To: linux-kernel@vger.kernel.org
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From: Bill Davidsen <davidsen@tmr.com>
Newsgroups: mail.linux-kernel
Subject: Re: [RFC, 2.6] a simple FIFO implementation
Date: Thu, 16 Sep 2004 11:57:34 -0400
Organization: TMR Associates, Inc
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Stelian Pop wrote:
> Hi all,
> 
> Is there a reason there is no API implementing a simple in-kernel
> FIFO ? A linked list is a bit overkill...
> 
> Besides my sonypi and meye drivers which could use this, there are
> quite a few other drivers which re-implement the circular buffer
> over and over again...
> 
> An initial implementation follows below. Comments ?

Many.

- you don't need both size and len, just the length
- you don't need a count of what's in the fifo, calc from tail-head
- you don't need remaining, when the tail reaches the head
   you're out of data.
- you want to do at most two memcpy operations, the loop is just
   unproductive overhead.
- if the fifo goes empty set the head and tail back to zero so you don't
   wrap (assumes doing just two memcpy ops) when you don't need to

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me
-
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