Improve documentation.

README.md

@@ -5,4 +5,44 @@ BLC channel
 - Author    : [Arnaud Blanchard](http://arnaudblanchard.thoughtsheet.com)  
 - Licence   : [CeCILL v2.1](http://www.cecill.info/licences/Licence_CeCILL_V2-en.html)  
 
-See [online documentation](https://framagit.org/blaar/blc_channel/wikis/home)
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+Functions to easily share data through shared memory (shm_... functions). The advantage is that it is the fastest and the more econom in memory ( no copy in each process ) way to share informtation between processes. At this moment in anly works in asynchronous mode.
+
+The idea is that you hav ae structure blc_channel which is like a blc_array ( https://framagit.org/blaar/blc_core/blob/master/t_array/main.cpp ) but has a name starting with '/' to identificate it on your system.
+
+Example
+=======
+
+For exemple you create a channel in one program to write data:
+
+    #Creating shared called '/my_channel_name', this program will write on it, it is char ('INT8') with no specific format ('NDEF') of dimension 1 (vector) of 32 elements.
+    
+    blc_channel my_channel.create("/my_channel_name", BLC_CHANNEL_WRITE, 'INT8', 'NDEF', 1, 32);
+    snprintf(my_channel.chars, 32, "Hello world !\n");
+    
+and read this data in another program:
+	
+	#Opening shared memory called '/my_channel_name', this program will only read it.
+
+     blc_channel my_receiving_channel.open("/my_channel_name", BLC_CHANNEL_READ);
+     printf("%s", my_receiving_channel.chars);
+     
+The second program prints 'Hello world !'.
+
+Demo
+====
+
+`blc_channel/demo.sh` launches two processes. 
+- **t_channel_reader** reading each second the content of '/channel_example' and printing it.
+- **t_channel_writer** waiting for the user to enter text and filing the channel '/channel_example' with this text.  Each second the reader will print this text. 
+
+Press 'q' to quit.
+
+Details
+=======
+
+The information about the properties of the blc_channels (type, format, sizes) is stored in a special file: '/tmp/blc_channels.txt'. You are not suppose to use it but you can check at anytime the status of the blc_channels using `./run.sh i_channels` in your blaar directory.
+
+You will see all the existing blc_channels, the process reading or writing and the possibility to destroy channels.
+
+On Linux we can see and manipulate a virtual file containing this memory in /run/shm/<name of your shared memory>, on OSX you cannot but anyway it is only used for debug.
+