riscv/icsim.cc

   1 #include "icsim.h"
   2 #include <stdexcept>
   3 #include <iostream>
   4 #include <iomanip>
   5
   6 icsim_t::icsim_t(size_t _sets, size_t _ways, size_t _linesz)
   7 {
   8   sets = _sets;
   9   ways = _ways;
  10   linesz = _linesz;
  11
  12   if(sets == 0 || (sets & (sets-1)))
  13     throw std::logic_error("sets not a power of 2");
  14   if(linesz == 0 || (linesz & (linesz-1)))
  15     throw std::logic_error("linesz not a power of 2");
  16   if(ways != 1)
  17     throw std::logic_error("set associativity currently unsupported");
  18
  19   idx_mask = sets-1;
  20   idx_shift = 0;
  21   while(_linesz >>= 1)
  22     idx_shift++;
  23
  24   tags = new uint64_t[sets*ways];
  25   memset(tags, 0, sets*ways*sizeof(uint64_t));
  26 }
  27
  28 icsim_t::~icsim_t()
  29 {
  30   float mr = 100.0f*misses/accesses;
  31   float cr = 100.0f*bytes_fetched/(4*accesses);
  32
  33   std::cout << "Instruction cache statsistics" << std::endl;
  34   std::cout << "Bytes fetched: " << bytes_fetched << std::endl;
  35   std::cout << "Hits: " << (accesses-misses) << std::endl;
  36   std::cout << "Misses: " << misses << std::endl;
  37   std::cout << "Miss rate: " << std::setprecision(3) << mr << '%' << std::endl;
  38   std::cout << "RVC compression ratio: " << cr << '%' << std::endl;
  39
  40   delete [] tags;
  41 }
  42
  43 void icsim_t::tick(uint64_t pc, int insnlen)
  44 {
  45   accesses++;
  46   bytes_fetched += insnlen;
  47
  48   size_t idx = (pc >> idx_shift) & idx_mask;
  49   size_t tag = (pc >> idx_shift) | VALID;
  50   if(tag != tags[idx])
  51   {
  52     misses++;
  53     tags[idx] = tag;
  54   }
  55 }