How to set EMACS C STYLE to hack KAMAILIO code

Kamailio (former OpenSER) is a SIP proxy server, call router, and user agent registration server used in Voice over Internet Protocol and instant messaging applications. Kamailio is free software (GPL licensed).

In this post we are going to learn how to configure emacs to follow kamailio coding style guidelines.

KAMAILIO CODING STYLE GUIDELINES

From Kamailio documentation: http://sip-router.org/wiki/coding_style

As a resume:

• Use tabs for indentation instead of spaces.
• Set tab stops to 4 spaces.
• Wrap lines that are longer than 78 characters (80 characters - two characters for window decorations).
• Avoid C++ style comments (//)
• Do not declare variables inside blocks.
• Use the following style for function declarations

int func(int x)
{
    /* body */
}

EMACS C KAMAILIO CODING STYLE

We are going to create an emacs C coding style in order to comply with most of those rules.

Read more »

My .emacs configuration file

This post describes my .emacs configuration file.

.emacs configuration file is loaded by emacs editor when it starts.

Let's divide the .emacs configuration file into parts to describe it better:

Customized variables
Install user customizations of variable values specified in arguments.

(custom-set-variables
  ;; custom-set-variables was added by Custom.
  ;; If you edit it by hand, you could mess it up, so be careful.
  ;; Your init file should contain only one such instance.
  ;; If there is more than one, they won't work right.
 '(column-number-mode t)
 '(desktop-save-mode t)
 '(display-battery-mode t)
 '(display-time-24hr-format t)
 '(display-time-day-and-date nil)
 '(display-time-mode t)
 '(fringe-mode 0 nil (fringe))
 '(menu-bar-mode nil)
 '(network-speed-format-string " [%NI %AX %AB] ")
;; '(network-speed-interface-list (list "eth0" "eth1"))
 '(network-speed-interface-list (list "eth1"))
 '(network-speed-precision 1)
 '(network-speed-update-interval 2)
;; '(org-agenda-files (quote ("~/org/task_list.org")))
 '(scroll-bar-mode nil)
 '(size-indication-mode t)
 '(tool-bar-mode nil)
 '(tooltip-mode nil)
 '(w3m-session-load-last-sessions t))

Read more »

Installing and Configuring ANYTHING.EL for Emacs

anything.el is an application framework written by TamasPatrovics (current maintainer is rubikitch).
It provides a better way to choose between alternatives when typing a command, switching buffers, searching for help, files, etc.
After you select a candidate option from the list anything provides, you can choose between several actions.

DOWNLOAD ANYTHING
We are going to download anything from its source code repository.
$ cd ~/.emacs.d
$ git clone git://repo.or.cz/anything-config.git

CONFIGURE .emacs FILE

;; Anything.el
(add-to-list 'load-path "~/.emacs.d/anything-config/")
(add-to-list 'load-path "~/.emacs.d/anything-config/extensions/")
(require 'anything-startup)

That it is enough for using anything:
e.g: M-x anything

Also common functions like switch-to-buffer are automatically remapped to anything ones.


However you could also customize your anything buffers, selecting the anything sources you want:

Read more »

How to Show Network Speed in Emacs Mode Line

Copy this file as network-speed.el. Place it where emacs can find it (see load-path variable).

Configure your .emacs file:

;; network-speed configuration:
(add-to-list 'load-path "/path/to/network-speed.el")
(require 'network-speed)
(network-speed-start) 

Reload your .emacs file: M-x load-file RET /path/to/.emacs

To stop showing network speed in mode line execute:
M-x network-speed-stop

;;; network-speed.el --- display network speed information  -*- coding: mule-utf-8 -*-

;; Copyright (C) 2009 Vicente Hernando Ara

;; Author: Vicente Hernando Ara 

;; Created: 1 Jan 2010

;; Keywords: hardware

;; This file 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 file 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.



;;; Commentary:

;; network-speed.el package displays network speed in emacs mode line for the interfaces the user selects.


;; There are several configurable options:

;;   network-speed-update_interval: time interval after which speed is calculated.

;;   network-speed-interface-list: list containing all network interfaces we want to show data about.

;;   network-speed-precision: every floating point number will show this number of figures after decimal point.

;;   network-speed-format-string: customizable string to be shown in the mode line.
;;   There are several scape strings which will be sustituted by data.
;;     %NI == network interface
;;     %RX == received bytes speed 
;;     %TX == transmitted bytes speed
;;     %AX == received + transmitted bytes speed
;;     %RB == total received bytes
;;     %TB == total transmitted bytes
;;     %AB == total received plus transmitted bytes
;;     %%% == % character"

;; After this file is loaded, it is necessary to call `network-speed-start' function.
;; To stop network-speed working  you need to call `network-speed-stop' function.

;;      
;; A lot of ideas were taken from `battery.el.gz' file.


;;; NETWORK-SPEED CONFIGURATION
;;
;; Add something like this in your .emacs file:
;;
;; ;; Custom variables:
;;  '(network-speed-update-interval 2)   ; Shows network speed every 2 seconds.
;;  '(network-speed-interface-list (list "ppp0" "eth0"))  ; Network interfaces to be shown in mode line.
;;  '(network-speed-precision 1)  ; Number of figures after decimal point.
;;  '(network-speed-format-string " [%NI total: %AX] ") ; String format.
;;
;; ;; network-speed configuration:
;; (add-to-list 'load-path "/path/to/network-speed.el")
;; (require 'network-speed)
;; (network-speed-start) ; 
;;
;; ;; to stop network-speed, call "network-speed-stop" interactive function.
;; ;; (network-speed-stop)


;;; Code:

;;; CUSTOM VARIABLES:

;; Network interface list to be shown in mode line.  
;;   E.g: `(list "ppp0" "eth0" "ppp1")'
(defcustom network-speed-interface-list (list "eth0") "Network interface list to be shown in mode line."
:type '(repeat string) )

(defcustom network-speed-update-interval 1 "Network speed is calculated every network-speed-update-interval seconds."
:type 'number )

(defcustom network-speed-precision 2 "Number of digits after point in numbers shown in mode line."
:type 'integer )

;; String used to build the output string shown in emacs mode line.
(defcustom network-speed-format-string " [%NI rx:%RX tx:%TX] " "Format string. 
%NI == network interface
%RX == received bytes speed 
%TX == transmitted bytes speed
%AX == received + transmitted bytes speed
%RB == total received bytes
%TB == total transmitted bytes
%AB == total received plus transmitted bytes
%%% == % character"
:type 'string
)


(defvar network-speed-update-timer nil)

;; List that contains vectors like this: [ network-interface-string received-bytes transmitted-bytes rx-speed tx-speed ]
;; This variable is only for internal use.
(defvar network-speed-data-list nil) 

;; We will parse /proc/net/dev file using the returned regexp.
(defun network-speed-get-regex (network-interface)
"Returns the right regular expression needed to find received and transmitted bytes for NETWORK-INTERFACE."
(concat "^\\( *" network-interface ":[ ]*\\)"
"\\([0-9]+\\)" ; received bytes.
"\\( +[0-9]+\\)\\{7\\} +"
"\\([0-9]+\\)"))  ; transmitted bytes.


(defun network-speed-get-rx-tx-bytes ()
"Gets received and transmitted bytes for every required network interface and calculates received and transmitted speeds.
Received and transmitted bytes are read from `/proc/net/dev' file"
(mapc
(lambda (network-speed-data)
(with-temp-buffer
(ignore-errors (insert-file-contents "/proc/net/dev")) 
(cond ((re-search-forward (network-speed-get-regex (aref network-speed-data 0)) (point-max) t)
(let ((old-received-bytes (aref network-speed-data 1)) ; get old received bytes.
(old-transmitted-bytes (aref network-speed-data 2)) ; get old transmitted bytes.
(received-bytes (string-to-number (match-string 2))) ; get updated received bytes.
(transmitted-bytes (string-to-number (match-string 4)))) ; get updated transmitted bytes.

;; Save received and transmitted bytes.
(aset network-speed-data 1 received-bytes) 
(aset network-speed-data 2 transmitted-bytes)

;; Save received and transmitted speed.
(aset network-speed-data 3 (/ (float (- received-bytes old-received-bytes)) network-speed-update-interval))
(aset network-speed-data 4 (/ (float (- transmitted-bytes old-transmitted-bytes)) network-speed-update-interval))))
(t 
(aset network-speed-data 3 -1 ) ; There is no network interface available.
(aset network-speed-data 4 -1 ))))) ; There is no network interface available.

network-speed-data-list))


(defun network-speed-add-units (speed)
"Returns speed in adequate units e.g: B/s, KB/s or MB/s."
(cond 
((< speed 0) (format "*")) ; Network interface not available right now.
((< speed 1000) (format "%d B/s" speed))  
((< speed 1000000) (format (concat "%." (number-to-string network-speed-precision) "f KB/s") (/ speed 1000)))
(t (format (concat "%." (number-to-string network-speed-precision) "f MB/s") (/ speed 1000000)))))


(defun network-speed-parse-format (vector-data)
"Substitute %XX sequences in network-speed-format-string."
(replace-regexp-in-string 
;;;   "%NI\\|%RX\\|%TX\\|%AX\\|%RB\\|%TB\\|%%%"
"%\\(NI\\|RX\\|TX\\|AX\\|RB\\|TB\\|AB\\|%%\\)"
(lambda (str)
(cond 
((equal str "%NI") (aref vector-data 0))  ; network interface.
((equal str "%RX") (network-speed-add-units (aref vector-data 3)))  ; received bytes speed.
((equal str "%TX") (network-speed-add-units (aref vector-data 4)))  ; transmitted bytes speed.
((equal str "%AX") (network-speed-add-units (+ (aref vector-data 3) (aref vector-data 4)))) ; received + transmitted speed.
((equal str "%RB") (format "%d" (aref vector-data 1))) ; received bytes.
((equal str "%TB") (format "%d" (aref vector-data 2))) ; transmitted bytes.
((equal str "%AB") (format "%d" (+ (aref vector-data 1) (aref vector-data 2)))) ; received + transmitted bytes.
((equal str "%%%") "%") ; % character.
)
)
network-speed-format-string t t)
)


(defun network-speed-update-handler()
"This function is called every `network-speed-update-interval' seconds to calculate data and show network speed in modeline."
(network-speed-get-rx-tx-bytes)

(setq network-speed-mode-line-string "")
(mapc 
(lambda (network-speed-data)
(setq network-speed-mode-line-string 
(concat network-speed-mode-line-string 
(network-speed-parse-format network-speed-data))))  ; Obtains the string we will show.
network-speed-data-list)

(force-mode-line-update)
(sit-for 0))


(defun network-speed-start ()
"Shows network speed in mode line. 
This function initializes all needed data. 
Speed is not shown inmediately but after `network-speed-update-interval' seconds when first correct value is calculated."
(interactive)

;; Adding network-speed-mode-line-string to global mode line.
(setq network-speed-mode-line-string "")
(add-to-list 'global-mode-string 'network-speed-mode-line-string t)

;; Initialize all needed vectors in `network-speed-data-list'.
(setq network-speed-data-list ())
(mapc 
(lambda (x)
(add-to-list 'network-speed-data-list (vector x 0 0 0 0) t))  ; Initialices and element of network-speed-data list.
network-speed-interface-list)

;; Calculate speeds.
(network-speed-get-rx-tx-bytes)

;; Create network-speed-update-timer. 
(and network-speed-update-timer (cancel-timer network-speed-update-timer))
;; This does not inmediately show speeds but it waits `network-speed-update-interval' seconds to start showing it.
(setq network-speed-update-timer (run-at-time network-speed-update-interval network-speed-update-interval 'network-speed-update-handler)))


(defun network-speed-stop ()
"Stops displaying network speed in mode line."
(interactive)
;; Delete the text from global mode line.
(setq global-mode-string (delq 'network-speed-mode-line-string global-mode-string))

;; Cancel timer.
(and network-speed-update-timer (cancel-timer network-speed-update-timer)))


(provide 'network-speed)

;;; filename ends here

Hello World program examples

Hello World is the first program every user usually codes when he learns a new programming language.

Its goal is learning the basics to edit, compile and execute a program which sends a "hello world" string to standard output.


We have used an Ubuntu Hardy distro based system. Most commands will serve to other distros as well, like Debian.

BASH Shell Scripting Hello World

bash command line interpreter is usually already installed in your system.

if it is not installed we type: $sudo aptitude install bash


Now we create hello.sh script using whatever text editor we prefer.
e.g: $ gedit hello.sh


Copy this lines into your hello.sh script

#!/bin/bash
echo "hello world"

Bash shell scripting is an interpreted language so we have not to compile anything. We directly execute the shell script file:

We give the shell script execution permissions:
$ chmod a+x hello.sh

and launch the program
$ ./hello.sh

PYTHON Scripting Hello World

If you do not have python installed in your system, exec:

$ sudo aptitude install python

Read more »