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@46: #include <chrono> // requires -std=c++11
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@47: // run this program: make run
franta-hg@46: // depending on 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@50: // TODO: data types revision
franta-hg@51: // TODO: time units s, μs, ns – naming convention / unification
franta-hg@50: 
franta-hg@51: /**
franta-hg@51:  * generates square wave signal on a parallel port pin with given frequency and duty cycle
franta-hg@51:  * mode info: https://blog.frantovo.cz/c/358/Paraleln%C3%AD%20port%20jako%20gener%C3%A1tor%20sign%C3%A1lu
franta-hg@51:  */
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@49: 
franta-hg@49:   // configuration ----
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@48:   int outputPower = 20; // duty cycle; 100 = 100 %
franta-hg@46:   int duration = 1; // in seconds; total sleep time, see note above
franta-hg@49:   // ------------------
franta-hg@49: 
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@46:   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@46:   wprintf(L"%*ls %*d %% duty cycle\n",  labelWidth, L"Output power:", valueWidth, outputPower);
franta-hg@46:   wprintf(L"%*ls %'*d s\n", labelWidth, L"Duration:", valueWidth, duration);
franta-hg@44: 
franta-hg@45:   // in microseconds:
franta-hg@50:   auto oneSecond = 1000 * 1000;
franta-hg@50:   auto timeOn =  oneSecond *        outputPower  / 100 / baseFreq;
franta-hg@50:   auto timeOff = oneSecond * (100 - outputPower) / 100 / baseFreq;
franta-hg@44: 
franta-hg@50:   auto cycleCount = duration * baseFreq;
franta-hg@45:   wprintf(L"%*ls %'*d ×\n", labelWidth, L"Cycle count:", valueWidth, cycleCount);
franta-hg@46:   wprintf(L"%*ls %'*d μs 1× in each cycle\n", labelWidth, L"Time on:",  valueWidth, timeOn);
franta-hg@46:   wprintf(L"%*ls %'*d μs 1× in each cycle\n", labelWidth, L"Time off:", valueWidth, timeOff);
franta-hg@44: 
franta-hg@46:   //wprintf(L"%*ls %*ls\n", labelWidth, L"unicode test:", valueWidth, L"čeština → …");
franta-hg@44: 
franta-hg@49:   wprintf(L"\n");
franta-hg@45: 
franta-hg@50:   // TODO: test whether this address is an parallel port
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: 
franta-hg@49:   // calibration
franta-hg@46:   auto startTimestamp = chrono::high_resolution_clock::now();
franta-hg@49:   auto calibrationCycles = 10000;
franta-hg@49:   auto calibrationSleepTime = 10;
franta-hg@49: 
franta-hg@51:   for (auto i = calibrationCycles; i > 0; i--) {
franta-hg@49:     outb(0b00000000, addr);
franta-hg@49:     usleep(calibrationSleepTime);
franta-hg@49:     outb(0b00000000, addr);
franta-hg@49:     usleep(calibrationSleepTime);
franta-hg@49:   }
franta-hg@49: 
franta-hg@49:   auto finishTimestamp = chrono::high_resolution_clock::now();
franta-hg@49:   auto measuredDuration = chrono::duration_cast<chrono::nanoseconds>(finishTimestamp - startTimestamp).count();
franta-hg@49: 
franta-hg@49:   auto singleOutbCostNano = (measuredDuration - calibrationCycles*2*calibrationSleepTime*1000)/calibrationCycles/2;
franta-hg@49:   auto singleOutbCostMicro = singleOutbCostNano/1000;
franta-hg@49: 
franta-hg@49:   wprintf(L"%*ls %'*d μs 2× in each calibration cycle\n", labelWidth, L"Single outb():", valueWidth, singleOutbCostMicro);
franta-hg@49:   wprintf(L"%*ls %'*d ns 2× in each calibration cycle\n", labelWidth, L"Single outb():", valueWidth, singleOutbCostNano);
franta-hg@49: 
franta-hg@49:   auto minPower = 100*singleOutbCostNano/(1000*1000*1000/baseFreq);
franta-hg@49:   auto maxPower = 100-minPower;
franta-hg@49:   wprintf(L"%*ls %*d %% feasible duty cycle\n",  labelWidth, L"Minimum power:", valueWidth, minPower);
franta-hg@49:   wprintf(L"%*ls %*d %% feasible duty cycle\n",  labelWidth, L"Maximum power:", valueWidth, maxPower);
franta-hg@49: 
franta-hg@49:   if (singleOutbCostMicro < timeOn && singleOutbCostMicro < timeOff) {
franta-hg@49:     wprintf(L"%*ls %*ls both frequency and duty cycle should be correct\n",  labelWidth, L"Calibration:", valueWidth, L"OK");
franta-hg@49:     timeOn  -= singleOutbCostMicro;
franta-hg@49:     timeOff -= singleOutbCostMicro;
franta-hg@49:   } else if (2*singleOutbCostMicro < (timeOn + timeOff)) {
franta-hg@49:     wprintf(L"%*ls %*ls frequency should be OK, but duty cycle is not feasible\n",  labelWidth, L"Calibration:", valueWidth, L"WARNING");
franta-hg@49:     timeOn  -= singleOutbCostMicro;
franta-hg@49:     timeOff -= singleOutbCostMicro;
franta-hg@49: 
franta-hg@49:     if (timeOn < 0) {
franta-hg@49:       timeOff -= timeOn;
franta-hg@49:       timeOn = 0;
franta-hg@49:     } else {
franta-hg@49:       timeOn -= timeOff;
franta-hg@49:       timeOff = 0;
franta-hg@49:     }
franta-hg@49:   } else {
franta-hg@49:     wprintf(L"%*ls %*ls both frequency and duty cycle are not feasible\n",  labelWidth, L"Calibration:", valueWidth, L"ERROR");
franta-hg@49:     timeOn  = 0;
franta-hg@49:     timeOff = 0;
franta-hg@49:   }
franta-hg@49: 
franta-hg@49:   wprintf(L"%*ls %'*d μs 1× in each cycle\n", labelWidth, L"Sleep on:",  valueWidth, timeOn);
franta-hg@49:   wprintf(L"%*ls %'*d μs 1× in each cycle\n", labelWidth, L"Sleep off:", valueWidth, timeOff);
franta-hg@49: 
franta-hg@49:   wprintf(L"\n");
franta-hg@49: 
franta-hg@49: 
franta-hg@49:   // actual signal generation
franta-hg@49:   startTimestamp = chrono::high_resolution_clock::now();
franta-hg@46: 
franta-hg@50:   for (auto i = cycleCount; i > 0;  i--) {
franta-hg@46:     outb(0b00000001, addr); // first data out pin = data out 0 = pin 2 on DB-25 connector
franta-hg@45:     usleep(timeOn);
franta-hg@44:     outb(0b00000000, addr);
franta-hg@45:     usleep(timeOff);
franta-hg@44:   }
franta-hg@44: 
franta-hg@49:   finishTimestamp = chrono::high_resolution_clock::now();
franta-hg@49:   measuredDuration = chrono::duration_cast<chrono::nanoseconds>(finishTimestamp - startTimestamp).count();
franta-hg@46: 
franta-hg@49:   wprintf(L"%*ls %'*d μs in total\n", labelWidth, L"Deviation:", valueWidth, (measuredDuration-duration*oneSecond*1000)/1000);
franta-hg@49:   wprintf(L"%*ls %'*d ns in each cycle\n", labelWidth, L"Deviation:", valueWidth, (measuredDuration-duration*oneSecond*1000)/cycleCount);
franta-hg@44: 
franta-hg@44: }