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  1. #include <string.h>
  2.  
  3. #include <iostream>
  4. #include <chrono>
  5. #include <iostream>
  6. #include <iomanip>
  7.  
  8. using namespace std::chrono;
  9.  
  10. // based on
  11. // http://w...content-available-to-author-only...t.org/doc/libs/1_54_0/libs/chrono/example/await_keystroke.cpp
  12. template<class Clock>
  13. class Timer
  14. {
  15. typename Clock::time_point start;
  16.  
  17. public:
  18. Timer()
  19. : start(Clock::now()) {
  20. }
  21.  
  22. typename Clock::duration elapsed() const {
  23. return (Clock::now() - start);
  24. }
  25.  
  26. double seconds() const {
  27. return (elapsed().count() *
  28. ((double)Clock::period::num / Clock::period::den));
  29. }
  30. };
  31.  
  32. #define BUFFERSIZE (100 * 1024 * 1024) // 100 mb
  33. #define LOOPS 10
  34. #define MAXSTRIDE 128
  35.  
  36. int main()
  37. {
  38. char *b1 = (char *)::malloc(BUFFERSIZE + MAXSTRIDE);
  39. char *b2 = (char *)::malloc(BUFFERSIZE + MAXSTRIDE);
  40. ::memset(b1, 0, BUFFERSIZE + MAXSTRIDE);
  41.  
  42. // Each test is performed |LOOP| times; the average run-time is then printed.
  43.  
  44.  // Test memcpy() by copying from buffer b1 to b2
  45. {Timer<high_resolution_clock> t;
  46. for (int i = 0; i < LOOPS; i++)
  47. memcpy(b2, b1, BUFFERSIZE);
  48. double seconds = t.seconds();
  49. std::cout << "memcpy " << (seconds / LOOPS) << std::endl;
  50. }
  51. // Test memcpy() by copying from buffer b1 to b2
  52. Timer<high_resolution_clock> t;
  53. for (int i = 0; i < LOOPS; i++)
  54. memcpy(b2, b1, BUFFERSIZE);
  55. double seconds = t.seconds();
  56. std::cout << "memcpy " << (seconds / LOOPS) << std::endl;
  57.  
  58. // Test memmove() by inserting a small gap at the beginning of the buffer
  59. for (int stride = 2; stride <= MAXSTRIDE; stride *= 2) {
  60. Timer<high_resolution_clock> t;
  61. for (int i = 0; i < LOOPS; i++)
  62. memmove(b2, b1, BUFFERSIZE);
  63. double seconds = t.seconds();
  64. std::cout << "memmove (" << std::setfill('0') << std::setw(3)
  65. << stride << ") " << (seconds / LOOPS) << std::endl;
  66. }
  67.  
  68. ::free(b1);
  69. ::free(b2);
  70. }
Time limit exceeded #stdin #stdout 5s 207936KB
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stdin
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Standard input is empty
stdout
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memcpy 0.0688002
memcpy 0.0583162
memmove (002) 0.0577443
memmove (004) 0.05862
memmove (008) 0.0601029
memmove (016) 0.0601265
memmove (032) 0.0592741
memmove (064) 0.0604098
https://ideone.com/8EEAcA
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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