franta-hg@44: /**
franta-hg@44:  * LPT signal generator
franta-hg@44:  * Copyright © 2017 František Kučera (frantovo.cz)
franta-hg@44:  *
franta-hg@44:  * This program is free software: you can redistribute it and/or modify
franta-hg@44:  * it under the terms of the GNU General Public License as published by
franta-hg@44:  * the Free Software Foundation, either version 3 of the License, or
franta-hg@44:  * (at your option) any later version.
franta-hg@44:  *
franta-hg@44:  * This program is distributed in the hope that it will be useful,
franta-hg@44:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
franta-hg@44:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
franta-hg@44:  * GNU General Public License for more details.
franta-hg@44:  *
franta-hg@44:  * You should have received a copy of the GNU General Public License
franta-hg@44:  * along with this program. If not, see <http://www.gnu.org/licenses/>.
franta-hg@44:  */
franta-hg@44: 
franta-hg@44: #include <stdlib.h>
franta-hg@44: #include <iostream>
franta-hg@44: #include <stdio.h>
franta-hg@44: #include <math.h>
franta-hg@44: #include <sys/io.h>
franta-hg@44: #include <unistd.h>
franta-hg@44: 
franta-hg@45: /**
franta-hg@45:  * can not mix printf and wprintf
franta-hg@45:  * see https://stackoverflow.com/questions/8681623/printf-and-wprintf-in-single-c-code
franta-hg@45:  * > This is to be expected; your code is invoking undefined behavior.
franta-hg@45:  * > Per the C standard, each FILE stream has associated with it an "orientation" (either "byte" or "wide)
franta-hg@45:  * > which is set by the first operation performed on it, and which can be inspected with the fwide function.
franta-hg@45:  * > Calling any function whose orientation conflicts with the orientation of the stream results in undefined behavior.
franta-hg@45:  */
franta-hg@45: #include <wchar.h>
franta-hg@45: #include <locale.h>
franta-hg@45: 
franta-hg@45: 
franta-hg@44: using namespace std;
franta-hg@44: 
franta-hg@45: // run this program: g++ lpt.cpp && time chrt 1 ./a.out
franta-hg@45: // depending to frequency and machine performance the total time will be more than given duration
franta-hg@45: // despite the real-time priority, because some additional time is spent in outb() functions
franta-hg@45: // so "duration" means total sleep time
franta-hg@44: 
franta-hg@44: int main() {
franta-hg@45:   //cout << "LPT!" << endl; // same as using printf → breaks all folllowing wprintf() calls, see note above
franta-hg@44: 
franta-hg@45:   /*
franta-hg@45:    * if setlocale() is missing, unicode characters are replaced with ? or „→“ with „->“ because C/POSIX locale is used, 
franta-hg@45:    * see man setlocale:
franta-hg@45:    * > On startup of the main program, the portable "C" locale is selected as default.
franta-hg@45:    * > If locale is an empty string, "", each part of the locale that should be modified is set according to the environment variables.
franta-hg@45:    */
franta-hg@45:   setlocale(LC_ALL,"");
franta-hg@44: 
franta-hg@45:   int addr = 0xe400; // parallel port address; first number of given port in: cat /proc/ioports | grep parport
franta-hg@45:   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
franta-hg@45:   int outputPower = 10; // duty cycle; 100 = 100 %
franta-hg@45:   int duration = 5; // in seconds; total sleep time, see note above
franta-hg@44: 
franta-hg@45:   int valueWidth =  10; // just for padding of printed values
franta-hg@45:   int labelWidth = -15; // just for padding of printed labels
franta-hg@44: 
franta-hg@45:   // ' = thousand separator
franta-hg@45:   // * = padding
franta-hg@45:   wprintf(L"%*ls %*x\n",     labelWidth, L"Parallel port:", valueWidth, addr); // or %#*x – adds 0x prefix
franta-hg@45:   wprintf(L"%*ls %'*d Hz\n", labelWidth, L"Base frequency:", valueWidth, baseFreq);
franta-hg@45:   wprintf(L"%*ls %*d %%\n",  labelWidth, L"Output power:", valueWidth, outputPower);
franta-hg@45:   wprintf(L"%*ls %'*d s\n",  labelWidth, L"Duration:", valueWidth, duration);
franta-hg@44: 
franta-hg@45:   // in microseconds:
franta-hg@45:   int oneSecond = 1000 * 1000;
franta-hg@45:   int timeOn =  oneSecond *        outputPower  / 100 / baseFreq;
franta-hg@45:   int timeOff = oneSecond * (100 - outputPower) / 100 / baseFreq;
franta-hg@44: 
franta-hg@45:   int cycleCount = duration * baseFreq;
franta-hg@45:   wprintf(L"%*ls %'*d ×\n", labelWidth, L"Cycle count:", valueWidth, cycleCount);
franta-hg@45:   wprintf(L"%*ls %'*d μs in each cycle\n", labelWidth, L"Time on:",  valueWidth, timeOn);
franta-hg@45:   wprintf(L"%*ls %'*d μs in each cycle\n", labelWidth, L"Time off:", valueWidth, timeOff);
franta-hg@44: 
franta-hg@45:   wprintf(L"%*ls %*ls\n", labelWidth, L"unicode test:", valueWidth, L"čeština → …");
franta-hg@44: 
franta-hg@45: 
franta-hg@45:   if (ioperm(addr,1,1)) { fwprintf(stderr, L"Access denied to port %#x\n", addr), exit(1); }
franta-hg@45: 
franta-hg@45:   outb(0b00000000, addr);
franta-hg@45: 
franta-hg@45:   for (int i = 0; i < cycleCount; i++) {
franta-hg@45:     outb(0b00000001, addr);
franta-hg@45:     usleep(timeOn);
franta-hg@44:     outb(0b00000000, addr);
franta-hg@45:     usleep(timeOff);
franta-hg@44:   }
franta-hg@44: 
franta-hg@45:   wprintf(L"finished\n");
franta-hg@44: 
franta-hg@44: }