C-C-C-Combo Maker

Piotr Szotkowski

chastell.net

class Integer
  def sqrt_prime?
    (2..Math.sqrt(self).floor).all? { |i| (self % i).nonzero? }
  end
end

(2..100_000).each &:sqrt_prime?   #=> 1.1 s

class Integer
  def skipping_prime?
    return true  if self == 2
    return false if self.even?
    3.step(Math.sqrt(self).floor, 2).all? { |i| (self % i).nonzero? }
  end
end

(2..100_000).each &:skipping_prime?   #=> 0.6 s

require 'inline'

class Integer
  inline do |builder|
    builder.include '<math.h>'
    builder.c '
      VALUE inline_prime() {
        long i, number = NUM2LONG(self);
        if (number == 2)     return Qtrue;
        if (number % 2 == 0) return Qfalse;
        for (i = 3; i <= floor(sqrt(number)); i = i + 2) {
          if (number % i == 0) return Qfalse;
        }
        return Qtrue;
      }
    '
  end
end

require 'prime'

(2..100_000).each &:prime?

require 'benchmark'
require 'inline'
require 'prime'

class Integer
  # …
end

range = 2..100_000

Benchmark.bmbm do |bench|
  bench.report('sqrt:')     { range.each &:sqrt_prime?     }
  bench.report('skipping:') { range.each &:skipping_prime? }
  bench.report('inline:')   { range.each &:inline_prime    }
  bench.report('stdlib:')   { range.each &:prime?          }
end

popcount

ile dana liczba ma jedynek

w reprezentacji binarnej

class Integer
  def popcount_to_s
    to_s(2).count '1'
  end
end

require 'inline'

class Integer
  inline do |builder|
    builder.c '
      int popcount_builtin() {
        return __builtin_popcountl(NUM2LONG(self));
      }
    '
  end
end

require 'benchmark'
require 'inline'

class Integer
  # …
end

range = 0...2**22

Benchmark.bmbm do |bench|
  bench.report('to_s:')    { range.each &:popcount_to_s    }
  bench.report('builtin:') { range.each &:popcount_builtin }
end

#include "nf2util.h"

unsigned get_register(unsigned reg) {
  struct nf2device nf2;
  unsigned val;

  nf2.device_name = "nf2c0";
  check_iface(&nf2);
  openDescriptor(&nf2);

  readReg(&nf2, reg, &val);

  closeDescriptor(&nf2);

  return val;
}

#include "nf2util.h"

void set_register(unsigned reg, unsigned val) {
  struct nf2device nf2;

  nf2.device_name = "nf2c0";
  check_iface(&nf2);
  openDescriptor(&nf2);

  writeReg(&nf2, reg, val);

  closeDescriptor(&nf2);
}

require 'ffi'

class NetFPGA::Bridge
  extend FFI::Library
  ffi_lib "regset.so"

  attach_function :get_register, [:uint],        :uint
  attach_function :set_register, [:uint, :uint], :void
end

bridge = NetFPGA::Bridge.new
bridge.get_register 0x2000200               #=> 0xbaadf00d
bridge.set_register 0x2000204, 0xdeadbeef   #=> nil