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 #include <memory>
  11 #ifdef HAVE_MALLOC_H
  12 #include <malloc.h>
  13 #endif
  14
  15
  16 void *al_malloc(size_t alignment, size_t size)
  17 {
  18     assert((alignment & (alignment-1)) == 0);
  19     alignment = std::max(alignment, alignof(std::max_align_t));
  20
  21 #if defined(HAVE_POSIX_MEMALIGN)
  22     void *ret{};
  23     if(posix_memalign(&ret, alignment, size) == 0)
  24         return ret;
  25     return nullptr;
  26 #elif defined(HAVE__ALIGNED_MALLOC)
  27     return _aligned_malloc(size, alignment);
  28 #else
  29     size_t total_size{size + alignment-1 + sizeof(void*)};
  30     void *base{std::malloc(total_size)};
  31     if(base != nullptr)
  32     {
  33         void *aligned_ptr{static_cast<char*>(base) + sizeof(void*)};
  34         total_size -= sizeof(void*);
  35
  36         std::align(alignment, size, aligned_ptr, total_size);
  37         *(static_cast<void**>(aligned_ptr)-1) = base;
  38         base = aligned_ptr;
  39     }
  40     return base;
  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) std::memset(ret, 0, size);
  48     return ret;
  49 }
  50
  51 void al_free(void *ptr) noexcept
  52 {
  53 #if defined(HAVE_POSIX_MEMALIGN)
  54     std::free(ptr);
  55 #elif defined(HAVE__ALIGNED_MALLOC)
  56     _aligned_free(ptr);
  57 #else
  58     if(ptr != nullptr)
  59         std::free(*(static_cast<void**>(ptr) - 1));
  60 #endif
  61 }