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Factors out the stuff of time warping.

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Thomas Harte
2020-02-09 22:11:06 -05:00
parent 705d14259c
commit 0b0a7e241b
4 changed files with 98 additions and 41 deletions
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ClockReceiver/ScanSynchroniser.hpp
+79
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@@ -0,0 +1,79 @@
//
// ScanSynchroniser.hpp
// Clock Signal
//
// Created by Thomas Harte on 09/02/2020.
// Copyright © 2020 Thomas Harte. All rights reserved.
//
#ifndef ScanSynchroniser_h
#define ScanSynchroniser_h
#include "../Outputs/ScanTarget.hpp"
#include <cmath>
namespace Time {
/*!
Where an emulated machine is sufficiently close to a host machine's frame rate that a small nudge in
its speed multiplier will bring it into frame synchronisation, the ScanSynchroniser provides a sequence of
speed multipliers designed both to adjust the machine to the proper speed and, in a reasonable amount
of time, to bring it into phase.
*/
class ScanSynchroniser {
public:
/*!
@returns @c true if the emulated machine can be synchronised with the host frame output based on its
current @c [scan]status and the host machine's @c frame_duration; @c false otherwise.
*/
bool can_synchronise(const Outputs::Display::ScanStatus &scan_status, double frame_duration) {
ratio_ = 1.0;
if(scan_status.field_duration_gradient < 0.00001) {
// Check out the machine's current frame time.
// If it's within 3% of a non-zero integer multiple of the
// display rate, mark this time window to be split over the sync.
ratio_ = frame_duration / scan_status.field_duration;
const double integer_ratio = round(ratio_);
if(integer_ratio > 0.0) {
ratio_ /= integer_ratio;
return ratio_ <= maximum_rate_adjustment && ratio_ >= 1.0 / maximum_rate_adjustment;
}
}
return false;
}
/*!
@returns The appropriate speed multiplier for the next frame based on the inputs previously supplied to @c can_synchronise.
Results are undefined if @c can_synchroise returned @c false.
*/
double next_speed_multiplier(const Outputs::Display::ScanStatus &scan_status) {
// The host versus emulated ratio is calculated based on the current perceived frame duration of the machine.
// Either that number is exactly correct or it's already the result of some sort of low-pass filter. So there's
// no benefit to second guessing it here — just take it to be correct.
//
// ... with one slight caveat, which is that it is desireable to adjust phase here, to align vertical sync points.
// So the set speed multiplier may be adjusted slightly to aim for that.
double speed_multiplier = 1.0 / ratio_;
if(scan_status.current_position > 0.0) {
if(scan_status.current_position < 0.5) speed_multiplier /= phase_adjustment_ratio;
else speed_multiplier *= phase_adjustment_ratio;
}
speed_multiplier_ = (speed_multiplier_ * 0.95) + (speed_multiplier * 0.05);
return speed_multiplier_;
}
private:
static constexpr double maximum_rate_adjustment = 1.03;
static constexpr double phase_adjustment_ratio = 1.005;
// Managed local state.
double speed_multiplier_ = 1.0;
// Temporary storage to bridge the can_synchronise -> next_speed_multiplier gap.
double ratio_ = 1.0;
};
}
#endif /* ScanSynchroniser_h */
OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
+2
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@@ -1129,6 +1129,7 @@
4B643F391D77AD1900D431D6 /* CSStaticAnalyser.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = CSStaticAnalyser.mm; path = StaticAnalyser/CSStaticAnalyser.mm; sourceTree = "<group>"; };
4B643F3C1D77AE5C00D431D6 /* CSMachine+Target.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "CSMachine+Target.h"; sourceTree = "<group>"; };
4B643F3E1D77B88000D431D6 /* DocumentController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DocumentController.swift; sourceTree = "<group>"; };
4B644ED023F0FB55006C0CC5 /* ScanSynchroniser.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = ScanSynchroniser.hpp; sourceTree = "<group>"; };
4B65085F22F4CF8D009C1100 /* Keyboard.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Keyboard.cpp; sourceTree = "<group>"; };
4B680CE123A5553100451D43 /* 68000ComparativeTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = 68000ComparativeTests.mm; sourceTree = "<group>"; };
4B680CE323A555CA00451D43 /* 68000 Comparative Tests */ = {isa = PBXFileReference; lastKnownFileType = folder; path = "68000 Comparative Tests"; sourceTree = "<group>"; };
@@ -3726,6 +3727,7 @@
4BB06B211F316A3F00600C7A /* ForceInline.hpp */,
4B80214322EE7C3E00068002 /* JustInTime.hpp */,
4B449C942063389900A095C8 /* TimeTypes.hpp */,
4B644ED023F0FB55006C0CC5 /* ScanSynchroniser.hpp */,
);
name = ClockReceiver;
path = ../../ClockReceiver;
OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
+1 -1
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@@ -67,7 +67,7 @@
</Testables>
</TestAction>
<LaunchAction
buildConfiguration = "Release"
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
enableASanStackUseAfterReturn = "YES"
OSBindings/Mac/Clock Signal/Machine/CSMachine.mm
+16 -40
View File
@@ -21,6 +21,9 @@
#include "Typer.hpp"
#include "../../../../Activity/Observer.hpp"
#include "../../../../ClockReceiver/TimeTypes.hpp"
#include "../../../../ClockReceiver/ScanSynchroniser.hpp"
#import "CSStaticAnalyser+TargetVector.h"
#import "NSBundle+DataResource.h"
#import "NSData+StdVector.h"
@@ -154,11 +157,12 @@ struct ActivityObserver: public Activity::Observer {
CSHighPrecisionTimer *_timer;
CGSize _pixelSize;
std::atomic_flag _isUpdating;
int64_t _syncTime;
int64_t _timeDiff;
Time::Nanos _syncTime;
Time::Nanos _timeDiff;
double _refreshPeriod;
BOOL _isSyncLocking;
double _speedMultiplier;
Time::ScanSynchroniser _scanSynchroniser;
NSTimer *_joystickTimer;
@@ -169,7 +173,6 @@ struct ActivityObserver: public Activity::Observer {
self = [super init];
if(self) {
_analyser = result;
_speedMultiplier = 1.0;
Machine::Error error;
std::vector<ROMMachine::ROM> missing_roms;
@@ -726,13 +729,13 @@ struct ActivityObserver: public Activity::Observer {
- (void)openGLViewDisplayLinkDidFire:(CSOpenGLView *)view now:(const CVTimeStamp *)now outputTime:(const CVTimeStamp *)outputTime {
// First order of business: grab a timestamp.
const auto timeNow = std::chrono::high_resolution_clock::now().time_since_epoch().count();
const auto timeNow = Time::nanos_now();
CGSize pixelSize = view.backingSize;
BOOL isSyncLocking;
@synchronized(self) {
// Store a means to map from CVTimeStamp.hostTime to std::chrono::high_resolution_clock;
// there is an extremely dodgy assumption here that both are in the same units (and, below, that both as in ns).
// Store a means to map from CVTimeStamp.hostTime to Time::Nanos;
// there is an extremely dodgy assumption here that the former is in ns.
if(!_timeDiff) {
_timeDiff = int64_t(now->hostTime) - int64_t(timeNow);
}
@@ -761,11 +764,11 @@ struct ActivityObserver: public Activity::Observer {
#define TICKS 600
- (void)start {
__block auto lastTime = std::chrono::high_resolution_clock::now().time_since_epoch().count();
__block auto lastTime = Time::nanos_now();
_timer = [[CSHighPrecisionTimer alloc] initWithTask:^{
// Grab the time now and, therefore, the amount of time since the timer last fired.
const auto timeNow = std::chrono::high_resolution_clock::now().time_since_epoch().count();
const auto timeNow = Time::nanos_now();
const auto duration = timeNow - lastTime;
@@ -774,42 +777,15 @@ struct ActivityObserver: public Activity::Observer {
@synchronized(self) {
// If this tick includes vsync then inspect the machine.
if(timeNow >= self->_syncTime && lastTime < self->_syncTime) {
// Grab the scan status and check out the machine's current frame time.
// If it's stable and within 3% of a non-zero integer multiple of the
// display rate, mark this time window to be split over the sync.
const auto scan_status = self->_machine->crt_machine()->get_scan_status();
double ratio = 1.0;
if(scan_status.field_duration_gradient < 0.00001) {
ratio = self->_refreshPeriod / scan_status.field_duration;
const double integerRatio = round(ratio);
if(integerRatio > 0.0) {
ratio /= integerRatio;
constexpr double maximumAdjustment = 1.03;
splitAndSync = ratio <= maximumAdjustment && ratio >= 1 / maximumAdjustment;
}
}
self->_isSyncLocking = splitAndSync;
splitAndSync = self->_isSyncLocking = self->_scanSynchroniser.can_synchronise(self->_machine->crt_machine()->get_scan_status(), self->_refreshPeriod);
// If the time window is being split, run up to the split, then check out machine speed, possibly
// adjusting multiplier, then run after the split.
if(splitAndSync) {
self->_machine->crt_machine()->run_for((double)(self->_syncTime - lastTime) / 1e9);
// The host versus emulated ratio is calculated based on the current perceived frame duration of the machine.
// Either that number is exactly correct or it's already the result of some sort of low-pass filter. So there's
// no benefit to second guessing it here — just take it to be correct.
//
// ... with one slight caveat, which is that it is desireable to adjust phase here, to align vertical sync points.
// So the set speed multiplier may be adjusted slightly to aim for that.
double speed_multiplier = 1.0 / ratio;
if(scan_status.current_position > 0.0) {
constexpr double adjustmentRatio = 1.005;
if(scan_status.current_position < 0.5) speed_multiplier /= adjustmentRatio;
else speed_multiplier *= adjustmentRatio;
}
self->_speedMultiplier = (self->_speedMultiplier * 0.95) + (speed_multiplier * 0.05);
self->_machine->crt_machine()->set_speed_multiplier(self->_speedMultiplier);
self->_machine->crt_machine()->set_speed_multiplier(
self->_scanSynchroniser.next_speed_multiplier(self->_machine->crt_machine()->get_scan_status())
);
self->_machine->crt_machine()->run_for((double)(timeNow - self->_syncTime) / 1e9);
}
}