Zelda64Recomp/ultramodern/timer.cpp

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#include <thread>
#include <variant>
#include <set>
#include "blockingconcurrentqueue.h"
#include "ultra64.h"
#include "ultramodern.hpp"
// Start time for the program
static std::chrono::system_clock::time_point start_time = std::chrono::system_clock::now();
// Game speed multiplier (1 means no speedup)
constexpr uint32_t speed_multiplier = 1;
// N64 CPU counter ticks per millisecond
constexpr uint32_t counter_per_ms = 46'875 * speed_multiplier;
struct OSTimer {
PTR(OSTimer) unused1;
PTR(OSTimer) unused2;
OSTime interval;
OSTime timestamp;
PTR(OSMesgQueue) mq;
OSMesg msg;
};
struct AddTimerAction {
PTR(OSTimer) timer;
};
struct RemoveTimerAction {
PTR(OSTimer) timer;
};
using Action = std::variant<AddTimerAction, RemoveTimerAction>;
struct {
std::thread thread;
moodycamel::BlockingConcurrentQueue<Action> action_queue{};
} timer_context;
uint64_t duration_to_ticks(std::chrono::system_clock::duration duration) {
uint64_t delta_micros = std::chrono::duration_cast<std::chrono::microseconds>(duration).count();
// More accurate than using a floating point timer, will only overflow after running for 12.47 years
// Units: (micros * (counts/millis)) / (micros/millis) = counts
uint64_t total_count = (delta_micros * counter_per_ms) / 1000;
return total_count;
}
std::chrono::microseconds ticks_to_duration(uint64_t ticks) {
using namespace std::chrono_literals;
return ticks * 1000us / counter_per_ms;
}
std::chrono::system_clock::time_point ticks_to_timepoint(uint64_t ticks) {
return start_time + ticks_to_duration(ticks);
}
uint64_t time_now() {
return duration_to_ticks(std::chrono::system_clock::now() - start_time);
}
void timer_thread(RDRAM_ARG1) {
ultramodern::set_native_thread_name("Timer Thread");
ultramodern::set_native_thread_priority(ultramodern::ThreadPriority::VeryHigh);
// Lambda comparator function to keep the set ordered
auto timer_sort = [PASS_RDRAM1](PTR(OSTimer) a_, PTR(OSTimer) b_) {
OSTimer* a = TO_PTR(OSTimer, a_);
OSTimer* b = TO_PTR(OSTimer, b_);
// Order by timestamp if the timers have different timestamps
if (a->timestamp != b->timestamp) {
return a->timestamp < b->timestamp;
}
// If they have the exact same timestamp then order by address instead
return a < b;
};
// Ordered set of timers that are currently active
std::set<PTR(OSTimer), decltype(timer_sort)> active_timers{timer_sort};
// Lambda to process a timer action to handle adding and removing timers
auto process_timer_action = [&](const Action& action) {
// Determine the action type and act on it
if (const auto* add_action = std::get_if<AddTimerAction>(&action)) {
active_timers.insert(add_action->timer);
} else if (const auto* remove_action = std::get_if<RemoveTimerAction>(&action)) {
active_timers.erase(remove_action->timer);
}
};
while (true) {
// Empty the action queue
Action cur_action;
while (timer_context.action_queue.try_dequeue(cur_action)) {
process_timer_action(cur_action);
}
// If there's no timer to act on, wait for one to come in from the action queue
while (active_timers.empty()) {
timer_context.action_queue.wait_dequeue(cur_action);
process_timer_action(cur_action);
}
// Get the timer that's closest to running out
PTR(OSTimer) cur_timer_ = *active_timers.begin();
OSTimer* cur_timer = TO_PTR(OSTimer, cur_timer_);
// Remove the timer from the queue (it may get readded if waiting is interrupted)
active_timers.erase(cur_timer_);
// Determine how long to wait to reach the timer's timestamp
auto wait_duration = ticks_to_timepoint(cur_timer->timestamp) - std::chrono::system_clock::now();
auto wait_us = std::chrono::duration_cast<std::chrono::microseconds>(wait_duration);
// Wait for either the duration to complete or a new action to come through
if (timer_context.action_queue.wait_dequeue_timed(cur_action, wait_duration)) {
// Timer was interrupted by a new action
// Add the current timer back to the queue (done first in case the action is to remove this timer)
active_timers.insert(cur_timer_);
// Process the new action
process_timer_action(cur_action);
}
else {
// Waiting for the timer completed, so send the timer's message to its message queue
osSendMesg(PASS_RDRAM cur_timer->mq, cur_timer->msg, OS_MESG_NOBLOCK);
// If the timer has a specified interval then reload it with that value
if (cur_timer->interval != 0) {
cur_timer->timestamp = cur_timer->interval + time_now();
active_timers.insert(cur_timer_);
}
}
}
}
void ultramodern::init_timers(RDRAM_ARG1) {
timer_context.thread = std::thread{ timer_thread, PASS_RDRAM1 };
timer_context.thread.detach();
}
uint32_t ultramodern::get_speed_multiplier() {
return speed_multiplier;
}
std::chrono::system_clock::time_point ultramodern::get_start() {
return start_time;
}
std::chrono::system_clock::duration ultramodern::time_since_start() {
return std::chrono::system_clock::now() - start_time;
}
extern "C" u32 osGetCount() {
uint64_t total_count = time_now();
// Allow for overflows, which is how osGetCount behaves
return (uint32_t)total_count;
}
extern "C" OSTime osGetTime() {
uint64_t total_count = time_now();
return total_count;
}
extern "C" int osSetTimer(RDRAM_ARG PTR(OSTimer) t_, OSTime countdown, OSTime interval, PTR(OSMesgQueue) mq, OSMesg msg) {
OSTimer* t = TO_PTR(OSTimer, t_);
// Determine the time when this timer will trigger off
if (countdown == 0) {
// Set the timestamp based on the interval
t->timestamp = interval + time_now();
} else {
t->timestamp = countdown + time_now();
}
t->interval = interval;
t->mq = mq;
t->msg = msg;
timer_context.action_queue.enqueue(AddTimerAction{ t_ });
return 0;
}
extern "C" int osStopTimer(RDRAM_ARG PTR(OSTimer) t_) {
timer_context.action_queue.enqueue(RemoveTimerAction{ t_ });
// TODO don't blindly return 0 here; requires some response from the timer thread to know what the returned value was
return 0;
}