libuuu/bmap.h

   1 #pragma once
   2
   3 #include <string>
   4 #include <vector>
   5
   6 struct bmap_t {
   7         using bmap_type = std::vector<std::pair<size_t, size_t>>;
   8
   9         bmap_t() = default;
  10         // fully mapped image
  11         bmap_t(size_t img_size, size_t blk_size = 4096)
  12         : m_img_size(img_size),
  13           m_blk_size(blk_size),
  14           m_blk_count(default_blocks_count(img_size, blk_size))
  15         {
  16                 set_mapped_range(0, m_blk_count - 1);
  17         }
  18
  19         bmap_t& set_image_size(size_t size) {
  20                 m_img_size = size;
  21                 return *this;
  22         }
  23
  24         bmap_t& set_block_size(size_t size = 4096) {
  25                 m_blk_size = size;
  26                 return *this;
  27         }
  28
  29         bmap_t& set_blocks_count(size_t size = 0) {
  30                 if (size)
  31                         m_blk_count = size;
  32                 else
  33                         m_blk_count = default_blocks_count(m_img_size, m_blk_size);
  34                 return *this;
  35         }
  36
  37         bmap_t& set_mapped_range(size_t begin, size_t end) {
  38                 m_blk_map.emplace_back(begin, end);
  39                 return *this;
  40         }
  41
  42         static size_t default_blocks_count(size_t img_size, size_t blk_size) {
  43                 return img_size / blk_size + (img_size % blk_size ? 1 : 0);
  44         }
  45
  46         size_t image_size() const { return m_img_size; }
  47         size_t block_size() const { return m_blk_size; }
  48         size_t blocks_count() const { return m_blk_count; }
  49
  50         const bmap_type& mapped_ranges() const { return m_blk_map; }
  51
  52         bool is_mapped_block(size_t index) const;
  53
  54 private:
  55         size_t m_img_size = 0;
  56         size_t m_blk_size = 4096;
  57         size_t m_blk_count = 0;
  58         bmap_type m_blk_map;
  59         mutable bool m_gap_set = false;
  60         mutable size_t m_gap_begin = 0;
  61         mutable size_t m_gap_end = 0;
  62         mutable size_t m_next_gap_begin = 0;
  63 };
  64
  65 bool load_bmap(const std::string& filename, bmap_t& bmap);