# HG changeset patch
# User František Kučera <franta-hg@frantovo.cz>
# Date 1496581153 -7200
# Node ID ea8642c174958df5e3f65221e2f06aafe8209f2d
# Parent  896eca3d40d8a53cf5c1d130ae718a7d9e3f542c
lpt-signal-generator: parametrizace, unicode

diff -r 896eca3d40d8 -r ea8642c17495 c++/lpt-signal-generator/lpt.cpp
--- a/c++/lpt-signal-generator/lpt.cpp	Sun Jun 04 14:57:42 2017 +0200
+++ b/c++/lpt-signal-generator/lpt.cpp	Sun Jun 04 14:59:13 2017 +0200
@@ -23,35 +23,75 @@
 #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;
 
-// g++ lpt.cpp && ./a.out
+// 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;
+  //cout << "LPT!" << endl; // same as using printf → breaks all folllowing wprintf() calls, see note above
 
-  //int addr = 0x378; // parport0
+  /*
+   * 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; // parport1
+  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 addr = 0x278;
+  int valueWidth =  10; // just for padding of printed values
+  int labelWidth = -15; // just for padding of printed labels
 
-  //int addr = 0xc800;
+  // ' = 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;
 
-  if (ioperm(addr,1,1)) { fprintf(stderr, "Access denied to %x\n", addr), exit(1); }
+  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 → …");
 
-  for (int i = 0; i < 30; i++) {
-    cout << "cyklus" << endl;
-    usleep(100*1000);
-    outb(0b11111111, addr);
-    usleep(10*1000);
+
+  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);
   }
 
-
-  cout << "hotovo" << endl;
-
+  wprintf(L"finished\n");
 
 }