Removed some NTNU info

Reviewed-on: #4

Gemfile

@@ -7,7 +7,7 @@ source "https://rubygems.org"
 #
 # This will help ensure the proper Jekyll version is running.
 # Happy Jekylling!
-gem "jekyll", "~> 4.1.1"
+gem "jekyll", "~> 4.3.0"
 # This is the default theme for new Jekyll sites. You may change this to anything you like.
 
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
@@ -18,3 +18,5 @@ gem "jekyll", "~> 4.1.1"
 #  gem "jekyll-feed", "~> 0.12"
 #end
 
+
+gem "webrick", "~> 1.8"

LICENSE

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
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+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    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 <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

_config.yml

@@ -32,11 +32,10 @@ author:
   git_username:  oyvindskaaden
 
 
+
 collections:
   posts:
     excerpt_separator: <!--more-->
-    permalink: 
-    
 
 
 markdown:         kramdown
@@ -53,7 +52,7 @@ defaults:
       type: "posts"
     values:
       layout: layouts/post
-      permalink: /prosjekter/:year/:month/:day/:title
+      permalink: /prosjekter/:categories/:year/:month/:day/:title
   -
     scope:
       path: "ntnu/*"

_data/home.yml

@@ -1,7 +1,7 @@
 - 
   title: NTNU
   href: /ntnu/
-  description: Alt som er relatert til NTNU, både fag og filer. Her kan du finne tidligere eksamensoppgaver, LF, mine løsninger og oppsummeringer.
+  description: Alt som er relatert til NTNU, både fag og noen filer. Her kan du finne mine løsninger og oppsummeringer.
   icon: fa-graduation-cap
 
 - 

_data/ntnu-courses.yml

@@ -1,4 +1,30 @@
+# Våren 2021
+-
+  name: Våren 2021
+  href: 21v
+  courses:
+    - 
+      course: ttt4280
+      desc: Sensorer og instrumentering, våren 2021.
+      updated: 2021-01-11
+    -
+      course: tfe4130
+      desc: Bølgeforplantning, våren 2021.
+      updated: 2021-01-12
+    -
+      course: ttk4145
+      desc: Sanntidsprogrammering, våren 2021.
+      updated: 2021-05-18
+    # -
+    #   course: tiø4252
+    #   desc: Teknologiledelse, våren 2021.
+    #   updated: 2021-05-13
+
 # Høsten 2020
+-
+  name: Høsten 2020
+  href: 20h
+  courses:
     - 
       course: tfe4152
       desc: Design av integrerte kretser, høsten 2020.
@@ -21,12 +47,20 @@
       href: tfe4146/summary
 
 # Våren 2020
+-
+  name: Våren 2020
+  href: 20v
+  courses:
     - 
       course: ttt4270
       desc: Elektronisk systemdesign, prosjekt, våren 2020.
       updated: 2020-05-05
 
 # Høsten 2019
+-
+  name: Høsten 2019
+  href: 19h
+  courses:
     - 
       course: ttt4265
       desc: Elektronisk systemdesign og -analyse II, høsten 2019.
@@ -37,14 +71,18 @@
       updated: 2019-11-28
 
 # Våren 2019
+-
+  name: Våren 2019
+  href: 19v
+  courses:
     - 
       course: ttt4260
       desc: Elektronisk systemdesign og -analyse I, våren 2019.
       updated: 2019-05-05
-- 
-  course: tma4105
-  desc: Matematikk 2, våren 2019.
-  updated: 2019-05-21
+    # - 
+    #   course: tma4105
+    #   desc: Matematikk 2, våren 2019.
+    #   updated: 2019-05-21
     - 
       course: tdt4102
       desc: Prosedyre og objektorientert programmering, våren 2019.

_includes/structure/head.html

@@ -1,4 +1,5 @@
 <head>
+
 	<meta name="HandheldFriendly" content="True">
 	<meta name="MobileOptimized" content="320">
 	<meta charset="utf-8">
@@ -17,6 +18,7 @@
 		<link rel="stylesheet" href="{{ "/assets/css/default.css" | relative_url }}"/>
 	{% endif %}
 	
+
 	<title>
 		{% if page.title %}
 				{{ page.title }} &middot; {{ site.title }}

_includes/utils/scripts.html

@@ -2,6 +2,7 @@
 <script src="{{ "/assets/js/jquery-3.5.1.min.js" | relative_url }}"></script>
 <script src="{{ "/assets/js/bootstrap.bundle.min.js" | relative_url }}"></script>
 <script src="{{ "/assets/js/bootstrap-toc.min.js" | relative_url }}"></script>
+
 <!--Anchors-->
 <script src="{{ "/assets/js/anchor.min.js" | relative_url }}"></script>
 <script>

_layouts/layouts/lecture.html

@@ -0,0 +1,20 @@
+---
+layout: default
+---
+<div class="jumbotron">
+	<div class="container">
+		<h1 class="no-anchor" data-toc-skip>{{ page.title }}</h1>
+		<p>{{ page.description }}</p>
+		<small>Forelesningsdato {{ page.date | date: "%d.%m.%Y" }}</small>
+	</div>
+</div>
+<div class="container" id="main">
+	<div class="row row-offcanvas row-offcanvas-right">
+		<div class="col-xs-12 col-sm-12 col-md-9">
+			{{ content }}
+		</div>
+		<div class="col-md-3 d-none d-md-block" id="sidebar">
+			<nav id="toc" data-toggle="toc" class="sticky-top" style="z-index:1"></nav>
+		</div>
+	</div>
+</div>

_posts/2020-12-26-glados.no.md

@@ -1,32 +0,0 @@
----
-title:  "glados.no"
-description: Hvordan generere nettsider med git og jekyll
-date:   2020-12-26
-categories: glados
-tags: website glados jekyll git gitea
----
-
-Hvordan er egentlig [glados.no](https://glados.no) satt opp som en kontinuerlig integrasjon ved hjelp av jekyll, bootstrap og git.
-
-<!--MORE-->
-
-## Prinsipp
-
-Jeg er er en ganske lat person, men jeg ønsker å lage en velutformet personlig nettside med alt fra personlige prosjekter til fag på NTNU.
-Derfor ønsker jeg å sette opp en statisk nettsidegenerator som gjør det enkelt for meg å oppdatere og legge nye til til på nettstedet. 
-
-### Statisk nettsidegenerator
-
-En bra løsning på dette problemet er å bruke en statisk nettsidegenerator. 
-Da er det mulig å skrive hele nettsteder i det enkle språket markdown, som bruker en syntaks for å beskrive hvilke elementer som brukes. 
-Språket brukes på alt fra GitHub (på README filene) til å skrive større dokumentasjon med Pandoc.
-
-Det finens uttallige forskjellige generatorer, men de to store (i dag) er [jekyll](https://jekyllrb.com/) og [HUGO](https://gohugo.io/). 
-Begge baserer seg på markdown, har en ganske lik filstruktur og er begge brukt masse. 
-Jekyll brukes faktisk for å generere [Github Pages](https://pages.github.com/). 
-
-### Versjonskontroll
-
-
-
-

about.md

@@ -1,7 +1,11 @@
 ---
-layout: layouts/page
+layout: layouts/list
 title: Om
 permalink: /om/
 ---
 
-Mitt navn er Øyvind Skaaden. Jeg er 21 år gammel og studerer Elektronisk systemdesign og innovasjon på NTNU.
+Mitt navn er Øyvind Skaaden. Jeg er 24 år gammel og studerer Elektronisk systemdesign og innovasjon på NTNU.
+
+Jeg er stor fan av open-source og prøver så godt jeg kan å fremme dette. 
+
+Jeg har både en [github](https://github.com/oyvindskaaden) og en [personlig git](https://git.glados.no/).

assets/css/components/theme.css

@@ -102,6 +102,7 @@ blockquote {
 
 a {
   color: var(--link-color);
+  text-decoration: none;
 }
 
 a:hover {

assets/css/home.css

@@ -27,7 +27,13 @@
   min-height: calc(100vh - 47.75rem);
 }
 
-.home-link>a {
+/*
+.home-link a{
+  text-decoration: none;
+}
+*/
+
+a.home-link:hover{
   text-decoration: none;
 }
 

index.html

@@ -1,21 +1,20 @@
 ---
 layout: layouts/home
-description: Personlig nettside for Øyvind Skaaden. Inneholder det meste av personlige prosjekter og fag fra NTNU.
+description: Personlig nettside for Øyvind Skaaden. Inneholder det meste av personlige prosjekter og noen ting fra NTNU.
 ---
 
 <div class="homepage-main">
   <div class="row">
     {% for home in site.data.home %}
     <div class="col-md-4">
-      <a href="{{ home.href }}">
+      <a class="home-link" href="{{ home.href }}">
         <div class="icon">
           <i class="fas {{ home.icon }}"></i>
         </div>
+        <h3 class="no-anchor home-link">{{ home.title }}</h3>
       </a>
-      <h3 class="no-anchor home-link"><a class="" href="{{ home.href }}">{{ home.title }}</a></h3>
       <p>{{ home.description }}</p>
     </div>
     {% endfor %}
   </div>
 </div>
-

ntnu/21v/tfe4130/lectures/2021-01-12/2021-01-12.md

@@ -0,0 +1,74 @@
+---
+title: "TFE4130 - 1D Bølger"
+description: "2021-01-12"
+math: true
+---
+
+## Hva er bølger?
+
+Bevegelse av partikler i et medium.
+
+Dispersive gjør at signalet kan endre seg over tid og strekning.
+Bølgehastigheten er avhengig av frekvensen.
+
+Ikke-dispersive betyr at bølgen beveger seg med samme hastighet hele tiden, og vil derfor være lik ved alle distanser.
+
+Bølger kan inteferere.
+
+Kurset handler mest om EM-bølger, men mekaniske bølger er enklere.
+Det er da kun trykk som beskriver en bølge, mot en vektor med flere komponenter i EM-bølger.
+
+Velocity potential:
+
+$$WIP$$
+
+Velocities at depth:
+
+$$WIP$$
+
+Dispersjonsrelasjonen i havbølger
+
+$$ \omega^2 = gk \tanh kd $$
+
+Der $g$ er tyngdeakserelasjonen, $k$ er bølgetallet og $d$ er dybden.
+
+### Forskjellige typer bølger
+
+Longitudinale: Langsgående bølger.
+
+Transversale: Bølger som beveger seg normalt på propageringsretningen.
+
+### Matematisk
+
+Bølgene er løsningen på bølgelikningen i forskjellige dimensjoner.
+
+$$ \ddot{u} = \frac{\partial^2 u}{\partial t^2} = c^2 \nabla^2 u $$
+
+Denne løses som en partiell differensiallikning.
+
+En ikke-dispersiv hamonisk bølge er definert:
+
+$$ p(x, t) = \hat{p} \sin(\omega t - kx) $$
+
+Der $\omega = 2\pi f$ er frekvensen, $k = \tfrac{\omega}{c}$ er bølgekonstanten, $c$ er propageringshastigheten og $\hat{p}$ er bølgeamplituden.
+
+## Lydbølger
+
+Lydbølger er endringer i lydtrykket rundt standardtrykket/det statiske trykket. 
+
+$$ \underbrace{P_\text{total}(x,t)}_{\text{Lufttrykk, [Pa]}} = \underbrace{P_\text{atm}}_\text{Statisk trykk} + \underbrace{p(x,t)}_\text{endringer i trykket, lyd} $$
+
+
+Bølgelikningen for lydbølger:
+
+$$ \frac{\partial^2 p}{\partial x^2} - \frac{1}{c^2} \frac{\partial^2 p}{\partial t^2} $$
+
+## Helmholtz' likning
+
+Spesialtilfelle av bølgelikningen når bølgen er en harmonisk svingning.
+
+$$ p(x,t) = p(x) e^{j\omega t} $$
+
+Den tidsavhengige faktoren kan faktoriseres ut av likningen og vi står igjen med en ODE.
+
+$$ \frac{\partial^2 p(x)}{\partial x^2} + k^2 p(x) = 0 $$

ntnu/21v/tfe4130/lectures/2021-01-14/2021-01-14.md

@@ -0,0 +1,24 @@
+---
+layout: layouts/lecture
+title: "TFE4130"
+description: "1D Bølger forts."
+date: "2021-01-14"
+math: true
+---
+
+## Akustisk impedanse
+
+## Akustisk intensitet
+
+$$ \boldsymbol{I} = \frac{1}{T}\int_0^T p_\text{real}\boldsymbol{v}_\text{real}(t) dt $$
+
+FOr en planbølge
+
+$$ I_x = \frac{p_\text{rms}}{p_x c}$$
+
+## Refleksjon og transmisjon
+
+Dersom en børge beveger seg over en grenseflate mellom to forskjellige impedanser.
+
+* Trykket nå være kontinuerlig over grenseflaten
+* Farten over grenseflaten må være konstant.

ntnu/21v/tfe4130/tfe4130.md

@@ -0,0 +1,11 @@
+---
+layout: layouts/list
+title: "TFE4130"
+description: "Bølgeforplantning"
+---
+
+## Forelesninger
+
+[2021-01-12](./lectures/2021-01-12/) - Intro
+
+[2021-01-14](./lectures/2021-01-14/) - Bølger forts.

ntnu/21v/tiø4252/tiø4252.md

@@ -0,0 +1,68 @@
+---
+title: TIØ4252
+description: Teknologiledelse, våren 2021
+date: 2021-05-13
+---
+
+
+## Formelark
+
+Formelark i TIØ4252 kan finnes [her][formel].
+
+Kildekoden ligger på [git][git_formel].
+
+[formel]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/formelark/formelark.pdf
+[git_formel]:https://git.glados.no/oyvindskaaden/TIO4252/src/branch/main/formelark/
+
+## Eksamen
+
+Alle filer er tilgjengelig på [git][git].
+
+[git]: https://git.glados.no/oyvindskaaden/TIO4252
+
+Kombinert løsningsforslag for alle eksamener finnes [her][LF_alle].
+
+[LF_alle]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/LF.pdf
+
+| År   | Eksamen | Oppgave       | LF       |
+| :--- | :------ | :------------ | :------- |
+| 2020 | Høst    | [Oppgave][1]  | [LF][2]  |
+| 2020 | Sommer  | [Oppgave][3]  | [LF][4]  |
+| 2020 | Vår     | [Oppgave][5]  | [LF][6]  |
+| 2019 | Høst    | [Oppgave][7]  | [LF][8]  |
+| 2019 | Sommer  | [Oppgave][9]  | [LF][10] |
+| 2018 | Høst    | [Oppgave][11] | [LF][12] |
+| 2018 | Sommer  | [Oppgave][13] | [LF][14] |
+| 2018 | Vår     | [Oppgave][15] | [LF][16] |
+| 2017 | Høst    | [Oppgave][17] | [LF][18] |
+| 2017 | Vår     | [Oppgave][19] | [LF][20] |
+| 2014 | Sommer  | [Oppgave][21] | [LF][22] |
+| 2013 | Sommer  | [Oppgave][23] | [LF][24] |
+{: .table-responsive-lg .table }
+
+[1]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20H/Eksamen_20H.pdf
+[2]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20H/Losning_20H.pdf
+[3]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20S/Eksamen_20S.pdf
+[4]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20S/Losning_20S.pdf
+[5]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20V/Eksamen_20V.pdf
+[6]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/20V/Losning_20V.pdf
+[7]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/19H/Eksamen_19H.pdf
+[8]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/19H/Losning_19H.pdf
+[9]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/19S/Eksamen_19S.pdf
+[10]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/19S/Losning_19S.pdf
+[11]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18H/Eksamen_18H.pdf
+[12]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18H/Losning_18H.pdf
+[13]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18S/Eksamen_18S.pdf
+[14]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18S/Losning_18S.pdf
+[15]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18V/Eksamen_18V.pdf
+[16]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/18V/Losning_18V.pdf
+[17]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/17H/Eksamen_17H.pdf
+[18]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/17H/Losning_17H.pdf
+[19]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/17V/Eksamen_17V.pdf
+[20]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/17V/Losning_17V.pdf
+[21]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/14S/Eksamen_14S.pdf
+[22]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/14S/Losning_14S.pdf
+[23]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/13S/Eksamen_13S.pdf
+[24]:https://git.glados.no/oyvindskaaden/TIO4252/raw/branch/main/eksamen/13S/Losning_13S.pdf
+
+

ntnu/21v/ttk4145/summary/summary.md

@@ -0,0 +1,540 @@
+---
+title: "Oppsumering av TTK4145"
+description: "Lot of theory and discussion, some fomulas, spring 2021."
+date: 2021-05-04
+math: true
+---
+
+## Fault tolerance
+
+Hard to capture faults. 
+
+
+### Bugs
+
+* 1 bug per 50 lines before testing
+* 1 bug per 500 at release
+* 1 bug per 550 after a year, the constant
+
+1. Make the program work within specs.
+2. Run/Tests of the program-
+3. Errors happen
+4. Locate errors
+    * Incomplete spec
+    * Missing handleling of som situation
+5. Fix code
+
+### Traditional error handeling
+
+{% highlight java %}
+FILE *
+openConfigFile(){
+    FILE * f = fopen("/path/to/config.conf");
+    if (f == NULL) {
+        switch(errno){
+            case ENOMEM: {
+                ...
+                break;
+            }
+            case ENOTDIR: {
+                ...
+                break;
+            }
+            // Do this for all errors
+        }
+    }
+}
+{% endhighlight %}
+
+### Causes of errors
+
+* Incomplete specification
+* Software bugs
+* HW problems
+* Communication problems
+
+### Fault tolerance in real time systems
+
+The problem with traditional errorhandleing is that errors can happen at any possible time.
+This is extremely hard to test. 
+
+This is some of the error handling real time programming have.
+
+* Handling of unexpected errors
+* More threads hanles errors
+* Can not test the conventional way
+    * Can only show extistence of errors
+    * Can not find errors in specification
+    * Can not find race conditions
+
+The fault path is shown under.
+
+![Fault tolerance](figures/fault-path.svg)
+
+With fault tolerance the path looks something more like the figure under.
+
+![Fault tolerance](figures/fault-tolarance.svg)
+
+### Error handling
+
+Keep it simple!
+
+The error modes is a part of the module interface.
+
+One way is to handle all errors the same way.
+Handle the as if it was the worst error.
+Crash and start again.
+
+A different approach is to check that everything is OK.
+
+To test how the systems responds for a unknown error is to insert a failed acceptance test (a not OK signal).
+
+### Redundancy
+
+* If I have $N$ copies of my data, it is possible to handle that one is destroyed.
+* Sending $N$ messages, trying $N$ times.
+
+**Static redundancy**
+
+* $N$ active copies. Sending $N$ messages if it is necessary or not.
+* Detecting errors is not important.
+* Handles cosmic rays easily.
+
+**Dynammic redunancy**
+
+* Relies on detecting the error and recovering
+    * Resend if timeout and not receiving "ack"
+    * Go with default if no messages have been received
+* The acceptancetest must be good.
+
+
+### Fault model
+
+#### Example with storage functions.
+
+**Step 1: Failure modes**
+
+Find the failure modes: What could go wrong?
+
+* **Write**: May return "I failed". Does not know why it faield
+* **Read**: May return "I failed". Does not know why it failed.
+
+**Step 2: Detect, Simplify, Inject errors**
+
+* Write information on where/what/how the process is doing.
+* All errors --> Fail
+* Inject errors
+
+**Step 3: Handling with redundancy**
+
+* Have multiple copies of the the information
+    * Use only the newest
+
+#### Example with communication function
+
+**Step 1: Failure modes**
+
+* Message
+    * Lost
+    * Delayed
+    * Corrupted
+    * Duplicated
+    * Wrong recipient
+
+**Step 2: Detection, Merging of errormodes and error injection**
+
+* Adding information to message
+    * Checksum
+    * Session ID
+    * Sequence number
+* Adding "ack" on well recieved messages
+* All errors will be treaded as "Lost message"
+* Injection
+    * Occasionally throw away some messages
+
+**Step 3: Handling with redundancy**
+
+* Timeout 
+* Retransmit message
+
+#### Example with processes and caculations
+
+A calculation is an abstract, so how can we talk generally about the failure modes.
+
+**Step 1: Failure modes**
+
+One failure mode
+
+**Step 2: Detect, simplify, inject errors**
+
+All failed acceptance tests will "PANIC" or "STOP".
+
+**Step 3: Handling with redundancy**
+
+There are three solutions:
+
+1. Checkpoint restart
+    * Do all the work incuding the acceptance test
+    * Wait with the "side effects"
+    * Store a checkpoint
+    * Do the "side effects"
+2. Process pairs
+        * Crash and let an another process take over
+3. Presistent processes
+
+
+## Transactions
+
+A transaction is a design framework for Damage Confinement and Error Recovery.
+
+* An *atomic action*, just without the backward recovery error mode as standard mode
+* invincible and instantaneous "calculation" seen from the outside
+* A transformation from one consistent state to another'
+* A modular computation
+
+### Four features: ACID
+
+* **A**tomicity: Either all side effects happens or none
+* **C**oncistency: Leaves the system in a consistent state when finished
+* **I**solation: Errors does not spread
+* **D**urability: Results are not lost
+
+### Atomic Actions
+
+**Resumption vs. Termination mode**
+* If we continue where we were (e.g. after the interrupt) --> *Resumption*
+* If we continue somewhere else (i.e. terminating what we where doing) --> Termination
+
+**Async Notification (AN) = Low level thread interaction**
+* Async event handling. ("Signals") (resumption)
+    * Modeled after a HW interrupt
+    * Can be sent to the correct thread
+    * Can be handled, ignored, blocked --> The domain can be controlled.
+    * Often lead to polling
+        * Could rather skip the signal and poll a status variable or a message queue
+        * Useless
+* ATC --> Async transfer of Control (termination)
+    * Canceling threads
+    * setjmpt/longjmp could convert signals to ATC (not really, but still)
+    * ADA: a strictured mechanism for ATV is integraded with the selected statement
+    * RT Java: A structured mechanism for ATC is integraded with the exception-handling mechanism
+
+#### Cancelling threads
+
+**Yes, killing threads is ATC!**
+
+* Can make termination model by letting domain be a thread
+    * "Create a `doWork` thread, and kill it if the action fails"
+* Ca still control domain by disabling "cancelstate"
+
+**But, but, but: It leaves ut in undifined state!?**
+* Not if we have...
+    * Full control over changed state (like logs or recovery points) or some other way of recovering well.
+    * A lock manager that can unlock on behalf of killed thread
+    * Some control of where we were killed (like nok in the middle of a lock manager or log call)
+* An this is what we have!
+
+
+## Shared variable synchronization
+
+### Non-Preemptive scheduling
+
+Controlling a pump filling a tank.
+
+**Spec:**
+* Every second: measure the water level of the tank and generate the reference to the pump
+* 10 times a second: Set the power of the pump motor
+* Do some GUI: let the human control the process
+
+#### A trivial solution: "Cyclic Exectutive"
+
+{% highlight java %}
+oldTime = now();
+i = 0;
+while(true) {
+    i = i + 1;
+    if (i % 10 == 0) {
+        i = 0;
+        calculatePumpReference();
+    }
+    controlPump();
+    do {
+        handleUserEvent();
+    } while(now() < oldTime + 0.1);
+    oldTime = oldTime + 0.1;
+}
+{% endhighlight %}
+
+**Drawbacks**
+
+* OK tasks?
+* Timing hard to tune (what if pump sampling should be $\pi$/10?)
+* Overload (what if `calucaltePumpReference` uses more than 1/10 seconds?)
+* How to add new tasks? (Everything is coupled)
+* Waste of time in the do-loop?
+* What is priority of `handleUserEvents`?
+* How are erros, exceptions, alarms etc. handled?
+
+#### Better soulution with Non-preemptive scheduler
+
+* *3 taskts* administered by a scheduler
+* The scheduler takes care of who runs and timing
+* Scheduler often inculuded in OSes
+* Introducing priorities
+
+{% highlight java %}
+/**
+    * scheduler_registerThread(function, time, priority)
+    * Higher priority numer means higher priority in scheduler
+    */
+main() {
+        scheduler_registrerThread(controlPump, 0.1, 3);
+        scheduler_registrerThread(calculatePumpReference, 1, 2);
+        scheduler_registrerThread(handleUserEvents, 0.2, 1);
+        scheduler_mainLoop();
+}
+{% endhighlight %}
+
+**Some notes on priorities**
+* Priority is generally not important; rather, the main rule is to give higher priority to shorter-deadline tasks. 
+    * This allows tasks to reach its deadlines.
+* ... but this is not always the case - if e.g. the tasks are cooperating
+* We still handle overload badly
+* And: What connection between deadline and priority to start with?
+    * Is this a good dependency seen from a code quality perspective?
+
+### Pros and cons of nonpreemptive scheduling
+
+| **Pros**                                       | **Cons**                                                                   |
+| :--------------------------------------------- | :------------------------------------------------------------------------- |
+| Simple, intuitive, predictable                 | C macro hell                                                               |
+| No kernel                                      | Threads must cooperate <-- a form of dependency breaking module boundaries |
+| Fast switching times                           | Heavy threads must be divided                                              |
+| Some elegant sunchronization patterns possible | Can we handle blocking of library functions?                               |
+|                                                | Unrobust to errors                                                         |
+|                                                | Unrobust to (heavy) error handling                                         |
+|                                                | Hard to tune at end of project                                             |
+{: .table-responsive-lg .table }
+
+
+
+### Preemptive Kernel
+
+* Preemption, thread objects and the timer interrupt
+* Enabling synchronization: Busy waiting, tes-and-set, disabling the timer interrupt
+* Blocking and suspend & resume
+* An API for synchronization? Semaphores!
+
+
+#### Preemption
+
+* Make a handler for a timer interrupt
+* Store all registers (including IP & SP) in a "thread object"
+* Organize queue of processes (Round Robin e.g. - a collection of thread objects?)
+* Can synchronize by: `while(!ready);` (busy wating, "spin locks")
+
+**Bad solution**
+
+{% highlight java%}
+while(lock==1) {}
+lock = 1;
+    // We may run
+lock = 0;
+{% endhighlight %}
+
+**Better solution**
+
+{% highlight java%}
+void t1() {
+    flag1 = 1;  // Declare my intention
+    turn  = 2;  // But try to be polite
+    while(flag2 == 1 && turn == 2) {}
+    // We may run
+    flag1 = 0;
+}
+{% endhighlight %}
+
+##### Looking more closely at the arsenal
+
+**How can we make basic synchronization under preemption?**
+
+* Spin locks (wasting time and cpu)
+* Test&Set (swap) assembly instruction (atomic, but not obvious)
+* Disable interrupt (steals control from OS/scheduler)
+
+**But**
+* If we disable the timer interrupt we don not have preemption any more
+* And... Are these good abstractions in the application programmer domain?
+
+#### Blocked threads
+
+**Let us introduce another queue; the collection of threads not running, waiting for something**
+
+* Fixes the bad performance of spin locks. Is conceptually better.
+* `suspend` moves a thread object from "run" queue to "blocked" queue
+* `resume` moves it back.
+
+##### Two bad solutions
+
+{% highlight java%}
+t1(){
+    while(busy == 1) suspend();
+    busy = 1;   // It is free; tak it - No
+        // Run
+    busy = 0;   // Release resource
+
+    resume t2 // No
+}
+{% endhighlight %}
+
+or 
+
+{% highlight java%}
+t1(){
+    while(TestNSet(busy, 1) == 1) suspend();
+        // We own resource
+        // Run
+    busy = 0;
+
+    resume t2 // No
+}
+{% endhighlight %}
+
+##### The suspend/resume problem
+
+{% highlight java%}
+// Global variables
+bool g_initDone = False;
+
+// Threads
+t1(){                           t2(){
+    /* Do init */                   if (g_initDone == False) {
+    g_initDone = True;                  Suspend();
+    resume(t2)                      }
+    // Continue executing           // Continue exectuting
+}                               }
+{% endhighlight %}
+
+#### Priorities
+
+* Threads mey have different *priorities*. (A sortet run-queue, or more of them.)
+* Only if there are no running threads on a higher priority, a thread will run.
+* We are not aiming for some sens of fairness (!). But predictability.
+* And priorities supports schedulability proofs.
+* But we open ourselves up to *starvation*. A thread may not ever get to run, even if it is runnable.
+
+
+#### Application-level syncronization
+
+**SO, the application programmer needs some syncronozation primitives...**
+
+* `sleep()`? - Ok
+* Publish `suspend` and `resume` - No
+* Events (`wait` and `signal`) - Just named versions of suspend & resume semantics.
+  * Fixes the need to know aboud "thread objects". But no
+* ...or "Condition variables" - same
+
+
+### Semaphores
+
+**A counting semaphore**
+
+* `signal(SEM)` increases the counter (possibly resuming a thread waiting for the semaphore)
+* `wait(SEM)` decrements the counter - will block (be suspended) `if SEM == 0`
+  * The semaphores value can not be negative
+* Of course; These calls are protected from interleaving by disabling the timer interrupt
+
+**We solve beautifully:**
+* Mutual Exclusion
+* Conditional Synchronization (ref `suspend`/`resume`)
+* Basic resource allocation
+
+**Semaphore variations**
+
+* `wait` and `signal` nay take parameter value to add or subtract
+* `getValue(SEM)` returning the value of the semaphore. (Fishy)
+* BInary semaphores (`signal` will fail `if SEM == 1`)
+* Who is woken at `signal` (FIFO, Arbitrary, Highest priority)
+* The mutex
+  * binary
+  * ownership
+  * allows mulitple waits by owner
+  * regions (may be released by Javas `wait` or POSIX condition variables)
+* RTFM
+
+**Semaphore challenges**
+
+* Breaks modules (both ways)
+  * Does not scale!
+* Deadlocks
+  * Global analysis --> Does not scale
+* Can not release "temporarily
+* "Limited expressive power". Some reasonalbe problems are hard to solve
+  * Ref ["The Little Book of Semaphores"](https://greenteapress.com/semaphores/LittleBookOfSemaphores.pdf)
+
+### Why shared-variable synchronization
+
+**Why not?**
+
+* "Shared variables" is bad code quality
+  * Ref global variables, and data members in module interfaces
+* An obvious bottleneck? Scales terribly
+* "Variables" are passive objects
+  * They can not protect themselves
+* Why use synchronization when it is communication we need?
+* Technology transfers badly to distibuted systems
+* ... and this is before we start discussing how hard it is
+
+**Why?**
+
+* Part of the "real-time" design pattern
+  * "One thread per timing demand" 
+  * We do have scheduling proofs and best practises
+* Timing analysis is global anyway
+  * Scalability and deadlock analysis may not be the limiting constraint
+* HW is shared memory architecture
+  * Infrastucture is avalible
+* Communication systems requires infrastucture that we may not have
+
+#### *All* resources are shared!
+
+* Memory, certainly
+* "Hidden" memory used by libraries (.. your own modules and the kernel)
+  * If the library takes care of this itself, it is called *"reentrant"*
+* Sensors and actuators
+* "CPU" - Computing capacity 
+  * *This* is real-time programming; We solve it by *Scheduling*
+* ... any other interface
+
+
+#### Some standard problems/pit-falls
+
+* **Race condition**: A bug that surfaces by unfortunate timing or order of events
+* **Deadlock:** system in circular wait
+  * Special case of livelock
+  * Does not use CPU
+* **Livelock:** system locked in a subset of states 
+  * like deadlock, but we use CPU
+  * Busy-Waiting is a livelock
+* **Starvation:** A thread does "by accident" not get the necessary resources
+
+
+#### Features in syncronization
+
+* Critical Section - Code that must not be interupted
+* Mutual Exclusion - More piecesof code that must not interrupt each other
+* Bounded buffer - Buffer with full/empty synchronization
+* Read/Write Locks
+  * Readers can interleave eachother
+  * Writers have mutual exclusion
+* Condition Syncronization - Blocking on event or status
+  * Guards etc.
+* Resource allocation
+  * More than mutual exclution!
+  * Ref: The lock manager
+* Rendezvouz/barriere - Synchronization point
+  * Ref: AA "end boundary"
+* Communication
+* Broadcast
+* ...
+

ntnu/21v/ttk4145/ttk4145.md

@@ -0,0 +1,11 @@
+---
+layout: layouts/list
+title: "TTK4145"
+description: "Sanntidsprogrammering"
+---
+
+## Oppsummering
+
+[Oppsummering](summary/) av faget TTK4145.
+
+

ntnu/21v/ttt4280/lab/1/1.md

@@ -0,0 +1,34 @@
+---
+layout: layouts/lecture
+title: "TTT4280"
+description: "Labforelesning 1"
+date: "2021-01-18"
+math: false
+---
+
+## Laboratorium
+
+### System
+
+* Raspberry Pi
+* Linux
+* A/D omformere
+* Python
+
+### Oppgaver
+
+* Systemoppsett
+  * Klargjøre rPi og instrumenteringskrets
+* Akustikk
+  * Beregne retning til lydkilde
+* Radar
+  * Doppler
+* Optikk
+
+## Laboppgave 1
+
+1. Tegne blokkdiagram
+2. Studere datablat for ADC
+3. Drøfte fordeler med DMA
+
+![Blokk](figures/TTT4280%20-%20Lab%20Blokk.png)

ntnu/21v/ttt4280/lectures/2021-01-11/2021-01-11.md

@@ -0,0 +1,57 @@
+---
+title: "TTT4280 - Måleusikkerhet"
+description: "2021-01-11"
+math: true
+---
+
+## Faglig innhold
+
+* Måleusikkerhet
+* Støyanalyse
+* Sensorer og aktuatorer
+* Sensortyper
+
+## Hva er sensorer
+
+Noe som kan lese den fysiske verdenen til noe vi kan prosessere.
+
+Finnes mange forskjellige sensorer. Flere i biler, telefoner, klokker osv.
+
+Tidligere ble det estimert at vi skulle ha ca 50 milliarder sensorer i 2020. 
+
+## Måleusikkerhet
+
+Bruk av sensor = Utføre en måling.
+
+...og måleverdier har en usikkerhet.
+
+I visse situasjoner har måleusikkerheten masse å si, i andre har det ikke så mye å si.
+
+Sensitivitet er en måling for å ikke gjøre en Type II feil (alarmen løser **ikke** ut).
+
+Spesifisitet er en måling for å ikke gjøre en Type I feil (**falsk** alarm).
+
+
+
+### Grunnmodell for måleprosess
+
+![Grunnmodell](figures/grunnmodell.jpg)
+
+I realiteten er det støy i alle ledd.
+
+Sannsynligheten for at et sensorsystem gir riktig svar påvirkes av (minst) to faktorer:
+
+* Hvor entydig er underliggende sammenhenger?
+* Hvor nøyaktig kan vi måle de fysiske størrelsene?
+
+$$ \text{SNR} = \frac{\text{(Effekten for) sann verdi}}{\text{(Effekten for) støy}} $$
+
+### Målefeil
+
+Stokastiske feil (Type A feil) påvirker målingens *presisjon*. 
+Presisjonen beskriver hvor reproduserbar en måling er.
+
+Systematiske feil (Type B feil) påvirker målingens *sannhet*. 
+Sannheten er en måling på hvor langt unna den sanne verdien en måling er.
+
+![Målefeil](figures/true-prec.jpg)