chore: improve accuracy of frame limiter

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-03-14 20:38:29 -03:00
parent 3623362f72
commit c6e6b42869
3 changed files with 29 additions and 15 deletions

View File

@ -49,28 +49,42 @@ pub fn runEmuThread(quit: *Atomic(bool), pause: *Atomic(bool), fps: *Atomic(u64)
// ns_late is non zero if we are late. // ns_late is non zero if we are late.
var ns_late = timestamp -| wake_time; var ns_late = timestamp -| wake_time;
// Calculate the new Thread wake time // log.info("timestamp: {} | late: {}", .{ timestamp, ns_late });
wake_time += frame_period;
// If we're more than a frame late, skip the rest of this loop // If we're more than a frame late, skip the rest of this loop
if (ns_late > frame_period) continue; // Recalculate what our new wake time should be so that we can
// get "back on track"
if (ns_late > frame_period) {
wake_time = timestamp + frame_period;
continue;
}
if (sync_to_video) std.time.sleep(frame_period - ns_late); if (sync_to_video) {
// Employ several sleep calls in periods of 10ms
// By doing this the behaviour should average out to be
// more consistent
// Backup Busy Loop Routine const sleep_for = frame_period - ns_late;
// if (sync_to_video) spinLoop(&timer, wake_time); const loop_count = sleep_for / (std.time.ns_per_ms * 10); // How many groups of 10ms
var i: usize = 0;
while (i < loop_count) : (i += 1) {
std.time.sleep(std.time.ns_per_ms * 10);
}
// Spin to make up the difference if there is a need
// Make sure that we're using the old wake time and not the onne we recalcualted
spinLoop(&timer, wake_time);
}
// Update to the new wake time
wake_time += frame_period;
} }
} }
} }
fn spinLoop(timer: *Timer, wake_time: u64) void { fn spinLoop(timer: *Timer, wake_time: u64) void {
while (true) { while (true) if (timer.read() > wake_time) break;
const timestamp = timer.read();
if (timestamp >= wake_time) {
break;
}
}
} }
fn emuFps(left: u64) u64 { fn emuFps(left: u64) u64 {

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@ -177,7 +177,7 @@ pub fn main() anyerror!void {
fps_avg.add(emu_fps.load(.Unordered)); fps_avg.add(emu_fps.load(.Unordered));
const avg = fps_avg.calc(); const avg = fps_avg.calc();
const dyn_title = std.fmt.bufPrint(&dyn_title_buf, "{s} [Emu: {d:0>3}fps, {d:0>3}%] ", .{ title, avg, (avg * 100 / 59) }) catch unreachable; const dyn_title = std.fmt.bufPrint(&dyn_title_buf, "{s} [Emu: {d:0>3}fps, {d:0>3}%] ", .{ title, avg, (avg * 100 / 60) }) catch unreachable;
SDL.SDL_SetWindowTitle(window, dyn_title.ptr); SDL.SDL_SetWindowTitle(window, dyn_title.ptr);
} }

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@ -18,7 +18,7 @@ pub const FpsAverage = struct {
} }
pub fn add(self: *Self, sample: u64) void { pub fn add(self: *Self, sample: u64) void {
if (self.sample_count == 1000) return self.reset(sample); if (self.sample_count == 600) return self.reset(sample);
self.total += sample; self.total += sample;
self.sample_count += 1; self.sample_count += 1;