fork(2) download
copy 
  1. //#define FSE 1
  2.  
  3. #include <iostream>
  4. #include <fstream>
  5. #include <vector>
  6. #include <numeric>
  7. #include <algorithm>
  8. #ifdef FSE
  9. #include "fse.h"
  10. #endif
  11. using namespace std;
  12.  
  13. enum {
  14.     kUncomprSize = 250000,
  15.     kUncomprBytes = kUncomprSize * sizeof(uint32_t),
  16. };
  17.  
  18. using Buffer = vector<uint32_t>;
  19.  
  20. unsigned int_log(uint32_t x)
  21. {
  22.     return 32 - __builtin_clz(x);
  23. }
  24.  
  25. template<unsigned L>
  26. unsigned elias(const Buffer& deltas)
  27. {
  28.     unsigned compr_size = 0;
  29.     unsigned top = int_log(*max_element(begin(deltas), end(deltas)));
  30.     unsigned bottom = top  + 1 - (1 << L);
  31.  
  32.     for (auto x: deltas)
  33.     {
  34.         auto il = max(int_log(x), bottom);
  35.         compr_size += L;
  36.         compr_size += il - 1;
  37.     }
  38.  
  39.     return compr_size / 8;
  40. }
  41.  
  42. template<unsigned LSB>
  43. unsigned golomb(const Buffer& deltas)
  44. {
  45.     unsigned compr_size = 0;
  46.  
  47.     for (auto x: deltas)
  48.     {
  49.         auto il = int_log(x);
  50.         compr_size += LSB;
  51.         compr_size += (il > LSB)? 2 * (il - LSB) - 1: 1;
  52.     }
  53.  
  54.     return compr_size / 8;
  55. }
  56.  
  57. #ifdef FSE
  58. template<unsigned MSB>
  59. unsigned fse(const Buffer& deltas)
  60. {
  61.     vector<char> compressible(deltas.size());
  62.     transform(begin(deltas), end(deltas), begin(compressible), [](uint32_t x)
  63.     {
  64.         auto il = int_log(x);
  65.         auto res = x << (32 - il);
  66.         res >>= 32 - MSB;
  67.         res += il << MSB;
  68.         return static_cast<char>(res);
  69.     });
  70.     vector<char> compressed(2 * deltas.size());
  71.  
  72.     auto compr_res = FSE_compress(
  73.         compressed.data(), compressed.size(),
  74.         compressible.data(), compressible.size()
  75.     );
  76.     if (FSE_isError(compr_res))
  77.     {
  78.         std::cout << "FSE error: " << FSE_getErrorName(compr_res) << "\n";
  79.     }
  80.     unsigned compr_size = 8 * static_cast<unsigned>(compr_res);
  81.  
  82.     for (auto x: deltas)
  83.     {
  84.         auto il = int_log(x);
  85.         compr_size += (il > MSB)? il - MSB - 1: 0;
  86.     }
  87.  
  88.     return compr_size / 8;
  89. }
  90. #endif
  91.  
  92. int main() {
  93.     Buffer uncompr(kUncomprSize);
  94.     Buffer deltas(kUncomprSize);
  95.     ifstream in("/dev/random", ios_base::in | ios_base::binary);
  96.     in.read(reinterpret_cast<char*>(uncompr.data()), kUncomprBytes);
  97.     sort(begin(uncompr), end(uncompr));
  98.     adjacent_difference(begin(uncompr), end(uncompr), begin(deltas));
  99.  
  100.     std::cout << "Elias4: " << elias<4>(deltas) << '\n';
  101.     std::cout << "Elias3: " << elias<3>(deltas) << '\n';
  102.     std::cout << "Elias2: " << elias<2>(deltas) << '\n';
  103.     std::cout << "Golomb12: " << golomb<12>(deltas) << '\n';
  104.     std::cout << "Golomb13: " << golomb<13>(deltas) << '\n';
  105.     std::cout << "Golomb14: " << golomb<14>(deltas) << '\n';
  106.     std::cout << "Golomb15: " << golomb<15>(deltas) << '\n';
  107. #ifdef FSE
  108.     std::cout << "FSE1: " << fse<1>(deltas) << '\n';
  109.     std::cout << "FSE2: " << fse<2>(deltas) << '\n';
  110.     std::cout << "FSE3: " << fse<3>(deltas) << '\n';
  111. #endif
  112. }
Time limit exceeded #stdin #stdout 5s 5232KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
https://ideone.com/ulmPzO
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!