class Register
{
private:
DWORD ax,dx,cx,bx; // POH
DWORD bp,sp;
DWORD flag, ip;
public:
//====================================================
Register()
{
ax = 0x0;
dx = 0x0;
cx = 0x0;
bx = 0x0;
bp = 0x0;
//memset(&this->sp,0,sizeof(sp));
sp = 0x0;
flag = 0x0;
ip = 0x0;
}
//====================================================
~Register()
{
}
//====================================================
void setAx(DWORD d)
{
ax=d;
}
//====================================================
DWORD getSp()
{
return sp;
}
}*PReg;
Why does function getSp(); gives an Access Violation error?
You have forgotten to instantiate your class. You have made a variable that is a pointer to the class Register, but you have not instantiated it.
What you get is a pointer that is either null or pointing to some random memory location, and you are assuming that it is pointing to your instance of the class. So when you try to access any of the member variables your are actually accessing memory locations you do not have access to.
What you need to do is create a new instance of the class:
PReg = new Register();
May I at the same time suggest that you move the variable declaration away from the class prototype (which I assume resides in your header file).
Related
From here, we know if malloc_logger global function is defined, it will be called whenever there is a malloc or free operation. I want to use it to record memory allocations in my app like this:
typedef void(malloc_logger_t)(uint32_t type,
uintptr_t arg1,
uintptr_t arg2,
uintptr_t arg3,
uintptr_t result,
uint32_t num_hot_frames_to_skip);
extern malloc_logger_t *malloc_logger;
void my_malloc_stack_logger(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3, uintptr_t result, uint32_t num_hot_frames_to_skip);
malloc_logger = my_malloc_stack_logger;
void my_malloc_stack_logger(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3, uintptr_t result, uint32_t num_hot_frames_to_skip)
{
// do my work
}
In my_malloc_stack_logger, I can directly get the allocated size and address. But how about object types? I want to record the class name if it is an NSObject instance. Is it possible to get this information?
After playing around with the hook, it looks like what you want to achieve is not quite possible.
First problem here is that if you try to read a class name from within this function (by calling any of object_getClassName, class_getName
or NSStringFromClass), this action on its own tends to trigger new allocations. That apparently happens because some Cocoa classes load lazily. I noticed however that when requesting all classes with objc_getClassList it makes a lot of preliminary allocations that helps to avoid them later on. So my idea is to cache all class names before subscribing to the allocations hook and refer to the cached values when needed. For the storage I used Apple's CFMutableDictionary:
CFMutableDictionaryRef objc_class_records;
void refresh_objc_class_list(void) {
pthread_mutex_lock(&objc_class_records_mutex);
if (objc_class_records) {
CFRelease(objc_class_records);
}
objc_class_records = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, NULL, &kCFTypeDictionaryValueCallBacks);
// The buffer needs to accomodate at least 26665 instances
static const unsigned buffer_length = 100000;
Class registered_classes[buffer_length];
objc_getClassList(registered_classes, buffer_length);
for (unsigned i = 0; i < buffer_length; ++i) {
if (!registered_classes[i]) {
break;
}
const Class class = registered_classes[i];
const CFStringRef class_name = CFStringCreateWithCString(kCFAllocatorDefault, class_getName(class), kCFStringEncodingUTF8);
CFDictionarySetValue(objc_class_records, class, class_name);
CFRelease(class_name);
}
}
Be advised that you don't want to have it called when the malloc logger is enabled (especially from within the hook itself).
Now you need to obtain a Class instance from the Objective-C objects. Depending on the type of allocation, the pointer argument goes to fifth or third parameter:
void my_malloc_logger(uint32_t type, uintptr_t param0, uintptr_t param1, uintptr_t param2,
uintptr_t param3, uint32_t frames_to_skip) {
void *ptr = NULL;
unsigned size = 0;
switch (type) {
case MALLOC_OP_MALLOC:
case MALLOC_OP_CALLOC:
ptr = (void *)param3;
size = (unsigned)param1;
break;
case MALLOC_OP_REALLOC:
ptr = (void *)param3;
size = (unsigned)param2;
break;
case MALLOC_OP_FREE:
ptr = (void *)param1;
break;
}
id objc_ptr = (id)ptr;
Class objc_class = object_getClass(objc_ptr);
if (!objc_class) {
return;
}
const CFStringRef class_name;
const bool found = CFDictionaryGetValueIfPresent(objc_class_records, objc_class, (const void **)&class_name);
if (found) {
const static unsigned name_max_length = 256;
char c_class_name[name_max_length];
if (CFStringGetCString(class_name, c_class_name, name_max_length, kCFStringEncodingUTF8)) {
const char *alloc_name = alloc_type_name(type);
nomalloc_printf_sync("%7s: Pointer: %p; Size: %u; Obj-C class: \"%s\"\n", alloc_name, objc_ptr, size, c_class_name);
}
}
}
And now why it won't work as expected:
object_getClass is not able to tell whether a pointer is an object of Cococa classes at the time of allocation (it will find the class, however, when the object is already allocated, e.g. before deallocation). Thus, the following code:
[NSObject new];
Will produce output similar to this:
CALLOC: Pointer: 0x600000600080; Size: 16
FREE: Pointer: 0x600000600080; Size: 0; Obj-C class: "NSObject"
Most of the standard Cocoa classes are in fact so-called Class Clusters and under the hood the actual allocation happens for an instance of a private class (which is not always recognisable by its public interface), thus this information is incomplete and sometimes misleading.
There are also many other factors which need to be taken into account (which i didn't cover here because it's beyond the question asked): the way you output data to standard output should not cause allocation by itself; the logging needs synchronisation since allocation happens a lot from any number of threads; if you want to enable/disable recording the Objective-C classes (or update the cache occasionally) access to the storage also needs to be synchronised.
Having that said if you are satisfied with what can be done with it, feel free to refer to the repository I made where this approach is already implemented in a form of a static library.
See update 1 below for my guess as to why the error is happening
I'm trying to develop an application with some C#/WPF and C++. I am having a problem on the C++ side on a part of the code that involves optimizing an object using GNU Scientific Library (GSL) optimization functions. I will avoid including any of the C#/WPF/GSL code in order to keep this question more generic and because the problem is within my C++ code.
For the minimal, complete and verifiable example below, here is what I have. I have a class Foo. And a class Optimizer. An object of class Optimizer is a member of class Foo, so that objects of Foo can optimize themselves when it is required.
The way GSL optimization functions take in external parameters is through a void pointer. I first define a struct Params to hold all the required parameters. Then I define an object of Params and convert it into a void pointer. A copy of this data is made with memcpy_s and a member void pointer optimParamsPtr of Optimizer class points to it so it can access the parameters when the optimizer is called to run later in time. When optimParamsPtr is accessed by CostFn(), I get the following error.
Managed Debugging Assistant 'FatalExecutionEngineError' : 'The runtime
has encountered a fatal error. The address of the error was at
0x6f25e01e, on thread 0x431c. The error code is 0xc0000005. This error
may be a bug in the CLR or in the unsafe or non-verifiable portions of
user code. Common sources of this bug include user marshaling errors
for COM-interop or PInvoke, which may corrupt the stack.'
Just to ensure the validity of the void pointer I made, I call CostFn() at line 81 with the void * pointer passed as an argument to InitOptimizer() and everything works. But in line 85 when the same CostFn() is called with the optimParamsPtr pointing to data copied by memcpy_s, I get the error. So I am guessing something is going wrong with the memcpy_s step. Anyone have any ideas as to what?
#include "pch.h"
#include <iostream>
using namespace System;
using namespace System::Runtime::InteropServices;
using namespace std;
// An optimizer for various kinds of objects
class Optimizer // GSL requires this to be an unmanaged class
{
public:
double InitOptimizer(int ptrID, void *optimParams, size_t optimParamsSize);
void FreeOptimizer();
void * optimParamsPtr;
private:
double cost = 0;
};
ref class Foo // A class whose objects can be optimized
{
private:
int a; // An internal variable that can be changed to optimize the object
Optimizer *fooOptimizer; // Optimizer for a Foo object
public:
Foo(int val) // Constructor
{
a = val;
fooOptimizer = new Optimizer;
}
~Foo()
{
if (fooOptimizer != NULL)
{
delete fooOptimizer;
}
}
void SetA(int val) // Mutator
{
a = val;
}
int GetA() // Accessor
{
return a;
}
double Optimize(int ptrID); // Optimize object
// ptrID is a variable just to change behavior of Optimize() and show what works and what doesn't
};
ref struct Params // Parameters required by the cost function
{
int cost_scaling;
Foo ^ FooObj;
};
double CostFn(void *params) // GSL requires cost function to be of this type and cannot be a member of a class
{
// Cast void * to Params type
GCHandle h = GCHandle::FromIntPtr(IntPtr(params));
Params ^ paramsArg = safe_cast<Params^>(h.Target);
h.Free(); // Deallocate
// Return the cost
int val = paramsArg->FooObj->GetA();
return (double)(paramsArg->cost_scaling * val);
}
double Optimizer::InitOptimizer(int ptrID, void *optimParamsArg, size_t optimParamsSizeArg)
{
optimParamsPtr = ::operator new(optimParamsSizeArg);
memcpy_s(optimParamsPtr, optimParamsSizeArg, optimParamsArg, optimParamsSizeArg);
double ret_val;
// Here is where the GSL stuff would be. But I replace that with a call to CostFn to show the error
if (ptrID == 1)
{
ret_val = CostFn(optimParamsArg); // Works
}
else
{
ret_val = CostFn(optimParamsPtr); // Doesn't work
}
return ret_val;
}
// Release memory used by unmanaged variables in Optimizer
void Optimizer::FreeOptimizer()
{
if (optimParamsPtr != NULL)
{
delete optimParamsPtr;
}
}
double Foo::Optimize(int ptrID)
{
// Create and initialize params object
Params^ paramsArg = gcnew Params;
paramsArg->cost_scaling = 11;
paramsArg->FooObj = this;
// Convert Params type object to void *
void * paramsArgVPtr = GCHandle::ToIntPtr(GCHandle::Alloc(paramsArg)).ToPointer();
size_t paramsArgSize = sizeof(paramsArg); // size of memory block in bytes pointed to by void pointer
double result = 0;
// Initialize optimizer
result = fooOptimizer->InitOptimizer(ptrID, paramsArgVPtr, paramsArgSize);
// Here is where the loop that does the optimization will be. Removed from this example for simplicity.
return result;
}
int main()
{
Foo Foo1(2);
std::cout << Foo1.Optimize(1) << endl; // Use orig void * arg in line 81 and it works
std::cout << Foo1.Optimize(2) << endl; // Use memcpy_s-ed new void * public member of Optimizer in line 85 and it doesn't work
}
Just to reiterate I need to copy the params to a member in the optimizer because the optimizer will run all through the lifetime of the Foo object. So it needs to exist as long as the Optimizer object exist and not just in the scope of Foo::Optimize()
/clr support need to be selected in project properties for the code to compile. Running on an x64 solution platform.
Update 1: While trying to debug this, I got suspicious of the way I get the size of paramsArg at line 109. Looks like I am getting the size of paramsArg as size of int cost_scaling plus size of the memory storing the address to FooObj instead of the size of memory storing FooObj itself. I realized this after stumbling across this answer to another post. I confirmed this by checking the value of paramsArg after adding some new dummy double members to Foo class. As expected the value of paramsArg doesn't change. I suppose this explains why I get the error. A solution would be to write code to correctly calculate the size of a Foo class object and set that to paramsArg instead of using sizeof. But that is turning out to be too complicated and probably another question in itself. For example, how to get size of a ref class object? Anyways hopefully someone will find this helpful.
Suppose I'm working with the following C snippet:
void inc(int *num) {*num++;}
void dec(int *num) {*num--;}
void f(int var) {
inc(&var);
dec(&var);
}
By using a static analyzer, I want to be able to tell if the value of var didn't change during the function's execution. I know I have to keep its state on my own (that's the point of writing a Clang checker), but I'm having troubles getting a unique reference of this variable.
For example: if I use the following API
void MySimpleChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
SymbolRef MyArg = Call.getArgSVal(0).getAsSymbol();
}
I'd expect it to return a pointer to this symbol's representation in my checker's context. However, I always get 0 into MyArg by using it this way. This happens for both inc and dec functions in the pre and post callbacks.
What am I missing here? What concepts did I get wrong?
Note: I'm currently reading the Clang CFE Internals Manual and I've read the excellent How to Write a Checker in 24 Hours material. I still couldn't find my answer so far.
Interpretation of question
Specifically, you want to count the calls to inc and dec applied to each variable and report when they do not balance for some path in a function.
Generally, you want to know how to associate an abstract value, here a number, with a program variable, and be able to update and query that value along each execution path.
High-level answer
Whereas the tutorial checker SimpleStreamChecker.cpp associates an abstract value with the value stored in a variable, here we want associate an abstract value with the variable itself. That is what IteratorChecker.cpp does when tracking containers, so I based my solution on it.
Within the static analyzer's abstract state, each variable is represented by a MemRegion object. So the first step is to make a map where MemRegion is the key:
REGISTER_MAP_WITH_PROGRAMSTATE(TrackVarMap, MemRegion const *, int)
Next, when we have an SVal that corresponds to a pointer to a variable, we can use SVal::getAsRegion to get the corresponding MemRegion. For instance, given a CallEvent, call, with a first argument that is a pointer, we can do:
if (MemRegion const *region = call.getArgSVal(0).getAsRegion()) {
to get the region that the pointer points at.
Then, we can access our map using that region as its key:
state = state->set<TrackVarMap>(region, newValue);
Finally, in checkDeadSymbols, we use SymbolReaper::isLiveRegion to detect when a region (variable) is going out of scope:
const TrackVarMapTy &Map = state->get<TrackVarMap>();
for (auto const &I : Map) {
MemRegion const *region = I.first;
int delta = I.second;
if (SymReaper.isLiveRegion(region) || (delta==0))
continue; // Not dead, or unchanged; skip.
Complete example
To demonstrate, here is a complete checker that reports unbalanced use of inc and dec:
// TrackVarChecker.cpp
// https://stackoverflow.com/questions/23448540/how-to-keep-track-of-a-variable-with-clangs-static-analyzer
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
using namespace clang;
using namespace ento;
namespace {
class TrackVarChecker
: public Checker< check::PostCall,
check::DeadSymbols >
{
mutable IdentifierInfo *II_inc, *II_dec;
mutable std::unique_ptr<BuiltinBug> BT_modified;
public:
TrackVarChecker() : II_inc(nullptr), II_dec(nullptr) {}
void checkPostCall(CallEvent const &Call, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
};
} // end anonymous namespace
// Map from memory region corresponding to a variable (that is, the
// variable itself, not its current value) to the difference between its
// current and original value.
REGISTER_MAP_WITH_PROGRAMSTATE(TrackVarMap, MemRegion const *, int)
void TrackVarChecker::checkPostCall(CallEvent const &call, CheckerContext &C) const
{
const FunctionDecl *FD = dyn_cast<FunctionDecl>(call.getDecl());
if (!FD || FD->getKind() != Decl::Function) {
return;
}
ASTContext &Ctx = C.getASTContext();
if (!II_inc) {
II_inc = &Ctx.Idents.get("inc");
}
if (!II_dec) {
II_dec = &Ctx.Idents.get("dec");
}
if (FD->getIdentifier() == II_inc || FD->getIdentifier() == II_dec) {
// We expect the argument to be a pointer. Get the memory region
// that the pointer points at.
if (MemRegion const *region = call.getArgSVal(0).getAsRegion()) {
// Increment the associated value, creating it first if needed.
ProgramStateRef state = C.getState();
int delta = (FD->getIdentifier() == II_inc)? +1 : -1;
int const *curp = state->get<TrackVarMap>(region);
int newValue = (curp? *curp : 0) + delta;
state = state->set<TrackVarMap>(region, newValue);
C.addTransition(state);
}
}
}
void TrackVarChecker::checkDeadSymbols(
SymbolReaper &SymReaper, CheckerContext &C) const
{
ProgramStateRef state = C.getState();
const TrackVarMapTy &Map = state->get<TrackVarMap>();
for (auto const &I : Map) {
// Check for a memory region (variable) going out of scope that has
// a non-zero delta.
MemRegion const *region = I.first;
int delta = I.second;
if (SymReaper.isLiveRegion(region) || (delta==0)) {
continue; // Not dead, or unchanged; skip.
}
//llvm::errs() << region << " dead with delta " << delta << "\n";
if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
if (!BT_modified) {
BT_modified.reset(
new BuiltinBug(this, "Delta not zero",
"Variable changed from its original value."));
}
C.emitReport(llvm::make_unique<BugReport>(
*BT_modified, BT_modified->getDescription(), N));
}
}
}
void ento::registerTrackVarChecker(CheckerManager &mgr) {
mgr.registerChecker<TrackVarChecker>();
}
bool ento::shouldRegisterTrackVarChecker(const LangOptions &LO) {
return true;
}
To hook this in to the rest of Clang, add entries to:
clang/include/clang/StaticAnalyzer/Checkers/Checkers.td and
clang/lib/StaticAnalyzer/Checkers/CMakeLists.txt
Example input to test it:
// trackvar.c
// Test for TrackVarChecker.
// The behavior of these functions is hardcoded in the checker.
void inc(int *num);
void dec(int *num);
void call_inc(int var) {
inc(&var);
} // reported
void call_inc_dec(int var) {
inc(&var);
dec(&var);
} // NOT reported
void if_inc(int var) {
if (var > 2) {
inc(&var);
}
} // reported
void indirect_inc(int val) {
int *p = &val;
inc(p);
} // reported
Sample run:
$ gcc -E -o trackvar.i trackvar.c
$ ~/bld/llvm-project/build/bin/clang -cc1 -analyze -analyzer-checker=alpha.core.TrackVar trackvar.i
trackvar.c:10:1: warning: Variable changed from its original value
}
^
trackvar.c:21:1: warning: Variable changed from its original value
}
^
trackvar.c:26:1: warning: Variable changed from its original value
}
^
3 warnings generated.
I think you missed the check that this call event is a call to your function inc/dec. You should have something like
void MySimpleChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
const IdentifierInfo* callee = Call.getCalleeIdentifier();
if (callee->getName().str() == "inc" || callee->getName().str() == "dec")
SymbolRef MyArg = Call.getArgSVal(0).getAsSymbol();
}
I'm trying to figure out how to manage the whole game loop manually in a Windows game, without using the regular Game Microsoft.Xna.Framework.Game class.
The reason for this is using the regular Game class causes some stuttering in my game. Not much, but because of the specific nature of the game it is still quite visible.
After trying a bunch of different settings (vsync, fixedtimestep, various framerates etc.) I decided to try write my own Game class to have full control of the timing. I am not sure that will fix it, but at least this way I have full control.
Basically I need to:
Set up the game window
In a loop: Do all rendering as usual, and then flush the result to the screen, manage backbuffers etc.
Anyone knows how to do this? It sounds quite easy in fact, but could not find any documentation on how to do it.
Not sure what I am doing wrong, but I have the following code (just for testing, timing will be handled differently), and the loop will run for a little while then stop. Once I pass my mousepointer over the window the loop will run for a little while again.
private void Application_Idle(object pSender, EventArgs pEventArgs)
{
Thread.Sleep(500);
//Message message;
//while (!PeekMessage(out message, IntPtr.Zero, 0, 0, 0))
{
gametime.update();
Update(gametime);
Draw(gametime);
GraphicsDevice.Present();
}
}
If enabling the "while PeekMessage", the loop will run continuously, but ignoring the sleep and also stopping when the mouse is moving over the window. Not sure what is going on here...
I think optimally I would just want to do something simple like this in the main render loop:
while (alive)
{
Thread.Sleep(100);
gametime.update();
Update(gametime);
Draw(gametime);
GraphicsDevice.Present();
}
But in this case the window remains blank, as it seems the window is not actually being redrawn with the new content. I tried a form.Refresh(), but still no go... Any ideas?
(added xbox information)
for windows you Basically need to create a Form and Show it, then store its handle and the form itself.
Using this handle you can create a GraphicsDevice.
Then you hook Application.Idle to your own function that calls your update and render.
For example
public class MyGame
{
public Form form;
public GraphicsDevice GraphicsDevice;
public MyGame()
{
form = new Form();
form.ClientSize = new Size(1280, 1024);
form.MainMenuStrip = null;
form.Show();
}
public void Run()
{
PresentationParameters pp = new PresentationParameters();
pp.DeviceWindowHandle = form.Handle;
pp.BackBufferFormat = SurfaceFormat.Color;
pp.BackBufferWidth = 1280;
pp.BackBufferHeight = 1024;
pp.RenderTargetUsage = RenderTargetUsage.DiscardContents;
pp.IsFullScreen = false;
pp.MultiSampleCount = 16;
pp.DepthStencilFormat = DepthFormat.Depth24Stencil8;
GraphicsDevice = new GraphicsDevice(GraphicsAdapter.DefaultAdapter,
GraphicsProfile.HiDef,
pp);
Application.Idle += new EventHandler(Application_Idle);
Application.Run(form);
}
private void Application_Idle(object pSender, EventArgs pEventArgs)
{
Message message;
while (!PeekMessage(out message, IntPtr.Zero, 0, 0, 0))
{
/* Your logic goes here
Custom timing and so on
Update();
Render();
*/
}
}
void Render()
{
GraphicsDevice.Clear(ClearOptions.DepthBuffer | ClearOptions.Target, Color.Black, 1, 0);
//Your logic here.
GraphicsDevice.Present();
}
[StructLayout(LayoutKind.Sequential)]
private struct Message
{
public IntPtr hWnd;
public int msg;
public IntPtr wParam;
public IntPtr lParam;
public uint time;
public Point p;
}
[return: MarshalAs(UnmanagedType.Bool)]
[SuppressUnmanagedCodeSecurity, DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern bool PeekMessage(out Message msg, IntPtr hWnd, uint
messageFilterMin, uint messageFilterMax, uint flags);
}
EDIT 1
For xbox you may just be able to place your own custom run function with your game loop in a throttled while true loop. Inside that run outside the top of the while true you will probably have to do the graphics device initialization and verification with IntPtr.Zero as your handle
EDIT 2
i use something like this ( got from http://www.koonsolo.com/news/dewitters-gameloop/ )
private long nextGameTick;
private Stopwatch stopwatch;
const int ticksPerSecond = 60;
const int skipTicks = 1000 / ticksPerSecond;
private const int maxSkip = 10;
`constructor
stopwatch = Stopwatch.StartNew();
nextGameTick = stopwatch.ElapsedMilliseconds;
`loop
int loops = 0;
long currentTick = stopwatch.ElapsedMilliseconds;
while ( (ulong)(currentTick - nextGameTick) > skipTicks && loops < maxSkip)
{
Update(16.667f);
nextGameTick += skipTicks;
loops++;
}
PreRender();
Render();
PostRender();
EDIT 3
Creating a content manager was a little more work, but still managable. You need to create a class that implements IServiceProvider. This class takes a GraphicsDevice in its constructor in order to create the next class the implements IGraphicsDeviceProvider. in addition I implement GetService like this
//in implementer of IServiceProvider
public object GetService ( Type serviceType )
{
if ( serviceType == typeof ( IGraphicsDeviceService ) )
{
return myGraphicsService;
}
return null;
}
For convenience i also add a method to the class to create and return managers
//in implementer of IServiceProvider
public ContentManager CreateContentManager( string sPath )
{
ContentManager content = new ContentManager(this);
content.RootDirectory = sPath;
return content;
}
In addition i create a class that implements IGraphicsDeviceService and takes a reference to my GraphicsDevice. then I create a property and field in it like so
//in implementer of IGraphicsDeviceService
private GraphicsDevice graphicsDevice;
public GraphicsDevice GraphicsDevice
{
get
{
return graphicsDevice;
}
}
So the call ends up being somehting like
MyServiceProvider m = new MyServiceProvider(graphicsDevice);
ContentManager content = m.CreateContentManager("Content");
where
MyServiceProvider(GraphicsDevice graphicsDevice)
{
myGraphicsService = new MyGraphicsDeviceService(graphicsDevice);
}
MyGraphicsDeviceService(GraphicsDevice gfxDevice)
{
graphicsDevice = gfxDevice;
}
-Sorry for fragmenting the code around but its not something i wrote too recently so im having difficulty remembering parts.
EDIT 4
i had an odd case with my custom game i just remembered when i new the Form for it i
had to bind
private void IgnoreAlt(object pSender, KeyEventArgs pEventArgs)
{
if (pEventArgs.Alt && pEventArgs.KeyCode != Keys.F4)
pEventArgs.Handled = true;
}
to
form.KeyUp += IgnoreAlt;
form.KeyDown += IgnoreAlt;
otherwise i got some horrible stalls.
Because my userdata objects reference themselves, I need to delete and nil a variable for the garbage collector to work.
Lua code:
obj = object:new()
--
-- Some time later
obj:delete() -- Removes the self reference
obj = nil -- Ready for collection
C Code:
typedef struct {
int self; // Reference to the object
int callback; // Reference to a Lua function
// Other members and function references removed
} Object;
// Called from Lua to create a new object
static int object_new( lua_State *L ) {
Object *obj = lua_newuserdata( L, sizeof( Object ) );
// Create the 'self' reference, userdata is on the stack top
obj->self = luaL_ref( L, LUA_REGISTRYINDEX );
// Put the userdata back on the stack before returning
lua_rawgeti( L, LUA_REGISTRYINDEX, obj->self );
// The object pointer is also stored outside of Lua for processing in C
return 1;
}
// Called by Lua to delete an object
static int object_delete( lua_State *L ) {
Object *obj = lua_touserdata( L, 1 );
// Remove the objects self reference
luaL_unref( L, LUA_REGISTRYINDEX, obj->self );
return 0;
}
// Called from Lua to set a callback function
static int object_set_callback( lua_State *L ) {
Object *obj = lua_touserdata( L, 1 );
// Unref an existing callbacks
if ( obj->callback != 0 ) {
luaL_unref( L, LUA_REGISTRYINDEX, obj->callback );
obj->callback = 0;
}
// Set the new callback - function is on top of the stack
obj->callback = luaL_ref( L, LUA_REGISTRYINDEX );
}
// Called from C to call a Lua function for the obj
static void do_callback( Object *obj ) {
// Push the Lua function onto the stack
lua_rawgeti( L, LUA_REGISTRYINDEX, obj->callback );
// Push the userdata onto the stack
lua_rawgeti( L, LUA_REGISTRYINDEX, obj->self );
// Call the function
lua_call( L, 1, 0 );
}
Is there some way I can set the object to nil in Lua, and have the delete() method called automatically? Alternatively, can the delete method nil all variables that reference the object? Can the self reference be made 'weak'?
EDIT 1: I've included code to show why the object references itself; see the do_callback function. Each object is part of a tree-like structure, with the bulk of the processing done in C, but a user can set a custom Lua function that is called under certain conditions.
EDIT 2: Another possible solution comes to mind; Instead of each obj keeping a reference to itself, can I lookup the object in the global index when I need to pass it to Lua, using its address as a key?
You could try creating a weak table in the registry and store your references there, that way setting all references of your object to nil should make it available for the gc.