[asterisk-dev] RFC: move struct ast_format to include/asterisk/file.h ?

[Luigi Rizzo]

On Thu, Feb 02, 2006 at 11:46:45AM -0600, Kevin P. Fleming wrote:
> Luigi Rizzo wrote:
> 
> > related - what's the purpose of AST_FRIENDLY_OFFSET that is
> > used in various places ?
> > i understand that it is some extra leading space that
> > one tries to leave empty to possibly accommodate headers etc,
> > but what is the invariant that we can use to be sure that
> > we do not move before the beginning ?
> 
> That is exactly what it is for. I don't understand your last question, 
> though.

so you have 3 data-related fields in a buffer:

	offset
	data
	datalen;

i suppose that if you move data x bytes behind, you do

	if (offset < x)
		<error, offset too large>
	else {
		offset -= x;
		data -= x;
		datalen += x;
	}

correct ?
	
btw - many of the ast_filestream fields in format_*.c have one
'empty' field between the 'waste[AST_FRIENDLY_OFFSET]'
and the actuall buffer. What is this for, just safety belt ?

cheers
luigi

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