Re: [avr-chat] HowTo split a program into several files ?

[Till Harbaum]

Hi,

On Monday 12 September 2005 19:33, Vincent Trouilliez wrote:
> Thanks Till, I tried that, but the compiler complains that my lcd.c (not
> 'foo', but lcd.. ;-) uses undeclared functions and defines, despite in
> main.c (let's call the main C source file this way, I took care to
> include my lcd.h statement UNDER all other usual includes.
So it complains about things missing in lcd.c? Where are these things actually 
located? In main.c? In theory you'd then have to write a main.h containing 
the prototypes of all parts of main.c you are intending to use in ldc.c. 

BUT: You're probably starting to write ugly code! Try to think in hierarchies: 
There's main.c. It uses routines from lcd.c and therefore includes lcd.h. 
lcd.c may then again use routines from charset.c or i2c.c (if e.g. your 
display is attached via i2c) and includes charset.h and i2c.h. If there are 
routines back in main that are used in main.c _and_ and lcd.c, then you might 
either move them to lcd.c as well (since they are lcd related) or to a 
seperate file, because they have a seperate purpose like e.g. some fancy port 
access routines. There's usually no need for "circular" includes.

> main.c :
> -------
> #include <stdio.h>
> #include <stdlib.h>
> #include <avr/io.h>
> #include <avr/interrupt.h>
> #include <avr/signal.h>
> #include <avr/delay.h>
>
> #include "lcd.h"    <----------- my file with LCD related routines
> (well, only the prototyptes of course)
This is exaclty how it should be.

> Am I supposed to copy all the "regular" includes at the top of lcd.h as
> well ?
Uhm, if there's stuff in lcd.c that uses some of the avr library 
functionality: Yes, of course. For the compiler your lcd.c is a completely 
seperate thing. You'll have to include all the system headers you are using.

But do you really need all the system includes in main.c anymore? It's a good 
habit to check every now and then if your file really needs all these 
includes. Removing unused includes speeds up compilation but more important 
it makes your code more readable. If i see the  "#include <avr/interrupt.h>" 
in your main.c, i'd assume that you have placed interrupt routines in main.c, 
which may not be true anymore, since you removed some of your code from 
there.

Till

-- 
Dr.Ing. Till Harbaum, address@hidden