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From: Paul Rubin <no.email@nospam.invalid>
Newsgroups: comp.lang.forth
Subject: Re: Ruby/Forth challenge for WJ
Date: Tue, 12 Jan 2016 16:24:42 -0800
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Paul Rubin <no.email@nospam.invalid> writes:
>> with my 32 bit native code generating forth I get 983 ms on the same laptop
> Interestingly, your 32 bit Forth is beating 64 bit C++ by a wide margin,
> even with C++ running on a considerably faster machine (i7-3770).

Oh never mind, with optimization off and subscript checking on, I was
getting about 1 sec (GCC 4.7.2).  With optimization -O3 and unsafe
subscripts, I get 141 ms.  This is just for the counting part, not the
random initialization, which depends considerably on which PRNG you use.
The subscript checking actually only makes a tiny difference.

================================================================

#include <iostream>
#include <random>
#include <array>
#include <cstdint>
#include <chrono>

const int Bufsize = 1<<28;
std::array<std::uint8_t, Bufsize+3> buf;

void init_array()
{
  std::minstd_rand rd;
  for (int i = 0; i < buf.size(); i += 3)
    {
      int r = rd();
      buf[i] = r&0xff;
      r >>= 8; 
      buf[i+1] = r&0xff;
      r >>= 8; 
      buf[i+2] = r&0xff;
    }
 }

int main(int argc, char **argv) {
  auto t0 = std::chrono::high_resolution_clock::now();
  init_array();
  auto t1 = std::chrono::high_resolution_clock::now();

  static std::array<std::uint32_t, 256> counts;
  for (uint8_t b: buf) {
    ++counts[b];
  }
  auto t2 = std::chrono::high_resolution_clock::now();
  std::chrono::duration<double> d1 = t1 - t0;
  std::chrono::duration<double> d2 = t2 - t1;
  std::cout << d1.count () << " " << d2.count() << std::endl;
  return 0;  
}