Re: Printing binary data in embedded C

[Martin Hunt <hunt at redhat dot com>]

On Fri, 2007-12-21 at 23:50 -0500, Perry Cheng wrote:
> I've been trying to convert some of my existing scripts from printing 
> ascii data to binary data to improve probe speed.  I've stated using the 
> %b modifier via _stp_printf with success.  However, my data naturally 
> comes in as a char[] of known length and printing it one word at a time 
> with %4b doesn't seem like the best way.  On the other hand, I can't use a 
> bulk function like _stp_print since it interprets the buffer as a C string 
> and will misinterpret my binary 0's as a string terminator.  Looking at 
> the implementation of _stp_print, it's clear that this is an easy feature 
> to add. 
> 
> Is there an existing function that I have missed or is there a simple 
> workaround?  

Yes.  _stp_reserve_bytes() reserves space in the output buffer. Then you
can memcpy into it.

	ptr = _stp_reserve_bytes(len);
	memcpy(ptr, data, len);

> If not, how fragile is it for me to clone _stp_print and then 
> replace the call to strlen with the my buffer length?

That would be equivalent but might break in the future if we change the
internals.

Martin