QP active object frameworks for embedded systems
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Author Archives: te-bachi
Word Hints&Tips
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$ ls -la total 39466 drwx------+ 1 ???????? mkpasswd 0 Sep 29 10:17 . drwx------+ 1 ???????? ???????? 0 Apr 7 15:54 .. -rwx------+ 1 AndreasB mkpasswd 162 Sep 23 16:30 ~$I2_ProtocolRevK_abachmann.docx
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Feldfunktionen: DocProperty-Feld
Hinzufügen oder Löschen von Beschriftungen
Hinzufügen oder Löschen von Beschriftungen
Inhaltsverzeichnis Erstellen und Formatieren
Formatieren oder Anpassen eines Inhaltsverzeichnisses
Formatieren eines Inhaltsverzeichnisses
Einfügen eines nicht umbrechendes Leerzeichens (“non-breaking space”)
CTRL + SHIFT + SPACE
Word 2010 Listen-Fehler: Die Zahl muss zwischen 1 und 600 (bzw. 1638) liegen.
Formatvorlagen -> Neue Formatvorlage -> Formatvorlagentyp: Liste
Liste mit mehreren Ebenen -> Listenformatvorlage:
Word 2010 Fehler: Die Zahl muss zwischen 1 und 600 (bzw. 1638) liegen.
Erstellen einer neuen Listenformatvorlage
Alle Felder aktualisieren
CTRL-A -> F9
Word 2010: Alle Felder aktualisieren
Seiten Orientierung
How to Omit the Page Number From the First Page of a Word 2013 Document Without Using Sections
Seitenzahlen
How to Omit the Page Number From the First Page of a Word 2013 Document Without Using Sections
VHDL Attributes
signal_name'pos signal_name'val signal_name'length signal_name'event T'POS(X) = is the integer position of X in the discrete type T. T'VAL(X) = is the value of discrete type T at integer position X. A'LENGTH = is the integer value of the number of elements in array A. A'LENGTH(N) = is the number of elements of dimension N of array A. S'EVENT = is true if signal S has had an event this simulation cycle.
VHDL Predefined Attributes
Attributes in VHDL
VHDL Reference Guide – Attributes
User-defined Attributes
Finite-State Machine (FSM)
Types:
- Application-Based State Machine Models
- Event-Driven Model
General
Uni Hannover: Automaten
Schaltwerke
Electronics
AllAboutCircuits.com: Finite State Machines
Programming language
The State Design Pattern vs. State Machine, C++
Scripts
The Power of Finite State Machines: Application and Extension, Flash ActionScript
Wikipedia
Finite-state machine
Event-driven finite-state machine
State diagram
State pattern
UML state machine
UML Tools
Sparx Systems: Enterprise Architect
Cloudfier + TextUML Toolkit
Cloudfier is an innovative web-based platform for rapid development and deployment of business applications
TextUML Toolkit is a developer-centric open-source tool for creating UML models based on a textual notation.
Java 32-bit/64-bit Library Problems
Multicast IP/MAC-Address Mapping
Ethernet Internals
MAC Address
What range of MAC addresses can I safely use for my virtual machines?
MAC Address: Universally or Locally Administered Bit and Individual/Group Bit
Frame Check Sequence (FCS) = Cyclic Redundancy Check (CRC)
Cyclic Redundancy Check (CRC), Frame Check Sequence (FCS)
UDP Checksum
Short UDP Checksum Calculation HowTo
Following is a description by Ed Beroset of the calculation of the UDP checksum for this packet. Many thanks to Ed for figuring out the details and writing it up.
First, the checksum calculation is defined in RFC 768 but hints as to how to calculate it efficiently are in RFC 1071. Both are worth reading and contain a much more in-depth description that I’m going to write here.
The basic idea is that the UDP checksum is a the complement of a 16-bit one’s complement sum calculated over an IP “pseudo-header” and the actual UDP data. The IP pseudo-header is the source address, destination address, protocol (padded with a zero byte) and UDP length. So to take the example of this short packet, the source IP address is 152.1.51.27, and the destination IP address is 152.14.94.75. Divided into 16-bit quantities, these are 0x9801, 0x331b and 0x980e, 0x5e4b. If you add those together using two’s complement (e.g. with Windows calculator), you get 0x1c175. Note that this overflows a 16-bit quantity, but we’ll take care of that later. Next is to add in the protocol and UDP length. For this packet, the protocol is UDP so the protocol type byte is 17or 0x11. We pad that with zero to get 0x0011 and then add the UDP length which is 0x000a (10 bytes). So 0x1c175 + 0x0011 + 0x0! 00a = 0x1c190.
Now we add the entire UDP datagram, treating it all as 16-bit quantities and skipping the checksum (until we finish calculating it!). For this datagram, that’s 0xa08f, 0x2694, 0x000a, 0x6262, so if we add all that to our running sum, we get 0x1c190 + 0xa08f + 0x2694 + 0x000a + 0x6262 = 0x2eb1f.
Now to convert to a ones complement 16-bit sum we just treat our current sum (0x2eb1f) as a 32-bit quantity and add the high half to the low half. 0x0002 + 0xeb1f = 0xeb21. (If that still had an overflow, we’d add the high and low halves again until there was no longer an overflow.) Now we complement that quantity (i.e. flip all the bits, or do a NOT operation) and we get a value of 0x14de which is exactly what the reported checksum shows in the packet.
Short UDP Checksum Calculation HowTo
How to Calculate IP/TCP/UDP Checksum–Part 1 Theory
/*
* Our algorithm is simple, using a 32 bit accumulator (sum), we add
* sequential 16 bit words to it, and at the end, fold back all the
* carry bits from the top 16 bits into the lower 16 bits.
*/
uint16_t
raw_packet_calc_checksum(uint16_t *buffer, uint16_t len)
{
const uint16_t words = len / 2;
uint32_t sum;
uint16_t i;
sum = 0;
for (i = 0; i < words; i++) {
sum = sum + *(buffer + i);
}
/* add carry */
sum = (sum >> 16) + sum;
/* truncate to 16 bits */
return ~sum;
}
AES Stick Figure
tcpdump Packet Capture / Sniffer / Analyzer
$ tcpdump -i em0 -s 65535 -w packet.pcap $ xz -z packet.pcap
TCPDUMP Quick Reference (PDF)
Tcpdump Commands – A Network Sniffer Tool
A tcpdump Tutorial and Primer
How to gather DNS A record requests?
Monitoring DNS Queries with tcpdump
Packet Analyzer: 15 TCPDUMP Command Examples
tcpdump: Capturing with tcpdump for viewing with Wireshark
Manual pages
Wikipedia
tcpdump (de)
tcpdump (en)
pcap (de)
Change PCAP files
Bit-Twist: Libpcap-based Ethernet packet generator
Strip off GTP Headers
Bittwiste: pcap Capture File Editor (by Joke Snelders)
Strip radiotap headers from capture files?