summaryrefslogtreecommitdiffstats
path: root/src/core/core_timing.cpp
blob: 91c93e01f731acbf177c33162c244599adea6b5e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
// Copyright 2008 Dolphin Emulator Project / 2017 Citra Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include "core/core_timing.h"

#include <algorithm>
#include <cinttypes>
#include <mutex>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
#include "common/assert.h"
#include "common/logging/log.h"
#include "common/thread.h"
#include "common/threadsafe_queue.h"

namespace CoreTiming {

static s64 global_timer;
static int slice_length;
static int downcount;

struct EventType {
    TimedCallback callback;
    const std::string* name;
};

struct Event {
    s64 time;
    u64 fifo_order;
    u64 userdata;
    const EventType* type;
};

// Sort by time, unless the times are the same, in which case sort by the order added to the queue
static bool operator>(const Event& left, const Event& right) {
    return std::tie(left.time, left.fifo_order) > std::tie(right.time, right.fifo_order);
}

static bool operator<(const Event& left, const Event& right) {
    return std::tie(left.time, left.fifo_order) < std::tie(right.time, right.fifo_order);
}

// unordered_map stores each element separately as a linked list node so pointers to elements
// remain stable regardless of rehashes/resizing.
static std::unordered_map<std::string, EventType> event_types;

// The queue is a min-heap using std::make_heap/push_heap/pop_heap.
// We don't use std::priority_queue because we need to be able to serialize, unserialize and
// erase arbitrary events (RemoveEvent()) regardless of the queue order. These aren't accomodated
// by the standard adaptor class.
static std::vector<Event> event_queue;
static u64 event_fifo_id;
// the queue for storing the events from other threads threadsafe until they will be added
// to the event_queue by the emu thread
static Common::MPSCQueue<Event, false> ts_queue;

static constexpr int MAX_SLICE_LENGTH = 20000;

static s64 idled_cycles;

// Are we in a function that has been called from Advance()
// If events are sheduled from a function that gets called from Advance(),
// don't change slice_length and downcount.
static bool is_global_timer_sane;

static EventType* ev_lost = nullptr;

static void EmptyTimedCallback(u64 userdata, s64 cyclesLate) {}

EventType* RegisterEvent(const std::string& name, TimedCallback callback) {
    // check for existing type with same name.
    // we want event type names to remain unique so that we can use them for serialization.
    ASSERT_MSG(event_types.find(name) == event_types.end(),
               "CoreTiming Event \"{}\" is already registered. Events should only be registered "
               "during Init to avoid breaking save states.",
               name.c_str());

    auto info = event_types.emplace(name, EventType{callback, nullptr});
    EventType* event_type = &info.first->second;
    event_type->name = &info.first->first;
    return event_type;
}

void UnregisterAllEvents() {
    ASSERT_MSG(event_queue.empty(), "Cannot unregister events with events pending");
    event_types.clear();
}

void Init() {
    downcount = MAX_SLICE_LENGTH;
    slice_length = MAX_SLICE_LENGTH;
    global_timer = 0;
    idled_cycles = 0;

    // The time between CoreTiming being intialized and the first call to Advance() is considered
    // the slice boundary between slice -1 and slice 0. Dispatcher loops must call Advance() before
    // executing the first cycle of each slice to prepare the slice length and downcount for
    // that slice.
    is_global_timer_sane = true;

    event_fifo_id = 0;
    ev_lost = RegisterEvent("_lost_event", &EmptyTimedCallback);
}

void Shutdown() {
    MoveEvents();
    ClearPendingEvents();
    UnregisterAllEvents();
}

// This should only be called from the CPU thread. If you are calling
// it from any other thread, you are doing something evil
u64 GetTicks() {
    u64 ticks = static_cast<u64>(global_timer);
    if (!is_global_timer_sane) {
        ticks += slice_length - downcount;
    }
    return ticks;
}

void AddTicks(u64 ticks) {
    downcount -= static_cast<int>(ticks);
}

u64 GetIdleTicks() {
    return static_cast<u64>(idled_cycles);
}

void ClearPendingEvents() {
    event_queue.clear();
}

void ScheduleEvent(s64 cycles_into_future, const EventType* event_type, u64 userdata) {
    ASSERT(event_type != nullptr);
    s64 timeout = GetTicks() + cycles_into_future;

    // If this event needs to be scheduled before the next advance(), force one early
    if (!is_global_timer_sane)
        ForceExceptionCheck(cycles_into_future);

    event_queue.emplace_back(Event{timeout, event_fifo_id++, userdata, event_type});
    std::push_heap(event_queue.begin(), event_queue.end(), std::greater<Event>());
}

void ScheduleEventThreadsafe(s64 cycles_into_future, const EventType* event_type, u64 userdata) {
    ts_queue.Push(Event{global_timer + cycles_into_future, 0, userdata, event_type});
}

void UnscheduleEvent(const EventType* event_type, u64 userdata) {
    auto itr = std::remove_if(event_queue.begin(), event_queue.end(), [&](const Event& e) {
        return e.type == event_type && e.userdata == userdata;
    });

    // Removing random items breaks the invariant so we have to re-establish it.
    if (itr != event_queue.end()) {
        event_queue.erase(itr, event_queue.end());
        std::make_heap(event_queue.begin(), event_queue.end(), std::greater<Event>());
    }
}

void RemoveEvent(const EventType* event_type) {
    auto itr = std::remove_if(event_queue.begin(), event_queue.end(),
                              [&](const Event& e) { return e.type == event_type; });

    // Removing random items breaks the invariant so we have to re-establish it.
    if (itr != event_queue.end()) {
        event_queue.erase(itr, event_queue.end());
        std::make_heap(event_queue.begin(), event_queue.end(), std::greater<Event>());
    }
}

void RemoveNormalAndThreadsafeEvent(const EventType* event_type) {
    MoveEvents();
    RemoveEvent(event_type);
}

void ForceExceptionCheck(s64 cycles) {
    cycles = std::max<s64>(0, cycles);
    if (downcount > cycles) {
        // downcount is always (much) smaller than MAX_INT so we can safely cast cycles to an int
        // here. Account for cycles already executed by adjusting the g.slice_length
        slice_length -= downcount - static_cast<int>(cycles);
        downcount = static_cast<int>(cycles);
    }
}

void MoveEvents() {
    for (Event ev; ts_queue.Pop(ev);) {
        ev.fifo_order = event_fifo_id++;
        event_queue.emplace_back(std::move(ev));
        std::push_heap(event_queue.begin(), event_queue.end(), std::greater<Event>());
    }
}

void Advance() {
    MoveEvents();

    int cycles_executed = slice_length - downcount;
    global_timer += cycles_executed;
    slice_length = MAX_SLICE_LENGTH;

    is_global_timer_sane = true;

    while (!event_queue.empty() && event_queue.front().time <= global_timer) {
        Event evt = std::move(event_queue.front());
        std::pop_heap(event_queue.begin(), event_queue.end(), std::greater<Event>());
        event_queue.pop_back();
        evt.type->callback(evt.userdata, static_cast<int>(global_timer - evt.time));
    }

    is_global_timer_sane = false;

    // Still events left (scheduled in the future)
    if (!event_queue.empty()) {
        slice_length = static_cast<int>(
            std::min<s64>(event_queue.front().time - global_timer, MAX_SLICE_LENGTH));
    }

    downcount = slice_length;
}

void Idle() {
    idled_cycles += downcount;
    downcount = 0;
}

u64 GetGlobalTimeUs() {
    return GetTicks() * 1000000 / BASE_CLOCK_RATE;
}

int GetDowncount() {
    return downcount;
}

} // namespace CoreTiming