AVR-Chat

I believe it's the difference between

void foo();

And

void foo(void);

The first is a function that takes unspecified parameters and the second
is a function that takes no parameters.

-- Paul.

> -----Original Message-----
> From: Chuck Hackett [mailto:egroupscdh@WhiteTrout.net] 
> Sent: 08 April 2005 13:13
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Code Conversion
> 
> 
> I have purchased an ATMega16 based board to connect a project 
> to the Internet.
> I'm attempting to compile my first real embedded program.  
> The example code that came with the board was written for 
> ImageCraft's ICCAVR Pro C compiler and I'm currently 
> converting it to WINAVR.  I'm trying to digest all the 
> documentation but my unfamiliarity with both compilers is 
> hampering me.  If you would indulge me with a couple of questions:
> 
> I have two functions that are being flagged with the 
> following warning:
> 
> "function declaration isn't a prototype"
> 
> One is declared:
> 
> void overrun()
> {
> ...
> }
> 
> ... and the other ...
> 
> void init_ASIX88796L()
> {
> ...
> }
> 
> Both functions are declared prior to their first use and 
> there are other "void funct()" functions which do not cause warnings.
> 
> - What exactly is this trying to tell me?
> - Where can I find descriptions of the various warnings and 
> errors from WINAVR?
> 
> 
> I came across a couple of occurrences of:
> 
>     do{
>         ...
>         result = byte_read & RDC;
>     }while (result = 0);
> 
> Shouldn't "while (result = 0)" be "while (result == 0)" ?
> 
> 
> If I understand it correctly I should convert the following code:
> 
> #pragma interrupt_handler USART_RX_interrupt:iv_USART_RX ...
> void USART_RX_interrupt( void )
> {
> ...
> }   
> 
> ... to ...
> 
> SIGNAL(SIG_USART_RECV)
> {
> ...
> }   
> 
> 
> Are there general guidelines available on the Internet 
> concerning converting ImageCraft's ICCAVR Pro C code to WINAVR?
> 
> Thanks in advance for your help.
> 
> Cheers,
> 
> Chuck Hackett
> "Good judgment comes from experience, experience comes from 
> bad judgment"
> 7.5" gauge Union Pacific Northern (4-8-4) 844 
> http://www.whitetrout.net/Chuck
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 
>

> From: Paul Curtis [mailto:plc@rowley.co.uk]
> 
> I believe it's the difference between
> 
> void foo();
> 
> And
> 
> void foo(void);
> 
> The first is a function that takes unspecified parameters and the second
> is a function that takes no parameters.
> 
> -- Paul.
> ....

That makes sense except that there are many functions declared similar to "void
foo()" that do not generate warnings.  I'm at a loss to see what makes these
particular two different.

Cheers,

Chuck Hackett
"Good judgment comes from experience, experience comes from bad judgment"
7.5" gauge Union Pacific Northern (4-8-4) 844
http://www.whitetrout.net/Chuck

On Fri, Apr 08, 2005 at 02:08:15PM +0100, Paul Curtis wrote:

"I believe it's the difference between

void foo();

And

void foo(void);

The first is a function that takes unspecified parameters and the second
is a function that takes no parameters."

Please forgive me if I make serious mistakes here, but I believe that

void foo();

may take unspecified parameters in K & R C but must take no parameters in
C89

and

void foo(void);

takes no parameters in K & R C and C89.

and

in C89, one may declare a prototype for a function whose quantity of
parameters is unspecified with

void foo(...);

and in so far as this discussion goes, I suspect that C89 and C99 are the
same (with void foo(); being equivalent to void foo(void); ), not that
GCC actually supports C99 ( HTTP://GCC.GNU.org/gcc-3.4/c99status.html ).

As for solving Chuck Hackett's porting problem, this does not. I do not
know why you are having problems. Chuck Hackett had said:

"[..]

Both functions are declared prior to their first use and
there are other "void funct()" functions which do not cause warnings.

[..]"

Where are the two rejected declarations declared (you did say "there" but 
that is a common English idiom)? Perhaps you need to check your
#ifdef settings. Though they might be declared before first being used,
where are they being used? Perhaps where they are called from is treated
as being part of a header file by GCC (with no function calls allowed) and
so their calls are being misinterpreted as declarations. Is a semicolon or
somesuch missing from before the declarations? Good luck.