64bit版 Mersenne Twister（C言語での実装）の unsigned long 出力を signed long 出力に変換する。

README.md

README

mt19937-64.out.txt に掲載されている、1000 outputs of genrand64_int64() を、Fortran で読み取れるように、 バイナリデータは保持しつつ、unsigned long から signed long に変換するための C++ と Fortran のソースコード。

参考文献

• Mersenne Twister: A random number generator (since 1997/10)
  • mt19937-64.out.txt

compile.cpp.sh

g++ -std=c++17 -Wall --pedantic-errors -o ./main.exe ./main.cpp

compile.f90.sh

gfortran -fbacktrace -fbounds-check -ffree-line-length-none -g -O0 -pedantic -std=f2008 -Wall -Werror -Wextra -o ./main.exe ./main.f90

main.cpp

#include <array>
// std::array

#include <cstdlib>
// EXIT_SUCCESS

#include <fstream>
// std::fstream

#include <iostream>
// std::cerr

#include <iomanip>
// std::setw

#include <string>
// std::string

const size_t length_sample_data = 1000;
const size_t num_digit          = 20;

void check_length_sample_data (std::ifstream &ifstream_sample_data, const std::size_t &length_sample_data_true)
{
	char        buffer[21];
	std::size_t length_sample_data_raw = 0;

	while( ifstream_sample_data.getline( buffer, sizeof(buffer) ) )
	{
		++length_sample_data_raw;
	}

	if ( length_sample_data_raw < length_sample_data_true )
	{
		std::cerr << "The detected number of sample data is "      << length_sample_data_raw  << std::endl;
		std::cerr << "The number of sample data must be equal to " << length_sample_data_true << std::endl;
	}

	ifstream_sample_data.clear();

	ifstream_sample_data.seekg(0, std::ios::beg);

	return;
}

int main (void)
{
	const std::string filename_sample_data_txt = "genrand64_int64_unsigned.txt";
	const std::string filename_sample_data_bin = "genrand64_int64_unsigned.bin";

	// STEP.01
	// Open the file which constains the sample data.
	std::ifstream ifstream_sample_data(filename_sample_data_txt);

	if( !ifstream_sample_data )
	{
		std::cerr << "Failed to open a file: " << filename_sample_data_txt << std::endl;
	}

	// STEP.02
	// Check the number of recorded sample data.
	check_length_sample_data( ifstream_sample_data, length_sample_data );

	// STEP.03
	// Read the sample data.
	std::array<uint64_t, length_sample_data> value_sample_data;

	for (std::size_t itr = 0; itr < length_sample_data; ++itr)
	{
		char  buffer[num_digit + 1];
		char *buffer_endptr;
		ifstream_sample_data.getline( buffer, sizeof(buffer) );
		value_sample_data.at(itr) = strtoul( buffer, &buffer_endptr, 10 );

		/* print debug */
		// std::cout << std::setw(num_digit) << value_sample_data.at(itr) << std::endl;
	}

	// STEP.04
	// Close the file which contains the sample data.
	ifstream_sample_data.close();

	// STEP.05
	// Open a file to write read sample data as binary.
	std::ofstream ofstream_sample_data_bin(filename_sample_data_bin, std::ios::binary);

	for (std::size_t itr = 0; itr < length_sample_data; ++itr)
	{
		ofstream_sample_data_bin.write( reinterpret_cast<char *>(&value_sample_data.at(itr)), sizeof(uint64_t) );

		/* print debug */
		// std::cout << std::setw(num_digit) << value_sample_data.at(itr) << std::endl;
	}

	// STEP.06
	// Close the file.
	ofstream_sample_data_bin.close();

	// STEP.END
	return EXIT_SUCCESS;
}

main.f90

program main

    ! <module>s to import
    use, intrinsic :: iso_fortran_env

    ! require all variables to be explicitly declared
    implicit none

    ! constant(s) for this <program>
    integer(INT32)   , parameter :: len_sample_data   = 1000_INT32
    character(len=*) , parameter :: filename_read     = 'genrand64_int64_unsigned.bin'
    character(len=*) , parameter :: filename_save_bin = 'genrand64_int64_signed.bin'
    character(len=*) , parameter :: filename_save_txt = 'genrand64_int64_signed.txt'

    ! variable(s) for this <program>
    integer        :: unit_read
    integer        :: unit_save_bin
    integer        :: unit_save_txt
    integer(INT64) :: val_sample_data (len_sample_data)

    ! support variable(s) for this <program>
    integer(INT32) :: itr_data

    ! STEP.01
    ! Open files to read/write the given sample data.
    open(&!
        newunit = unit_read     , &!
        access  = 'stream'      , &!
        action  = 'read'        , &!
        file    = filename_read , &!
        form    = 'unformatted' , &!
        status  = 'old'           &!
    )

    open(&!
        newunit = unit_save_bin     , &!
        access  = 'stream'          , &!
        action  = 'write'           , &!
        file    = filename_save_bin , &!
        form    = 'unformatted'     , &!
        status  = 'replace'           &!
    )

    open(&!
        newunit = unit_save_txt     , &!
        action  = 'write'           , &!
        file    = filename_save_txt , &!
        form    = 'formatted'       , &!
        status  = 'replace'           &!
    )

    ! STEP.02
    ! Read/Write the given sample data.
    do itr_data = 1_INT32 , len_sample_data , 1_INT32
        read ( unit= unit_read     )                             val_sample_data(itr_data)
        write( unit= unit_save_bin )                             val_sample_data(itr_data)
        write( unit= unit_save_txt, fmt='(I20)', advance='yes' ) val_sample_data(itr_data)
    end do

    ! STEP.03
    ! Close the opened files.
    close( unit= unit_read     , status= 'keep' )
    close( unit= unit_save_bin , status= 'keep' )
    close( unit= unit_save_txt , status= 'keep' )

end program main