Example #1
0
        public static void _DecrementRefCount(byte *objPtr)
        {
            if ((uint)objPtr < (uint)sizeof(GCHeader))
            {
                BasicConsole.SetTextColour(BasicConsole.error_colour);
                BasicConsole.WriteLine("Error! GC can't decrement ref count of an object in low memory.");
                BasicConsole.DelayOutput(5);
                BasicConsole.SetTextColour(BasicConsole.default_colour);
            }

            GCHeader *gcHeaderPtr = (GCHeader *)(objPtr - sizeof(GCHeader));

            if (CheckSignature(gcHeaderPtr))
            {
                gcHeaderPtr->RefCount--;

                //If the ref count goes below 0 then there was a circular reference somewhere.
                //  In actuality we don't care we can just only do cleanup when the ref count is
                //  exactly 0.
                if (gcHeaderPtr->RefCount == 0)
                {
#if GC_TRACE
                    BasicConsole.WriteLine("Cleaned up object.");
#endif

                    Testing2.Object obj = (Testing2.Object)Utilities.ObjectUtilities.GetObject(objPtr);
                    if (obj is Testing2.Array)
                    {
                        //Decrement ref count of elements
                        Testing2.Array arr = (Testing2.Array)obj;
                        if (!arr.elemType.IsValueType)
                        {
                            Testing2.Object[] objArr = (Testing2.Object[])Utilities.ObjectUtilities.GetObject(objPtr);
                            for (int i = 0; i < arr.length; i++)
                            {
                                DecrementRefCount(objArr[i], true);
                            }
                        }
                    }
                    //Cleanup fields
                    FieldInfo *FieldInfoPtr = obj._Type.FieldTablePtr;
                    //Loop through all fields. The if-block at the end handles moving to parent
                    //  fields.
                    while (FieldInfoPtr != null)
                    {
                        if (FieldInfoPtr->Size > 0)
                        {
                            Testing2.Type fieldType = (Testing2.Type)Utilities.ObjectUtilities.GetObject(FieldInfoPtr->FieldType);
                            if (!fieldType.IsValueType &&
                                !fieldType.IsPointer)
                            {
                                byte *          fieldPtr    = objPtr + FieldInfoPtr->Offset;
                                Testing2.Object theFieldObj = (Testing2.Object)Utilities.ObjectUtilities.GetObject(fieldPtr);

                                DecrementRefCount(theFieldObj, true);

#if GC_TRACE
                                BasicConsole.WriteLine("Cleaned up field.");
#endif
                            }

                            FieldInfoPtr++;
                        }

                        if (FieldInfoPtr->Size == 0)
                        {
                            FieldInfoPtr = (FieldInfo *)FieldInfoPtr->FieldType;
                        }
                    }

                    AddObjectToCleanup(gcHeaderPtr, objPtr);
                }
            }
        }
Example #2
0
        public static void *NewArr(int length, Testing2.Type elemType)
        {
            if (!Enabled)
            {
                BasicConsole.SetTextColour(BasicConsole.warning_colour);
                BasicConsole.WriteLine("Warning! GC returning null pointer because GC not enabled.");
                BasicConsole.DelayOutput(10);
                BasicConsole.SetTextColour(BasicConsole.default_colour);

                return(null);
            }

            //try
            {
                if (length < 0)
                {
                    UART.Write("length < 0. Overflow exception.");
                    return(null);
                    //ExceptionMethods.Throw_OverflowException();
                }

                InsideGC = true;

                //Alloc space for GC header that prefixes object data
                //Alloc space for new array object
                //Alloc space for new array elems

                uint totalSize = ((Testing2.Type) typeof(Testing2.Array)).Size;
                if (elemType.IsValueType)
                {
                    totalSize += elemType.Size * (uint)length;
                }
                else
                {
                    totalSize += elemType.StackSize * (uint)length;
                }
                totalSize += (uint)sizeof(GCHeader);

                GCHeader *newObjPtr = (GCHeader *)Heap.AllocZeroed(totalSize, "GC : NewArray");

                if ((UInt32)newObjPtr == 0)
                {
                    InsideGC = false;

                    BasicConsole.SetTextColour(BasicConsole.error_colour);
                    BasicConsole.WriteLine("Error! GC can't create a new array because the heap returned a null pointer.");
                    BasicConsole.DelayOutput(10);
                    BasicConsole.SetTextColour(BasicConsole.default_colour);

                    return(null);
                }

                NumObjs++;

                //Initialise the GCHeader
                SetSignature(newObjPtr);
                newObjPtr->RefCount = 1;

                Testing2.Array newArr = (Testing2.Array)Utilities.ObjectUtilities.GetObject(newObjPtr + 1);
                newArr._Type    = (Testing2.Type) typeof(Testing2.Array);
                newArr.length   = length;
                newArr.elemType = elemType;

                //Move past GCHeader
                byte *newObjBytePtr = (byte *)(newObjPtr + 1);

                InsideGC = false;

                return(newObjBytePtr);
            }
            //finally
            {
            }
        }