1 /*
2 Copyright (c) 2003-2006 Gino van den Bergen / Erwin Coumans  http://continuousphysics.com/Bullet/
3 
4 This software is provided 'as-is', without any express or implied warranty.
5 In no event will the authors be held liable for any damages arising from the use of this software.
6 Permission is granted to anyone to use this software for any purpose,
7 including commercial applications, and to alter it and redistribute it freely,
8 subject to the following restrictions:
9 
10 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
11 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
12 3. This notice may not be removed or altered from any source distribution.
13 */
14 
15 /*
16 StackAlloc extracted from GJK-EPA collision solver by Nathanael Presson
17 Nov.2006
18 */
19 
20 #ifndef BT_STACK_ALLOC
21 #define BT_STACK_ALLOC
22 
23 #include "btScalar.h" //for btAssert
24 #include "btAlignedAllocator.h"
25 
26 ///The btBlock class is an internal structure for the btStackAlloc memory allocator.
27 struct btBlock
28 {
29 	btBlock*			previous;
30 	unsigned char*		address;
31 };
32 
33 ///The StackAlloc class provides some fast stack-based memory allocator (LIFO last-in first-out)
34 class btStackAlloc
35 {
36 public:
37 
btStackAlloc(unsigned int size)38 	btStackAlloc(unsigned int size)	{ ctor();create(size); }
~btStackAlloc()39 	~btStackAlloc()		{ destroy(); }
40 
create(unsigned int size)41 	inline void		create(unsigned int size)
42 	{
43 		destroy();
44 		data		=  (unsigned char*) btAlignedAlloc(size,16);
45 		totalsize	=	size;
46 	}
destroy()47 	inline void		destroy()
48 	{
49 		btAssert(usedsize==0);
50 		//Raise(L"StackAlloc is still in use");
51 
52 		if(usedsize==0)
53 		{
54 			if(!ischild && data)
55 				btAlignedFree(data);
56 
57 			data				=	0;
58 			usedsize			=	0;
59 		}
60 
61 	}
62 
getAvailableMemory()63 	int	getAvailableMemory() const
64 	{
65 		return static_cast<int>(totalsize - usedsize);
66 	}
67 
allocate(unsigned int size)68 	unsigned char*			allocate(unsigned int size)
69 	{
70 		const unsigned int	nus(usedsize+size);
71 		if(nus<totalsize)
72 		{
73 			usedsize=nus;
74 			return(data+(usedsize-size));
75 		}
76 		btAssert(0);
77 		//&& (L"Not enough memory"));
78 
79 		return(0);
80 	}
beginBlock()81 	SIMD_FORCE_INLINE btBlock*		beginBlock()
82 	{
83 		btBlock*	pb = (btBlock*)allocate(sizeof(btBlock));
84 		pb->previous	=	current;
85 		pb->address		=	data+usedsize;
86 		current			=	pb;
87 		return(pb);
88 	}
endBlock(btBlock * block)89 	SIMD_FORCE_INLINE void		endBlock(btBlock* block)
90 	{
91 		btAssert(block==current);
92 		//Raise(L"Unmatched blocks");
93 		if(block==current)
94 		{
95 			current		=	block->previous;
96 			usedsize	=	(unsigned int)((block->address-data)-sizeof(btBlock));
97 		}
98 	}
99 
100 private:
ctor()101 	void		ctor()
102 	{
103 		data		=	0;
104 		totalsize	=	0;
105 		usedsize	=	0;
106 		current		=	0;
107 		ischild		=	false;
108 	}
109 	unsigned char*		data;
110 	unsigned int		totalsize;
111 	unsigned int		usedsize;
112 	btBlock*	current;
113 	bool		ischild;
114 };
115 
116 #endif //BT_STACK_ALLOC
117