C++ bits fields speed test

C++ bits fields speed test


原始程式碼

https://github.com/poi5305/utility/blob/master/bits_fields_speed_test.cpp

 //=========================================//

 RT.start_timer("old");

 for(uint32_t i=0; i < genome.size()/4; i++)

 {

  uint8_t cpint ( table[ genome[ (i<<2)+0 ] ] );

  for(uint32_t j=1; j<4; j++)

  {

   cpint = cpint << 2;

   cpint = cpint | table[ genome[ (i<<2)+j ]];

  }

  compressed_genome_2[i] = cpint;

 }

 RT.print_timer("old");

 //=========================================//







 //=========================================//

 RT.start_timer("bits fields version 1");

 for(uint32_t i=0; i < genome.size()/4; i++)

 {

  compressed_genome_1[i].bits.b4 = table[ genome[ (i<<2)+0 ] ];

  compressed_genome_1[i].bits.b3 = table[ genome[ (i<<2)+1 ] ];

  compressed_genome_1[i].bits.b2 = table[ genome[ (i<<2)+2 ] ];

  compressed_genome_1[i].bits.b1 = table[ genome[ (i<<2)+3 ] ];

 }

 RT.print_timer("bits fields version 1");

 //=========================================//





 //=========================================//

 RT.start_timer("bits fields version 2");

 for(uint32_t i=0; i < genome.size()/4; i++)

 {

  compressed_genome_3[i].bits = {

   table[ genome[ (i<<2)+3 ] ],

   table[ genome[ (i<<2)+2 ] ],

   table[ genome[ (i<<2)+1 ] ],

   table[ genome[ (i<<2)+0 ] ]

  };

 }

 RT.print_timer("bits fields version 2");

 //=========================================//

 /* 

 Mac clang -O2

  Genome size: 400000000

  old: 7315

  bits fields version 1: 7258

  bits fields version 2: 6582

  Values of three methods are the same

  bits fields version 3: 6484

 Mac clang -O3

  Genome size: 400000000

  old: 398

  bits fields version 1: 779

  bits fields version 2: 500

  Values of three methods are the same

  bits fields version 3: 505

 Ubuntu g++-4.8 -O2

  Genome size: 400000000

  old: 1273

  bits fields version 1: 2079

  bits fields version 2: 1019

  Values of three methods are the same

  bits fields version 3: 981

 Ubuntu g++-4.8 -O3

  Genome size: 400000000

  old: 1335

  bits fields version 1: 2086

  bits fields version 2: 995

  Values of three methods are the same

  bits fields version 3: 937

 */