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/* $Id$ */
/*
* This file is part of OpenTTD.
* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file alloc_type.hpp Helper types related to the allocation of memory */
#ifndef ALLOC_TYPE_HPP
#define ALLOC_TYPE_HPP
#include "alloc_func.hpp"
/**
* A small 'wrapper' for allocations that can be done on most OSes on the
* stack, but are just too large to fit in the stack on devices with a small
* stack such as the NDS.
* So when it is possible a stack allocation is made, otherwise a heap
* allocation is made and this is freed once the struct goes out of scope.
* @param T the type to make the allocation for
* @param length the amount of items to allocate
*/
template <typename T, size_t length>
struct SmallStackSafeStackAlloc {
/** Storing the data on the stack */
T data[length];
/**
* Gets a pointer to the data stored in this wrapper.
* @return the pointer.
*/
inline operator T *()
{
return data;
}
/**
* Gets a pointer to the data stored in this wrapper.
* @return the pointer.
*/
inline T *operator -> ()
{
return data;
}
/**
* Gets a pointer to the last data element stored in this wrapper.
* @note needed because endof does not work properly for pointers.
* @return the 'endof' pointer.
*/
inline T *EndOf()
{
return endof(data);
}
};
/**
* A reusable buffer that can be used for places that temporary allocate
* a bit of memory and do that very often, or for places where static
* memory is allocated that might need to be reallocated sometimes.
*
* Every time Allocate or ZeroAllocate is called previous results of both
* functions will become invalid.
*/
template <typename T>
class ReusableBuffer {
private:
T *buffer; ///< The real data buffer
size_t count; ///< Number of T elements in the buffer
public:
/** Create a new buffer */
ReusableBuffer() : buffer(nullptr), count(0) {}
/** Clear the buffer */
~ReusableBuffer() { free(this->buffer); }
/**
* Get buffer of at least count times T.
* @note the buffer might be bigger
* @note calling this function invalidates any previous buffers given
* @param count the minimum buffer size
* @return the buffer
*/
T *Allocate(size_t count)
{
if (this->count < count) {
free(this->buffer);
this->buffer = MallocT<T>(count);
this->count = count;
}
return this->buffer;
}
/**
* Get buffer of at least count times T with zeroed memory.
* @note the buffer might be bigger
* @note calling this function invalidates any previous buffers given
* @param count the minimum buffer size
* @return the buffer
*/
T *ZeroAllocate(size_t count)
{
if (this->count < count) {
free(this->buffer);
this->buffer = CallocT<T>(count);
this->count = count;
} else {
memset(this->buffer, 0, sizeof(T) * count);
}
return this->buffer;
}
/**
* Get the currently allocated buffer.
* @return the buffer
*/
inline const T *GetBuffer() const
{
return this->buffer;
}
};
/**
* Base class that provides memory initialization on dynamically created objects.
* All allocated memory will be zeroed.
*/
class ZeroedMemoryAllocator
{
public:
ZeroedMemoryAllocator() {}
virtual ~ZeroedMemoryAllocator() {}
/**
* Memory allocator for a single class instance.
* @param size the amount of bytes to allocate.
* @return the given amounts of bytes zeroed.
*/
inline void *operator new(size_t size) { return CallocT<byte>(size); }
/**
* Memory allocator for an array of class instances.
* @param size the amount of bytes to allocate.
* @return the given amounts of bytes zeroed.
*/
inline void *operator new[](size_t size) { return CallocT<byte>(size); }
/**
* Memory release for a single class instance.
* @param ptr the memory to free.
*/
inline void operator delete(void *ptr) { free(ptr); }
/**
* Memory release for an array of class instances.
* @param ptr the memory to free.
*/
inline void operator delete[](void *ptr) { free(ptr); }
};
/**
* A smart pointer class that free()'s the pointer on destruction.
* @tparam T Storage type.
*/
template <typename T>
class AutoFreePtr
{
T *ptr; ///< Stored pointer.
public:
AutoFreePtr(T *ptr) : ptr(ptr) {}
~AutoFreePtr() { free(this->ptr); }
/**
* Take ownership of a new pointer and free the old one if needed.
* @param ptr NEw pointer.
*/
inline void Assign(T *ptr)
{
free(this->ptr);
this->ptr = ptr;
}
/** Dereference pointer. */
inline T *operator ->() { return this->ptr; }
/** Dereference pointer. */
inline const T *operator ->() const { return this->ptr; }
/** Cast to underlaying regular pointer. */
inline operator T *() { return this->ptr; }
/** Cast to underlaying regular pointer. */
inline operator const T *() const { return this->ptr; }
};
#endif /* ALLOC_TYPE_HPP */
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