/*!\file timer.c
 *
 *  Module for handling timers.
 *
 *  Modifications by GvB 2002-09
 *
 *  \todo To get rid of the timer problem once and for all we need a
 *        timer ISR that increments a 32-bit value no regard to day
 *        roll-over etc. Maybe hook up IRQ 8 to call a real-mode stub
 *        that we opy to DOS-memory (similar to the pkt_receiver stub
 *        code. Then far-peek at that timer variable.
 *
 * 09-Jan-2003: Bernd Omenitch <Omenitsch@cashpoint.at> contributed the
 *    Timer ISR code (init_timer_isr() etc). I rewrote it and added
 *    support for Borland/PowerPak/Pharlap).
 */

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <signal.h>
#include <time.h>
#include <math.h>
#include <errno.h>
#include <sys/wtime.h>

#include "wattcp.h"
#include "ioport.h"
#include "strings.h"
#include "gettod.h"
#include "pcconfig.h"
#include "pcqueue.h"
#include "language.h"
#include "cpumodel.h"
#include "powerpak.h"
#include "wdpmi.h"
#include "x32vm.h"
#include "rs232.h"
#include "misc.h"
#include "timer.h"

#if (DOSX & PHARLAP)
#include <mw/exc.h>  /* _dx_alloc_rmode_wrapper_iret() */
#endif

DWORD start_time = 0;      /**< Start-time of watt_sock_init() (in msec) */
DWORD start_day  = 0;      /**< Start-day of watt_sock_init() */

BOOL  has_8254   = FALSE;  /**< Do we have a working 8254 timer chip? */
BOOL  has_rdtsc  = FALSE;  /**< Do we have a CPU with RDTSC instruction? */
BOOL  use_rdtsc  = FALSE;  /**< Do not use RDTSC by default */
BOOL  using_int8 = FALSE;  /**< init_timer_isr() called */
DWORD clocks_per_usec;     /**< Measured CPU speed (MHz) */

time_t user_tick_base   = 0UL;   /* time() when user-tick started */
DWORD  user_tick_msec   = 0UL;   /* milli-sec user-tick counter */
BOOL   user_tick_active = FALSE;

static DWORD date    = 0;
static DWORD date_ms = 0;

#if defined(USE_PROFILER)
  /*
   * A simple execution profiler
   */
  BOOL profile_enable = FALSE;
  char profile_file [MAX_PATHLEN+1] = ".\\WATTCP.PRO";

  static FILE  *prof_fout;
  static uint64 prof_start;
  static uint64 num_profs;
#endif

/*
 * Things for the user installable timer ISR.
 */
#if !(DOSX & DJGPP)
  #define TIMER_ISR_PERIOD  10UL  /* 10 msec between interrupts */
  #define TIMER_INTR        8
#endif

#if (DOSX == 0) || (DOSX & DOS4GW)
  #define HAVE_TIMER_ISR

  static W32_IntrHandler old_int_8 = NULL;

#elif (DOSX & (PHARLAP|X32VM))
  #define HAVE_TIMER_ISR

  static REALPTR old_int_8, int8_cback;
  static FARPTR  old_int_8_pm;
  static RMC_BLK rmBlock_int8;

#elif (DOSX & DJGPP)
  #define HAVE_TIMER_ISR

  static DWORD            itimer_resolution = 0UL; /* in usec */
  static void           (*old_sigalrm)(int);
  static struct itimerval old_itimer;
#endif

#if defined(HAVE_TIMER_ISR) && !(DOSX & DJGPP)
  static DWORD tick_timer_8254 = 0UL;

  /* 1193181 = 4.77MHz/4 pulses per sec.
   */
  #define TIMER_8254_COUNT ((1193181UL * TIMER_ISR_PERIOD) / 1000UL)
#endif



/**
 * Setup timer stuff and measure CPU speed.
 * Called from init_misc().
 */
void init_timers (void)
{
#if (DOSX)             /* problems using 64-bit types in small/large models */
  hires_timer (TRUE);  /**< \todo check if 8254 PIT is really working */

#if defined(HAVE_UINT64)
  if (use_rdtsc && has_rdtsc)
  {
    clocks_per_usec = (DWORD) (get_cpu_speed() / S64_SUFFIX(1000000));
    if (clocks_per_usec == 0UL)
    {
      outsnl ("CPU speed is 0?");
      use_rdtsc = FALSE;
      has_rdtsc = FALSE;
    }
  }
  set_utc_offset();  /* don't pull in gettod.c unneccesary */
#endif
#endif

  chk_timeout (0UL); /* init 'date' variables */
}

/**
 * init_userSuppliedTimerTick() - setup timer handling for programs that are
 * already running a periodic interrupt or whatever (i.e. ALLEGRO & more).
 * This is called to signify that the 'user task' will periodically call
 * userTimerTick() to supply the elapsed time since the last call.
 * Best called once before sock_init(). There is no way to revert to
 * original timer handling once this is called.
 * By GvB 2002-09
 */
void init_userSuppliedTimerTick (void)
{
  SIO_TRACE (("init_userSuppliedTimerTick"));
  user_tick_active = TRUE;
  user_tick_base = time (NULL);
  has_8254 = FALSE;
}

/*
 * Disable stack-checking here
 */
#if defined(__HIGHC__)
  #pragma off(Call_trace)
  #pragma off(Prolog_trace)
  #pragma off(Epilog_trace)
#endif

#include "nochkstk.h"

/**
 * Provide timer-ticks from an application.
 * This should be periodically called from user code to increment the timer
 * count once activated via init_userSuppliedTimerTick().
 * Best called from a periodic interrupt handler (int 8/1Ch/70h) which
 * is the case now with init_timer_isr().
 * GvB 2002-09
 */
void userTimerTick (DWORD elapsed_time_msec)
{
  user_tick_msec += elapsed_time_msec;
}

#if defined(HAVE_TIMER_ISR)
/**
 * User defined 10ms counter ISR.
 */
#if (DOSX & (DJGPP|PHARLAP|X32VM))
  static void new_int_8 (void) /* not really an intr-handler */
#else
  static INTR_PROTOTYPE new_int_8 (void)
#endif
{
#if !(DOSX & DJGPP)
  tick_timer_8254 += TIMER_8254_COUNT;

  if (tick_timer_8254 >= 0x10000)
  {
    tick_timer_8254 -= 0x10000;

#if defined(__WATCOMC__)
    _chain_intr (old_int_8);    /* chain now */
#elif (DOSX & (PHARLAP|X32VM))
    _dx_call_real (old_int_8, &rmBlock_int8, 1);
#else
    (*old_int_8)();
#endif
  }
  else
    _outportb (0x20, 0x60);  /* specific EOI for IRQ 0 */

  userTimerTick (TIMER_ISR_PERIOD);

#else
  userTimerTick (itimer_resolution / 1000UL);
#endif   /* !DJGPP */


#if (DOSX & DJGPP)
  /* BEEP(); */  /* !! test */
#endif
}

void exit_timer_isr (void)
{
  if (!using_int8)
     return;

#if (DOSX & DJGPP)
  signal (SIGALRM, old_sigalrm);
  setitimer (ITIMER_REAL, &old_itimer, NULL);
#else
  if (old_int_8)
  {
    _outportb (0x43, 0x34);  /* restore default timer rate */
    _outportb (0x40, 0);
    _outportb (0x40, 0);

    PUSHF_CLI();

#if (DOSX & (PHARLAP|X32VM))
    _dx_rmiv_set (TIMER_INTR, old_int_8);
    if (int8_cback)
       _dx_free_rmode_wrapper (int8_cback);
    old_int_8 = 0;
#else
    _dos_setvect (TIMER_INTR, old_int_8);
    old_int_8 = NULL;
#endif

    POPF();
  }
#endif  /* DJGPP */

  /* This causes timeout calculations for timers started earlier
   * to go wrong.
   */
  user_tick_active = FALSE;
  using_int8 = FALSE;
}

/*
 * Hook INT 8 and modify rate of timer channel 0 for 55msec (djgpp)
 * or 10 msec (others) period.
 */
void init_timer_isr (void)
{
  /* Caller must do exit_timer_isr() before doing this again
   */
  if (using_int8)
     return;

#if (DOSX & DJGPP)
  {
    struct itimerval tim;

    memset (&tim, 0, sizeof(tim));
    tim.it_interval.tv_usec = 1;
    setitimer (ITIMER_REAL, &tim, NULL);
    setitimer (ITIMER_REAL, NULL, &tim);
    itimer_resolution = 1000000UL * tim.it_interval.tv_sec + /* should become 55000 */
                        tim.it_interval.tv_usec;
    tim.it_value.tv_sec  = tim.it_interval.tv_sec;
    tim.it_value.tv_usec = tim.it_interval.tv_usec;

    memset (&old_itimer, 0, sizeof(old_itimer));
    old_sigalrm = signal (SIGALRM, (W32_IntrHandler)new_int_8);
    setitimer (ITIMER_REAL, &tim, &old_itimer);
  }

#elif (DOSX & (PHARLAP|X32VM))
  #if 1
    int8_cback = _dx_alloc_rmode_wrapper_iret ((pmodeHook)new_int_8, 256);
    if (!int8_cback)
    {
      outsnl (_LANG("Cannot allocate real-mode timer callback"));
      return;
    }
    _dx_rmiv_get (8, &old_int_8);
    _dx_rmiv_set (8, int8_cback);
  #else
  {
    FARPTR fp;
    FP_SET (fp, new_int_8, MY_CS());
    _dx_pmiv_get (8, &old_int_8_pm);
    _dx_apmiv_set (8, fp);
  }
  #endif
#else
  old_int_8 = _dos_getvect (8);
  _dos_setvect (8, new_int_8);
#endif

#if !(DOSX & DJGPP)
  _outportb (0x43, 0x34);
  _outportb (0x40, loBYTE(TIMER_8254_COUNT));
  _outportb (0x40, hiBYTE(TIMER_8254_COUNT));
#endif

  init_userSuppliedTimerTick();
  using_int8 = TRUE;

  /* release it very early */
  RUNDOWN_ADD (exit_timer_isr, -2);
}

#else

void init_timer_isr (void)
{
#if defined(USE_DEBUG)
  if (debug_on)
     outsnl ("No timer-ISR in this environment");
#endif
}

void exit_timer_isr (void)
{
}
#endif

/**
 * Compare two timers with expirary at 't1' and 't2'.
 *   \retval \li -1 if t1 expires before t2
 *           \li  0 if t1 == t2
 *           \li +1 if t1 expires after t2
 *
 * \note This logic fails when timers approaches ULONG_MAX
 *       after approx. 50 days.
 */
int cmp_timers (DWORD t1, DWORD t2)
{
  if (t1 == t2)
     return (0);
  return (t1 < t2 ? -1 : +1);
}

/**
 * Control use of high-resolution timer.
 * When using Watt-32 together with programs that reprogram the PIT
 * (8254 timer chip), the millisec_clock() function may return wrong
 * values. In such cases it's best to use old-style 55ms timers.
 * Using Watt-32 with Allegro graphics library is one such case where
 * application program should call `˙hires_timer(0)' after `sock_init()'
 * has been called.
 */
int hires_timer (int on)
{
  int old = has_8254;

  SIO_TRACE (("hires_timer %s", on ? "on" : "off"));
  has_8254 = on;
  chk_timeout (0UL);
  return (old);
}


#if !defined(WIN32)
/*
 * The following 2 routines are modified versions from KA9Q NOS
 * by Phil Karn.
 *
 * clockbits() - Read low order bits of timer 0 (the TOD clock)
 * This works only for the 8254 chips used in ATs and 386+.
 *
 * Old version:
 *   The timer 0 runs in mode 3 (square wave mode), counting down
 *   by 2s, twice for each cycle. So it is necessary to read back the
 *   OUTPUT pin to see which half of the cycle we're in. I.e., the OUTPUT
 *   pin forms the most significant bit of the count. Unfortunately,
 *   the 8253 in the PC/XT lacks a command to read the OUTPUT pin...
 *
 * Now simply:
 *   The timer 0 runs in mode 2 (rate generator), counting down.
 *   We don't compare the OUTPUT pin to see what cycle we're in.
 *   A bit lower precision, but a bit faster.
 *
 * WARNING!: This can cause serious trouble if anything else is also using
 * timer interrupts. In that case use the above "userSuppliedTimerTick".
 * The reading of I/O registers gives bad precision under Windows.
 */
DWORD clockbits (void)
{
  static VOLATILE DWORD count;  /* static because of PUSHF_CLI() */
#if 1
  /*
   * The following version was suggested by Andrew Paulsen
   * <andrew.paulsen@ndsu.nodak.edu>. Seem to work fine.
   */
  static BOOL started = FALSE;

  PUSHF_CLI();

  if (!started)                  /* Initialize once, it is periodic */
  {
    _outportb (0x43, 0x34);      /* Set timer 0, mode 2 */
    _outportb (0x40, 0x00);      /* Count is decremented, then compared to 0 */
    _outportb (0x40, 0x00);      /* so set count to 0 to get 65536 */
    started = TRUE;
  }

  _outportb (0x43, 0x04);        /* Latch present counter value command */
  count  = _inportb (0x40);      /* LSB of count */
  count |= _inportb (0x40) << 8; /* MSB of count */

  POPF();

  return (count);

#else
  static VOLATILE DWORD stat, count;  /* static because of PUSHF_CLI() */

  do
  {
    PUSHF_CLI();
    _outportb (0x43, 0xC2);        /* Read Back Command (timer 0, 8254 only) */
    stat   = _inportb (0x40);      /* get status of timer 0 */
    count  = _inportb (0x40);      /* LSB of count */
    count |= _inportb (0x40) << 8; /* MSB of count */
    POPF();
  }
  while (stat & 0x40);             /* reread if NULL COUNT bit set */

  stat = (stat & 0x80) << 8;       /* Shift OUTPUT to MSB of 16-bit word */
  count >>= 1;                     /* count = count/2 */
  if (count == 0)
     return (stat ^ 0x8000UL);     /* return complement of OUTPUT bit */
  return (count | stat);           /* Combine OUTPUT with counter */
#endif
}

/*
 * Return hardware time-of-day in milliseconds. Resolution is improved
 * beyond 55 ms (the clock tick interval) by reading back the instantaneous
 * 8254 counter value and combining it with the clock tick counter.
 *
 * Reading the 8254 is a bit tricky since a tick could occur asynchronously
 * between the two reads in clockbits(). The tick counter is examined before
 * and after the hardware counter is read. If the tick counter changes, try
 * again.
 *
 * \note The hardware counter (lo) counts down from 65536 at a rate of
 *       1.193181 MHz (4.77/4). System tick count (hi) counts up.
 */
DWORD millisec_clock (void)
{
  DWORD  hi;
  WORD   lo;
  double x;

  do
  {
    hi = PEEKL (0, BIOS_CLK);
    lo = clockbits();
  }
  while (hi != PEEKL(0, BIOS_CLK));   /* tick count changed, try again */
  lo = 0 - lo;

  /* Emulating this would be slow. We'd better have a math-processor
   */
  x = ldexp ((double)hi, 16) + (double)lo;  /* x = hi*2^16 + lo */
  return (DWORD) (x * 4.0 / 4770.0);
}
#endif  /* !WIN32 */


/**
 * Return time for when given timeout (msec) expires.
 * Make sure it never returns 0 (it will confuse chk_timeout).
 */
DWORD set_timeout (DWORD msec)
{
  DWORD ret;

  if (user_tick_active)  /* using timer ISR or user-timer */
  {
    ret = user_tick_msec + msec;
  }
#if defined(HAVE_UINT64) /* CPU-clock, 8254 PIT or 55msec ticks */ || \
    defined(WIN32)       /* GetSystemTimeAsFileTime() */
  else
  {
    struct timeval now;

    gettimeofday2 (&now, NULL);
    ret = msec + 1000 * now.tv_sec + (DWORD)(now.tv_usec / 1000);
  }
#else
  else if (has_8254)    /* high-resolution PIT */
  {
    ret = msec + date_ms + millisec_clock();
  }
  else /* fallback to 55msec ticks */
  {
    DWORD ticks = 1;

    if (msec > 55)
       ticks = msec / 55UL;
 /* ret = ticks + ms_clock();  !!!! try this */
    ret = ticks + date + PEEKL (0,BIOS_CLK);
  }
#endif

  return (ret == 0 ? 1 : ret);
}

/**
 * Check if milli-sec value has expired:
 *  \retval \li  TRUE  timer expired
 *          \li  FALSE not expired (or value not set)
 */
BOOL chk_timeout (DWORD value)
{
  if (user_tick_active)      /* using timer ISR or user-timer */
  {
    if (value == 0)
       return (0);
    return (user_tick_msec >= value);
  }

#if defined(HAVE_UINT64) || defined(WIN32)
  if (value == 0UL)
     return (0);
  return (set_timeout(0) >= value);

#else
  {
    static char  oldHour = -1;
    static DWORD now_ms;
    static DWORD now;
    char   hour;

    now  = (DWORD) PEEKL (0, BIOS_CLK);
#if 1
    hour = (char)(now >> 16U);
#else
    hour = (char)(now/65543.33496093);  /* Jan De Geeter 17.12.01 */
#endif

    if (hour != oldHour)
    {
      if (hour < oldHour)               /* midnight passed */
      {
#define CORR 290UL                      /* experimental correction */
        date    += 1572750UL + CORR;    /* Update date (0x1800B0UL) */
        date_ms += 3600UL*24UL*1000UL;  /* ~2^26 */
      }
      oldHour = hour;
    }

    if (value == 0L)        /* timer not initialised */
       return (0);          /* (or stopped) */

    if (has_8254)
    {
      now_ms = millisec_clock();
      return (now_ms + date_ms >= value);
    }
    now += date;            /* date extend current time */
    return (now >= value);  /* return true if expired */
  }
#endif   /* HAVE_UINT64 || WIN32 */
}

/**
 * Must be called by user right before or after a time change occurs.
 * Not used in Watt-32.
 */
int set_timediff (long msec)
{
  date_ms -= msec;
  date    -= msec/55;
  return (0);
}

/**
 * Return time difference between timers 'now' and 'tim'.
 * Check for day rollover. Max timer distance is 24 hours.
 * This function should be called immediately after chk_timeout()
 * is called.
 */
long get_timediff (DWORD now, DWORD tim)
{
#if defined(HAVE_UINT64) || defined(WIN32)
  return (long)(now - tim);
#else
  long dt = (long)(now - tim);

  if (has_8254)
       dt = dt % (3600L*24L*1000L);
  else dt = dt % (1572750L + CORR);
  return (dt);
#endif
}

/*
 * Return difference (in micro-sec) between timevals `*newer' and `*older'
 */
double timeval_diff (const struct timeval *newer, const struct timeval *older)
{
  long d_sec  = (long)newer->tv_sec - (long)older->tv_sec;
  long d_usec = newer->tv_usec - older->tv_usec;
  return (1E6 * (double)d_sec + (double)d_usec);
}

#if defined(WIN32)
/*
 * Return FILETIME in seconds.
 */
double filetime_sec (const void *filetime)
{
#if 0
  const FILETIME *ft = (const FILETIME*) filetime;
  long double rc = (long double)ft->dwHighDateTime * (long double)(ULONG_MAX+1);

  rc += (long double) ft->dwLowDateTime;
#else
  const LARGE_INTEGER ft = *(const LARGE_INTEGER*) filetime;
  long double rc = (long double)ft.QuadPart;
#endif
  return (double) (rc/1E7);    /* from 100 nano-sec periods to sec */
}
#endif

#if defined(USE_DEBUG)
/*
 * Return string "x.xx" for timeout value.
 * 'val' is always in milli-sec units if we're using the 8254 PIT,
 * RDTSC timestamps, timer ISR or user-supplied timer.
 */
const char *time_str (DWORD val)
{
  static char  buf[30];
  char   fmt[6];
  double flt_val;

  if (has_8254 || has_rdtsc || user_tick_active)
  {
    flt_val = (double)val / 1000.0F;
    strcpy (fmt, "%.3f");
  }
  else
  {
    flt_val = (double)val / 18.2F;
    strcpy (fmt, "%.2f");
  }

#if (!DOSX) && defined(__BORLANDC__) && 0 /* Bug? Try "%.xlf" */
  fmt[3] = 'l';
  fmt[4] = 'f';
  fmt[5] = '\0';
#endif

  sprintf (buf, fmt, flt_val);
  return (buf);
}

/*
 * Return string "HH:MM:SS" for a time in seconds.
 */
const char *hms_str (DWORD sec)
{
  static char buf[30];
  WORD   hour = (WORD) (sec / 3600UL);
  WORD   min  = (WORD) (sec / 60) - (60 * hour);

  sprintf (buf, "%02u:%02u:%02u", hour, min, (UINT)(sec % 60UL));
  return (buf);
}

/*
 * Return string "xx:xx" for time elapsed since started.
 * Handles max 24 days. Or max 49 days with user_tick_active.
 */
const char *elapsed_str (DWORD val)
{
  static char buf[30];
  WORD   hour, min, msec;
  DWORD  sec;
  BOOL   is_win = (DOSX & WINWATT);

  if (val == 0UL)
     return ("00:00:00.000");

  if (!user_tick_active && val < start_time)   /* wrapped? */
     val = ULONG_MAX - val + start_time;

  /* If user-ticks is used, 'val' should be correct msec count
   * since init_userSuppliedTimerTick()() was called.
   */
  if (user_tick_active)
  {
    sec  = val / 1000UL;
    msec = (WORD) (val % 1000UL);
  }
  else if (has_8254 || has_rdtsc || is_win)
  {
    val -= start_time;
    sec  = val / 1000UL;
    msec = (WORD) (val % 1000UL);
  }
  else
  {
    val -= start_time;
    sec  = val / 18;
    msec = 55 * (WORD)(val % 18UL);
  }

  hour = (WORD) (sec / 3600UL);
  min  = (WORD) (sec / 60UL) - 60 * hour;
  sec  = sec % 60UL;
  sprintf (buf, "%02u:%02u:%02lu.%03u", hour, min, sec, msec);
  return (buf);
}
#endif /* USE_DEBUG */


#if !defined(WIN32)
/*
 * The following was contributed by
 * "Alain" <alainm@pobox.com>
 */
#define TICKS_DAY 1573067UL   /* Number of ticks in one day */

DWORD ms_clock (void)
{
  static DWORD lastTick, tickOffset;
  static char  firstTime = 1;
  DWORD  tick = PEEKL (0, 0x46C);

  if (firstTime)
  {
    firstTime = 0;
    lastTick  = tickOffset = tick;
    return (0);
  }
  if (lastTick > tick)        /* day changed */
     tickOffset -= TICKS_DAY;
  lastTick = tick;
  return (tick - tickOffset);
}
#endif  /* WIN32 */


#if defined(USE_PROFILER)
/*
 * Called on entry of something to profile.
 */
void profile_start (const char *str)
{
  if (prof_fout)
  {
    fprintf (prof_fout, "  profiling %-12.12s ", str);
    prof_start = get_rdtsc();
    num_profs++;
  }
}

/*
 * Dumps the time taken (milli-sec and CPU clocks).
 */
void profile_stop (void)
{
  if (prof_fout && clocks_per_usec)
  {
    int64  clocks = (int64) (get_rdtsc() - prof_start);
    double msec   = (double)clocks / ((double)clocks_per_usec * 1000.0);
    fprintf (prof_fout, "%10.3f msec (%" S64_FMT " clk)\n", msec, clocks);
  }
}

static void profile_exit (void)
{
  if (prof_fout)
  {
    fclose (prof_fout);
    prof_fout = NULL;
    if (num_profs)
       (*_printf) ("profiling info written to \"%s\"\n", profile_file);
  }
}

/*
 * Dump some arbitrary data to profile dump file.
 */
void profile_dump (const uint64 *data, size_t num)
{
  unsigned i;

  if (!prof_fout || !clocks_per_usec)
     return;

  for (i = 0; i < num; i++)
  {
    double msec = (double)data[i] / ((double)clocks_per_usec * 1000.0);

    fprintf (prof_fout, "profile_dump: %3u: %12.3f msec (%" U64_FMT " clk)\n",
             i, msec, data[i]);
  }
}

/*
 * Profile speed of receving a packet. Write the difference of
 *   get - time of 2nd packet upcall for DOS or time reported
 *         by NPF.SYS on Windows.
 *   put - time when we called pkt_poll_recv().
 *
 * DOS:   the 'put' and 'get' are CPU clock timestamps.
 * WIN32: these are 'timeval' values.
 */
void profile_recv (const uint64 *putp, const uint64 *getp)
{
  uint64 put, get;

  if (!prof_fout || !clocks_per_usec)
     return;

  WATT_ASSERT (putp && getp);

  put = *putp;
  get = *getp;

  fputs ("  profiling pkt_receiver ", prof_fout);
  if (get == U64_SUFFIX(0) || put == U64_SUFFIX(0))
     fputs ("<not enabled>\n", prof_fout);
  else
  {
#if defined(WIN32)
    const struct timeval *tv_get = (const struct timeval*)getp;
    const struct timeval *tv_put = (const struct timeval*)putp;
    double usec   = timeval_diff (tv_get, tv_put);
    int64  clocks = (int64) (usec * clocks_per_usec);

    fprintf (prof_fout, "%10.3f msec (%" S64_FMT " clk)\n",
             usec / 1000.0, clocks);
#else
    int64  clocks = (int64)(get - put);
    double msec   = (double)clocks / ((double)clocks_per_usec * 1000.0);
    fprintf (prof_fout, "%10.3f msec (%" S64_FMT " clk)\n", msec, clocks);
#endif
  }
}

/*
 * Must be called after init_timers() or init_misc().
 */
int profile_init (void)
{
  uint64 overhead, start;
  time_t now;

  if (!profile_enable || !profile_file[0])
     return (0);

  if (!has_rdtsc || !clocks_per_usec)
  {
    profile_enable = FALSE;
    (*_printf) (_LANG("Profiling not available (no RDTSC or $USE_RDTSC=1)\n"));
    return (0);
  }

  prof_fout = fopen (profile_file, "at");
  if (!prof_fout)
  {
    (*_printf) (_LANG("Failed to open %s: %s\n"),
                profile_file, strerror(errno));
    return (0);
  }

#if !defined(__BORLANDC__)  /* buggy output with this */
  {
    static char fbuf [256];
    setvbuf (prof_fout, fbuf, _IOLBF, sizeof(fbuf));  /* line-buffered */
  }
#endif

  now = time (NULL);

  fprintf (prof_fout, "\nProfiling %s, %.15s, %s\n",
           get_argv0(), ctime(&now)+4, dos_extender_name());

  num_profs = 0;
  start = get_rdtsc();
  profile_start ("dummy");
  profile_stop();
  overhead = get_rdtsc() - start;

  fprintf (prof_fout, "  CPU-speed %lu MHz, overhead %" U64_FMT " clocks\n",
           clocks_per_usec, overhead);
  RUNDOWN_ADD (profile_exit, 90);
  return (1);
}

int profile_on (void)
{
  return (prof_fout != NULL);
}
#endif  /* USE_PROFILER */


#if (DOSX) && defined(HAVE_UINT64)
/*
 * Wait for BIOS timer-tick to change 'num' times.
 */
static void Wait_N_ticks (int num)
{
  DWORD tim;

  while (num--)
  {
#if defined(WIN32)
    tim = GetTickCount() + 55;
    while (GetTickCount() < tim)
          Sleep (0);
#else
    tim = PEEKL (0, BIOS_CLK);
    while (PEEKL(0,BIOS_CLK) == tim)
    {
#ifdef __DJGPP__
      ENABLE();    /* CWSDPMI requires this! */
#else
      ((void)0);
#endif
    }
#endif
  }
}

/**
 * Return estimated CPU speed in Hz.
 */
uint64 get_cpu_speed (void)
{
  #define NUM_SAMPLES 3
  #define WAIT_TICKS  2

  uint64 speed;
  uint64 sample [NUM_SAMPLES];
  int    i;

  Wait_N_ticks (1);

  for (i = 0; i < NUM_SAMPLES; i++)
  {
    uint64 start = get_rdtsc();

    Wait_N_ticks (WAIT_TICKS);
    sample[i] = 1000 * (get_rdtsc() - start) / (WAIT_TICKS*55);
  }

  speed = 0;
  for (i = 0; i < NUM_SAMPLES; i++)
      speed += sample[i];
  return (speed / NUM_SAMPLES);
}
#endif  /* DOSX && HAVE_UINT64 */