src/lib/gscpaux/block_allocator.cpp

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