/**

 * LPT signal generator

 * Copyright © 2017 František Kučera (frantovo.cz)

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. If not, see <http://www.gnu.org/licenses/>.

 */

#include <stdlib.h>

#include <iostream>

#include <stdio.h>

#include <math.h>

#include <sys/io.h>

#include <unistd.h>

/**

 * can not mix printf and wprintf

 * see https://stackoverflow.com/questions/8681623/printf-and-wprintf-in-single-c-code

 * > This is to be expected; your code is invoking undefined behavior.

 * > Per the C standard, each FILE stream has associated with it an "orientation" (either "byte" or "wide)

 * > which is set by the first operation performed on it, and which can be inspected with the fwide function.

 * > Calling any function whose orientation conflicts with the orientation of the stream results in undefined behavior.

 */

#include <wchar.h>

#include <locale.h>

using namespace std;

// run this program: g++ lpt.cpp && time chrt 1 ./a.out

// depending to frequency and machine performance the total time will be more than given duration

// despite the real-time priority, because some additional time is spent in outb() functions

// so "duration" means total sleep time

int main() {

  //cout << "LPT!" << endl; // same as using printf → breaks all folllowing wprintf() calls, see note above

  /*

   * if setlocale() is missing, unicode characters are replaced with ? or „→“ with „->“ because C/POSIX locale is used, 

   * see man setlocale:

   * > On startup of the main program, the portable "C" locale is selected as default.

   * > If locale is an empty string, "", each part of the locale that should be modified is set according to the environment variables.

   */

  setlocale(LC_ALL,"");

  int addr = 0xe400; // parallel port address; first number of given port in: cat /proc/ioports | grep parport

  int baseFreq = 10000; // base frequency in Hz, should be between 5 000 between 10 000 Hz; lower frequency leads to dashed/dotted lines instead of greyscale

  int outputPower = 10; // duty cycle; 100 = 100 %

  int duration = 5; // in seconds; total sleep time, see note above

  int valueWidth =  10; // just for padding of printed values

  int labelWidth = -15; // just for padding of printed labels

  // ' = thousand separator

  // * = padding

  wprintf(L"%*ls %*x\n",     labelWidth, L"Parallel port:", valueWidth, addr); // or %#*x – adds 0x prefix

  wprintf(L"%*ls %'*d Hz\n", labelWidth, L"Base frequency:", valueWidth, baseFreq);

  wprintf(L"%*ls %*d %%\n",  labelWidth, L"Output power:", valueWidth, outputPower);

  wprintf(L"%*ls %'*d s\n",  labelWidth, L"Duration:", valueWidth, duration);

  // in microseconds:

  int oneSecond = 1000 * 1000;

  int timeOn =  oneSecond *        outputPower  / 100 / baseFreq;

  int timeOff = oneSecond * (100 - outputPower) / 100 / baseFreq;

  int cycleCount = duration * baseFreq;

  wprintf(L"%*ls %'*d ×\n", labelWidth, L"Cycle count:", valueWidth, cycleCount);

  wprintf(L"%*ls %'*d μs in each cycle\n", labelWidth, L"Time on:",  valueWidth, timeOn);

  wprintf(L"%*ls %'*d μs in each cycle\n", labelWidth, L"Time off:", valueWidth, timeOff);

  wprintf(L"%*ls %*ls\n", labelWidth, L"unicode test:", valueWidth, L"čeština → …");

  if (ioperm(addr,1,1)) { fwprintf(stderr, L"Access denied to port %#x\n", addr), exit(1); }

  outb(0b00000000, addr);

  for (int i = 0; i < cycleCount; i++) {

    outb(0b00000001, addr);

    usleep(timeOn);

    outb(0b00000000, addr);

    usleep(timeOff);

  }

  wprintf(L"finished\n");

}