include/core/GP_TempAlloc.h

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2012 Cyril Hrubis <metan@ucw.cz>                       *
  20  *                                                                           *
  21  *****************************************************************************/
  22
  23 /*
  24
  25   Temporary block allocator implementation.
  26
  27   Creates pool for block allocation (small ones are done on the stack, bigger
  28   using malloc).
  29
  30   The usage is:
  31
  32   // Creates new allocation pool
  33   GP_TempAllocCrate(buf, 3 * 1024);
  34
  35   // Make use of it
  36   int *R = GP_TempAllocGet(buf, 1024);
  37   int *G = GP_TempAllocGet(buf, 1024);
  38   int *B = GP_TempAllocGet(buf, 1024);
  39
  40   ...
  41
  42   // Free it
  43   GP_TempAllocDestroy(buf);
  44
  45  */
  46
  47 #ifndef CORE_GP_TEMP_ALLOC_H
  48 #define CORE_GP_TEMP_ALLOC_H
  49
  50 #include <alloca.h>
  51 #include <stdlib.h>
  52
  53 #include "core/GP_Common.h"
  54
  55 #ifndef GP_ALLOCA_THRESHOLD
  56 # define GP_ALLOCA_THRESHOLD 2048
  57 #endif
  58
  59 struct GP_TempAlloc {
  60         void *buffer;
  61         size_t pos;
  62         size_t size;
  63 };
  64
  65 #define GP_TEMP_ALLOC(size) ({                                        \
  66         ((size) > GP_ALLOCA_THRESHOLD) ? malloc(size) : alloca(size); \
  67 })
  68
  69 #define GP_TempAllocCreate(name, bsize)                              \
  70         struct GP_TempAlloc name = {.size = (bsize), .pos = 0,       \
  71                                     .buffer = GP_TEMP_ALLOC(bsize)};
  72
  73 #define GP_TempAllocGet(self, bsize) ({           \
  74         GP_ASSERT(self.pos + bsize <= self.size); \
  75         size_t _pos = self.pos;                   \
  76         self.pos += bsize;                        \
  77         (void*)(((char*)(self.buffer)) + _pos);   \
  78 })
  79
  80 #define GP_TempAllocFree(self) do {          \
  81         if (self.size > GP_ALLOCA_THRESHOLD) \
  82                 free(self.buffer);           \
  83 } while (0)
  84
  85 #endif /* CORE_GP_TEMP_ALLOC_H */