RE: [avr-libc-dev] [bug #28881] nop() macro for NOP instruction

[Weddington, Eric]

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of Weddington, Eric
> Sent: Friday, February 12, 2010 11:49 PM
> To: Soren Jorvang; Joerg Wunsch; address@hidden
> Subject: RE: [avr-libc-dev] [bug #28881] nop() macro for NOP 
> instruction
> 
>  
> 
> > -----Original Message-----
> > From: 
> > address@hidden 
> > [mailto:address@hidden
> > org] On Behalf Of Joerg Wunsch
> > Sent: Friday, February 12, 2010 5:35 PM
> > To: Soren Jorvang; Joerg Wunsch; address@hidden
> > Subject: [avr-libc-dev] [bug #28881] nop() macro for NOP instruction
> > 
> > 
> > Follow-up Comment #1, bug #28881 (project avr-libc):
> > 
> > You guessed it: there's no real place for the nop() macro
> > to go into.  That's the main reason it's not yet there.
> > 
> 
> I agree that there is not a convenient place to put such a 
> macro. But I would also argue now that we do not need to have 
> such a macro in avr-libc. The only use for the NOP 
> instruction is for some sort of delay, typically by a 
> specific number of cycles. This has been available via 
> patches to GCC for a while now. These patches add intrinsic 
> functions to the AVR port of GCC and one of those intrinsic 
> functions allows the user to delay a specified number of 
> cycles. GCC will then generate inline code to do this which 
> takes advantage of NOP and other instructions to implement 
> this. These patches are included in the WinAVR release, and 
> should be available in other distributions, though I haven't 
> checked on other platforms.

Oh, I also wanted to add that these patches *will* make their way upstream into 
the GCC source code, but it's a process to get it done. I don't have an exact 
time frame for this yet.