Re: [avr-gcc-list] do-while problem

[Jesper Hansen]

You need to declare ABC as 'volatile' !

/Jesper
 
----- Original Message ----- 
From: "Arne Lynge Madsen" <address@hidden>
To: <address@hidden>
Sent: Wednesday, June 05, 2002 11:33 AM
Subject: [avr-gcc-list] do-while problem


> Hi,
> 
> I just realized that there migth be a bug in the generated assempler...
> 
> 
> do
>  {
>   } while (ABC == 0x01 );
> 
>  166: 80 91 60 00    lds r24, 0x0060
>  16a: 81 30                cpi r24, 0x01 ; 1
>  16c: f1 f3                    breq .-4       ; 0x16a
> 
> ABC is updated by an interrupt routine. breq.-4 only jumps back to the
> cpi statement, so the updated ABC is not taken into account. Loops
> forever!
> 
> 
> do
>  {
>   } while (somefunction() != 0);
> 
>  132: 86 d1        rcall .+780     ; 0x440
>  134: 88 23        and r24, r24
>  136: e9 f7        brne .-6       ; 0x132
> 
> somefunction() returns ABC. Here brne.-6 jumps back to rcall. It works!
> 
> I currently use these packages:
> binutils-2.11.2
> gcc-3.0
> avr-libc-20011208
> 
> Questions:
> Where is this error located? binutils, gcc or avr-libc?
> Could it be corrected in later versions, if so which one?
> Where to report the error?
> 
> Best regards
> Arne
> 
> 
> 
> 
> avr-gcc-list at http://avr1.org
> 


avr-gcc-list at http://avr1.org