src/LinearMath/btStackAlloc.h

   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
  38         btStackAlloc(unsigned int size) { ctor();create(size); }
  39         ~btStackAlloc()         { destroy(); }
  40
  41         inline void             create(unsigned int size)
  42         {
  43                 destroy();
  44                 data            =  (unsigned char*) btAlignedAlloc(size,16);
  45                 totalsize       =       size;
  46         }
  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
  63         int     getAvailableMemory() const
  64         {
  65                 return static_cast<int>(totalsize - usedsize);
  66         }
  67
  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         }
  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         }
  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:
 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