Blockstructured Adaptive Mesh Refinement in object-oriented C++

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fastAlloc.C

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#include "fastAlloc.h"

#define MINALLOC (1)

inline unsigned int Max(const unsigned int a, const unsigned int b)
  {
   return((a > b) ? a : b);
  }

/*
*************************************************************************
*                                                                       *
* fastAlloc::fastAlloc(const unsigned int size,                         *
*                      const unsigned int atatime)                      *
*                                                                       *
* Class constructor fastAlloc() creates a class instance which returns  *
* blocks of size bytes.  When new blocks are allocated, atatime blocks  *
* are allocated.                                                        *
*                                                                       *
* We want to align the data on powers-of-two boundaries 4, 8, or 16     *
* since many architectures restrict the address of some data objects    *
* such as doubles.                                                      *
*                                                                       *
*************************************************************************
*/

fastAlloc::fastAlloc(const unsigned int size, const unsigned int atatime)
  {
   const unsigned int block = Max(size, sizeof(struct link *));
   const unsigned int align = ((block > 8) ? 16 : ((block > 4) ? 8 : 4));
   blocksize = (block+align-1) & (~(align-1));
   nblocks = Max(atatime, MINALLOC);
   head = ((struct link *) 0);
   top = new longlink;
   cur = top;
  }

/*
*************************************************************************
*                                                                       *
* fastAlloc::malloc()                                                   *
*                                                                       *
* Function malloc() allocates new memory, which is linked into the free *
* memory list.                                                          *
*                                                                       *
*************************************************************************
*/

void fastAlloc::malloc()
  {
   char *chunk, *end;

   chunk = new char[blocksize*nblocks];
   assert (chunk != 0);

   end = chunk+(nblocks-1)*blocksize;
   for (char *p = chunk; p < end; p += blocksize)
      ((struct link *) p)->next == (struct link *) (p+blocksize);

   cur->item = head = (struct link *) chunk;
   if (!cur->next) cur->next = new longlink;
   cur = cur->next;
   ((struct link *) end)->next == ((struct link *) 0);
  }

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last update: 06/01/04