// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************
schedule.c
Core device execution and scheduling engine.
***************************************************************************/
#include "emu.h"
#include "debugger.h"
//**************************************************************************
// DEBUGGING
//**************************************************************************
#define VERBOSE 0
#define LOG(...) do { if (VERBOSE) machine().logerror(__VA_ARGS__); } while (0)
#define PRECISION
//**************************************************************************
// CONSTANTS
//**************************************************************************
// internal trigger IDs
enum
{
TRIGGER_INT = -2000,
TRIGGER_YIELDTIME = -3000,
TRIGGER_SUSPENDTIME = -4000
};
//**************************************************************************
// EMU TIMER
//**************************************************************************
//-------------------------------------------------
// emu_timer - constructor
//-------------------------------------------------
emu_timer::emu_timer() :
m_machine(nullptr),
m_next(nullptr),
m_prev(nullptr),
m_param(0),
m_ptr(nullptr),
m_enabled(false),
m_temporary(false),
m_period(attotime::zero),
m_start(attotime::zero),
m_expire(attotime::never),
m_device(nullptr),
m_id(0)
{
}
//-------------------------------------------------
// ~emu_timer - destructor
//-------------------------------------------------
emu_timer::~emu_timer()
{
}
//-------------------------------------------------
// init - completely initialize the state when
// re-allocated as a non-device timer
//-------------------------------------------------
inline emu_timer &emu_timer::init(running_machine &machine, timer_expired_delegate callback, void *ptr, bool temporary)
{
// ensure the entire timer state is clean
m_machine = &machine;
m_next = nullptr;
m_prev = nullptr;
m_callback = callback;
m_param = 0;
m_ptr = ptr;
m_enabled = false;
m_temporary = temporary;
m_period = attotime::never;
m_start = machine.time();
m_expire = attotime::never;
m_device = nullptr;
m_id = 0;
// if we're not temporary, register ourselves with the save state system
if (!m_temporary)
register_save();
// insert into the list
machine.scheduler().timer_list_insert(*this);
return *this;
}
//-------------------------------------------------
// init - completely initialize the state when
// re-allocated as a device timer
//-------------------------------------------------
inline emu_timer &emu_timer::init(device_t &device, device_timer_id id, void *ptr, bool temporary)
{
// ensure the entire timer state is clean
m_machine = &device.machine();
m_next = nullptr;
m_prev = nullptr;
m_callback = timer_expired_delegate(FUNC(emu_timer::device_timer_expired), this);
m_param = 0;
m_ptr = ptr;
m_enabled = false;
m_temporary = temporary;
m_period = attotime::never;
m_start = machine().time();
m_expire = attotime::never;
m_device = &device;
m_id = id;
// if we're not temporary, register ourselves with the save state system
if (!m_temporary)
register_save();
// insert into the list
machine().scheduler().timer_list_insert(*this);
return *this;
}
//-------------------------------------------------
// release - release us from the global list
// management when deallocating
//-------------------------------------------------
inline emu_timer &emu_timer::release()
{
// unhook us from the global list
machine().scheduler().timer_list_remove(*this);
return *this;
}
//-------------------------------------------------
// enable - enable/disable a timer
//-------------------------------------------------
bool emu_timer::enable(bool enable)
{
// reschedule only if the state has changed
const bool old = m_enabled;
if (old != enable)
{
// set the enable flag
m_enabled = enable;
// remove the timer and insert back into the list
machine().scheduler().timer_list_remove(*this);
machine().scheduler().timer_list_insert(*this);
}
return old;
}
//-------------------------------------------------
// adjust - adjust the time when this timer will
// fire and specify a period for subsequent
// firings
//-------------------------------------------------
void emu_timer::adjust(attotime start_delay, s32 param, const attotime &period)
{
// if this is the callback timer, mark it modified
device_scheduler &scheduler = machine().scheduler();
if (scheduler.m_callback_timer == this)
scheduler.m_callback_timer_modified = true;
// compute the time of the next firing and insert into the list
m_param = param;
m_enabled = true;
// clamp negative times to 0
if (start_delay.seconds() < 0)
start_delay = attotime::zero;
// set the start and expire times
m_start = scheduler.time();
m_expire = m_start + start_delay;
m_period = period;
// remove and re-insert the timer in its new order
scheduler.timer_list_remove(*this);
scheduler.timer_list_insert(*this);
// if this was inserted as the head, abort the current timeslice and resync
if (this == scheduler.first_timer())
scheduler.abort_timeslice();
}
//-------------------------------------------------
// elapsed - return the amount of time since the
// timer was started
//-------------------------------------------------
attotime emu_timer::elapsed() const noexcept
{
return machine().time() - m_start;
}
//-------------------------------------------------
// remaining - return the amount of time
// remaining until the timer expires
//-------------------------------------------------
attotime emu_timer::remaining() const noexcept
{
attotime curtime = machine().time();
if (curtime >= m_expire)
return attotime::zero;
return m_expire - curtime;
}
//-------------------------------------------------
// register_save - register ourself with the save
// state system
//-------------------------------------------------
void emu_timer::register_save()
{
// determine our instance number and name
int index = 0;
std::string name;
// for non-device timers, it is an index based on the callback function name
if (m_device == nullptr)
{
name = m_callback.name() ? m_callback.name() : "unnamed";
for (emu_timer *curtimer = machine().scheduler().first_timer(); curtimer != nullptr; curtimer = curtimer->next())
if (!curtimer->m_temporary && curtimer->m_device == nullptr)
{
if (curtimer->m_callback.name() != nullptr && m_callback.name() != nullptr && strcmp(curtimer->m_callback.name(), m_callback.name()) == 0)
index++;
else if (curtimer->m_callback.name() == nullptr && m_callback.name() == nullptr)
index++;
}
}
// for device timers, it is an index based on the device and timer ID
else
{
name = string_format("%s/%d", m_device->tag(), m_id);
for (emu_timer *curtimer = machine().scheduler().first_timer(); curtimer != nullptr; curtimer = curtimer->next())
if (!curtimer->m_temporary && curtimer->m_device != nullptr && curtimer->m_device == m_device && curtimer->m_id == m_id)
index++;
}
// save the bits
machine().save().save_item(m_device, "timer", name.c_str(), index, NAME(m_param));
machine().save().save_item(m_device, "timer", name.c_str(), index, NAME(m_enabled));
machine().save().save_item(m_device, "timer", name.c_str(), index, NAME(m_period));
machine().save().save_item(m_device, "timer", name.c_str(), index, NAME(m_start));
machine().save().save_item(m_device, "timer", name.c_str(), index, NAME(m_expire));
}
//-------------------------------------------------
// schedule_next_period - schedule the next
// period
//-------------------------------------------------
inline void emu_timer::schedule_next_period()
{
// advance by one period
m_start = m_expire;
m_expire += m_period;
// remove and re-insert us
device_scheduler &scheduler = machine().scheduler();
scheduler.timer_list_remove(*this);
scheduler.timer_list_insert(*this);
}
//-------------------------------------------------
// dump - dump internal state to a single output
// line in the error log
//-------------------------------------------------
void emu_timer::dump() const
{
machine().logerror("%p: en=%d temp=%d exp=%15s start=%15s per=%15s param=%d ptr=%p", this, m_enabled, m_temporary, m_expire.as_string(PRECISION), m_start.as_string(PRECISION), m_period.as_string(PRECISION), m_param, m_ptr);
if (m_device == nullptr)
if (m_callback.name() == nullptr)
machine().logerror(" cb=NULL\n");
else
machine().logerror(" cb=%s\n", m_callback.name());
else
machine().logerror(" dev=%s id=%d\n", m_device->tag(), m_id);
}
//-------------------------------------------------
// device_timer_expired - trampoline to avoid a
// conditional jump on the hot path
//-------------------------------------------------
void emu_timer::device_timer_expired(emu_timer &timer, void *ptr, s32 param)
{
timer.m_device->timer_expired(timer, timer.m_id, param, ptr);
}
//**************************************************************************
// DEVICE SCHEDULER
//**************************************************************************
//-------------------------------------------------
// device_scheduler - constructor
//-------------------------------------------------
device_scheduler::device_scheduler(running_machine &machine) :
m_machine(machine),
m_executing_device(nullptr),
m_execute_list(nullptr),
m_basetime(attotime::zero),
m_timer_list(nullptr),
m_callback_timer(nullptr),
m_callback_timer_modified(false),
m_callback_timer_expire_time(attotime::zero),
m_suspend_changes_pending(true),
m_quantum_minimum(ATTOSECONDS_IN_NSEC(1) / 1000)
{
// append a single never-expiring timer so there is always one in the list
m_timer_list = &m_timer_allocator.alloc()->init(machine, timer_expired_delegate(), nullptr, true);
m_timer_list->adjust(attotime::never);
// register global states
machine.save().save_item(NAME(m_basetime));
machine.save().register_presave(save_prepost_delegate(FUNC(device_scheduler::presave), this));
machine.save().register_postload(save_prepost_delegate(FUNC(device_scheduler::postload), this));
}
//-------------------------------------------------
// device_scheduler - destructor
//-------------------------------------------------
device_scheduler::~device_scheduler()
{
// remove all timers
while (m_timer_list != nullptr)
m_timer_allocator.reclaim(m_timer_list->release());
}
//-------------------------------------------------
// time - return the current time
//-------------------------------------------------
attotime device_scheduler::time() const noexcept
{
// if we're currently in a callback, use the timer's expiration time as a base
if (m_callback_timer != nullptr)
return m_callback_timer_expire_time;
// if we're executing as a particular CPU, use its local time as a base
// otherwise, return the global base time
return (m_executing_device != nullptr) ? m_executing_device->local_time() : m_basetime;
}
//-------------------------------------------------
// can_save - return true if it's safe to save
// (i.e., no temporary timers outstanding)
//-------------------------------------------------
bool device_scheduler::can_save() const
{
// if any live temporary timers exit, fail
for (emu_timer *timer = m_timer_list; timer != nullptr; timer = timer->next())
if (timer->m_temporary && !timer->expire().is_never())
{
machine().logerror("Failed save state attempt due to anonymous timers:\n");
dump_timers();
return false;
}
// otherwise, we're good
return true;
}
//-------------------------------------------------
// apply_suspend_changes - applies suspend/resume
// changes to all device_execute_interfaces
//-------------------------------------------------
inline void device_scheduler::apply_suspend_changes()
{
u32 suspendchanged = 0;
for (device_execute_interface *exec = m_execute_list; exec != nullptr; exec = exec->m_nextexec)
{
suspendchanged |= exec->m_suspend ^ exec->m_nextsuspend;
exec->m_suspend = exec->m_nextsuspend;
exec->m_nextsuspend &= ~SUSPEND_REASON_TIMESLICE;
exec->m_eatcycles = exec->m_nexteatcycles;
}
// recompute the execute list if any CPUs changed their suspension state
if (suspendchanged != 0)
rebuild_execute_list();
else
m_suspend_changes_pending = false;
}
//-------------------------------------------------
// timeslice - execute all devices for a single
// timeslice
//-------------------------------------------------
void device_scheduler::timeslice()
{
bool call_debugger = ((machine().debug_flags & DEBUG_FLAG_ENABLED) != 0);
// build the execution list if we don't have one yet
if (UNEXPECTED(m_execute_list == nullptr))
rebuild_execute_list();
// if the current quantum has expired, find a new one
while (m_basetime >= m_quantum_list.first()->m_expire)
m_quantum_allocator.reclaim(m_quantum_list.detach_head());
// loop until we hit the next timer
while (m_basetime < m_timer_list->m_expire)
{
// by default, assume our target is the end of the next quantum
attotime target(m_basetime + attotime(0, m_quantum_list.first()->m_actual));
// however, if the next timer is going to fire before then, override
if (m_timer_list->m_expire < target)
target = m_timer_list->m_expire;
LOG("------------------\n");
LOG("cpu_timeslice: target = %s\n", target.as_string(PRECISION));
// do we have pending suspension changes?
if (m_suspend_changes_pending)
apply_suspend_changes();
// loop over all CPUs
for (device_execute_interface *exec = m_execute_list; exec != nullptr; exec = exec->m_nextexec)
{
// only process if this CPU is executing or truly halted (not yielding)
// and if our target is later than the CPU's current time (coarse check)
if (EXPECTED((exec->m_suspend == 0 || exec->m_eatcycles) && target.seconds() >= exec->m_localtime.seconds()))
{
// compute how many attoseconds to execute this CPU
attoseconds_t delta = target.attoseconds() - exec->m_localtime.attoseconds();
if (delta < 0 && target.seconds() > exec->m_localtime.seconds())
delta += ATTOSECONDS_PER_SECOND;
assert(delta == (target - exec->m_localtime).as_attoseconds());
if (exec->m_attoseconds_per_cycle == 0)
{
exec->m_localtime = target;
}
// if we have enough for at least 1 cycle, do the math
else if (delta >= exec->m_attoseconds_per_cycle)
{
// compute how many cycles we want to execute
int ran = exec->m_cycles_running = divu_64x32(u64(delta) >> exec->m_divshift, exec->m_divisor);
LOG(" cpu '%s': %d (%d cycles)\n", exec->device().tag(), delta, exec->m_cycles_running);
// if we're not suspended, actually execute
if (exec->m_suspend == 0)
{
g_profiler.start(exec->m_profiler);
// note that this global variable cycles_stolen can be modified
// via the call to cpu_execute
exec->m_cycles_stolen = 0;
m_executing_device = exec;
*exec->m_icountptr = exec->m_cycles_running;
if (!call_debugger)
exec->run();
else
{
exec->debugger_start_cpu_hook(target);
exec->run();
exec->debugger_stop_cpu_hook();
}
// adjust for any cycles we took back
assert(ran >= *exec->m_icountptr);
ran -= *exec->m_icountptr;
assert(ran >= exec->m_cycles_stolen);
ran -= exec->m_cycles_stolen;
g_profiler.stop();
}
// account for these cycles
exec->m_totalcycles += ran;
// update the local time for this CPU
attotime deltatime;
if (ran < exec->m_cycles_per_second)
deltatime = attotime(0, exec->m_attoseconds_per_cycle * ran);
else
{
u32 remainder;
s32 secs = divu_64x32_rem(ran, exec->m_cycles_per_second, &remainder);
deltatime = attotime(secs, u64(remainder) * exec->m_attoseconds_per_cycle);
}
assert(deltatime >= attotime::zero);
exec->m_localtime += deltatime;
LOG(" %d ran, %d total, time = %s\n", ran, s32(exec->m_totalcycles), exec->m_localtime.as_string(PRECISION));
// if the new local CPU time is less than our target, move the target up, but not before the base
if (exec->m_localtime < target)
{
target = std::max(exec->m_localtime, m_basetime);
LOG(" (new target)\n");
}
}
}
}
m_executing_device = nullptr;
// update the base time
m_basetime = target;
}
// execute timers
execute_timers();
}
//-------------------------------------------------
// abort_timeslice - abort execution for the
// current timeslice
//-------------------------------------------------
void device_scheduler::abort_timeslice()
{
if (m_executing_device != nullptr)
m_executing_device->abort_timeslice();
}
//-------------------------------------------------
// trigger - generate a global trigger
//-------------------------------------------------
void device_scheduler::trigger(int trigid, const attotime &after)
{
// ensure we have a list of executing devices
if (m_execute_list == nullptr)
rebuild_execute_list();
// if we have a non-zero time, schedule a timer
if (after != attotime::zero)
timer_set(after, timer_expired_delegate(FUNC(device_scheduler::timed_trigger), this), trigid);
// send the trigger to everyone who cares
else
for (device_execute_interface *exec = m_execute_list; exec != nullptr; exec = exec->m_nextexec)
exec->trigger(trigid);
}
//-------------------------------------------------
// boost_interleave - temporarily boosts the
// interleave factor
//-------------------------------------------------
void device_scheduler::boost_interleave(const attotime ×lice_time, const attotime &boost_duration)
{
// ignore timeslices > 1 second
if (timeslice_time.seconds() > 0)
return;
add_scheduling_quantum(timeslice_time, boost_duration);
}
//-------------------------------------------------
// timer_alloc - allocate a global non-device
// timer and return a pointer
//-------------------------------------------------
emu_timer *device_scheduler::timer_alloc(timer_expired_delegate callback, void *ptr)
{
return &m_timer_allocator.alloc()->init(machine(), callback, ptr, false);
}
//-------------------------------------------------
// timer_set - allocate an anonymous non-device
// timer and set it to go off after the given
// amount of time
//-------------------------------------------------
void device_scheduler::timer_set(const attotime &duration, timer_expired_delegate callback, int param, void *ptr)
{
m_timer_allocator.alloc()->init(machine(), callback, ptr, true).adjust(duration, param);
}
//-------------------------------------------------
// timer_alloc - allocate a global device timer
// and return a pointer
//-------------------------------------------------
emu_timer *device_scheduler::timer_alloc(device_t &device, device_timer_id id, void *ptr)
{
return &m_timer_allocator.alloc()->init(device, id, ptr, false);
}
//-------------------------------------------------
// timer_set - allocate an anonymous device timer
// and set it to go off after the given amount of
// time
//-------------------------------------------------
void device_scheduler::timer_set(const attotime &duration, device_t &device, device_timer_id id, int param, void *ptr)
{
m_timer_allocator.alloc()->init(device, id, ptr, true).adjust(duration, param);
}
//-------------------------------------------------
// eat_all_cycles - eat a ton of cycles on all
// CPUs to force a quick exit
//-------------------------------------------------
void device_scheduler::eat_all_cycles()
{
for (device_execute_interface *exec = m_execute_list; exec != nullptr; exec = exec->m_nextexec)
exec->eat_cycles(1000000000);
}
//-------------------------------------------------
// timed_trigger - generate a trigger after a
// given amount of time
//-------------------------------------------------
void device_scheduler::timed_trigger(void *ptr, s32 param)
{
trigger(param);
}
//-------------------------------------------------
// presave - before creating a save state
//-------------------------------------------------
void device_scheduler::presave()
{
// report the timer state after a log
LOG("Prior to saving state:\n");
#if VERBOSE
dump_timers();
#endif
}
//-------------------------------------------------
// postload - after loading a save state
//-------------------------------------------------
void device_scheduler::postload()
{
// remove all timers and make a private list of permanent ones
simple_list<emu_timer> private_list;
while (m_timer_list != nullptr)
{
emu_timer &timer = *m_timer_list;
// temporary timers go away entirely (except our special never-expiring one)
if (timer.m_temporary && !timer.expire().is_never())
m_timer_allocator.reclaim(timer.release());
// permanent ones get added to our private list
else
private_list.append(timer_list_remove(timer));
}
// now re-insert them; this effectively re-sorts them by time
emu_timer *timer;
while ((timer = private_list.detach_head()) != nullptr)
timer_list_insert(*timer);
m_suspend_changes_pending = true;
rebuild_execute_list();
// report the timer state after a log
LOG("After resetting/reordering timers:\n");
#if VERBOSE
dump_timers();
#endif
}
//-------------------------------------------------
// compute_perfect_interleave - compute the
// "perfect" interleave interval
//-------------------------------------------------
void device_scheduler::compute_perfect_interleave()
{
// ensure we have a list of executing devices
if (m_execute_list == nullptr)
rebuild_execute_list();
// start with the first one
device_execute_interface *first = m_execute_list;
if (first != nullptr)
{
// start with a huge time factor and find the 2nd smallest cycle time
attoseconds_t smallest = first->minimum_quantum();
attoseconds_t perfect = ATTOSECONDS_PER_SECOND - 1;
for (device_execute_interface *exec = first->m_nextexec; exec != nullptr; exec = exec->m_nextexec)
{
// find the 2nd smallest cycle interval
attoseconds_t curquantum = exec->minimum_quantum();
if (curquantum < smallest)
{
perfect = smallest;
smallest = curquantum;
}
else if (curquantum < perfect)
perfect = curquantum;
}
// if this is a new minimum quantum, apply it
if (m_quantum_minimum != perfect)
{
// adjust all the actuals; this doesn't affect the current
m_quantum_minimum = perfect;
for (quantum_slot &quant : m_quantum_list)
quant.m_actual = std::max(quant.m_requested, m_quantum_minimum);
}
}
}
//-------------------------------------------------
// rebuild_execute_list - rebuild the list of
// executing CPUs, moving suspended CPUs to the
// end
//-------------------------------------------------
void device_scheduler::rebuild_execute_list()
{
// if we haven't yet set a scheduling quantum, do it now
if (m_quantum_list.empty())
{
// set the core scheduling quantum, ensuring it's no longer than 60Hz
attotime min_quantum = machine().config().maximum_quantum(attotime::from_hz(60));
// if the configuration specifies a device to make perfect, pick that as the minimum
device_execute_interface *const exec(machine().config().perfect_quantum_device());
if (exec)
min_quantum = (std::min)(attotime(0, exec->minimum_quantum()), min_quantum);
// inform the timer system of our decision
add_scheduling_quantum(min_quantum, attotime::never);
}
// start with an empty list
device_execute_interface **active_tailptr = &m_execute_list;
*active_tailptr = nullptr;
// also make an empty list of suspended devices
device_execute_interface *suspend_list = nullptr;
device_execute_interface **suspend_tailptr = &suspend_list;
// iterate over all devices
for (device_execute_interface &exec : execute_interface_iterator(machine().root_device()))
{
// append to the appropriate list
exec.m_nextexec = nullptr;
if (exec.m_suspend == 0)
{
*active_tailptr = &exec;
active_tailptr = &exec.m_nextexec;
}
else
{
*suspend_tailptr = &exec;
suspend_tailptr = &exec.m_nextexec;
}
}
// append the suspend list to the end of the active list
*active_tailptr = suspend_list;
}
//-------------------------------------------------
// timer_list_insert - insert a new timer into
// the list at the appropriate location
//-------------------------------------------------
inline emu_timer &device_scheduler::timer_list_insert(emu_timer &timer)
{
// disabled timers sort to the end
const attotime expire = timer.m_enabled ? timer.m_expire : attotime::never;
// loop over the timer list
emu_timer *prevtimer = nullptr;
for (emu_timer *curtimer = m_timer_list; curtimer != nullptr; prevtimer = curtimer, curtimer = curtimer->next())
{
// if the current list entry expires after us, we should be inserted before it
if (curtimer->m_expire > expire)
{
// link the new guy in before the current list entry
timer.m_prev = prevtimer;
timer.m_next = curtimer;
if (prevtimer != nullptr)
prevtimer->m_next = &timer;
else
m_timer_list = &timer;
curtimer->m_prev = &timer;
return timer;
}
}
// need to insert after the last one
if (prevtimer != nullptr)
prevtimer->m_next = &timer;
else
m_timer_list = &timer;
timer.m_prev = prevtimer;
timer.m_next = nullptr;
return timer;
}
//-------------------------------------------------
// timer_list_remove - remove a timer from the
// linked list
//-------------------------------------------------
inline emu_timer &device_scheduler::timer_list_remove(emu_timer &timer)
{
// remove it from the list
if (timer.m_prev != nullptr)
timer.m_prev->m_next = timer.m_next;
else
m_timer_list = timer.m_next;
if (timer.m_next != nullptr)
timer.m_next->m_prev = timer.m_prev;
return timer;
}
//-------------------------------------------------
// execute_timers - execute timers that are due
//-------------------------------------------------
inline void device_scheduler::execute_timers()
{
LOG("execute_timers: new=%s head->expire=%s\n", m_basetime.as_string(PRECISION), m_timer_list->m_expire.as_string(PRECISION));
// now process any timers that are overdue
while (m_timer_list->m_expire <= m_basetime)
{
// if this is a one-shot timer, disable it now
emu_timer &timer = *m_timer_list;
bool was_enabled = timer.m_enabled;
if (timer.m_period.is_zero() || timer.m_period.is_never())
timer.m_enabled = false;
// set the global state of which callback we're in
m_callback_timer_modified = false;
m_callback_timer = &timer;
m_callback_timer_expire_time = timer.m_expire;
// call the callback
if (was_enabled)
{
g_profiler.start(PROFILER_TIMER_CALLBACK);
if (!timer.m_callback.isnull())
{
if (timer.m_device != nullptr)
LOG("execute_timers: timer device %s timer %d\n", timer.m_device->tag(), timer.m_id);
else
LOG("execute_timers: timer callback %s\n", timer.m_callback.name());
timer.m_callback(timer.m_ptr, timer.m_param);
}
g_profiler.stop();
}
// reset or remove the timer, but only if it wasn't modified during the callback
if (!m_callback_timer_modified)
{
// if the timer is temporary, remove it now
if (timer.m_temporary)
m_timer_allocator.reclaim(timer.release());
// otherwise, reschedule it
else
timer.schedule_next_period();
}
}
// clear the callback timer global
m_callback_timer = nullptr;
}
//-------------------------------------------------
// add_scheduling_quantum - add a scheduling
// quantum; the smallest active one is the one
// that is in use
//-------------------------------------------------
void device_scheduler::add_scheduling_quantum(const attotime &quantum, const attotime &duration)
{
assert(quantum.seconds() == 0);
attotime curtime = time();
attotime expire = curtime + duration;
const attoseconds_t quantum_attos = quantum.attoseconds();
// figure out where to insert ourselves, expiring any quanta that are out-of-date
quantum_slot *insert_after = nullptr;
quantum_slot *next;
for (quantum_slot *quant = m_quantum_list.first(); quant != nullptr; quant = next)
{
// if this quantum is expired, nuke it
next = quant->next();
if (curtime >= quant->m_expire)
m_quantum_allocator.reclaim(m_quantum_list.detach(*quant));
// if this quantum is shorter than us, we need to be inserted afterwards
else if (quant->m_requested <= quantum_attos)
insert_after = quant;
}
// if we found an exact match, just take the maximum expiry time
if (insert_after != nullptr && insert_after->m_requested == quantum_attos)
insert_after->m_expire = std::max(insert_after->m_expire, expire);
// otherwise, allocate a new quantum and insert it after the one we picked
else
{
quantum_slot &quant = *m_quantum_allocator.alloc();
quant.m_requested = quantum_attos;
quant.m_actual = std::max(quantum_attos, m_quantum_minimum);
quant.m_expire = expire;
m_quantum_list.insert_after(quant, insert_after);
}
}
//-------------------------------------------------
// dump_timers - dump the current timer state
//-------------------------------------------------
void device_scheduler::dump_timers() const
{
machine().logerror("=============================================\n");
machine().logerror("Timer Dump: Time = %15s\n", time().as_string(PRECISION));
for (emu_timer *timer = first_timer(); timer != nullptr; timer = timer->next())
timer->dump();
machine().logerror("=============================================\n");
}