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r17167:68f47a8db1b5
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(svn r21916) -Fix [FS#4442]: the minimum speed needed for (realistic) acceleration to work properly can sometimes be more than the (temporary) maximum speed causing Clamp to "fail". Make sure that the minimum speed always overrules the maximum speed
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/*
* 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 fixedsizearray.hpp A fixed size array that doesn't create items until needed. */
#ifndef FIXEDSIZEARRAY_HPP
#define FIXEDSIZEARRAY_HPP
#include "../core/alloc_func.hpp"
/**
* fixed size array
* Upon construction it preallocates fixed size block of memory
* for all items, but doesn't construct them. Item's construction
* is delayed.
*/
template <class T, uint C>
struct FixedSizeArray {
protected:
/** header for fixed size array */
struct ArrayHeader
{
uint items; ///< number of items in the array
uint reference_count; ///< block reference counter (used by copy constructor and by destructor)
};
/* make constants visible from outside */
static const uint Tsize = sizeof(T); // size of item
static const uint HeaderSize = sizeof(ArrayHeader); // size of header
/**
* the only member of fixed size array is pointer to the block
* of C array of items. Header can be found on the offset -sizeof(ArrayHeader).
*/
T *data;
/** return reference to the array header (non-const) */
FORCEINLINE ArrayHeader& Hdr() { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
/** return reference to the array header (const) */
FORCEINLINE const ArrayHeader& Hdr() const { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
/** return reference to the block reference counter */
FORCEINLINE uint& RefCnt() { return Hdr().reference_count; }
/** return reference to number of used items */
FORCEINLINE uint& SizeRef() { return Hdr().items; }
public:
/** Default constructor. Preallocate space for items and header, then initialize header. */
FixedSizeArray()
{
/* allocate block for header + items (don't construct items) */
data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
SizeRef() = 0; // initial number of items
RefCnt() = 1; // initial reference counter
}
/** Copy constructor. Preallocate space for items and header, then initialize header. */
FixedSizeArray(const FixedSizeArray<T, C>& src)
{
/* share block (header + items) with the source array */
data = src.data;
RefCnt()++; // now we share block with the source
}
/** destroy remaining items and free the memory block */
~FixedSizeArray()
{
/* release one reference to the shared block */
if ((--RefCnt()) > 0) return; // and return if there is still some owner
Clear();
/* free the memory block occupied by items */
free(((byte*)data) - HeaderSize);
data = NULL;
}
/** Clear (destroy) all items */
FORCEINLINE void Clear()
{
/* Walk through all allocated items backward and destroy them
* Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
* on some compilers with some architectures. (e.g. gcc with x86) */
for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
pItem->~T();
}
/* number of items become zero */
SizeRef() = 0;
}
/** return number of used items */
FORCEINLINE uint Length() const { return Hdr().items; }
/** return true if array is full */
FORCEINLINE bool IsFull() const { return Length() >= C; }
/** return true if array is empty */
FORCEINLINE bool IsEmpty() const { return Length() <= 0; }
/** add (allocate), but don't construct item */
FORCEINLINE T *Append() { assert(!IsFull()); return &data[SizeRef()++]; }
/** add and construct item using default constructor */
FORCEINLINE T *AppendC() { T *item = Append(); new(item)T; return item; }
/** return item by index (non-const version) */
FORCEINLINE T& operator [] (uint index) { assert(index < Length()); return data[index]; }
/** return item by index (const version) */
FORCEINLINE const T& operator [] (uint index) const { assert(index < Length()); return data[index]; }
};
#endif /* FIXEDSIZEARRAY_HPP */
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