RE: [lwip-devel] [task #7054] Clarification needed for variableinitialization

[Julian Gardner [RSD]]

Well when i start using any code i remove all 0 initialisation code, so this 
forces the compiler to stick the variable in the BSS section.

This is the way it should work, i think setting a variable to 0 is by default 
the norm.

As to the tcp_backoff this will make the code larger as if taking the 
tcp_backoff as an example we would have 13 stores and at least 7 loads.

leave the code as is and start removing the NULL and 0 assignments for GLOBAL 
variables

joolz

-----Original Message-----
From: address@hidden on behalf of Simon Goldschmidt
Sent: Tue 03/07/2007 22:55
To: Simon Goldschmidt; address@hidden
Subject: [lwip-devel] [task #7054] Clarification needed for 
variableinitialization
 

URL:
  <http://savannah.nongnu.org/task/?7054>

                 Summary: Clarification needed for variable initialization
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: goldsimon
            Submitted on: Dienstag 03.07.2007 um 19:43
                Category: None
         Should Start On: Dienstag 03.07.2007 um 00:00
   Should be Finished on: Dienstag 03.07.2007 um 00:00
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

    _______________________________________________________

Details:

The current code mixes:
- initialization to zero for global (and global static) variables
- uninitialized static arrays (initialized to 0 by compiler/loader)
- initialization to other values for global variables
- initialization in _init() functions

I'd favour making it the same for all files:
- always initialize non-zero global variables at declaration (e.g.
tcp_backoff array)
- create define to initialize global variables to zero or not (decides which
section they are put into and if they take place in the binary before
execution) (e.g. 'struct tcp_pcb *tcp_tw_pcbs INIT_NULL;' and '#define
INIT_NULL = 0' or '#define INIT_NULL') (there is a downside for arrays, so
arrays that should be zeroed - like sockets[NUM_SOCKETS] - would have to be
memset to NULL in an init function)
- generally don't zero variables in init functions that are already zeroed on
declaration

Any comments or preferences?




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  <http://savannah.nongnu.org/task/?7054>

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