common/almalloc.cpp

   1
   2 #include "config.h"
   3
   4 #include "almalloc.h"
   5
   6 #include <cassert>
   7 #include <cstddef>
   8 #include <cstdlib>
   9 #include <cstring>
  10 #ifdef HAVE_MALLOC_H
  11 #include <malloc.h>
  12 #endif
  13
  14
  15 #define ALIGNED_ALLOC_AVAILABLE (__STDC_VERSION__ >= 201112L || __cplusplus >= 201703L)
  16
  17 void *al_malloc(size_t alignment, size_t size)
  18 {
  19     assert((alignment & (alignment-1)) == 0);
  20     alignment = std::max(alignment, alignof(std::max_align_t));
  21
  22 #if ALIGNED_ALLOC_AVAILABLE
  23     size = (size+(alignment-1))&~(alignment-1);
  24     return aligned_alloc(alignment, size);
  25 #elif defined(HAVE_POSIX_MEMALIGN)
  26     void *ret;
  27     if(posix_memalign(&ret, alignment, size) == 0)
  28         return ret;
  29     return nullptr;
  30 #elif defined(HAVE__ALIGNED_MALLOC)
  31     return _aligned_malloc(size, alignment);
  32 #else
  33     auto *ret = static_cast<char*>(malloc(size+alignment));
  34     if(ret != nullptr)
  35     {
  36         *(ret++) = 0x00;
  37         while((reinterpret_cast<uintptr_t>(ret)&(alignment-1)) != 0)
  38             *(ret++) = 0x55;
  39     }
  40     return ret;
  41 #endif
  42 }
  43
  44 void *al_calloc(size_t alignment, size_t size)
  45 {
  46     void *ret = al_malloc(alignment, size);
  47     if(ret) memset(ret, 0, size);
  48     return ret;
  49 }
  50
  51 void al_free(void *ptr) noexcept
  52 {
  53 #if ALIGNED_ALLOC_AVAILABLE || defined(HAVE_POSIX_MEMALIGN)
  54     free(ptr);
  55 #elif defined(HAVE__ALIGNED_MALLOC)
  56     _aligned_free(ptr);
  57 #else
  58     if(ptr != nullptr)
  59     {
  60         auto *finder = static_cast<char*>(ptr);
  61         do {
  62             --finder;
  63         } while(*finder == 0x55);
  64         free(finder);
  65     }
  66 #endif
  67 }