20181112/photo-20181112-173737.txt

-README: Differentialgleichung für gleichförmige und gleichmäßig beschleunigte Bewegung

20181119/higher-math-5.c

-#include <stdio.h>
-
-#define VIER (2 + 2)
-
-int main (void)
-{
-  printf ("3 * 4 = %d\n", 3 * VIER);
-  return 0;
-}

20181119/hp-uebung-20181119.tex

-% hp-uebung-20181119.pdf - Exercises on Low-Level Programming / Applied Computer Sciences
-% Copyright (C) 2013, 2015, 2016, 2017, 2018  Peter Gerwinski
-%
-% This document is free software: you can redistribute it and/or
-% modify it either under the terms of the Creative Commons
-% Attribution-ShareAlike 3.0 License, or 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 document 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 document.  If not, see <http://www.gnu.org/licenses/>.
-%
-% You should have received a copy of the Creative Commons
-% Attribution-ShareAlike 3.0 Unported License along with this
-% document.  If not, see <http://creativecommons.org/licenses/>.
-
-% README: Arrays mit Zahlen, hüpfender Ball
-
-\documentclass[a4paper]{article}
-
-\usepackage{pgscript}
-
-\begin{document}
-
-%  \thispagestyle{empty}
-
-  \section*{Hardwarenahe Programmierung\\
-            Übungsaufgaben -- 19.\ November 2018}
-
-  Diese Übung enthält Punkteangaben wie in einer Klausur.
-  Um zu "`bestehen"', müssen Sie innerhalb von 60 Minuten
-  unter Verwendung ausschließlich zugelassener Hilfsmittel
-  10 Punkte (von insgesamt \totalpoints) erreichen.
-
-  \exercise{Arrays mit Zahlen}
-
-  \begin{minipage}[t]{0.5\textwidth}
-    Wir betrachten das folgende Programm\\
-    (Datei: \gitfile{hp}{20181119}{aufgabe-1.c}):
-    \begin{lstlisting}[gobble=6]
-      #include <stdio.h>
-
-      void f (int *s0, int *s1)
-      {
-        while (*s0 >= 0)
-        {
-          int *s = s1;
-          while (*s >= 0)
-            if (*s0 == *s++)
-              printf ("%d ", *s0);
-          s0++;
-        }
-        printf ("\n");
-      }
-
-      int main (void)
-      {
-        int a[] = { 10, 4, 3, 7, 12, 0, 1, -1 };
-        int b[] = { 7, 14, 0, 8, 9, 22, 10, -1 };
-        f (a, b);
-        return 0;
-      }
-    \end{lstlisting}
-  \end{minipage}\hfill
-  \begin{minipage}[t]{0.5\textwidth}
-    \vspace*{-\bigskipamount}
-    \begin{enumerate}[\quad(a)]
-      \item
-        Was bewirkt die Funktion \lstinline{f},\\
-        und wie funktioniert sie?
-        \points{4}
-%      \item
-%        Von welcher Ordnung (Landau-Symbol) ist die Funktion und warum?
-%
-%        Wir beziehen uns hierbei auf die Anzahl der Vergleiche
-%        in Abhängigkeit von der Länge der Eingabedaten \lstinline{s0} und \lstinline{s1}.
-%        Für die Rechnung dürfen Sie beide Längen mit $n$ gleichsetzen,
-%        obwohl sie normalerweise nicht gleich sind.
-%        \points{2}
-      \item
-        Was passiert, wenn Sie beim Aufruf der Funktion für einen der
-        Parameter den Wert \lstinline{NULL} übergeben und warum?
-        \points{2}
-      \item
-        Was kann passieren, wenn Sie das Hauptprogramm wie folgt abändern
-        (\gitfile{hp}{20181119}{aufgabe-1d.c}) und warum?
-        \begin{lstlisting}[gobble=8]
-          int main (void)
-          {
-            int a[] = { 10, 4, 3, 7, 12, 0, 1 };
-            int b[] = { 7, 14, 0, 8, 9, 22, 10 };
-            f (a, b);
-            return 0;
-          }
-        \end{lstlisting}
-        \points{2}
-%      \item
-%        Beschreiben Sie -- in Worten und/oder als C-Quelltext --, wie
-%        sich die Funktion \lstinline{f} effizienter gestalten läßt,
-%        wenn man die ihr übergebenen Arrays \lstinline{s0} und
-%        \lstinline{s1} als sortiert voraussetzt.
-%        \points{5}
-%
-%        Hinweis: Wie würden Sie als Mensch die Aufgabe erledigen?
-%      \item
-%        Von welcher
-%        Ordnung (Landau-Symbol) ist Ihre effizientere Version der Funktion und warum?
-%        \points{2}
-    \end{enumerate}
-  \end{minipage}
-
-  \exercise{Fehlerhaftes Programm: Hüpfender Ball}
-
-  Das auf der nächsten Seite abgedruckte GTK+-Programm
-  (Datei: \gitfile{hp}{20181119}{aufgabe-2.c}) soll einen
-  hüpfenden Ball darstellen, ist jedoch fehlerhaft.
-
-  \begin{enumerate}[\quad(a)]
-    \item
-      Warum sieht man lediglich ein leeres Fenster?
-      Welchen Befehl muß man ergänzen, um diesen Fehler zu beheben?
-      \points{3}
-    \item
-      Nach der Fehlerbehebung in Aufgabenteil (a)
-      zeigt das Programm einen unbeweglichen Ball.
-      Welchen Befehl muß man ergänzen, um diesen Fehler zu beheben, und warum?
-      \points{2}
-    \item
-      Erklären Sie das merkwürdige Hüpfverhalten des Balls.
-      Wie kommt es zustande?
-      Was an diesem Verhalten ist korrekt, und was ist fehlerhaft? \points{5}
-    \item
-      Welche Befehle muß man in welcher Weise ändern,
-      um ein realistischeres Hüpf-Verhalten zu bekommen? \points{2}
-  \end{enumerate}
-
-  Hinweis: Das Hinzuziehen von Beispiel-Programmen aus der Vorlesung
-  ist ausdrücklich erlaubt -- auch in der Klausur.
-
-  Allgemeiner Hinweis:
-  Wenn Sie die Übungsaufgaben zu dieser Lehrveranstaltung
-  als PDF-Datei betrachten und darin auf die Dateinamen klicken,
-  können Sie die Beispiel-Programme direkt herunterladen.
-  Dadurch vermeiden Sie Übertragungsfehler.
-
-  \bigskip
-
-  \begin{flushright}
-    \textit{Viel Erfolg!}
-  \end{flushright}
-
-  \clearpage
-
-  \vbox to \textheight{\vspace*{-0.5cm}\begin{lstlisting}
-    #include <gtk/gtk.h>
-
-    #define WIDTH 320
-    #define HEIGHT 240
-
-    double t = 0.0;
-    double dt = 0.2;
-
-    int r = 5;
-
-    double x = 10;
-    double y = 200;
-    double vx = 20;
-    double vy = -60;
-    double g = 9.81;
-
-    gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
-    {
-      GdkRGBA blue = { 0.0, 0.5, 1.0, 1.0 };
-
-      gdk_cairo_set_source_rgba (c, &blue);
-      cairo_arc (c, x, y, r, 0, 2 * G_PI);
-      cairo_fill (c);
-
-      return FALSE;
-    }
-
-    gboolean timer (GtkWidget *widget)
-    {
-      t += dt;
-      x += vx * dt;
-      y += vy * dt;
-      vx = vx;
-      vy = 0.5 * g * (t * t);
-      if (y + r >= HEIGHT)
-        vy = -vy * 0.9;
-      if (x + r >= WIDTH)
-        vx = -vx * 0.9;
-      if (x - r <= 0)
-        vx = -vx * 0.9;
-      gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
-      g_timeout_add (50, (GSourceFunc) timer, widget);
-      return FALSE;
-    }
-
-    int main (int argc, char **argv)
-    {
-      gtk_init (&argc, &argv);
-
-      GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
-      gtk_widget_show (window);
-      gtk_window_set_title (GTK_WINDOW (window), "Hello");
-      g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
-
-      GtkWidget *drawing_area = gtk_drawing_area_new ();
-      gtk_widget_show (drawing_area);
-      gtk_container_add (GTK_CONTAINER (window), drawing_area);
-      gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
-
-      gtk_main ();
-      return 0;
-    }
-  \end{lstlisting}\vss}
-
-  \makeatletter
-    \immediate\write\@mainaux{\string\gdef\string\totalpoints{\arabic{points}}}
-  \makeatother
-
-\end{document}

20181119/pendulum-0a.c

-#include <gtk/gtk.h>
-#include <math.h>
-
-int width = 320;
-int height = 240;
-int gap;
-int r;
-double visual_length;
-
-double phi0 = -0.5;
-double omega0 = 0.0;
-double t0 = 0.0;
-double g = 9.81;
-double l = 1.0;
-double dt = 0.02;
-
-double t;
-double phi;
-double omega;
-
-gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
-{
-  GdkRGBA blue = { 0.0, 0.5, 1.0, 1.0 };
-
-  int x = width / 2 + visual_length * sin (phi);
-  int y = gap + visual_length * cos (phi);
-
-  gdk_cairo_set_source_rgba (c, &blue);
-  cairo_move_to (c, width / 2, 10);
-  cairo_line_to (c, x, y);
-  cairo_stroke (c);
-  cairo_arc (c, x, y, r, 0, 2 * G_PI);
-  cairo_fill (c);
-
-  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
-                    FALSE to propagate the event further. */
-}
-
-gboolean timer (GtkWidget *widget)
-{
-  t += dt;
-  phi += omega * dt;
-  omega += - dt * g / l * sin (phi);
-
-  gtk_widget_queue_draw_area (widget, 0, 0, width, height);
-  g_timeout_add (50, (GSourceFunc) timer, widget);
-  return FALSE;
-}
-
-int main (int argc, char **argv)
-{
-  gap = height / 20;
-  r = gap;
-  visual_length = height - 2 * gap - r;
-  t = t0;
-  phi = phi0;
-  omega = omega0;
-
-  gtk_init (&argc, &argv);
-
-  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
-  gtk_widget_show (window);
-  gtk_window_set_title (GTK_WINDOW (window), "Hello");
-  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
-
-  GtkWidget *drawing_area = gtk_drawing_area_new ();
-  gtk_widget_show (drawing_area);
-  gtk_container_add (GTK_CONTAINER (window), drawing_area);
-  gtk_widget_set_size_request (drawing_area, width, height);
-  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
-
-  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
-
-  gtk_main ();
-  return 0;
-}

20181119/pendulum-1.c

-#include <gtk/gtk.h>
-#include <math.h>
-
-#define WIDTH 320
-#define HEIGHT 240
-#define GAP (HEIGHT / 20)
-#define r GAP
-#define visual_length (HEIGHT - 2 * GAP - r)
-
-#define phi0 (-0.5)
-#define omega0 0.0
-#define t0 0.0
-#define g 9.81
-#define l 1.0
-#define dt 0.02
-
-double t = t0;
-double phi = phi0;
-double omega = omega0;
-
-gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
-{
-  GdkRGBA blue = { 0.0, 0.5, 1.0, 1.0 };
-
-  int x = WIDTH / 2 + visual_length * sin (phi);
-  int y = GAP + visual_length * cos (phi);
-
-  gdk_cairo_set_source_rgba (c, &blue);
-  cairo_move_to (c, WIDTH / 2, 10);
-  cairo_line_to (c, x, y);
-  cairo_stroke (c);
-  cairo_arc (c, x, y, r, 0, 2 * G_PI);
-  cairo_fill (c);
-
-  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
-                    FALSE to propagate the event further. */
-}
-
-gboolean timer (GtkWidget *widget)
-{
-  t += dt;
-  phi += omega * dt;
-  omega += - dt * g / l * sin (phi);
-
-  gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
-  g_timeout_add (50, (GSourceFunc) timer, widget);
-  return FALSE;
-}
-
-int main (int argc, char **argv)
-{
-  gtk_init (&argc, &argv);
-
-  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
-  gtk_widget_show (window);
-  gtk_window_set_title (GTK_WINDOW (window), "Hello");
-  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
-
-  GtkWidget *drawing_area = gtk_drawing_area_new ();
-  gtk_widget_show (drawing_area);
-  gtk_container_add (GTK_CONTAINER (window), drawing_area);
-  gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
-  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
-
-  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
-
-  gtk_main ();
-  return 0;
-}

20181119/pendulum-2.c

-#include <gtk/gtk.h>
-#include <math.h>
-
-#define WIDTH 320
-#define HEIGHT 240
-#define GAP (HEIGHT / 20)
-#define r GAP
-#define visual_length (HEIGHT - 2 * GAP - r)
-
-#define phi0 (-0.5)
-#define omega0 0.0
-#define t0 0.0
-#define g 9.81
-#define l 1.0
-#define dt 0.02
-
-double t = t0;
-double phi = phi0;
-double omega = omega0;
-
-gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
-{
-  GdkRGBA orange = { 1.0, 0.5, 0.0, 1.0 };
-
-  int x = WIDTH / 2 + visual_length * sin (phi);
-  int y = GAP + visual_length * cos (phi);
-
-  gdk_cairo_set_source_rgba (c, &orange);
-  cairo_move_to (c, WIDTH / 2, 10);
-  cairo_line_to (c, x, y);
-  cairo_stroke (c);
-  cairo_arc (c, x, y, r, 0, 2 * G_PI);
-  cairo_fill (c);
-
-  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
-                    FALSE to propagate the event further. */
-}
-
-gboolean timer (GtkWidget *widget)
-{
-  t += dt;
-  phi += omega * dt;
-  omega += - dt * g / l * phi;
-
-  gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
-  g_timeout_add (50, (GSourceFunc) timer, widget);
-  return FALSE;
-}
-
-int main (int argc, char **argv)
-{
-  gtk_init (&argc, &argv);
-
-  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
-  gtk_widget_show (window);
-  gtk_window_set_title (GTK_WINDOW (window), "Hello");
-  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
-
-  GtkWidget *drawing_area = gtk_drawing_area_new ();
-  gtk_widget_show (drawing_area);
-  gtk_container_add (GTK_CONTAINER (window), drawing_area);
-  gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
-  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
-
-  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
-
-  gtk_main ();
-  return 0;
-}

20181126/compiling-philosophy.txt

-cassini/home/peter/bo/2018ws/hp/20181126> cat philosophy.c
-#include <stdio.h>
-#include "answer.h"
-
-int main (void)
-{
-  printf ("The answer is %d.\n", answer ());
-  return 0;
-}
-cassini/home/peter/bo/2018ws/hp/20181126> cat answer.h
-extern int answer (void);
-cassini/home/peter/bo/2018ws/hp/20181126> cat answer.c
-#include "answer.h"
-
-int answer (void)
-{
-  return 23;
-}
-cassini/home/peter/bo/2018ws/hp/20181126> gcc -Wall -O philosophy.c -o philosophy
-/tmp/ccnyOpK1.o: In function `main':
-philosophy.c:(.text+0x5): undefined reference to `answer'
-collect2: error: ld returned 1 exit status
-cassini/home/peter/bo/2018ws/hp/20181126> gcc -Wall -O philosophy.c answer.c -o philosophy
-cassini/home/peter/bo/2018ws/hp/20181126> ./philosophy
-The answer is 23.
-cassini/home/peter/bo/2018ws/hp/20181126> gcc -Wall -O philosophy.c -c
-cassini/home/peter/bo/2018ws/hp/20181126> gcc -Wall -O answer.c -c
-cassini/home/peter/bo/2018ws/hp/20181126> ls -l philosophy* answer.*
--rw-r--r-- 1 peter peter   56 Okt 25  2017 answer.c
--rw-r--r-- 1 peter peter   26 Okt 25  2017 answer.h
--rw-r--r-- 1 peter peter 1224 Nov 26 16:21 answer.o
--rwxr-xr-x 1 peter peter 8712 Nov 26 16:21 philosophy
--rw-r--r-- 1 peter peter  117 Okt 25  2017 philosophy.c
--rw-r--r-- 1 peter peter 1648 Nov 26 16:21 philosophy.o
-cassini/home/peter/bo/2018ws/hp/20181126> gcc philosophy.o answer.o -o philosophy
-cassini/home/peter/bo/2018ws/hp/20181126> ./philosophy
-The answer is 23.
-cassini/home/peter/bo/2018ws/hp/20181126>

20181126/const-functions-0.c

-#include <stdio.h>
-
-double G = 6.67e-11;
-
-int main (void)
-{
-  printf ("G = %20.15lf\n", G);
-  return 0;
-}
-

20181126/const-functions-1.c

-#include <stdio.h>
-#include <math.h>
-
-double G = 6.67 * pow (10, -11);
-
-int main (void)
-{
-  printf ("G = %20.15lf\n", G);
-  return 0;
-}
-

20181126/const-functions-2.c

-#include <stdio.h>
-#include <math.h>
-
-double S2 = sqrt (2.0);
-
-int main (void)
-{
-  printf ("sqrt(2) = %20.15lf\n", S2);
-  return 0;
-}
-

20181126/photo-20181126-174025.txt

-README: Prakikumstermine, Bit-Operationen

20181203/blink-11.c

-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <stdint.h>
-
-#define F_CPU 16000000l
-#include <util/delay.h>
-
-volatile uint8_t key_pressed = 0;
-
-ISR (INT0_vect)  /* PD2 */
-{
-  key_pressed = 1;
-}
-
-int main (void)
-{
-  cli ();
-  EICRA = 1 << ISC00 | 1 << ISC01;  /* INT0: steigende Flanke */
-  EIMSK = 1 << INT0;  /* INT0 einschalten */
-  sei ();
-  DDRD = 0xfb;   /* binär: 1111 1011 */
-  PORTD = 0x40;  /* binär: 0100 0000 */
-  while (1)
-    {
-      while (!key_pressed)
-        ;  /* just wait */
-      _delay_ms (1);
-      PORTD ^= 0x40;
-      key_pressed = 0;
-    }
-  return 0;
-}

20181203/blink-3a.c

-#include <avr/io.h>
-
-#define F_CPU 16000000
-#include <util/delay.h>
-
-int main (void)
-{
-  DDRD = 0x11;
-  PORTD = 0x11;
-  while (1)
-    {
-      while ((PIND & 0x02) == 0)
-        ; /* just wait */
-      _delay_ms (100);
-      PORTD ^= 0x01;
-    }
-  return 0;
-}