%
% (c) The GRASP/AQUA Project, Glasgow University, 1995
%
\subsection[getCPUTime.lc]{getCPUTime Runtime Support}

\begin{code}
#define NON_POSIX_SOURCE /*needed for solaris2 only?*/

/* how is this to work given we have not read platform.h yet? */
#ifdef hpux_TARGET_OS
#define _INCLUDE_HPUX_SOURCE
#endif

#include "rtsdefs.h"
#include "stgio.h"

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_TIMES_H
#include <sys/times.h>
#endif

#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#if defined(HAVE_SYS_RESOURCE_H) && ! irix_TARGET_OS
#include <sys/resource.h>
#endif

#ifdef HAVE_SYS_TIMEB_H
#include <sys/timeb.h>
#endif

#ifdef hpux_TARGET_OS
#include <sys/syscall.h>
#define getrusage(a, b)  syscall(SYS_GETRUSAGE, a, b)
#define HAVE_GETRUSAGE
#endif

/* 
 * Our caller wants a pointer to four StgInts,
 * user seconds, user nanoseconds, system seconds, system nanoseconds.
 * Yes, the timerval has unsigned components, but nanoseconds take only
 * 30 bits, and our CPU usage would have to be over 68 years for the 
 * seconds to overflow 31 bits.
 */

StgByteArray
getCPUTime(cpuStruct)
StgByteArray cpuStruct;
{
    StgInt *cpu=(StgInt *)cpuStruct;

#if defined(HAVE_GETRUSAGE) && ! irix_TARGET_OS
    struct rusage t;

    getrusage(RUSAGE_SELF, &t);
    cpu[0] = t.ru_utime.tv_sec;
    cpu[1] = 1000 * t.ru_utime.tv_usec;
    cpu[2] = t.ru_stime.tv_sec;
    cpu[3] = 1000 * t.ru_stime.tv_usec;

#else
# if defined(HAVE_TIMES)
    struct tms t;
#  if defined(CLK_TCK)
#   define ticks CLK_TCK
#  else
    long ticks;
    ticks = sysconf(_SC_CLK_TCK);
#  endif

    times(&t);
    cpu[0] = t.tms_utime / ticks;
    cpu[1] = (t.tms_utime - cpu[0] * ticks) * (1000000000 / ticks);
    cpu[2] = t.tms_stime / ticks;
    cpu[3] = (t.tms_stime - cpu[2] * ticks) * (1000000000 / ticks);

# else
    return NULL;
# endif
#endif
    return (StgByteArray) cpuStruct;
}

\end{code}