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////////////////////////////////////////////////////////////////////////

// $Id: virt_timer.cc 11183 2012-05-17 09:11:48Z vruppert $

/////////////////////////////////////////////////////////////////////////

//

//  Copyright (C) 2002-2009  The Bochs Project

//

//  This library is free software; you can redistribute it and/or

//  modify it under the terms of the GNU Lesser General Public

//  License as published by the Free Software Foundation; either

//  version 2 of the License, or (at your option) any later version.

//

//  This library is distributed in the hope that it will be useful,

//  but WITHOUT ANY WARRANTY; without even the implied warranty of

//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

//  Lesser General Public License for more details.

//

//  You should have received a copy of the GNU Lesser General Public

//  License along with this library; if not, write to the Free Software

//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA

////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////

//

//Realtime Algorithm (with gettimeofday)

//  HAVE:

//    Real number of usec.

//    Emulated number of usec.

//  WANT:

//    Number of ticks to use.

//    Number of emulated usec to wait until next try.

//

//  ticks=number of ticks needed to match total real usec.

//  if(desired ticks > max ticks for elapsed real time)

//     ticks = max ticks for elapsed real time.

//  if(desired ticks > max ticks for elapsed emulated usec)

//     ticks = max ticks for emulated usec.

//  next wait ticks = number of ticks until next event.

//  next wait real usec = (current ticks + next wait ticks) * usec per ticks

//  next wait emulated usec = next wait real usec * emulated usec / real usec

//  if(next wait emulated usec < minimum emulated usec for next wait ticks)

//     next wait emulated usec = minimum emulated usec for next wait ticks.

//  if(next wait emulated usec > max emulated usec wait)

//     next wait emulated usec = max emulated usec wait.

//

//  How to calculate elapsed real time:

//    store an unused time value whenever no ticks are used in a given time.

//    add this to the current elapsed time.

//  How to calculate elapsed emulated time:

//    same as above.

//  Above can be done by not updating last_usec and last_sec.

//

//  How to calculate emulated usec/real usec:

//    Each time there are actual ticks:

//      Alpha_product(old emulated usec, emulated usec);

//      Alpha_product(old real usec, real usec);

//    Divide resulting values.

//

/////////////////////////////////////////////////////////////////////////

#include "bochs.h"

#include "param_names.h"

#include "virt_timer.h"

//Important constant #defines:

#define USEC_PER_SECOND (1000000)

// define a macro to convert floating point numbers into 64-bit integers.

// In MSVC++ you can convert a 64-bit float into a 64-bit signed integer,

// but it will not convert a 64-bit float into a 64-bit unsigned integer.

// This macro works around that.

#define F2I(x)  ((Bit64u)(Bit64s) (x))

#define I2F(x)  ((double)(Bit64s) (x))

//CONFIGURATION #defines:

//MAINLINE Configuration (For realtime PIT):

//How much faster than real time we can go:

#define MAX_MULT (1.25)

//Minimum number of emulated useconds per second.

//  Now calculated using BX_MIN_IPS, the minimum number of

//   instructions per second.

#define MIN_USEC_PER_SECOND (((((Bit64u)USEC_PER_SECOND)*((Bit64u)BX_MIN_IPS))/((Bit64u)ips))+(Bit64u)1)

//DEBUG configuration:

//Debug with printf options.

#define DEBUG_REALTIME_WITH_PRINTF 0

#define GET_VIRT_REALTIME64_USEC() (bx_get_realtime64_usec())

//Set up Logging.

#define LOG_THIS bx_virt_timer.

//A single instance.

bx_virt_timer_c bx_virt_timer;

//USEC_ALPHA is multiplier for the past.

//USEC_ALPHA_B is 1-USEC_ALPHA, or multiplier for the present.

#define USEC_ALPHA ((double)(.8))

#define USEC_ALPHA_B ((double)(((double)1)-USEC_ALPHA))

#define USEC_ALPHA2 ((double)(.5))

#define USEC_ALPHA2_B ((double)(((double)1)-USEC_ALPHA2))

#define ALPHA_LOWER(old,new) ((Bit64u)((old<new)?((USEC_ALPHA*(I2F(old)))+(USEC_ALPHA_B*(I2F(new)))):((USEC_ALPHA2*(I2F(old)))+(USEC_ALPHA2_B*(I2F(new))))))

//Conversion between emulated useconds and optionally realtime ticks.

#define TICKS_TO_USEC(a) (((a)*usec_per_second)/ticks_per_second)

#define USEC_TO_TICKS(a) (((a)*ticks_per_second)/usec_per_second)

bx_virt_timer_c::bx_virt_timer_c()

{

  put("virt_timer", "VTIME");

  setup();

}

const Bit64u bx_virt_timer_c::NullTimerInterval = BX_MAX_VIRTUAL_TIME;

void bx_virt_timer_c::nullTimer(void* this_ptr)

{

  UNUSED(this_ptr);

}

void bx_virt_timer_c::periodic(Bit64u time_passed)

{

  //Assert that we haven't skipped any events.

  BX_ASSERT (time_passed <= timers_next_event_time);

  BX_ASSERT(!in_timer_handler);

  //Update time variables.

  timers_next_event_time -= time_passed;

  current_timers_time += time_passed;

  //If no events are occurring, just pass the time and we're done.

  if (time_passed < timers_next_event_time) return;

  //Starting timer handler calls.

  in_timer_handler = 1;

  //Otherwise, cause any events to occur that should.

  unsigned i;

  for (i=0;i<numTimers;i++) {

    if (timer[i].inUse && timer[i].active) {

      //Assert that we haven't skipped any timers.

      BX_ASSERT(current_timers_time <= timer[i].timeToFire);

      if (timer[i].timeToFire == current_timers_time) {

        if (timer[i].continuous) {

          timer[i].timeToFire += timer[i].period;

        } else {

          timer[i].active = 0;

        }

        //This function MUST return, or the timer mechanism

        // will be broken.

        timer[i].funct(timer[i].this_ptr);

      }

    }

  }

  //Finished timer handler calls.

  in_timer_handler = 0;

  //Use a second FOR loop so that a timer function call can

  //  change the behavior of another timer.

  //timers_next_event_time normally contains a cycle count, not a cycle time.

  //  here we use it as a temporary variable that IS a cycle time,

  //  but then convert it back to a cycle count afterwards.

  timers_next_event_time = current_timers_time + BX_MAX_VIRTUAL_TIME;

  for (i=0;i<numTimers;i++) {

    if (timer[i].inUse && timer[i].active && ((timer[i].timeToFire)<timers_next_event_time)) {

      timers_next_event_time = timer[i].timeToFire;

    }

  }

  timers_next_event_time -= current_timers_time;

  next_event_time_update();

  //FIXME

}

//Get the current virtual time.

//  This may return the same value on subsequent calls.

Bit64u bx_virt_timer_c::time_usec()

{

  //Update the time here only if we're not in a timer handler.

  //If we're in a timer handler we're up-to-date, and otherwise

  // this prevents call stack loops.

  if (!in_timer_handler) {

    timer_handler();

  }

  return current_timers_time;

}

//Get the current virtual time.

//  This will return a monotonically increasing value.

// MUST NOT be called from within a timer interrupt.

Bit64u bx_virt_timer_c::time_usec_sequential(void)

{

  //Can't prevent call stack loops here, so this

  // MUST NOT be called from within a timer handler.

  BX_ASSERT(timers_next_event_time>0);

  BX_ASSERT(!in_timer_handler);

  if (last_sequential_time >= current_timers_time) {

    periodic(1);

    last_sequential_time = current_timers_time;

  }

  return current_timers_time;

}

//Register a timer handler to go off after a given interval.

//Register a timer handler to go off with a periodic interval.

int bx_virt_timer_c::register_timer(void *this_ptr, bx_timer_handler_t handler,

                                    Bit32u useconds,

                                    bx_bool continuous, bx_bool active,

                                    const char *id)

{

  //We don't like starting with a zero period timer.

  BX_ASSERT((!active) || (useconds>0));

  //Search for an unused timer.

  unsigned int i;

  for (i=0; i < numTimers; i++) {

    if ((timer[i].inUse == 0) || (i == numTimers))

      break;

  }

  // If we didn't find a free slot, increment the bound, numTimers.

  if (i == numTimers)

    numTimers++; // One new timer installed.

  BX_ASSERT(numTimers<BX_MAX_VIRTUAL_TIMERS);

  timer[i].inUse = 1;

  timer[i].period = useconds;

  timer[i].timeToFire = current_timers_time + (Bit64u)useconds;

  timer[i].active = active;

  timer[i].continuous = continuous;

  timer[i].funct = handler;

  timer[i].this_ptr = this_ptr;

  strncpy(timer[i].id, id, BxMaxTimerIDLen);

  timer[i].id[BxMaxTimerIDLen-1]=0; //I like null terminated strings.

  if (useconds < timers_next_event_time) {

    timers_next_event_time = useconds;

    next_event_time_update();

    //FIXME

  }

  return i;

}

//unregister a previously registered timer.

bx_bool bx_virt_timer_c::unregisterTimer(unsigned timerID)

{

  BX_ASSERT(timerID < BX_MAX_VIRTUAL_TIMERS);

  if (timer[timerID].active) {

    BX_PANIC(("unregisterTimer: timer '%s' is still active!", timer[timerID].id));

    return(0); // Fail.

  }

  //No need to prevent doing this to unused timers.

  timer[timerID].inUse = 0;

  if (timerID == (numTimers-1)) numTimers--;

  return 1;

}

void bx_virt_timer_c::start_timers(void)

{

  //FIXME

}

//activate a deactivated but registered timer.

void bx_virt_timer_c::activate_timer(unsigned timer_index, Bit32u useconds,

                                     bx_bool continuous)

{

  BX_ASSERT(timer_index < BX_MAX_VIRTUAL_TIMERS);

  BX_ASSERT(timer[timer_index].inUse);

  BX_ASSERT(useconds>0);

  timer[timer_index].period = useconds;

  timer[timer_index].timeToFire = current_timers_time + (Bit64u)useconds;

  timer[timer_index].active = 1;

  timer[timer_index].continuous = continuous;

  if (useconds < timers_next_event_time) {

    timers_next_event_time = useconds;

    next_event_time_update();

    //FIXME

  }

}

//deactivate (but don't unregister) a currently registered timer.

void bx_virt_timer_c::deactivate_timer(unsigned timer_index)

{

  BX_ASSERT(timer_index < BX_MAX_VIRTUAL_TIMERS);

  //No need to prevent doing this to unused/inactive timers.

  timer[timer_index].active = 0;

}

void bx_virt_timer_c::advance_virtual_time(Bit64u time_passed)

{

  BX_ASSERT(time_passed <= virtual_next_event_time);

  current_virtual_time += time_passed;

  virtual_next_event_time -= time_passed;

  if (current_virtual_time > current_timers_time) {

    periodic(current_virtual_time - current_timers_time);

  }

}

//Called when next_event_time changes.

void bx_virt_timer_c::next_event_time_update(void)

{

  virtual_next_event_time = timers_next_event_time + current_timers_time - current_virtual_time;

  if (init_done) {

    bx_pc_system.deactivate_timer(system_timer_id);

    BX_ASSERT(virtual_next_event_time);

    bx_pc_system.activate_timer(system_timer_id,

                                (Bit32u)BX_MIN(0x7FFFFFFF,BX_MAX(1,TICKS_TO_USEC(virtual_next_event_time))),

                                0);

  }

}

void bx_virt_timer_c::setup(void)

{

  numTimers = 0;

  current_timers_time = 0;

  timers_next_event_time = BX_MAX_VIRTUAL_TIME;

  last_sequential_time = 0;

  in_timer_handler = 0;

  virtual_next_event_time = BX_MAX_VIRTUAL_TIME;

  current_virtual_time = 0;

  init_done = 0;

}

void bx_virt_timer_c::init(void)

{

  if ((SIM->get_param_enum(BXPN_CLOCK_SYNC)->get()!=BX_CLOCK_SYNC_REALTIME) &&

      (SIM->get_param_enum(BXPN_CLOCK_SYNC)->get()!=BX_CLOCK_SYNC_BOTH))

    virtual_timers_realtime = 0;

  else

    virtual_timers_realtime = 1;

  if (virtual_timers_realtime) {

    BX_INFO(("using 'realtime pit' synchronization method"));

  }

  // Local copy of IPS value to avoid reading it frequently in timer handler

  ips = SIM->get_param_num(BXPN_IPS)->get();

  register_timer(this, nullTimer, (Bit32u)NullTimerInterval, 1, 1, "Null Timer");

  system_timer_id = bx_pc_system.register_timer(this, pc_system_timer_handler,

                                                (Bit32u)virtual_next_event_time, 0, 1, "Virtual Timer");

  //Real time variables:

#if BX_HAVE_REALTIME_USEC

  last_real_time = GET_VIRT_REALTIME64_USEC();

#endif

  total_real_usec = 0;

  last_realtime_delta = 0;

  real_time_delay = 0;

  //System time variables:

  last_usec = 0;

  usec_per_second = USEC_PER_SECOND;

  stored_delta = 0;

  last_system_usec = 0;

  em_last_realtime = 0;

  //Virtual timer variables:

  total_ticks = 0;

  last_realtime_ticks = 0;

  ticks_per_second = USEC_PER_SECOND;

  init_done = 1;

}

void bx_virt_timer_c::register_state(void)

{

  bx_list_c *list = new bx_list_c(SIM->get_bochs_root(), "virt_timer", "Virtual Timer State");

  bx_list_c *vtimers = new bx_list_c(list, "timer");

  for (unsigned i = 0; i < numTimers; i++) {

    char name[4];

    sprintf(name, "%d", i);

    bx_list_c *bxtimer = new bx_list_c(vtimers, name);

    BXRS_PARAM_BOOL(bxtimer, inUse, timer[i].inUse);

    BXRS_DEC_PARAM_FIELD(bxtimer, period, timer[i].period);

    BXRS_DEC_PARAM_FIELD(bxtimer, timeToFire, timer[i].timeToFire);

    BXRS_PARAM_BOOL(bxtimer, active, timer[i].active);

    BXRS_PARAM_BOOL(bxtimer, continuous, timer[i].continuous);

  }

  BXRS_DEC_PARAM_SIMPLE(list, current_timers_time);

  BXRS_DEC_PARAM_SIMPLE(list, timers_next_event_time);

  BXRS_DEC_PARAM_SIMPLE(list, last_sequential_time);

  BXRS_DEC_PARAM_SIMPLE(list, virtual_next_event_time);

  BXRS_DEC_PARAM_SIMPLE(list, current_virtual_time);

  BXRS_DEC_PARAM_SIMPLE(list, last_real_time);

  BXRS_DEC_PARAM_SIMPLE(list, total_real_usec);

  BXRS_DEC_PARAM_SIMPLE(list, last_realtime_delta);

  BXRS_DEC_PARAM_SIMPLE(list, last_usec);

  BXRS_DEC_PARAM_SIMPLE(list, usec_per_second);

  BXRS_DEC_PARAM_SIMPLE(list, stored_delta);

  BXRS_DEC_PARAM_SIMPLE(list, last_system_usec);

  BXRS_DEC_PARAM_SIMPLE(list, em_last_realtime);

  BXRS_DEC_PARAM_SIMPLE(list, total_ticks);

  BXRS_DEC_PARAM_SIMPLE(list, last_realtime_ticks);

  BXRS_DEC_PARAM_SIMPLE(list, ticks_per_second);

}

void bx_virt_timer_c::timer_handler(void)

{

  if (!virtual_timers_realtime) {

    Bit64u temp_final_time = bx_pc_system.time_usec();

    temp_final_time -= current_virtual_time;

    while (temp_final_time) {

      if ((temp_final_time)>(virtual_next_event_time)) {

        temp_final_time -= virtual_next_event_time;

        advance_virtual_time(virtual_next_event_time);

      } else {

        advance_virtual_time(temp_final_time);

        temp_final_time -= temp_final_time;

      }

    }

    bx_pc_system.activate_timer(system_timer_id,

                                (Bit32u)BX_MIN(0x7FFFFFFF,(virtual_next_event_time>2)?(virtual_next_event_time-2):1),

                                0);

    return;

  }

  Bit64u usec_delta = bx_pc_system.time_usec()-last_usec;

  if (usec_delta) {

#if BX_HAVE_REALTIME_USEC

    Bit64u ticks_delta = 0;

    Bit64u real_time_delta = GET_VIRT_REALTIME64_USEC() - last_real_time - real_time_delay;

    Bit64u real_time_total = real_time_delta + total_real_usec;

    Bit64u system_time_delta = (Bit64u)usec_delta + (Bit64u)stored_delta;

    if (real_time_delta) {

      last_realtime_delta = real_time_delta;

      last_realtime_ticks = total_ticks;

    }

    ticks_per_second = USEC_PER_SECOND;

    //Start out with the number of ticks we would like

    // to have to line up with real time.

    ticks_delta = real_time_total - total_ticks;

    if (real_time_total < total_ticks) {

      //This slows us down if we're already ahead.

      //  probably only an issue on startup, but it solves some problems.

      ticks_delta = 0;

    }

    if (ticks_delta + total_ticks - last_realtime_ticks > (F2I(MAX_MULT * I2F(last_realtime_delta)))) {

      //This keeps us from going too fast in relation to real time.

#if 0

      ticks_delta = (F2I(MAX_MULT * I2F(last_realtime_delta))) + last_realtime_ticks - total_ticks;

#endif

      ticks_per_second = F2I(MAX_MULT * I2F(USEC_PER_SECOND));

    }

    if (ticks_delta > system_time_delta * USEC_PER_SECOND / MIN_USEC_PER_SECOND) {

      //This keeps us from having too few instructions between ticks.

      ticks_delta = system_time_delta * USEC_PER_SECOND / MIN_USEC_PER_SECOND;

    }

    if (ticks_delta > virtual_next_event_time) {

      //This keeps us from missing ticks.

      ticks_delta = virtual_next_event_time;

    }

    if (ticks_delta) {

#  if DEBUG_REALTIME_WITH_PRINTF

      //Every second print some info.

      if (((last_real_time + real_time_delta) / USEC_PER_SECOND) > (last_real_time / USEC_PER_SECOND)) {

        Bit64u temp1, temp2, temp3, temp4;

        temp1 = (Bit64u) total_real_usec;

        temp2 = (total_real_usec);

        temp3 = (Bit64u)total_ticks;

        temp4 = (Bit64u)((total_real_usec) - total_ticks);

        printf("useconds: " FMT_LL "u, ", temp1);

        printf("expect ticks: " FMT_LL "u, ", temp2);

        printf("ticks: " FMT_LL "u, ", temp3);

        printf("diff: "FMT_LL "u\n", temp4);

      }

#  endif

      last_real_time += real_time_delta;

      total_real_usec += real_time_delta;

      last_system_usec += system_time_delta;

      stored_delta = 0;

      total_ticks += ticks_delta;

    } else {

      stored_delta = system_time_delta;

    }

    Bit64u a = usec_per_second, b;

    if (real_time_delta) {

      //FIXME

      Bit64u em_realtime_delta = last_system_usec + stored_delta - em_last_realtime;

      b=((Bit64u)USEC_PER_SECOND * em_realtime_delta / real_time_delta);

      em_last_realtime = last_system_usec + stored_delta;

    } else {

      b=a;

    }

    usec_per_second = ALPHA_LOWER(a,b);

#else

    BX_ASSERT(0);

#endif

#if BX_HAVE_REALTIME_USEC

    advance_virtual_time(ticks_delta);

#endif

  }

  last_usec=last_usec + usec_delta;

  bx_pc_system.deactivate_timer(system_timer_id);

  BX_ASSERT(virtual_next_event_time);

  bx_pc_system.activate_timer(system_timer_id,

                              (Bit32u)BX_MIN(0x7FFFFFFF,BX_MAX(1,TICKS_TO_USEC(virtual_next_event_time))),

                              0);

}

void bx_virt_timer_c::pc_system_timer_handler(void* this_ptr)

{

  ((bx_virt_timer_c *)this_ptr)->timer_handler();

}

void bx_virt_timer_c::set_realtime_delay()

{

  if (virtual_timers_realtime) {

    real_time_delay = GET_VIRT_REALTIME64_USEC() - last_real_time;

  }

}