separate main tests in differents files and added comparison in readme

README.md

@@ -9,8 +9,8 @@
 - **socket :** creates an endpoint for communication and returns a file descriptor that refers to that endpoint
 - **listen :** marks a socket as a passive socket, that is, as a socket that will be used to accept incoming connection requests using accept()
 - **accept :** used with connection-based socket types. It extracts the first connection request on the queue of pending connections for the listening socket, creates a new connected socket, and returns a new file descriptor referring to that socket. The newly created socket is not in the listening state. The original socket is unaffected by this call
-- **send :** used to transmit a message to another socket. May be used only when the socket is in a connected state (so that the intended recipient is known). The only difference between send() and write() is the presence of flags. With a zero flags argument, send() is equivalent to write()
-- **recv :** used to receive messages from a socket. May be used to receive data on both connectionless and connection-oriented sockets. The only difference between recv() and read() is the presence of flags. With a zero flags argument, recv() is generally equivalent to read()
+- **send :** (~write) used to transmit a message to another socket. May be used only when the socket is in a connected state (so that the intended recipient is known). The only difference between send() and write() is the presence of flags. With a zero flags argument, send() is equivalent to write()
+- **recv :** (~read)  used to receive messages from a socket. May be used to receive data on both connectionless and connection-oriented sockets. The only difference between recv() and read() is the presence of flags. With a zero flags argument, recv() is generally equivalent to read()
 - **bind :** associate a socket fd to a local address. When a socket is created with socket(), it exists in a name space (address family) but has no address assigned to it. It is normally necessary to assign a local address using bind() before a socket may receive connections (see accept())
 - **connect :** connects a socket fd to a remote address
 - **inet_addr :** converts the Internet host address cp from IPv4 numbers-and-dots notation into binary data in network byte order. Use of this function is problematic because in case of error it returns -1, wich is a valid address (255.255.255.255). Avoid its use in favor of inet_aton(), inet_pton(), or getaddrinfo()
@@ -77,3 +77,84 @@
 - [bind() vs connect()](https://stackoverflow.com/questions/27014955/socket-connect-vs-bind)
 - [INADDR_ANY for bind](https://stackoverflow.com/questions/16508685/understanding-inaddr-any-for-socket-programming)
 
+## code architecture
+
+
+``` 
+       ______
+  sd = SOCKET()     : create a listening socket descriptor
+  __________
+  SETSOCKOPT(sd)    : allow socket descriptor to be reuseable
+  _____
+  IOCTL(sd)         : set listening socket and all incoming socket to be non-blocking
+  ____
+  BIND(port)        : associate listening socket to a port
+  ______
+  LISTEN(nb_queue)  : queue the incoming connections to listening socket
+                      up to a chosen number
+  ____
+  POLL(fds[])       : wait for event on files descriptors
+  ______
+  SELECT(fds[])     : wait for event on files descriptors
+  FD_SET()          : add a fd to a set
+  FD_CLR()          : remove a fd from a set
+  FD_ZERO()         : clears a set
+  FD_ISSET()        : test to see if a fd is part of the set
+           ______
+  new_sd = ACCEPT() : extract first connection request in queue of listening socket
+                      and creates a new socket that is connected
+  ____
+  RECV(new_sd)      : read data in socket created by accept()
+  ____
+  SEND(new_sd)      : write data in socket created by accept()
+  _____
+  CLOSE(new_sd)     : close open file (here socket) descriptor
+
+```
+
+compare architectures :
+
+```
+                                   POLL                           SELECT
+            ______                  ______                       ______
+  lstn_sd = SOCKET()  |  lstn_sd = SOCKET()         |  lstn_sd = SOCKET()
+                      |  __________                 |  __________
+                      |  SETSOCKOPT()               |  SETSOCKOPT()
+                      |  _____                      |  _____
+                      |  IOCTL()                    |  IOCTL()
+  ____                |  ____                       |  ____
+  BIND(port)          |  BIND(port)                 |  BIND(port)
+  ______              |  ______                     |  ______
+  LISTEN(nb_queue)    |  LISTEN(nb_queue)           |  LISTEN(nb_queue)
+                      |                             |
+                      |  fds[1] = lstn_sd           |  FD_SET(lstn_fd)
+                      |                             |
+                      |                             |  max_sd = lstn_sd
+                      |                             |
+  loop                |  loop                       |  loop
+  .  ____             |  .  ____                    |  .  ______
+  .  POLL()           |  .  POLL(fds[])             |  .  SELECT(fds[])
+  .                   |  .                          |  .
+  .                   |  .  loop through fds[]      |  .  loop i++ < max_fd
+  .                   |  .  .                       |  .  .
+  .                   |  .  .  POLLIN && lstn_sd ?  |  .  .  FD_ISSET(i) & lstn_fd ?
+  .  ______           |  .  .  .           ______   |  .  .  .           ______
+  .  ACCEPT()         |  .  .  .  new_sd = ACCEPT() |  .  .  .  new_sd = ACCEPT()
+  .                   |  .  .  .                    |  .  .  .
+  .                   |  .  .  .  fds[] += new_sd   |  .  .  .  FD_SET new_sd in fds[]
+  .                   |  .  .                       |  .  .  .
+  .                   |  .  .                       |  .  .  .  max_sd = new_sd
+  .                   |  .  .                       |  .  .
+  .                   |  .  .  POLLIN ?             |  .  .  FD_ISSET ?
+  .  ____             |  .  .  .  ____              |  .  .  .  ____
+  .  RECV()           |  .  .  .  RECV()            |  .  .  .  RECV()
+  .  ____             |  .  .  .  ____              |  .  .  .  ____
+  .  SEND()           |  .  .  .  SEND()            |  .  .  .  SEND()
+  .                   |                             |
+  .                   |  loop through fds[]         |  loop through fds[]
+  .  _____            |  .  _____                   |  .  _____          
+  .  CLOSE(fds[])     |  .  CLOSE(fds[])            |  .  CLOSE(fds[])   
+
+
+```
+