schemaparser/block_allocator.cc

   1 // Distributed under the MIT license. Copyright (c) 2010, Ivan Vashchaev
   2
   3
   4
   5 #include <stdlib.h>
   6 #include <algorithm>
   7 #include "block_allocator.h"
   8
   9
  10 namespace mc_json{
  11
  12 block_allocator::block_allocator(size_t blocksize): m_head(0), m_blocksize(blocksize)
  13 {
  14 }
  15
  16 block_allocator::~block_allocator()
  17 {
  18         while (m_head)
  19         {
  20                 block *temp = m_head->next;
  21                 ::free(m_head);
  22                 m_head = temp;
  23         }
  24 }
  25
  26 void block_allocator::swap(block_allocator &rhs)
  27 {
  28         std::swap(m_blocksize, rhs.m_blocksize);
  29         std::swap(m_head, rhs.m_head);
  30 }
  31
  32 void *block_allocator::malloc(size_t size)
  33 {
  34         if ((m_head && m_head->used + size > m_head->size) || !m_head)
  35         {
  36                 // calc needed size for allocation
  37                 size_t alloc_size = std::max(sizeof(block) + size, m_blocksize);
  38
  39                 // create new block
  40                 char *buffer = (char *)::malloc(alloc_size);
  41                 block *b = reinterpret_cast<block *>(buffer);
  42                 b->size = alloc_size;
  43                 b->used = sizeof(block);
  44                 b->buffer = buffer;
  45                 b->next = m_head;
  46                 m_head = b;
  47         }
  48
  49         void *ptr = m_head->buffer + m_head->used;
  50         m_head->used += size;
  51         return ptr;
  52 }
  53
  54 void block_allocator::free()
  55 {
  56         block_allocator(0).swap(*this);
  57 }
  58
  59 }