the Hugs distribution for the purpose of benchmarking
 * the Hugs interpreter, comparing its performance across a variety of
 * different machines, and with other systems for similar languages.
 *
 * To make use of these functions, add -DWANT_TIMER to the CFLAGS line in
 * the Makefile, before compiling Hugs.
 *
 * It would be somewhat foolish to try to use the timings produced in this
 * way for anything other than the purpose described above.  In particular,
 * using timings to compare the performance of different versions of an
 * algorithm is likely to give very misleading results.  The current
 * implementation of Hugs as an interpreter, without any significant
 * optimizations, means that there are much more significant overheads than
 * can be accounted for by small variations in Hugs code.
 * ------------------------------------------------------------------------*/

#if UNIX
#include <sys/time.h>
#include <sys/resource.h>

void updateTimers Args((void));
long millisecs  Args((long));
long userElapsed, systElapsed;

void updateTimers() {
    static long lastUser = 0;
    static long lastSyst = 0;
    long curr;
    struct rusage ruse;
    getrusage(RUSAGE_SELF,&ruse);

    curr        = ruse.ru_utime.tv_sec*1000000L + ruse.ru_utime.tv_usec;
    userElapsed = curr - lastUser;
    lastUser    = curr;

    curr        = ruse.ru_stime.tv_sec*1000000L + ruse.ru_stime.tv_usec;
    systElapsed = curr - lastSyst;
    lastSyst    = curr;
}

long millisecs(t)
long t; {
    return (t+500)/1000;
}
#else
#include <time.h>

void updateTimers Args((void));
long millisecs    Args((clock_t));
clock_t userElapsed=0, systElapsed=0;

void updateTimers() {
    static clock_t lastUser = 0;
    clock_t curr;
    curr        = clock();
    userElapsed = curr - lastUser;
    lastUser    = curr;
}

long millisecs(t)
clock_t t; {
    return (long)((t * 1000)/CLK_TCK);
}
#endif

/*-------------------------------------------------------------------------*/